[friendica.git] / src / Protocol / Diaspora.php

<?php
/**
 * @copyright Copyright (C) 2020, Friendica
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

namespace Friendica\Protocol;

use Friendica\Content\Feature;
use Friendica\Content\Text\BBCode;
use Friendica\Content\Text\Markdown;
use Friendica\Core\Cache\Duration;
use Friendica\Core\Logger;
use Friendica\Core\Protocol;
use Friendica\Core\System;
use Friendica\Core\Worker;
use Friendica\Database\DBA;
use Friendica\DI;
use Friendica\Model\Contact;
use Friendica\Model\Conversation;
use Friendica\Model\GContact;
use Friendica\Model\Item;
use Friendica\Model\ItemURI;
use Friendica\Model\Mail;
use Friendica\Model\Post;
use Friendica\Model\Tag;
use Friendica\Model\User;
use Friendica\Network\Probe;
use Friendica\Util\Crypto;
use Friendica\Util\DateTimeFormat;
use Friendica\Util\Map;
use Friendica\Util\Network;
use Friendica\Util\Strings;
use Friendica\Util\XML;
use Friendica\Worker\Delivery;
use SimpleXMLElement;

/**
 * This class contain functions to create and send Diaspora XML files
 */
class Diaspora
{
        /**
         * Mark the relay contact of the given contact for archival
         * This is called whenever there is a communication issue with the server.
         * It avoids sending stuff to servers who don't exist anymore.
         * The relay contact is a technical contact entry that exists once per server.
         *
         * @param array $contact of the relay contact
         */
        public static function markRelayForArchival(array $contact)
        {
                if (!empty($contact['contact-type']) && ($contact['contact-type'] == Contact::TYPE_RELAY)) {
                        // This is already the relay contact, we don't need to fetch it
                        $relay_contact = $contact;
                } elseif (empty($contact['baseurl'])) {
                        if (!empty($contact['batch'])) {
                                $condition = ['uid' => 0, 'network' => Protocol::FEDERATED, 'batch' => $contact['batch'], 'contact-type' => Contact::TYPE_RELAY];
                                $relay_contact = DBA::selectFirst('contact', [], $condition);
                        } else {
                                return;
                        }
                } else {
                        $relay_contact = self::getRelayContact($contact['baseurl'], []);
                }

                if (!empty($relay_contact)) {
                        Logger::info('Relay contact will be marked for archival', ['id' => $relay_contact['id'], 'url' => $relay_contact['url']]);
                        Contact::markForArchival($relay_contact);
                }
        }

        /**
         * Return a list of relay servers
         *
         * The list contains not only the official relays but also servers that we serve directly
         *
         * @param integer $item_id  The id of the item that is sent
         * @param array   $contacts The previously fetched contacts
         *
         * @return array of relay servers
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        public static function relayList($item_id, array $contacts = [])
        {
                $serverlist = [];

                // Fetching relay servers
                $serverdata = DI::config()->get("system", "relay_server");

                if (!empty($serverdata)) {
                        $servers = explode(",", $serverdata);
                        foreach ($servers as $server) {
                                $serverlist[$server] = trim($server);
                        }
                }

                if (DI::config()->get("system", "relay_directly", false)) {
                        // We distribute our stuff based on the parent to ensure that the thread will be complete
                        $parent = Item::selectFirst(['uri-id'], ['id' => $item_id]);
                        if (!DBA::isResult($parent)) {
                                return;
                        }

                        // Servers that want to get all content
                        $servers = DBA::select('gserver', ['url'], ['relay-subscribe' => true, 'relay-scope' => 'all']);
                        while ($server = DBA::fetch($servers)) {
                                $serverlist[$server['url']] = $server['url'];
                        }
                        DBA::close($servers);

                        // All tags of the current post
                        $tags = DBA::select('tag-view', ['name'], ['uri-id' => $parent['uri-id'], 'type' => Tag::HASHTAG]);
                        $taglist = [];
                        while ($tag = DBA::fetch($tags)) {
                                $taglist[] = $tag['name'];
                        }
                        DBA::close($tags);

                        // All servers who wants content with this tag
                        $tagserverlist = [];
                        if (!empty($taglist)) {
                                $tagserver = DBA::select('gserver-tag', ['gserver-id'], ['tag' => $taglist]);
                                while ($server = DBA::fetch($tagserver)) {
                                        $tagserverlist[] = $server['gserver-id'];
                                }
                                DBA::close($tagserver);
                        }

                        // All adresses with the given id
                        if (!empty($tagserverlist)) {
                                $servers = DBA::select('gserver', ['url'], ['relay-subscribe' => true, 'relay-scope' => 'tags', 'id' => $tagserverlist]);
                                while ($server = DBA::fetch($servers)) {
                                        $serverlist[$server['url']] = $server['url'];
                                }
                                DBA::close($servers);
                        }
                }

                // Now we are collecting all relay contacts
                foreach ($serverlist as $server_url) {
                        // We don't send messages to ourselves
                        if (Strings::compareLink($server_url, DI::baseUrl())) {
                                continue;
                        }
                        $contact = self::getRelayContact($server_url);
                        if (is_bool($contact)) {
                                continue;
                        }

                        $exists = false;
                        foreach ($contacts as $entry) {
                                if ($entry['batch'] == $contact['batch']) {
                                        $exists = true;
                                }
                        }

                        if (!$exists) {
                                $contacts[] = $contact;
                        }
                }

                return $contacts;
        }

        /**
         * Return a contact for a given server address or creates a dummy entry
         *
         * @param string $server_url The url of the server
         * @param array $fields Fieldlist
         * @return array with the contact
         * @throws \Exception
         */
        private static function getRelayContact(string $server_url, array $fields = ['batch', 'id', 'url', 'name', 'network', 'protocol', 'archive', 'blocked'])
        {
                // Fetch the relay contact
                $condition = ['uid' => 0, 'nurl' => Strings::normaliseLink($server_url),
                        'contact-type' => Contact::TYPE_RELAY];
                $contact = DBA::selectFirst('contact', $fields, $condition);

                if (DBA::isResult($contact)) {
                        if ($contact['archive'] || $contact['blocked']) {
                                return false;
                        }
                        return $contact;
                } else {
                        self::setRelayContact($server_url);

                        $contact = DBA::selectFirst('contact', $fields, $condition);
                        if (DBA::isResult($contact)) {
                                return $contact;
                        }
                }

                // It should never happen that we arrive here
                return [];
        }

        /**
         * Update or insert a relay contact
         *
         * @param string $server_url     The url of the server
         * @param array  $network_fields Optional network specific fields
         * @throws \Exception
         */
        public static function setRelayContact($server_url, array $network_fields = [])
        {
                $fields = ['created' => DateTimeFormat::utcNow(),
                        'name' => 'relay', 'nick' => 'relay', 'url' => $server_url,
                        'nurl' => Strings::normaliseLink($server_url),
                        'network' => Protocol::DIASPORA, 'uid' => 0,
                        'batch' => $server_url . '/receive/public',
                        'rel' => Contact::FOLLOWER, 'blocked' => false,
                        'pending' => false, 'writable' => true,
                        'baseurl' => $server_url, 'contact-type' => Contact::TYPE_RELAY];

                $fields = array_merge($fields, $network_fields);

                $condition = ['uid' => 0, 'nurl' => Strings::normaliseLink($server_url)];
                $old = DBA::selectFirst('contact', [], $condition);
                if (DBA::isResult($old)) {
                        unset($fields['created']);
                        $condition = ['id' => $old['id']];

                        Logger::info('Update relay contact', ['fields' => $fields, 'condition' => $condition]);
                        DBA::update('contact', $fields, $condition, $old);
                } else {
                        Logger::info('Create relay contact', ['fields' => $fields]);
                        Contact::insert($fields);
                }
        }

        /**
         * Return a list of participating contacts for a thread
         *
         * This is used for the participation feature.
         * One of the parameters is a contact array.
         * This is done to avoid duplicates.
         *
         * @param array $item     Item that is about to be delivered
         * @param array $contacts The previously fetched contacts
         *
         * @return array of relay servers
         * @throws \Exception
         */
        public static function participantsForThread(array $item, array $contacts)
        {
                if (!in_array($item['private'], [Item::PUBLIC, Item::UNLISTED]) || in_array($item["verb"], [Activity::FOLLOW, Activity::TAG])) {
                        return $contacts;
                }

                $items = Item::select(['author-id', 'author-link', 'parent-author-link', 'parent-guid'],
                        ['parent' => $item['parent'], 'gravity' => [GRAVITY_COMMENT, GRAVITY_ACTIVITY]]);
                while ($item = DBA::fetch($items)) {
                        $contact = DBA::selectFirst('contact', ['id', 'url', 'name', 'protocol', 'batch', 'network'],
                                ['id' => $item['author-id']]);
                        if (!DBA::isResult($contact) || empty($contact['batch']) ||
                                ($contact['network'] != Protocol::DIASPORA) ||
                                Strings::compareLink($item['parent-author-link'], $item['author-link'])) {
                                continue;
                        }

                        $exists = false;
                        foreach ($contacts as $entry) {
                                if ($entry['batch'] == $contact['batch']) {
                                        $exists = true;
                                }
                        }

                        if (!$exists) {
                                Logger::info('Add participant to receiver list', ['parent' => $item['parent-guid'], 'item' => $item['guid'], 'participant' => $contact['url']]);
                                $contacts[] = $contact;
                        }
                }
                DBA::close($items);

                return $contacts;
        }

        /**
         * repairs a signature that was double encoded
         *
         * The function is unused at the moment. It was copied from the old implementation.
         *
         * @param string  $signature The signature
         * @param string  $handle    The handle of the signature owner
         * @param integer $level     This value is only set inside this function to avoid endless loops
         *
         * @return string the repaired signature
         * @throws \Exception
         */
        private static function repairSignature($signature, $handle = "", $level = 1)
        {
                if ($signature == "") {
                        return ($signature);
                }

                if (base64_encode(base64_decode(base64_decode($signature))) == base64_decode($signature)) {
                        $signature = base64_decode($signature);
                        Logger::log("Repaired double encoded signature from Diaspora/Hubzilla handle ".$handle." - level ".$level, Logger::DEBUG);

                        // Do a recursive call to be able to fix even multiple levels
                        if ($level < 10) {
                                $signature = self::repairSignature($signature, $handle, ++$level);
                        }
                }

                return($signature);
        }

        /**
         * verify the envelope and return the verified data
         *
         * @param string $envelope The magic envelope
         *
         * @return string verified data
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function verifyMagicEnvelope($envelope)
        {
                $basedom = XML::parseString($envelope, true);

                if (!is_object($basedom)) {
                        Logger::log("Envelope is no XML file");
                        return false;
                }

                $children = $basedom->children('http://salmon-protocol.org/ns/magic-env');

                if (sizeof($children) == 0) {
                        Logger::log("XML has no children");
                        return false;
                }

                $handle = "";

                $data = Strings::base64UrlDecode($children->data);
                $type = $children->data->attributes()->type[0];

                $encoding = $children->encoding;

                $alg = $children->alg;

                $sig = Strings::base64UrlDecode($children->sig);
                $key_id = $children->sig->attributes()->key_id[0];
                if ($key_id != "") {
                        $handle = Strings::base64UrlDecode($key_id);
                }

                $b64url_data = Strings::base64UrlEncode($data);
                $msg = str_replace(["\n", "\r", " ", "\t"], ["", "", "", ""], $b64url_data);

                $signable_data = $msg.".".Strings::base64UrlEncode($type).".".Strings::base64UrlEncode($encoding).".".Strings::base64UrlEncode($alg);

                if ($handle == '') {
                        Logger::log('No author could be decoded. Discarding. Message: ' . $envelope);
                        return false;
                }

                $key = self::key($handle);
                if ($key == '') {
                        Logger::log("Couldn't get a key for handle " . $handle . ". Discarding.");
                        return false;
                }

                $verify = Crypto::rsaVerify($signable_data, $sig, $key);
                if (!$verify) {
                        Logger::log('Message from ' . $handle . ' did not verify. Discarding.');
                        return false;
                }

                return $data;
        }

        /**
         * encrypts data via AES
         *
         * @param string $key  The AES key
         * @param string $iv   The IV (is used for CBC encoding)
         * @param string $data The data that is to be encrypted
         *
         * @return string encrypted data
         */
        private static function aesEncrypt($key, $iv, $data)
        {
                return openssl_encrypt($data, 'aes-256-cbc', str_pad($key, 32, "\0"), OPENSSL_RAW_DATA, str_pad($iv, 16, "\0"));
        }

        /**
         * decrypts data via AES
         *
         * @param string $key       The AES key
         * @param string $iv        The IV (is used for CBC encoding)
         * @param string $encrypted The encrypted data
         *
         * @return string decrypted data
         */
        private static function aesDecrypt($key, $iv, $encrypted)
        {
                return openssl_decrypt($encrypted, 'aes-256-cbc', str_pad($key, 32, "\0"), OPENSSL_RAW_DATA, str_pad($iv, 16, "\0"));
        }

        /**
         * Decodes incoming Diaspora message in the new format
         *
         * @param string  $raw      raw post message
         * @param string  $privKey   The private key of the importer
         * @param boolean $no_exit  Don't do an http exit on error
         *
         * @return array
         * 'message' -> decoded Diaspora XML message
         * 'author' -> author diaspora handle
         * 'key' -> author public key (converted to pkcs#8)
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function decodeRaw(string $raw, string $privKey = '', bool $no_exit = false)
        {
                $data = json_decode($raw);

                // Is it a private post? Then decrypt the outer Salmon
                if (is_object($data)) {
                        $encrypted_aes_key_bundle = base64_decode($data->aes_key);
                        $ciphertext = base64_decode($data->encrypted_magic_envelope);

                        $outer_key_bundle = '';
                        @openssl_private_decrypt($encrypted_aes_key_bundle, $outer_key_bundle, $privKey);
                        $j_outer_key_bundle = json_decode($outer_key_bundle);

                        if (!is_object($j_outer_key_bundle)) {
                                Logger::log('Outer Salmon did not verify. Discarding.');
                                if ($no_exit) {
                                        return false;
                                } else {
                                        throw new \Friendica\Network\HTTPException\BadRequestException();
                                }
                        }

                        $outer_iv = base64_decode($j_outer_key_bundle->iv);
                        $outer_key = base64_decode($j_outer_key_bundle->key);

                        $xml = self::aesDecrypt($outer_key, $outer_iv, $ciphertext);
                } else {
                        $xml = $raw;
                }

                $basedom = XML::parseString($xml, true);

                if (!is_object($basedom)) {
                        Logger::log('Received data does not seem to be an XML. Discarding. '.$xml);
                        if ($no_exit) {
                                return false;
                        } else {
                                throw new \Friendica\Network\HTTPException\BadRequestException();
                        }
                }

                $base = $basedom->children(ActivityNamespace::SALMON_ME);

                // Not sure if this cleaning is needed
                $data = str_replace([" ", "\t", "\r", "\n"], ["", "", "", ""], $base->data);

                // Build the signed data
                $type = $base->data[0]->attributes()->type[0];
                $encoding = $base->encoding;
                $alg = $base->alg;
                $signed_data = $data.'.'.Strings::base64UrlEncode($type).'.'.Strings::base64UrlEncode($encoding).'.'.Strings::base64UrlEncode($alg);

                // This is the signature
                $signature = Strings::base64UrlDecode($base->sig);

                // Get the senders' public key
                $key_id = $base->sig[0]->attributes()->key_id[0];
                $author_addr = base64_decode($key_id);
                if ($author_addr == '') {
                        Logger::log('No author could be decoded. Discarding. Message: ' . $xml);
                        if ($no_exit) {
                                return false;
                        } else {
                                throw new \Friendica\Network\HTTPException\BadRequestException();
                        }
                }

                $key = self::key($author_addr);
                if ($key == '') {
                        Logger::log("Couldn't get a key for handle " . $author_addr . ". Discarding.");
                        if ($no_exit) {
                                return false;
                        } else {
                                throw new \Friendica\Network\HTTPException\BadRequestException();
                        }
                }

                $verify = Crypto::rsaVerify($signed_data, $signature, $key);
                if (!$verify) {
                        Logger::log('Message did not verify. Discarding.');
                        if ($no_exit) {
                                return false;
                        } else {
                                throw new \Friendica\Network\HTTPException\BadRequestException();
                        }
                }

                return ['message' => (string)Strings::base64UrlDecode($base->data),
                                'author' => XML::unescape($author_addr),
                                'key' => (string)$key];
        }

        /**
         * Decodes incoming Diaspora message in the deprecated format
         *
         * @param string $xml      urldecoded Diaspora salmon
         * @param string $privKey  The private key of the importer
         *
         * @return array
         * 'message' -> decoded Diaspora XML message
         * 'author' -> author diaspora handle
         * 'key' -> author public key (converted to pkcs#8)
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function decode(string $xml, string $privKey = '')
        {
                $public = false;
                $basedom = XML::parseString($xml);

                if (!is_object($basedom)) {
                        Logger::log("XML is not parseable.");
                        return false;
                }
                $children = $basedom->children('https://joindiaspora.com/protocol');

                $inner_aes_key = null;
                $inner_iv = null;

                if ($children->header) {
                        $public = true;
                        $author_link = str_replace('acct:', '', $children->header->author_id);
                } else {
                        // This happens with posts from a relais
                        if (empty($privKey)) {
                                Logger::log("This is no private post in the old format", Logger::DEBUG);
                                return false;
                        }

                        $encrypted_header = json_decode(base64_decode($children->encrypted_header));

                        $encrypted_aes_key_bundle = base64_decode($encrypted_header->aes_key);
                        $ciphertext = base64_decode($encrypted_header->ciphertext);

                        $outer_key_bundle = '';
                        openssl_private_decrypt($encrypted_aes_key_bundle, $outer_key_bundle, $privKey);

                        $j_outer_key_bundle = json_decode($outer_key_bundle);

                        $outer_iv = base64_decode($j_outer_key_bundle->iv);
                        $outer_key = base64_decode($j_outer_key_bundle->key);

                        $decrypted = self::aesDecrypt($outer_key, $outer_iv, $ciphertext);

                        Logger::log('decrypted: '.$decrypted, Logger::DEBUG);
                        $idom = XML::parseString($decrypted);

                        $inner_iv = base64_decode($idom->iv);
                        $inner_aes_key = base64_decode($idom->aes_key);

                        $author_link = str_replace('acct:', '', $idom->author_id);
                }

                $dom = $basedom->children(ActivityNamespace::SALMON_ME);

                // figure out where in the DOM tree our data is hiding

                $base = null;
                if ($dom->provenance->data) {
                        $base = $dom->provenance;
                } elseif ($dom->env->data) {
                        $base = $dom->env;
                } elseif ($dom->data) {
                        $base = $dom;
                }

                if (!$base) {
                        Logger::log('unable to locate salmon data in xml');
                        throw new \Friendica\Network\HTTPException\BadRequestException();
                }


                // Stash the signature away for now. We have to find their key or it won't be good for anything.
                $signature = Strings::base64UrlDecode($base->sig);

                // unpack the  data

                // strip whitespace so our data element will return to one big base64 blob
                $data = str_replace([" ", "\t", "\r", "\n"], ["", "", "", ""], $base->data);


                // stash away some other stuff for later

                $type = $base->data[0]->attributes()->type[0];
                $keyhash = $base->sig[0]->attributes()->keyhash[0];
                $encoding = $base->encoding;
                $alg = $base->alg;


                $signed_data = $data.'.'.Strings::base64UrlEncode($type).'.'.Strings::base64UrlEncode($encoding).'.'.Strings::base64UrlEncode($alg);


                // decode the data
                $data = Strings::base64UrlDecode($data);


                if ($public) {
                        $inner_decrypted = $data;
                } else {
                        // Decode the encrypted blob
                        $inner_encrypted = base64_decode($data);
                        $inner_decrypted = self::aesDecrypt($inner_aes_key, $inner_iv, $inner_encrypted);
                }

                if (!$author_link) {
                        Logger::log('Could not retrieve author URI.');
                        throw new \Friendica\Network\HTTPException\BadRequestException();
                }
                // Once we have the author URI, go to the web and try to find their public key
                // (first this will look it up locally if it is in the fcontact cache)
                // This will also convert diaspora public key from pkcs#1 to pkcs#8

                Logger::log('Fetching key for '.$author_link);
                $key = self::key($author_link);

                if (!$key) {
                        Logger::log('Could not retrieve author key.');
                        throw new \Friendica\Network\HTTPException\BadRequestException();
                }

                $verify = Crypto::rsaVerify($signed_data, $signature, $key);

                if (!$verify) {
                        Logger::log('Message did not verify. Discarding.');
                        throw new \Friendica\Network\HTTPException\BadRequestException();
                }

                Logger::log('Message verified.');

                return ['message' => (string)$inner_decrypted,
                                'author' => XML::unescape($author_link),
                                'key' => (string)$key];
        }


        /**
         * Dispatches public messages and find the fitting receivers
         *
         * @param array $msg The post that will be dispatched
         *
         * @return int The message id of the generated message, "true" or "false" if there was an error
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function dispatchPublic($msg)
        {
                $enabled = intval(DI::config()->get("system", "diaspora_enabled"));
                if (!$enabled) {
                        Logger::log("diaspora is disabled");
                        return false;
                }

                if (!($fields = self::validPosting($msg))) {
                        Logger::log("Invalid posting");
                        return false;
                }

                $importer = ["uid" => 0, "page-flags" => User::PAGE_FLAGS_FREELOVE];
                $success = self::dispatch($importer, $msg, $fields);

                return $success;
        }

        /**
         * Dispatches the different message types to the different functions
         *
         * @param array            $importer Array of the importer user
         * @param array            $msg      The post that will be dispatched
         * @param SimpleXMLElement $fields   SimpleXML object that contains the message
         *
         * @return int The message id of the generated message, "true" or "false" if there was an error
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function dispatch(array $importer, $msg, SimpleXMLElement $fields = null)
        {
                // The sender is the handle of the contact that sent the message.
                // This will often be different with relayed messages (for example "like" and "comment")
                $sender = $msg["author"];

                // This is only needed for private postings since this is already done for public ones before
                if (is_null($fields)) {
                        $private = true;
                        if (!($fields = self::validPosting($msg))) {
                                Logger::log("Invalid posting");
                                return false;
                        }
                } else {
                        $private = false;
                }

                $type = $fields->getName();

                Logger::log("Received message type ".$type." from ".$sender." for user ".$importer["uid"], Logger::DEBUG);

                switch ($type) {
                        case "account_migration":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveAccountMigration($importer, $fields);

                        case "account_deletion":
                                return self::receiveAccountDeletion($fields);

                        case "comment":
                                return self::receiveComment($importer, $sender, $fields, $msg["message"]);

                        case "contact":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveContactRequest($importer, $fields);

                        case "conversation":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveConversation($importer, $msg, $fields);

                        case "like":
                                return self::receiveLike($importer, $sender, $fields);

                        case "message":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveMessage($importer, $fields);

                        case "participation":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveParticipation($importer, $fields);

                        case "photo": // Not implemented
                                return self::receivePhoto($importer, $fields);

                        case "poll_participation": // Not implemented
                                return self::receivePollParticipation($importer, $fields);

                        case "profile":
                                if (!$private) {
                                        Logger::log('Message with type ' . $type . ' is not private, quitting.');
                                        return false;
                                }
                                return self::receiveProfile($importer, $fields);

                        case "reshare":
                                return self::receiveReshare($importer, $fields, $msg["message"]);

                        case "retraction":
                                return self::receiveRetraction($importer, $sender, $fields);

                        case "status_message":
                                return self::receiveStatusMessage($importer, $fields, $msg["message"]);

                        default:
                                Logger::log("Unknown message type ".$type);
                                return false;
                }
        }

        /**
         * Checks if a posting is valid and fetches the data fields.
         *
         * This function does not only check the signature.
         * It also does the conversion between the old and the new diaspora format.
         *
         * @param array $msg Array with the XML, the sender handle and the sender signature
         *
         * @return bool|SimpleXMLElement If the posting is valid then an array with an SimpleXML object is returned
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function validPosting($msg)
        {
                $data = XML::parseString($msg["message"]);

                if (!is_object($data)) {
                        Logger::log("No valid XML ".$msg["message"], Logger::DEBUG);
                        return false;
                }

                // Is this the new or the old version?
                if ($data->getName() == "XML") {
                        $oldXML = true;
                        foreach ($data->post->children() as $child) {
                                $element = $child;
                        }
                } else {
                        $oldXML = false;
                        $element = $data;
                }

                $type = $element->getName();
                $orig_type = $type;

                Logger::log("Got message type ".$type.": ".$msg["message"], Logger::DATA);

                // All retractions are handled identically from now on.
                // In the new version there will only be "retraction".
                if (in_array($type, ["signed_retraction", "relayable_retraction"]))
                        $type = "retraction";

                if ($type == "request") {
                        $type = "contact";
                }

                $fields = new SimpleXMLElement("<".$type."/>");

                $signed_data = "";
                $author_signature = null;
                $parent_author_signature = null;

                foreach ($element->children() as $fieldname => $entry) {
                        if ($oldXML) {
                                // Translation for the old XML structure
                                if ($fieldname == "diaspora_handle") {
                                        $fieldname = "author";
                                }
                                if ($fieldname == "participant_handles") {
                                        $fieldname = "participants";
                                }
                                if (in_array($type, ["like", "participation"])) {
                                        if ($fieldname == "target_type") {
                                                $fieldname = "parent_type";
                                        }
                                }
                                if ($fieldname == "sender_handle") {
                                        $fieldname = "author";
                                }
                                if ($fieldname == "recipient_handle") {
                                        $fieldname = "recipient";
                                }
                                if ($fieldname == "root_diaspora_id") {
                                        $fieldname = "root_author";
                                }
                                if ($type == "status_message") {
                                        if ($fieldname == "raw_message") {
                                                $fieldname = "text";
                                        }
                                }
                                if ($type == "retraction") {
                                        if ($fieldname == "post_guid") {
                                                $fieldname = "target_guid";
                                        }
                                        if ($fieldname == "type") {
                                                $fieldname = "target_type";
                                        }
                                }
                        }

                        if (($fieldname == "author_signature") && ($entry != "")) {
                                $author_signature = base64_decode($entry);
                        } elseif (($fieldname == "parent_author_signature") && ($entry != "")) {
                                $parent_author_signature = base64_decode($entry);
                        } elseif (!in_array($fieldname, ["author_signature", "parent_author_signature", "target_author_signature"])) {
                                if ($signed_data != "") {
                                        $signed_data .= ";";
                                }

                                $signed_data .= $entry;
                        }
                        if (!in_array($fieldname, ["parent_author_signature", "target_author_signature"])
                                || ($orig_type == "relayable_retraction")
                        ) {
                                XML::copy($entry, $fields, $fieldname);
                        }
                }

                // This is something that shouldn't happen at all.
                if (in_array($type, ["status_message", "reshare", "profile"])) {
                        if ($msg["author"] != $fields->author) {
                                Logger::log("Message handle is not the same as envelope sender. Quitting this message.");
                                return false;
                        }
                }

                // Only some message types have signatures. So we quit here for the other types.
                if (!in_array($type, ["comment", "like"])) {
                        return $fields;
                }
                // No author_signature? This is a must, so we quit.
                if (!isset($author_signature)) {
                        Logger::log("No author signature for type ".$type." - Message: ".$msg["message"], Logger::DEBUG);
                        return false;
                }

                if (isset($parent_author_signature)) {
                        $key = self::key($msg["author"]);
                        if (empty($key)) {
                                Logger::log("No key found for parent author ".$msg["author"], Logger::DEBUG);
                                return false;
                        }

                        if (!Crypto::rsaVerify($signed_data, $parent_author_signature, $key, "sha256")) {
                                Logger::log("No valid parent author signature for parent author ".$msg["author"]. " in type ".$type." - signed data: ".$signed_data." - Message: ".$msg["message"]." - Signature ".$parent_author_signature, Logger::DEBUG);
                                return false;
                        }
                }

                $key = self::key($fields->author);
                if (empty($key)) {
                        Logger::log("No key found for author ".$fields->author, Logger::DEBUG);
                        return false;
                }

                if (!Crypto::rsaVerify($signed_data, $author_signature, $key, "sha256")) {
                        Logger::log("No valid author signature for author ".$fields->author. " in type ".$type." - signed data: ".$signed_data." - Message: ".$msg["message"]." - Signature ".$author_signature, Logger::DEBUG);
                        return false;
                } else {
                        return $fields;
                }
        }

        /**
         * Fetches the public key for a given handle
         *
         * @param string $handle The handle
         *
         * @return string The public key
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function key($handle)
        {
                $handle = strval($handle);

                Logger::log("Fetching diaspora key for: ".$handle);

                $r = self::personByHandle($handle);
                if ($r) {
                        return $r["pubkey"];
                }

                return "";
        }

        /**
         * Fetches data for a given handle
         *
         * @param string $handle The handle
         * @param boolean $update true = always update, false = never update, null = update when not found or outdated
         *
         * @return array the queried data
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function personByHandle($handle, $update = null)
        {
                $person = DBA::selectFirst('fcontact', [], ['network' => Protocol::DIASPORA, 'addr' => $handle]);
                if (!DBA::isResult($person)) {
                        $urls = [$handle, str_replace('http://', 'https://', $handle), Strings::normaliseLink($handle)];
                        $person = DBA::selectFirst('fcontact', [], ['network' => Protocol::DIASPORA, 'url' => $urls]);
                }

                if (DBA::isResult($person)) {
                        Logger::debug("In cache " . print_r($person, true));

                        if (is_null($update)) {
                                // update record occasionally so it doesn't get stale
                                $d = strtotime($person["updated"]." +00:00");
                                if ($d < strtotime("now - 14 days")) {
                                        $update = true;
                                }

                                if ($person["guid"] == "") {
                                        $update = true;
                                }
                        }
                } elseif (is_null($update)) {
                        $update = !DBA::isResult($person);
                } else {
                        $person = [];
                }

                if ($update) {
                        Logger::log("create or refresh", Logger::DEBUG);
                        $r = Probe::uri($handle, Protocol::DIASPORA);

                        // Note that Friendica contacts will return a "Diaspora person"
                        // if Diaspora connectivity is enabled on their server
                        if ($r && ($r["network"] === Protocol::DIASPORA)) {
                                self::updateFContact($r);

                                $person = self::personByHandle($handle, false);
                        }
                }

                return $person;
        }

        /**
         * Updates the fcontact table
         *
         * @param array $arr The fcontact data
         * @throws \Exception
         */
        private static function updateFContact($arr)
        {
                $fields = ['name' => $arr["name"], 'photo' => $arr["photo"],
                        'request' => $arr["request"], 'nick' => $arr["nick"],
                        'addr' => strtolower($arr["addr"]), 'guid' => $arr["guid"],
                        'batch' => $arr["batch"], 'notify' => $arr["notify"],
                        'poll' => $arr["poll"], 'confirm' => $arr["confirm"],
                        'alias' => $arr["alias"], 'pubkey' => $arr["pubkey"],
                        'updated' => DateTimeFormat::utcNow()];

                $condition = ['url' => $arr["url"], 'network' => $arr["network"]];

                DBA::update('fcontact', $fields, $condition, true);
        }

        /**
         * get a handle (user@domain.tld) from a given contact id
         *
         * @param int $contact_id  The id in the contact table
         * @param int $pcontact_id The id in the contact table (Used for the public contact)
         *
         * @return string the handle
         * @throws \Exception
         */
        private static function handleFromContact($contact_id, $pcontact_id = 0)
        {
                $handle = false;

                Logger::log("contact id is ".$contact_id." - pcontact id is ".$pcontact_id, Logger::DEBUG);

                if ($pcontact_id != 0) {
                        $contact = DBA::selectFirst('contact', ['addr'], ['id' => $pcontact_id]);

                        if (DBA::isResult($contact) && !empty($contact["addr"])) {
                                return strtolower($contact["addr"]);
                        }
                }

                $r = q(
                        "SELECT `network`, `addr`, `self`, `url`, `nick` FROM `contact` WHERE `id` = %d",
                        intval($contact_id)
                );

                if (DBA::isResult($r)) {
                        $contact = $r[0];

                        Logger::log("contact 'self' = ".$contact['self']." 'url' = ".$contact['url'], Logger::DEBUG);

                        if ($contact['addr'] != "") {
                                $handle = $contact['addr'];
                        } else {
                                $baseurl_start = strpos($contact['url'], '://') + 3;
                                // allows installations in a subdirectory--not sure how Diaspora will handle
                                $baseurl_length = strpos($contact['url'], '/profile') - $baseurl_start;
                                $baseurl = substr($contact['url'], $baseurl_start, $baseurl_length);
                                $handle = $contact['nick'].'@'.$baseurl;
                        }
                }

                return strtolower($handle);
        }

        /**
         * get a url (scheme://domain.tld/u/user) from a given Diaspora*
         * fcontact guid
         *
         * @param mixed $fcontact_guid Hexadecimal string guid
         *
         * @return string the contact url or null
         * @throws \Exception
         */
        public static function urlFromContactGuid($fcontact_guid)
        {
                Logger::log("fcontact guid is ".$fcontact_guid, Logger::DEBUG);

                $r = q(
                        "SELECT `url` FROM `fcontact` WHERE `url` != '' AND `network` = '%s' AND `guid` = '%s'",
                        DBA::escape(Protocol::DIASPORA),
                        DBA::escape($fcontact_guid)
                );

                if (DBA::isResult($r)) {
                        return $r[0]['url'];
                }

                return null;
        }

        /**
         * Get a contact id for a given handle
         *
         * @todo  Move to Friendica\Model\Contact
         *
         * @param int    $uid    The user id
         * @param string $handle The handle in the format user@domain.tld
         *
         * @return array Contact data
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function contactByHandle($uid, $handle)
        {
                $cid = Contact::getIdForURL($handle, $uid);
                if (!$cid) {
                        Logger::log("Haven't found a contact for user " . $uid . " and handle " . $handle, Logger::DEBUG);
                        return false;
                }

                $contact = DBA::selectFirst('contact', [], ['id' => $cid]);
                if (!DBA::isResult($contact)) {
                        // This here shouldn't happen at all
                        Logger::log("Haven't found a contact for user " . $uid . " and handle " . $handle, Logger::DEBUG);
                        return false;
                }

                return $contact;
        }

        /**
         * Checks if the given contact url does support ActivityPub
         *
         * @param string  $url    profile url
         * @param boolean $update true = always update, false = never update, null = update when not found or outdated
         * @return boolean
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function isSupportedByContactUrl($url, $update = null)
        {
                return !empty(self::personByHandle($url, $update));
        }

        /**
         * Check if posting is allowed for this contact
         *
         * @param array $importer   Array of the importer user
         * @param array $contact    The contact that is checked
         * @param bool  $is_comment Is the check for a comment?
         *
         * @return bool is the contact allowed to post?
         */
        private static function postAllow(array $importer, array $contact, $is_comment = false)
        {
                /*
                 * Perhaps we were already sharing with this person. Now they're sharing with us.
                 * That makes us friends.
                 * Normally this should have handled by getting a request - but this could get lost
                 */
                // It is deactivated by now, due to side effects. See issue https://github.com/friendica/friendica/pull/4033
                // It is not removed by now. Possibly the code is needed?
                //if (!$is_comment && $contact["rel"] == Contact::FOLLOWER && in_array($importer["page-flags"], array(User::PAGE_FLAGS_FREELOVE))) {
                //      DBA::update(
                //              'contact',
                //              array('rel' => Contact::FRIEND, 'writable' => true),
                //              array('id' => $contact["id"], 'uid' => $contact["uid"])
                //      );
                //
                //      $contact["rel"] = Contact::FRIEND;
                //      Logger::log("defining user ".$contact["nick"]." as friend");
                //}

                // Contact server is blocked
                if (Network::isUrlBlocked($contact['url'])) {
                        return false;
                        // We don't seem to like that person
                } elseif ($contact["blocked"]) {
                        // Maybe blocked, don't accept.
                        return false;
                        // We are following this person?
                } elseif (($contact["rel"] == Contact::SHARING) || ($contact["rel"] == Contact::FRIEND)) {
                        // Yes, then it is fine.
                        return true;
                        // Is it a post to a community?
                } elseif (($contact["rel"] == Contact::FOLLOWER) && in_array($importer["page-flags"], [User::PAGE_FLAGS_COMMUNITY, User::PAGE_FLAGS_PRVGROUP])) {
                        // That's good
                        return true;
                        // Is the message a global user or a comment?
                } elseif (($importer["uid"] == 0) || $is_comment) {
                        // Messages for the global users and comments are always accepted
                        return true;
                }

                return false;
        }

        /**
         * Fetches the contact id for a handle and checks if posting is allowed
         *
         * @param array  $importer   Array of the importer user
         * @param string $handle     The checked handle in the format user@domain.tld
         * @param bool   $is_comment Is the check for a comment?
         *
         * @return array The contact data
         * @throws \Exception
         */
        private static function allowedContactByHandle(array $importer, $handle, $is_comment = false)
        {
                $contact = self::contactByHandle($importer["uid"], $handle);
                if (!$contact) {
                        Logger::log("A Contact for handle ".$handle." and user ".$importer["uid"]." was not found");
                        // If a contact isn't found, we accept it anyway if it is a comment
                        if ($is_comment && ($importer["uid"] != 0)) {
                                return self::contactByHandle(0, $handle);
                        } elseif ($is_comment) {
                                return $importer;
                        } else {
                                return false;
                        }
                }

                if (!self::postAllow($importer, $contact, $is_comment)) {
                        Logger::log("The handle: ".$handle." is not allowed to post to user ".$importer["uid"]);
                        return false;
                }
                return $contact;
        }

        /**
         * Does the message already exists on the system?
         *
         * @param int    $uid  The user id
         * @param string $guid The guid of the message
         *
         * @return int|bool message id if the message already was stored into the system - or false.
         * @throws \Exception
         */
        private static function messageExists($uid, $guid)
        {
                $item = Item::selectFirst(['id'], ['uid' => $uid, 'guid' => $guid]);
                if (DBA::isResult($item)) {
                        Logger::log("message ".$guid." already exists for user ".$uid);
                        return $item["id"];
                }

                return false;
        }

        /**
         * Checks for links to posts in a message
         *
         * @param array $item The item array
         * @return void
         */
        private static function fetchGuid(array $item)
        {
                $expression = "=diaspora://.*?/post/([0-9A-Za-z\-_@.:]{15,254}[0-9A-Za-z])=ism";
                preg_replace_callback(
                        $expression,
                        function ($match) use ($item) {
                                self::fetchGuidSub($match, $item);
                        },
                        $item["body"]
                );

                preg_replace_callback(
                        "&\[url=/?posts/([^\[\]]*)\](.*)\[\/url\]&Usi",
                        function ($match) use ($item) {
                                self::fetchGuidSub($match, $item);
                        },
                        $item["body"]
                );
        }

        /**
         * Checks for relative /people/* links in an item body to match local
         * contacts or prepends the remote host taken from the author link.
         *
         * @param string $body        The item body to replace links from
         * @param string $author_link The author link for missing local contact fallback
         *
         * @return string the replaced string
         */
        public static function replacePeopleGuid($body, $author_link)
        {
                $return = preg_replace_callback(
                        "&\[url=/people/([^\[\]]*)\](.*)\[\/url\]&Usi",
                        function ($match) use ($author_link) {
                                // $match
                                // 0 => '[url=/people/0123456789abcdef]Foo Bar[/url]'
                                // 1 => '0123456789abcdef'
                                // 2 => 'Foo Bar'
                                $handle = self::urlFromContactGuid($match[1]);

                                if ($handle) {
                                        $return = '@[url='.$handle.']'.$match[2].'[/url]';
                                } else {
                                        // No local match, restoring absolute remote URL from author scheme and host
                                        $author_url = parse_url($author_link);
                                        $return = '[url='.$author_url['scheme'].'://'.$author_url['host'].'/people/'.$match[1].']'.$match[2].'[/url]';
                                }

                                return $return;
                        },
                        $body
                );

                return $return;
        }

        /**
         * sub function of "fetchGuid" which checks for links in messages
         *
         * @param array $match array containing a link that has to be checked for a message link
         * @param array $item  The item array
         * @return void
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function fetchGuidSub($match, $item)
        {
                if (!self::storeByGuid($match[1], $item["author-link"])) {
                        self::storeByGuid($match[1], $item["owner-link"]);
                }
        }

        /**
         * Fetches an item with a given guid from a given server
         *
         * @param string $guid   the message guid
         * @param string $server The server address
         * @param int    $uid    The user id of the user
         *
         * @return int the message id of the stored message or false
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function storeByGuid($guid, $server, $uid = 0)
        {
                $serverparts = parse_url($server);

                if (empty($serverparts["host"]) || empty($serverparts["scheme"])) {
                        return false;
                }

                $server = $serverparts["scheme"]."://".$serverparts["host"];

                Logger::log("Trying to fetch item ".$guid." from ".$server, Logger::DEBUG);

                $msg = self::message($guid, $server);

                if (!$msg) {
                        return false;
                }

                Logger::log("Successfully fetched item ".$guid." from ".$server, Logger::DEBUG);

                // Now call the dispatcher
                return self::dispatchPublic($msg);
        }

        /**
         * Fetches a message from a server
         *
         * @param string $guid   message guid
         * @param string $server The url of the server
         * @param int    $level  Endless loop prevention
         *
         * @return array
         *      'message' => The message XML
         *      'author' => The author handle
         *      'key' => The public key of the author
         * @throws \Exception
         */
        private static function message($guid, $server, $level = 0)
        {
                if ($level > 5) {
                        return false;
                }

                // This will work for new Diaspora servers and Friendica servers from 3.5
                $source_url = $server."/fetch/post/".urlencode($guid);

                Logger::log("Fetch post from ".$source_url, Logger::DEBUG);

                $envelope = Network::fetchUrl($source_url);
                if ($envelope) {
                        Logger::log("Envelope was fetched.", Logger::DEBUG);
                        $x = self::verifyMagicEnvelope($envelope);
                        if (!$x) {
                                Logger::log("Envelope could not be verified.", Logger::DEBUG);
                        } else {
                                Logger::log("Envelope was verified.", Logger::DEBUG);
                        }
                } else {
                        $x = false;
                }

                if (!$x) {
                        return false;
                }

                $source_xml = XML::parseString($x);

                if (!is_object($source_xml)) {
                        return false;
                }

                if ($source_xml->post->reshare) {
                        // Reshare of a reshare - old Diaspora version
                        Logger::log("Message is a reshare", Logger::DEBUG);
                        return self::message($source_xml->post->reshare->root_guid, $server, ++$level);
                } elseif ($source_xml->getName() == "reshare") {
                        // Reshare of a reshare - new Diaspora version
                        Logger::log("Message is a new reshare", Logger::DEBUG);
                        return self::message($source_xml->root_guid, $server, ++$level);
                }

                $author = "";

                // Fetch the author - for the old and the new Diaspora version
                if ($source_xml->post->status_message && $source_xml->post->status_message->diaspora_handle) {
                        $author = (string)$source_xml->post->status_message->diaspora_handle;
                } elseif ($source_xml->author && ($source_xml->getName() == "status_message")) {
                        $author = (string)$source_xml->author;
                }

                // If this isn't a "status_message" then quit
                if (!$author) {
                        Logger::log("Message doesn't seem to be a status message", Logger::DEBUG);
                        return false;
                }

                $msg = ["message" => $x, "author" => $author];

                $msg["key"] = self::key($msg["author"]);

                return $msg;
        }

        /**
         * Fetches an item with a given URL
         *
         * @param string $url the message url
         *
         * @return int the message id of the stored message or false
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function fetchByURL($url, $uid = 0)
        {
                // Check for Diaspora (and Friendica) typical paths
                if (!preg_match("=(https?://.+)/(?:posts|display|objects)/([a-zA-Z0-9-_@.:%]+[a-zA-Z0-9])=i", $url, $matches)) {
                        Logger::info('Invalid url', ['url' => $url]);
                        return false;
                }

                $guid = urldecode($matches[2]);

                $item = Item::selectFirst(['id'], ['guid' => $guid, 'uid' => $uid]);
                if (DBA::isResult($item)) {
                        Logger::info('Found', ['id' => $item['id']]);
                        return $item['id'];
                }

                Logger::info('Fetch GUID from origin', ['guid' => $guid, 'server' => $matches[1]]);
                $ret = self::storeByGuid($guid, $matches[1], $uid);
                Logger::info('Result', ['ret' => $ret]);

                $item = Item::selectFirst(['id'], ['guid' => $guid, 'uid' => $uid]);
                if (DBA::isResult($item)) {
                        Logger::info('Found', ['id' => $item['id']]);
                        return $item['id'];
                } else {
                        Logger::info('Not found', ['guid' => $guid, 'uid' => $uid]);
                        return false;
                }
        }

        /**
         * Fetches the item record of a given guid
         *
         * @param int    $uid     The user id
         * @param string $guid    message guid
         * @param string $author  The handle of the item
         * @param array  $contact The contact of the item owner
         *
         * @return array the item record
         * @throws \Exception
         */
        private static function parentItem($uid, $guid, $author, array $contact)
        {
                $fields = ['id', 'parent', 'body', 'wall', 'uri', 'guid', 'private', 'origin',
                        'author-name', 'author-link', 'author-avatar',
                        'owner-name', 'owner-link', 'owner-avatar'];
                $condition = ['uid' => $uid, 'guid' => $guid];
                $item = Item::selectFirst($fields, $condition);

                if (!DBA::isResult($item)) {
                        $person = self::personByHandle($author);
                        $result = self::storeByGuid($guid, $person["url"], $uid);

                        // We don't have an url for items that arrived at the public dispatcher
                        if (!$result && !empty($contact["url"])) {
                                $result = self::storeByGuid($guid, $contact["url"], $uid);
                        }

                        if ($result) {
                                Logger::log("Fetched missing item ".$guid." - result: ".$result, Logger::DEBUG);

                                $item = Item::selectFirst($fields, $condition);
                        }
                }

                if (!DBA::isResult($item)) {
                        Logger::log("parent item not found: parent: ".$guid." - user: ".$uid);
                        return false;
                } else {
                        Logger::log("parent item found: parent: ".$guid." - user: ".$uid);
                        return $item;
                }
        }

        /**
         * returns contact details
         *
         * @param array $def_contact The default contact if the person isn't found
         * @param array $person      The record of the person
         * @param int   $uid         The user id
         *
         * @return array
         *      'cid' => contact id
         *      'network' => network type
         * @throws \Exception
         */
        private static function authorContactByUrl($def_contact, $person, $uid)
        {
                $condition = ['nurl' => Strings::normaliseLink($person["url"]), 'uid' => $uid];
                $contact = DBA::selectFirst('contact', ['id', 'network'], $condition);
                if (DBA::isResult($contact)) {
                        $cid = $contact["id"];
                        $network = $contact["network"];
                } else {
                        $cid = $def_contact["id"];
                        $network = Protocol::DIASPORA;
                }

                return ["cid" => $cid, "network" => $network];
        }

        /**
         * Is the profile a hubzilla profile?
         *
         * @param string $url The profile link
         *
         * @return bool is it a hubzilla server?
         */
        private static function isHubzilla($url)
        {
                return(strstr($url, '/channel/'));
        }

        /**
         * Generate a post link with a given handle and message guid
         *
         * @param string $addr        The user handle
         * @param string $guid        message guid
         * @param string $parent_guid optional parent guid
         *
         * @return string the post link
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function plink($addr, $guid, $parent_guid = '')
        {
                $contact = Contact::getDetailsByAddr($addr);
                if (empty($contact)) {
                        Logger::info('No contact data for address', ['addr' => $addr]);
                        return '';
                }

                if (empty($contact['baseurl'])) {
                        $contact['baseurl'] = 'https://' . substr($addr, strpos($addr, '@') + 1);
                        Logger::info('Create baseurl from address', ['baseurl' => $contact['baseurl'], 'url' => $contact['url']]);
                }

                $platform = '';
                $gserver = DBA::selectFirst('gserver', ['platform'], ['nurl' => Strings::normaliseLink($contact['baseurl'])]);
                if (!empty($gserver['platform'])) {
                        $platform = strtolower($gserver['platform']);
                        Logger::info('Detected platform', ['platform' => $platform, 'url' => $contact['url']]);
                }

                if (!in_array($platform, ['diaspora', 'friendica', 'hubzilla', 'socialhome'])) {
                        if (self::isHubzilla($contact['url'])) {
                                Logger::info('Detected unknown platform as Hubzilla', ['platform' => $platform, 'url' => $contact['url']]);
                                $platform = 'hubzilla';
                        } elseif ($contact['network'] == Protocol::DFRN) {
                                Logger::info('Detected unknown platform as Friendica', ['platform' => $platform, 'url' => $contact['url']]);
                                $platform = 'friendica';
                        }
                }

                if ($platform == 'friendica') {
                        return str_replace('/profile/' . $contact['nick'] . '/', '/display/' . $guid, $contact['url'] . '/');
                }

                if ($platform == 'hubzilla') {
                        return $contact['baseurl'] . '/item/' . $guid;
                }

                if ($platform == 'socialhome') {
                        return $contact['baseurl'] . '/content/' . $guid;
                }

                if ($platform != 'diaspora') {
                        Logger::info('Unknown platform', ['platform' => $platform, 'url' => $contact['url']]);
                        return '';
                }

                if ($parent_guid != '') {
                        return $contact['baseurl'] . '/posts/' . $parent_guid . '#' . $guid;
                } else {
                        return $contact['baseurl'] . '/posts/' . $guid;
                }
        }

        /**
         * Receives account migration
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool Success
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveAccountMigration(array $importer, $data)
        {
                $old_handle = Strings::escapeTags(XML::unescape($data->author));
                $new_handle = Strings::escapeTags(XML::unescape($data->profile->author));
                $signature = Strings::escapeTags(XML::unescape($data->signature));

                $contact = self::contactByHandle($importer["uid"], $old_handle);
                if (!$contact) {
                        Logger::log("cannot find contact for sender: ".$old_handle." and user ".$importer["uid"]);
                        return false;
                }

                Logger::log("Got migration for ".$old_handle.", to ".$new_handle." with user ".$importer["uid"]);

                // Check signature
                $signed_text = 'AccountMigration:'.$old_handle.':'.$new_handle;
                $key = self::key($old_handle);
                if (!Crypto::rsaVerify($signed_text, $signature, $key, "sha256")) {
                        Logger::log('No valid signature for migration.');
                        return false;
                }

                // Update the profile
                self::receiveProfile($importer, $data->profile);

                // change the technical stuff in contact and gcontact
                $data = Probe::uri($new_handle);
                if ($data['network'] == Protocol::PHANTOM) {
                        Logger::log('Account for '.$new_handle." couldn't be probed.");
                        return false;
                }

                $fields = ['url' => $data['url'], 'nurl' => Strings::normaliseLink($data['url']),
                                'name' => $data['name'], 'nick' => $data['nick'],
                                'addr' => $data['addr'], 'batch' => $data['batch'],
                                'notify' => $data['notify'], 'poll' => $data['poll'],
                                'network' => $data['network']];

                DBA::update('contact', $fields, ['addr' => $old_handle]);

                $fields = ['url' => $data['url'], 'nurl' => Strings::normaliseLink($data['url']),
                                'name' => $data['name'], 'nick' => $data['nick'],
                                'addr' => $data['addr'], 'connect' => $data['addr'],
                                'notify' => $data['notify'], 'photo' => $data['photo'],
                                'server_url' => $data['baseurl'], 'network' => $data['network']];

                DBA::update('gcontact', $fields, ['addr' => $old_handle]);

                Logger::log('Contacts are updated.');

                return true;
        }

        /**
         * Processes an account deletion
         *
         * @param object $data The message object
         *
         * @return bool Success
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function receiveAccountDeletion($data)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));

                $contacts = DBA::select('contact', ['id'], ['addr' => $author]);
                while ($contact = DBA::fetch($contacts)) {
                        Contact::remove($contact["id"]);
                }
                DBA::close($contacts);

                DBA::delete('gcontact', ['addr' => $author]);

                Logger::log('Removed contacts for ' . $author);

                return true;
        }

        /**
         * Fetch the uri from our database if we already have this item (maybe from ourselves)
         *
         * @param string  $author    Author handle
         * @param string  $guid      Message guid
         * @param boolean $onlyfound Only return uri when found in the database
         *
         * @return string The constructed uri or the one from our database
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function getUriFromGuid($author, $guid, $onlyfound = false)
        {
                $item = Item::selectFirst(['uri'], ['guid' => $guid]);
                if (DBA::isResult($item)) {
                        return $item["uri"];
                } elseif (!$onlyfound) {
                        $person = self::personByHandle($author);

                        $parts = parse_url($person['url']);
                        unset($parts['path']);
                        $host_url = Network::unparseURL($parts);

                        return $host_url . '/objects/' . $guid;
                }

                return "";
        }

        /**
         * Fetch the guid from our database with a given uri
         *
         * @param string $uri Message uri
         * @param string $uid Author handle
         *
         * @return string The post guid
         * @throws \Exception
         */
        private static function getGuidFromUri($uri, $uid)
        {
                $item = Item::selectFirst(['guid'], ['uri' => $uri, 'uid' => $uid]);
                if (DBA::isResult($item)) {
                        return $item["guid"];
                } else {
                        return false;
                }
        }

        /**
         * Find the best importer for a comment, like, ...
         *
         * @param string $guid The guid of the item
         *
         * @return array|boolean the origin owner of that post - or false
         * @throws \Exception
         */
        private static function importerForGuid($guid)
        {
                $item = Item::selectFirst(['uid'], ['origin' => true, 'guid' => $guid]);
                if (DBA::isResult($item)) {
                        Logger::log("Found user ".$item['uid']." as owner of item ".$guid, Logger::DEBUG);
                        $contact = DBA::selectFirst('contact', [], ['self' => true, 'uid' => $item['uid']]);
                        if (DBA::isResult($contact)) {
                                return $contact;
                        }
                }
                return false;
        }

        /**
         * Store the mentions in the tag table
         *
         * @param integer $uriid
         * @param string $text
         */
        private static function storeMentions(int $uriid, string $text)
        {
                preg_match_all('/([@!]){(?:([^}]+?); ?)?([^} ]+)}/', $text, $matches, PREG_SET_ORDER);
                if (empty($matches)) {
                        return;
                }

                /*
                 * Matching values for the preg match
                 * [1] = mention type (@ or !)
                 * [2] = name (optional)
                 * [3] = profile URL
                 */

                foreach ($matches as $match) {
                        if (empty($match)) {
                                continue;
                        }

                        $person = self::personByHandle($match[3]);
                        if (empty($person)) {
                                continue;
                        }

                        Tag::storeByHash($uriid, $match[1], $person['name'] ?: $person['nick'], $person['url']);
                }
        }

        /**
         * Processes an incoming comment
         *
         * @param array  $importer Array of the importer user
         * @param string $sender   The sender of the message
         * @param object $data     The message object
         * @param string $xml      The original XML of the message
         *
         * @return int The message id of the generated comment or "false" if there was an error
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveComment(array $importer, $sender, $data, $xml)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $parent_guid = Strings::escapeTags(XML::unescape($data->parent_guid));
                $text = XML::unescape($data->text);

                if (isset($data->created_at)) {
                        $created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($data->created_at)));
                } else {
                        $created_at = DateTimeFormat::utcNow();
                }

                if (isset($data->thread_parent_guid)) {
                        $thread_parent_guid = Strings::escapeTags(XML::unescape($data->thread_parent_guid));
                        $thr_uri = self::getUriFromGuid("", $thread_parent_guid, true);
                } else {
                        $thr_uri = "";
                }

                $contact = self::allowedContactByHandle($importer, $sender, true);
                if (!$contact) {
                        return false;
                }

                $message_id = self::messageExists($importer["uid"], $guid);
                if ($message_id) {
                        return true;
                }

                $parent_item = self::parentItem($importer["uid"], $parent_guid, $author, $contact);
                if (!$parent_item) {
                        return false;
                }

                $person = self::personByHandle($author);
                if (!is_array($person)) {
                        Logger::log("unable to find author details");
                        return false;
                }

                // Fetch the contact id - if we know this contact
                $author_contact = self::authorContactByUrl($contact, $person, $importer["uid"]);

                $datarray = [];

                $datarray["uid"] = $importer["uid"];
                $datarray["contact-id"] = $author_contact["cid"];
                $datarray["network"]  = $author_contact["network"];

                $datarray["author-link"] = $person["url"];
                $datarray["author-id"] = Contact::getIdForURL($person["url"], 0);

                $datarray["owner-link"] = $contact["url"];
                $datarray["owner-id"] = Contact::getIdForURL($contact["url"], 0);

                $datarray["guid"] = $guid;
                $datarray["uri"] = self::getUriFromGuid($author, $guid);
                $datarray['uri-id'] = ItemURI::insert(['uri' => $datarray['uri'], 'guid' => $datarray['guid']]);

                $datarray["verb"] = Activity::POST;
                $datarray["gravity"] = GRAVITY_COMMENT;

                if ($thr_uri != "") {
                        $datarray["parent-uri"] = $thr_uri;
                } else {
                        $datarray["parent-uri"] = $parent_item["uri"];
                }

                $datarray["object-type"] = Activity\ObjectType::COMMENT;

                $datarray["protocol"] = Conversation::PARCEL_DIASPORA;
                $datarray["source"] = $xml;

                $datarray["changed"] = $datarray["created"] = $datarray["edited"] = $created_at;

                $datarray["plink"] = self::plink($author, $guid, $parent_item['guid']);
                $body = Markdown::toBBCode($text);

                $datarray["body"] = self::replacePeopleGuid($body, $person["url"]);

                self::storeMentions($datarray['uri-id'], $text);
                Tag::storeRawTagsFromBody($datarray['uri-id'], $datarray["body"]);

                self::fetchGuid($datarray);

                // If we are the origin of the parent we store the original data.
                // We notify our followers during the item storage.
                if ($parent_item["origin"]) {
                        $datarray['diaspora_signed_text'] = json_encode($data);
                }

                $message_id = Item::insert($datarray);

                if ($message_id <= 0) {
                        return false;
                }

                if ($message_id) {
                        Logger::log("Stored comment ".$datarray["guid"]." with message id ".$message_id, Logger::DEBUG);
                        if ($datarray['uid'] == 0) {
                                Item::distribute($message_id, json_encode($data));
                        }
                }

                return true;
        }

        /**
         * processes and stores private messages
         *
         * @param array  $importer     Array of the importer user
         * @param array  $contact      The contact of the message
         * @param object $data         The message object
         * @param array  $msg          Array of the processed message, author handle and key
         * @param object $mesg         The private message
         * @param array  $conversation The conversation record to which this message belongs
         *
         * @return bool "true" if it was successful
         * @throws \Exception
         */
        private static function receiveConversationMessage(array $importer, array $contact, $data, $msg, $mesg, $conversation)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $subject = Strings::escapeTags(XML::unescape($data->subject));

                // "diaspora_handle" is the element name from the old version
                // "author" is the element name from the new version
                if ($mesg->author) {
                        $msg_author = Strings::escapeTags(XML::unescape($mesg->author));
                } elseif ($mesg->diaspora_handle) {
                        $msg_author = Strings::escapeTags(XML::unescape($mesg->diaspora_handle));
                } else {
                        return false;
                }

                $msg_guid = Strings::escapeTags(XML::unescape($mesg->guid));
                $msg_conversation_guid = Strings::escapeTags(XML::unescape($mesg->conversation_guid));
                $msg_text = XML::unescape($mesg->text);
                $msg_created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($mesg->created_at)));

                if ($msg_conversation_guid != $guid) {
                        Logger::log("message conversation guid does not belong to the current conversation.");
                        return false;
                }

                $body = Markdown::toBBCode($msg_text);
                $message_uri = $msg_author.":".$msg_guid;

                $person = self::personByHandle($msg_author);

                return Mail::insert([
                        'uid'        => $importer['uid'],
                        'guid'       => $msg_guid,
                        'convid'     => $conversation['id'],
                        'from-name'  => $person['name'],
                        'from-photo' => $person['photo'],
                        'from-url'   => $person['url'],
                        'contact-id' => $contact['id'],
                        'title'      => $subject,
                        'body'       => $body,
                        'uri'        => $message_uri,
                        'parent-uri' => $author . ':' . $guid,
                        'created'    => $msg_created_at
                ]);
        }

        /**
         * Processes new private messages (answers to private messages are processed elsewhere)
         *
         * @param array  $importer Array of the importer user
         * @param array  $msg      Array of the processed message, author handle and key
         * @param object $data     The message object
         *
         * @return bool Success
         * @throws \Exception
         */
        private static function receiveConversation(array $importer, $msg, $data)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $subject = Strings::escapeTags(XML::unescape($data->subject));
                $created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($data->created_at)));
                $participants = Strings::escapeTags(XML::unescape($data->participants));

                $messages = $data->message;

                if (!count($messages)) {
                        Logger::log("empty conversation");
                        return false;
                }

                $contact = self::allowedContactByHandle($importer, $msg["author"], true);
                if (!$contact) {
                        return false;
                }

                $conversation = DBA::selectFirst('conv', [], ['uid' => $importer["uid"], 'guid' => $guid]);
                if (!DBA::isResult($conversation)) {
                        $r = q(
                                "INSERT INTO `conv` (`uid`, `guid`, `creator`, `created`, `updated`, `subject`, `recips`)
                                VALUES (%d, '%s', '%s', '%s', '%s', '%s', '%s')",
                                intval($importer["uid"]),
                                DBA::escape($guid),
                                DBA::escape($author),
                                DBA::escape($created_at),
                                DBA::escape(DateTimeFormat::utcNow()),
                                DBA::escape($subject),
                                DBA::escape($participants)
                        );
                        if ($r) {
                                $conversation = DBA::selectFirst('conv', [], ['uid' => $importer["uid"], 'guid' => $guid]);
                        }
                }
                if (!$conversation) {
                        Logger::log("unable to create conversation.");
                        return false;
                }

                foreach ($messages as $mesg) {
                        self::receiveConversationMessage($importer, $contact, $data, $msg, $mesg, $conversation);
                }

                return true;
        }

        /**
         * Processes "like" messages
         *
         * @param array  $importer Array of the importer user
         * @param string $sender   The sender of the message
         * @param object $data     The message object
         *
         * @return int The message id of the generated like or "false" if there was an error
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveLike(array $importer, $sender, $data)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $parent_guid = Strings::escapeTags(XML::unescape($data->parent_guid));
                $parent_type = Strings::escapeTags(XML::unescape($data->parent_type));
                $positive = Strings::escapeTags(XML::unescape($data->positive));

                // likes on comments aren't supported by Diaspora - only on posts
                // But maybe this will be supported in the future, so we will accept it.
                if (!in_array($parent_type, ["Post", "Comment"])) {
                        return false;
                }

                $contact = self::allowedContactByHandle($importer, $sender, true);
                if (!$contact) {
                        return false;
                }

                $message_id = self::messageExists($importer["uid"], $guid);
                if ($message_id) {
                        return true;
                }

                $parent_item = self::parentItem($importer["uid"], $parent_guid, $author, $contact);
                if (!$parent_item) {
                        return false;
                }

                $person = self::personByHandle($author);
                if (!is_array($person)) {
                        Logger::log("unable to find author details");
                        return false;
                }

                // Fetch the contact id - if we know this contact
                $author_contact = self::authorContactByUrl($contact, $person, $importer["uid"]);

                // "positive" = "false" would be a Dislike - wich isn't currently supported by Diaspora
                // We would accept this anyhow.
                if ($positive == "true") {
                        $verb = Activity::LIKE;
                } else {
                        $verb = Activity::DISLIKE;
                }

                $datarray = [];

                $datarray["protocol"] = Conversation::PARCEL_DIASPORA;

                $datarray["uid"] = $importer["uid"];
                $datarray["contact-id"] = $author_contact["cid"];
                $datarray["network"]  = $author_contact["network"];

                $datarray["owner-link"] = $datarray["author-link"] = $person["url"];
                $datarray["owner-id"] = $datarray["author-id"] = Contact::getIdForURL($person["url"], 0);

                $datarray["guid"] = $guid;
                $datarray["uri"] = self::getUriFromGuid($author, $guid);

                $datarray["verb"] = $verb;
                $datarray["gravity"] = GRAVITY_ACTIVITY;
                $datarray["parent-uri"] = $parent_item["uri"];

                $datarray["object-type"] = Activity\ObjectType::NOTE;

                $datarray["body"] = $verb;

                // Diaspora doesn't provide a date for likes
                $datarray["changed"] = $datarray["created"] = $datarray["edited"] = DateTimeFormat::utcNow();

                // like on comments have the comment as parent. So we need to fetch the toplevel parent
                if ($parent_item["id"] != $parent_item["parent"]) {
                        $toplevel = Item::selectFirst(['origin'], ['id' => $parent_item["parent"]]);
                        $origin = $toplevel["origin"];
                } else {
                        $origin = $parent_item["origin"];
                }

                // If we are the origin of the parent we store the original data.
                // We notify our followers during the item storage.
                if ($origin) {
                        $datarray['diaspora_signed_text'] = json_encode($data);
                }

                $message_id = Item::insert($datarray);

                if ($message_id <= 0) {
                        return false;
                }

                if ($message_id) {
                        Logger::log("Stored like ".$datarray["guid"]." with message id ".$message_id, Logger::DEBUG);
                        if ($datarray['uid'] == 0) {
                                Item::distribute($message_id, json_encode($data));
                        }
                }

                return true;
        }

        /**
         * Processes private messages
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool Success?
         * @throws \Exception
         */
        private static function receiveMessage(array $importer, $data)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $conversation_guid = Strings::escapeTags(XML::unescape($data->conversation_guid));
                $text = XML::unescape($data->text);
                $created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($data->created_at)));

                $contact = self::allowedContactByHandle($importer, $author, true);
                if (!$contact) {
                        return false;
                }

                $conversation = null;

                $condition = ['uid' => $importer["uid"], 'guid' => $conversation_guid];
                $conversation = DBA::selectFirst('conv', [], $condition);

                if (!DBA::isResult($conversation)) {
                        Logger::log("conversation not available.");
                        return false;
                }

                $message_uri = $author.":".$guid;

                $person = self::personByHandle($author);
                if (!$person) {
                        Logger::log("unable to find author details");
                        return false;
                }

                $body = Markdown::toBBCode($text);

                $body = self::replacePeopleGuid($body, $person["url"]);

                return Mail::insert([
                        'uid'        => $importer['uid'],
                        'guid'       => $guid,
                        'convid'     => $conversation['id'],
                        'from-name'  => $person['name'],
                        'from-photo' => $person['photo'],
                        'from-url'   => $person['url'],
                        'contact-id' => $contact['id'],
                        'title'      => $conversation['subject'],
                        'body'       => $body,
                        'reply'      => 1,
                        'uri'        => $message_uri,
                        'parent-uri' => $author.":".$conversation['guid'],
                        'created'    => $created_at
                ]);
        }

        /**
         * Processes participations - unsupported by now
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool success
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveParticipation(array $importer, $data)
        {
                $author = strtolower(Strings::escapeTags(XML::unescape($data->author)));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $parent_guid = Strings::escapeTags(XML::unescape($data->parent_guid));

                $contact = self::allowedContactByHandle($importer, $author, true);
                if (!$contact) {
                        return false;
                }

                if (self::messageExists($importer["uid"], $guid)) {
                        return true;
                }

                $parent_item = self::parentItem($importer["uid"], $parent_guid, $author, $contact);
                if (!$parent_item) {
                        return false;
                }

                if (!in_array($parent_item['private'], [Item::PUBLIC, Item::UNLISTED])) {
                        Logger::info('Item is not public, participation is ignored', ['parent_guid' => $parent_guid, 'guid' => $guid, 'author' => $author]);
                        return false;
                }

                $person = self::personByHandle($author);
                if (!is_array($person)) {
                        Logger::log("Person not found: ".$author);
                        return false;
                }

                $author_contact = self::authorContactByUrl($contact, $person, $importer["uid"]);

                // Store participation
                $datarray = [];

                $datarray["protocol"] = Conversation::PARCEL_DIASPORA;

                $datarray["uid"] = $importer["uid"];
                $datarray["contact-id"] = $author_contact["cid"];
                $datarray["network"]  = $author_contact["network"];

                $datarray["owner-link"] = $datarray["author-link"] = $person["url"];
                $datarray["owner-id"] = $datarray["author-id"] = Contact::getIdForURL($person["url"], 0);

                $datarray["guid"] = $guid;
                $datarray["uri"] = self::getUriFromGuid($author, $guid);

                $datarray["verb"] = Activity::FOLLOW;
                $datarray["gravity"] = GRAVITY_ACTIVITY;
                $datarray["parent-uri"] = $parent_item["uri"];

                $datarray["object-type"] = Activity\ObjectType::NOTE;

                $datarray["body"] = Activity::FOLLOW;

                // Diaspora doesn't provide a date for a participation
                $datarray["changed"] = $datarray["created"] = $datarray["edited"] = DateTimeFormat::utcNow();

                $message_id = Item::insert($datarray);

                Logger::info('Participation stored', ['id' => $message_id, 'guid' => $guid, 'parent_guid' => $parent_guid, 'author' => $author]);

                // Send all existing comments and likes to the requesting server
                $comments = Item::select(['id', 'uri-id', 'parent', 'verb'], ['parent' => $parent_item['id']]);
                while ($comment = Item::fetch($comments)) {
                        if ($comment['id'] == $comment['parent'] || in_array($comment["verb"], [Activity::FOLLOW, Activity::TAG])) {
                                continue;
                        }

                        Logger::info('Deliver participation', ['item' => $comment['id'], 'contact' => $author_contact["cid"]]);
                        if (Worker::add(PRIORITY_HIGH, 'Delivery', Delivery::POST, $comment['id'], $author_contact["cid"])) {
                                Post\DeliveryData::incrementQueueCount($comment['uri-id'], 1);
                        }
                }
                DBA::close($comments);

                return true;
        }

        /**
         * Processes photos - unneeded
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool always true
         */
        private static function receivePhoto(array $importer, $data)
        {
                // There doesn't seem to be a reason for this function,
                // since the photo data is transmitted in the status message as well
                return true;
        }

        /**
         * Processes poll participations - unssupported
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool always true
         */
        private static function receivePollParticipation(array $importer, $data)
        {
                // We don't support polls by now
                return true;
        }

        /**
         * Processes incoming profile updates
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool Success
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveProfile(array $importer, $data)
        {
                $author = strtolower(Strings::escapeTags(XML::unescape($data->author)));

                $contact = self::contactByHandle($importer["uid"], $author);
                if (!$contact) {
                        return false;
                }

                $name = XML::unescape($data->first_name).((strlen($data->last_name)) ? " ".XML::unescape($data->last_name) : "");
                $image_url = XML::unescape($data->image_url);
                $birthday = XML::unescape($data->birthday);
                $about = Markdown::toBBCode(XML::unescape($data->bio));
                $location = Markdown::toBBCode(XML::unescape($data->location));
                $searchable = (XML::unescape($data->searchable) == "true");
                $nsfw = (XML::unescape($data->nsfw) == "true");
                $tags = XML::unescape($data->tag_string);

                $tags = explode("#", $tags);

                $keywords = [];
                foreach ($tags as $tag) {
                        $tag = trim(strtolower($tag));
                        if ($tag != "") {
                                $keywords[] = $tag;
                        }
                }

                $keywords = implode(", ", $keywords);

                $handle_parts = explode("@", $author);
                $nick = $handle_parts[0];

                if ($name === "") {
                        $name = $handle_parts[0];
                }

                if (preg_match("|^https?://|", $image_url) === 0) {
                        $image_url = "http://".$handle_parts[1].$image_url;
                }

                Contact::updateAvatar($image_url, $importer["uid"], $contact["id"]);

                // Generic birthday. We don't know the timezone. The year is irrelevant.

                $birthday = str_replace("1000", "1901", $birthday);

                if ($birthday != "") {
                        $birthday = DateTimeFormat::utc($birthday, "Y-m-d");
                }

                // this is to prevent multiple birthday notifications in a single year
                // if we already have a stored birthday and the 'm-d' part hasn't changed, preserve the entry, which will preserve the notify year

                if (substr($birthday, 5) === substr($contact["bd"], 5)) {
                        $birthday = $contact["bd"];
                }

                $fields = ['name' => $name, 'location' => $location,
                        'name-date' => DateTimeFormat::utcNow(), 'about' => $about,
                        'addr' => $author, 'nick' => $nick, 'keywords' => $keywords,
                        'unsearchable' => !$searchable, 'sensitive' => $nsfw];

                if (!empty($birthday)) {
                        $fields['bd'] = $birthday;
                }

                DBA::update('contact', $fields, ['id' => $contact['id']]);

                // @todo Update the public contact, then update the gcontact from that

                $gcontact = ["url" => $contact["url"], "network" => Protocol::DIASPORA, "generation" => 2,
                                        "photo" => $image_url, "name" => $name, "location" => $location,
                                        "about" => $about, "birthday" => $birthday,
                                        "addr" => $author, "nick" => $nick, "keywords" => $keywords,
                                        "hide" => !$searchable, "nsfw" => $nsfw];

                $gcid = GContact::update($gcontact);

                GContact::link($gcid, $importer["uid"], $contact["id"]);

                Logger::log("Profile of contact ".$contact["id"]." stored for user ".$importer["uid"], Logger::DEBUG);

                return true;
        }

        /**
         * Processes incoming friend requests
         *
         * @param array $importer Array of the importer user
         * @param array $contact  The contact that send the request
         * @return void
         * @throws \Exception
         */
        private static function receiveRequestMakeFriend(array $importer, array $contact)
        {
                if ($contact["rel"] == Contact::SHARING) {
                        DBA::update(
                                'contact',
                                ['rel' => Contact::FRIEND, 'writable' => true],
                                ['id' => $contact["id"], 'uid' => $importer["uid"]]
                        );
                }
        }

        /**
         * Processes incoming sharing notification
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         *
         * @return bool Success
         * @throws \Exception
         */
        private static function receiveContactRequest(array $importer, $data)
        {
                $author = XML::unescape($data->author);
                $recipient = XML::unescape($data->recipient);

                if (!$author || !$recipient) {
                        return false;
                }

                // the current protocol version doesn't know these fields
                // That means that we will assume their existance
                if (isset($data->following)) {
                        $following = (XML::unescape($data->following) == "true");
                } else {
                        $following = true;
                }

                if (isset($data->sharing)) {
                        $sharing = (XML::unescape($data->sharing) == "true");
                } else {
                        $sharing = true;
                }

                $contact = self::contactByHandle($importer["uid"], $author);

                // perhaps we were already sharing with this person. Now they're sharing with us.
                // That makes us friends.
                if ($contact) {
                        if ($following) {
                                Logger::log("Author ".$author." (Contact ".$contact["id"].") wants to follow us.", Logger::DEBUG);
                                self::receiveRequestMakeFriend($importer, $contact);

                                // refetch the contact array
                                $contact = self::contactByHandle($importer["uid"], $author);

                                // If we are now friends, we are sending a share message.
                                // Normally we needn't to do so, but the first message could have been vanished.
                                if (in_array($contact["rel"], [Contact::FRIEND])) {
                                        $user = DBA::selectFirst('user', [], ['uid' => $importer["uid"]]);
                                        if (DBA::isResult($user)) {
                                                Logger::log("Sending share message to author ".$author." - Contact: ".$contact["id"]." - User: ".$importer["uid"], Logger::DEBUG);
                                                self::sendShare($user, $contact);
                                        }
                                }
                                return true;
                        } else {
                                Logger::log("Author ".$author." doesn't want to follow us anymore.", Logger::DEBUG);
                                Contact::removeFollower($importer, $contact);
                                return true;
                        }
                }

                if (!$following && $sharing && in_array($importer["page-flags"], [User::PAGE_FLAGS_SOAPBOX, User::PAGE_FLAGS_NORMAL])) {
                        Logger::log("Author ".$author." wants to share with us - but doesn't want to listen. Request is ignored.", Logger::DEBUG);
                        return false;
                } elseif (!$following && !$sharing) {
                        Logger::log("Author ".$author." doesn't want anything - and we don't know the author. Request is ignored.", Logger::DEBUG);
                        return false;
                } elseif (!$following && $sharing) {
                        Logger::log("Author ".$author." wants to share with us.", Logger::DEBUG);
                } elseif ($following && $sharing) {
                        Logger::log("Author ".$author." wants to have a bidirectional conection.", Logger::DEBUG);
                } elseif ($following && !$sharing) {
                        Logger::log("Author ".$author." wants to listen to us.", Logger::DEBUG);
                }

                $ret = self::personByHandle($author);

                if (!$ret || ($ret["network"] != Protocol::DIASPORA)) {
                        Logger::log("Cannot resolve diaspora handle ".$author." for ".$recipient);
                        return false;
                }

                $cid = Contact::getIdForURL($ret['url'], $importer['uid']);
                if (!empty($cid)) {
                        $contact = DBA::selectFirst('contact', [], ['id' => $cid, 'network' => Protocol::NATIVE_SUPPORT]);
                } else {
                        $contact = [];
                }

                $item = ['author-id' => Contact::getIdForURL($ret['url']),
                        'author-link' => $ret['url']];

                $result = Contact::addRelationship($importer, $contact, $item, false);
                if ($result === true) {
                        $contact_record = self::contactByHandle($importer['uid'], $author);
                        if (!$contact_record) {
                                Logger::info('unable to locate newly created contact record.');
                                return;
                        }

                        $user = DBA::selectFirst('user', [], ['uid' => $importer['uid']]);
                        if (DBA::isResult($user)) {
                                self::sendShare($user, $contact_record);

                                // Send the profile data, maybe it weren't transmitted before
                                self::sendProfile($importer['uid'], [$contact_record]);
                        }
                }

                return true;
        }

        /**
         * Fetches a message with a given guid
         *
         * @param string $guid        message guid
         * @param string $orig_author handle of the original post
         * @return array The fetched item
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function originalItem($guid, $orig_author)
        {
                if (empty($guid)) {
                        Logger::log('Empty guid. Quitting.');
                        return false;
                }

                // Do we already have this item?
                $fields = ['body', 'title', 'attach', 'app', 'created', 'object-type', 'uri', 'guid',
                        'author-name', 'author-link', 'author-avatar'];
                $condition = ['guid' => $guid, 'visible' => true, 'deleted' => false, 'private' => [Item::PUBLIC, Item::UNLISTED]];
                $item = Item::selectFirst($fields, $condition);

                if (DBA::isResult($item)) {
                        Logger::log("reshared message ".$guid." already exists on system.");

                        // Maybe it is already a reshared item?
                        // Then refetch the content, if it is a reshare from a reshare.
                        // If it is a reshared post from another network then reformat to avoid display problems with two share elements
                        if (self::isReshare($item["body"], true)) {
                                $item = [];
                        } elseif (self::isReshare($item["body"], false) || strstr($item["body"], "[share")) {
                                $item["body"] = Markdown::toBBCode(BBCode::toMarkdown($item["body"]));

                                $item["body"] = self::replacePeopleGuid($item["body"], $item["author-link"]);

                                // Add OEmbed and other information to the body
                                $item["body"] = add_page_info_to_body($item["body"], false, true);

                                return $item;
                        } else {
                                return $item;
                        }
                }

                if (!DBA::isResult($item)) {
                        if (empty($orig_author)) {
                                Logger::log('Empty author for guid ' . $guid . '. Quitting.');
                                return false;
                        }

                        $server = "https://".substr($orig_author, strpos($orig_author, "@") + 1);
                        Logger::log("1st try: reshared message ".$guid." will be fetched via SSL from the server ".$server);
                        $stored = self::storeByGuid($guid, $server);

                        if (!$stored) {
                                $server = "http://".substr($orig_author, strpos($orig_author, "@") + 1);
                                Logger::log("2nd try: reshared message ".$guid." will be fetched without SSL from the server ".$server);
                                $stored = self::storeByGuid($guid, $server);
                        }

                        if ($stored) {
                                $fields = ['body', 'title', 'attach', 'app', 'created', 'object-type', 'uri', 'guid',
                                        'author-name', 'author-link', 'author-avatar'];
                                $condition = ['guid' => $guid, 'visible' => true, 'deleted' => false, 'private' => [Item::PUBLIC, Item::UNLISTED]];
                                $item = Item::selectFirst($fields, $condition);

                                if (DBA::isResult($item)) {
                                        // If it is a reshared post from another network then reformat to avoid display problems with two share elements
                                        if (self::isReshare($item["body"], false)) {
                                                $item["body"] = Markdown::toBBCode(BBCode::toMarkdown($item["body"]));
                                                $item["body"] = self::replacePeopleGuid($item["body"], $item["author-link"]);
                                        }

                                        return $item;
                                }
                        }
                }
                return false;
        }

        /**
         * Stores a reshare activity
         *
         * @param array   $item              Array of reshare post
         * @param integer $parent_message_id Id of the parent post
         * @param string  $guid              GUID string of reshare action
         * @param string  $author            Author handle
         */
        private static function addReshareActivity($item, $parent_message_id, $guid, $author)
        {
                $parent = Item::selectFirst(['uri', 'guid'], ['id' => $parent_message_id]);

                $datarray = [];

                $datarray['uid'] = $item['uid'];
                $datarray['contact-id'] = $item['contact-id'];
                $datarray['network'] = $item['network'];

                $datarray['author-link'] = $item['author-link'];
                $datarray['author-id'] = $item['author-id'];

                $datarray['owner-link'] = $datarray['author-link'];
                $datarray['owner-id'] = $datarray['author-id'];

                $datarray['guid'] = $parent['guid'] . '-' . $guid;
                $datarray['uri'] = self::getUriFromGuid($author, $datarray['guid']);
                $datarray['parent-uri'] = $parent['uri'];

                $datarray['verb'] = $datarray['body'] = Activity::ANNOUNCE;
                $datarray['gravity'] = GRAVITY_ACTIVITY;
                $datarray['object-type'] = Activity\ObjectType::NOTE;

                $datarray['protocol'] = $item['protocol'];

                $datarray['plink'] = self::plink($author, $datarray['guid']);
                $datarray['private'] = $item['private'];
                $datarray['changed'] = $datarray['created'] = $datarray['edited'] = $item['created'];

                $message_id = Item::insert($datarray);

                if ($message_id) {
                        Logger::info('Stored reshare activity.', ['guid' => $guid, 'id' => $message_id]);
                        if ($datarray['uid'] == 0) {
                                Item::distribute($message_id);
                        }
                }
        }

        /**
         * Processes a reshare message
         *
         * @param array  $importer Array of the importer user
         * @param object $data     The message object
         * @param string $xml      The original XML of the message
         *
         * @return int the message id
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveReshare(array $importer, $data, $xml)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($data->created_at)));
                $root_author = Strings::escapeTags(XML::unescape($data->root_author));
                $root_guid = Strings::escapeTags(XML::unescape($data->root_guid));
                /// @todo handle unprocessed property "provider_display_name"
                $public = Strings::escapeTags(XML::unescape($data->public));

                $contact = self::allowedContactByHandle($importer, $author, false);
                if (!$contact) {
                        return false;
                }

                $message_id = self::messageExists($importer["uid"], $guid);
                if ($message_id) {
                        return true;
                }

                $original_item = self::originalItem($root_guid, $root_author);
                if (!$original_item) {
                        return false;
                }

                $orig_url = DI::baseUrl()."/display/".$original_item["guid"];

                $datarray = [];

                $datarray["uid"] = $importer["uid"];
                $datarray["contact-id"] = $contact["id"];
                $datarray["network"]  = Protocol::DIASPORA;

                $datarray["author-link"] = $contact["url"];
                $datarray["author-id"] = Contact::getIdForURL($contact["url"], 0);

                $datarray["owner-link"] = $datarray["author-link"];
                $datarray["owner-id"] = $datarray["author-id"];

                $datarray["guid"] = $guid;
                $datarray["uri"] = $datarray["parent-uri"] = self::getUriFromGuid($author, $guid);
                $datarray['uri-id'] = ItemURI::insert(['uri' => $datarray['uri'], 'guid' => $datarray['guid']]);

                $datarray["verb"] = Activity::POST;
                $datarray["gravity"] = GRAVITY_PARENT;

                $datarray["protocol"] = Conversation::PARCEL_DIASPORA;
                $datarray["source"] = $xml;

                /// @todo Copy tag data from original post

                $prefix = share_header(
                        $original_item["author-name"],
                        $original_item["author-link"],
                        $original_item["author-avatar"],
                        $original_item["guid"],
                        $original_item["created"],
                        $orig_url
                );

                if (!empty($original_item['title'])) {
                        $prefix .= '[h3]' . $original_item['title'] . "[/h3]\n";
                }

                $datarray["body"] = $prefix.$original_item["body"]."[/share]";

                Tag::storeFromBody($datarray['uri-id'], $datarray["body"]);

                $datarray["attach"] = $original_item["attach"];
                $datarray["app"]  = $original_item["app"];

                $datarray["plink"] = self::plink($author, $guid);
                $datarray["private"] = (($public == "false") ? Item::PRIVATE : Item::PUBLIC);
                $datarray["changed"] = $datarray["created"] = $datarray["edited"] = $created_at;

                $datarray["object-type"] = $original_item["object-type"];

                self::fetchGuid($datarray);
                $message_id = Item::insert($datarray);

                self::sendParticipation($contact, $datarray);

                $root_message_id = self::messageExists($importer["uid"], $root_guid);
                if ($root_message_id) {
                        self::addReshareActivity($datarray, $root_message_id, $guid, $author);
                }

                if ($message_id) {
                        Logger::log("Stored reshare ".$datarray["guid"]." with message id ".$message_id, Logger::DEBUG);
                        if ($datarray['uid'] == 0) {
                                Item::distribute($message_id);
                        }
                        return true;
                } else {
                        return false;
                }
        }

        /**
         * Processes retractions
         *
         * @param array  $importer Array of the importer user
         * @param array  $contact  The contact of the item owner
         * @param object $data     The message object
         *
         * @return bool success
         * @throws \Exception
         */
        private static function itemRetraction(array $importer, array $contact, $data)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $target_guid = Strings::escapeTags(XML::unescape($data->target_guid));
                $target_type = Strings::escapeTags(XML::unescape($data->target_type));

                $person = self::personByHandle($author);
                if (!is_array($person)) {
                        Logger::log("unable to find author detail for ".$author);
                        return false;
                }

                if (empty($contact["url"])) {
                        $contact["url"] = $person["url"];
                }

                // Fetch items that are about to be deleted
                $fields = ['uid', 'id', 'parent', 'parent-uri', 'author-link', 'file'];

                // When we receive a public retraction, we delete every item that we find.
                if ($importer['uid'] == 0) {
                        $condition = ['guid' => $target_guid, 'deleted' => false];
                } else {
                        $condition = ['guid' => $target_guid, 'deleted' => false, 'uid' => $importer['uid']];
                }

                $r = Item::select($fields, $condition);
                if (!DBA::isResult($r)) {
                        Logger::log("Target guid ".$target_guid." was not found on this system for user ".$importer['uid'].".");
                        return false;
                }

                while ($item = Item::fetch($r)) {
                        if (strstr($item['file'], '[')) {
                                Logger::log("Target guid " . $target_guid . " for user " . $item['uid'] . " is filed. So it won't be deleted.", Logger::DEBUG);
                                continue;
                        }

                        // Fetch the parent item
                        $parent = Item::selectFirst(['author-link'], ['id' => $item["parent"]]);

                        // Only delete it if the parent author really fits
                        if (!Strings::compareLink($parent["author-link"], $contact["url"]) && !Strings::compareLink($item["author-link"], $contact["url"])) {
                                Logger::log("Thread author ".$parent["author-link"]." and item author ".$item["author-link"]." don't fit to expected contact ".$contact["url"], Logger::DEBUG);
                                continue;
                        }

                        Item::markForDeletion(['id' => $item['id']]);

                        Logger::log("Deleted target ".$target_guid." (".$item["id"].") from user ".$item["uid"]." parent: ".$item["parent"], Logger::DEBUG);
                }

                return true;
        }

        /**
         * Receives retraction messages
         *
         * @param array  $importer Array of the importer user
         * @param string $sender   The sender of the message
         * @param object $data     The message object
         *
         * @return bool Success
         * @throws \Exception
         */
        private static function receiveRetraction(array $importer, $sender, $data)
        {
                $target_type = Strings::escapeTags(XML::unescape($data->target_type));

                $contact = self::contactByHandle($importer["uid"], $sender);
                if (!$contact && (in_array($target_type, ["Contact", "Person"]))) {
                        Logger::log("cannot find contact for sender: ".$sender." and user ".$importer["uid"]);
                        return false;
                }

                if (!$contact) {
                        $contact = [];
                }

                Logger::log("Got retraction for ".$target_type.", sender ".$sender." and user ".$importer["uid"], Logger::DEBUG);

                switch ($target_type) {
                        case "Comment":
                        case "Like":
                        case "Post":
                        case "Reshare":
                        case "StatusMessage":
                                return self::itemRetraction($importer, $contact, $data);

                        case "PollParticipation":
                        case "Photo":
                                // Currently unsupported
                                break;

                        default:
                                Logger::log("Unknown target type ".$target_type);
                                return false;
                }
                return true;
        }

        /**
         * Receives status messages
         *
         * @param array            $importer Array of the importer user
         * @param SimpleXMLElement $data     The message object
         * @param string           $xml      The original XML of the message
         *
         * @return int The message id of the newly created item
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function receiveStatusMessage(array $importer, SimpleXMLElement $data, $xml)
        {
                $author = Strings::escapeTags(XML::unescape($data->author));
                $guid = Strings::escapeTags(XML::unescape($data->guid));
                $created_at = DateTimeFormat::utc(Strings::escapeTags(XML::unescape($data->created_at)));
                $public = Strings::escapeTags(XML::unescape($data->public));
                $text = XML::unescape($data->text);
                $provider_display_name = Strings::escapeTags(XML::unescape($data->provider_display_name));

                $contact = self::allowedContactByHandle($importer, $author, false);
                if (!$contact) {
                        return false;
                }

                $message_id = self::messageExists($importer["uid"], $guid);
                if ($message_id) {
                        return true;
                }

                $address = [];
                if ($data->location) {
                        foreach ($data->location->children() as $fieldname => $data) {
                                $address[$fieldname] = Strings::escapeTags(XML::unescape($data));
                        }
                }

                $body = Markdown::toBBCode($text);

                $datarray = [];

                // Attach embedded pictures to the body
                if ($data->photo) {
                        foreach ($data->photo as $photo) {
                                $body = "[img]".XML::unescape($photo->remote_photo_path).
                                        XML::unescape($photo->remote_photo_name)."[/img]\n".$body;
                        }

                        $datarray["object-type"] = Activity\ObjectType::IMAGE;
                } else {
                        $datarray["object-type"] = Activity\ObjectType::NOTE;

                        // Add OEmbed and other information to the body
                        if (!self::isHubzilla($contact["url"])) {
                                $body = add_page_info_to_body($body, false, true);
                        }
                }

                /// @todo enable support for polls
                //if ($data->poll) {
                //      foreach ($data->poll AS $poll)
                //              print_r($poll);
                //      die("poll!\n");
                //}

                /// @todo enable support for events

                $datarray["uid"] = $importer["uid"];
                $datarray["contact-id"] = $contact["id"];
                $datarray["network"] = Protocol::DIASPORA;

                $datarray["author-link"] = $contact["url"];
                $datarray["author-id"] = Contact::getIdForURL($contact["url"], 0);

                $datarray["owner-link"] = $datarray["author-link"];
                $datarray["owner-id"] = $datarray["author-id"];

                $datarray["guid"] = $guid;
                $datarray["uri"] = $datarray["parent-uri"] = self::getUriFromGuid($author, $guid);
                $datarray['uri-id'] = ItemURI::insert(['uri' => $datarray['uri'], 'guid' => $datarray['guid']]);

                $datarray["verb"] = Activity::POST;
                $datarray["gravity"] = GRAVITY_PARENT;

                $datarray["protocol"] = Conversation::PARCEL_DIASPORA;
                $datarray["source"] = $xml;

                $datarray["body"] = self::replacePeopleGuid($body, $contact["url"]);

                self::storeMentions($datarray['uri-id'], $text);
                Tag::storeRawTagsFromBody($datarray['uri-id'], $datarray["body"]);

                if ($provider_display_name != "") {
                        $datarray["app"] = $provider_display_name;
                }

                $datarray["plink"] = self::plink($author, $guid);
                $datarray["private"] = (($public == "false") ? Item::PRIVATE : Item::PUBLIC);
                $datarray["changed"] = $datarray["created"] = $datarray["edited"] = $created_at;

                if (isset($address["address"])) {
                        $datarray["location"] = $address["address"];
                }

                if (isset($address["lat"]) && isset($address["lng"])) {
                        $datarray["coord"] = $address["lat"]." ".$address["lng"];
                }

                self::fetchGuid($datarray);
                $message_id = Item::insert($datarray);

                self::sendParticipation($contact, $datarray);

                if ($message_id) {
                        Logger::log("Stored item ".$datarray["guid"]." with message id ".$message_id, Logger::DEBUG);
                        if ($datarray['uid'] == 0) {
                                Item::distribute($message_id);
                        }
                        return true;
                } else {
                        return false;
                }
        }

        /* ************************************************************************************** *
         * Here are all the functions that are needed to transmit data with the Diaspora protocol *
         * ************************************************************************************** */

        /**
         * returnes the handle of a contact
         *
         * @param array $contact contact array
         *
         * @return string the handle in the format user@domain.tld
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function myHandle(array $contact)
        {
                if (!empty($contact["addr"])) {
                        return $contact["addr"];
                }

                // Normally we should have a filled "addr" field - but in the past this wasn't the case
                // So - just in case - we build the the address here.
                if ($contact["nickname"] != "") {
                        $nick = $contact["nickname"];
                } else {
                        $nick = $contact["nick"];
                }

                return $nick . "@" . substr(DI::baseUrl(), strpos(DI::baseUrl(), "://") + 3);
        }


        /**
         * Creates the data for a private message in the new format
         *
         * @param string $msg     The message that is to be transmitted
         * @param array  $user    The record of the sender
         * @param array  $contact Target of the communication
         * @param string $prvkey  The private key of the sender
         * @param string $pubkey  The public key of the receiver
         *
         * @return string The encrypted data
         * @throws \Exception
         */
        public static function encodePrivateData($msg, array $user, array $contact, $prvkey, $pubkey)
        {
                Logger::log("Message: ".$msg, Logger::DATA);

                // without a public key nothing will work
                if (!$pubkey) {
                        Logger::log("pubkey missing: contact id: ".$contact["id"]);
                        return false;
                }

                $aes_key = openssl_random_pseudo_bytes(32);
                $b_aes_key = base64_encode($aes_key);
                $iv = openssl_random_pseudo_bytes(16);
                $b_iv = base64_encode($iv);

                $ciphertext = self::aesEncrypt($aes_key, $iv, $msg);

                $json = json_encode(["iv" => $b_iv, "key" => $b_aes_key]);

                $encrypted_key_bundle = "";
                openssl_public_encrypt($json, $encrypted_key_bundle, $pubkey);

                $json_object = json_encode(
                        ["aes_key" => base64_encode($encrypted_key_bundle),
                                        "encrypted_magic_envelope" => base64_encode($ciphertext)]
                );

                return $json_object;
        }

        /**
         * Creates the envelope for the "fetch" endpoint and for the new format
         *
         * @param string $msg  The message that is to be transmitted
         * @param array  $user The record of the sender
         *
         * @return string The envelope
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        public static function buildMagicEnvelope($msg, array $user)
        {
                $b64url_data = Strings::base64UrlEncode($msg);
                $data = str_replace(["\n", "\r", " ", "\t"], ["", "", "", ""], $b64url_data);

                $key_id = Strings::base64UrlEncode(self::myHandle($user));
                $type = "application/xml";
                $encoding = "base64url";
                $alg = "RSA-SHA256";
                $signable_data = $data.".".Strings::base64UrlEncode($type).".".Strings::base64UrlEncode($encoding).".".Strings::base64UrlEncode($alg);

                // Fallback if the private key wasn't transmitted in the expected field
                if ($user['uprvkey'] == "") {
                        $user['uprvkey'] = $user['prvkey'];
                }

                $signature = Crypto::rsaSign($signable_data, $user["uprvkey"]);
                $sig = Strings::base64UrlEncode($signature);

                $xmldata = ["me:env" => ["me:data" => $data,
                                                        "@attributes" => ["type" => $type],
                                                        "me:encoding" => $encoding,
                                                        "me:alg" => $alg,
                                                        "me:sig" => $sig,
                                                        "@attributes2" => ["key_id" => $key_id]]];

                $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];

                return XML::fromArray($xmldata, $xml, false, $namespaces);
        }

        /**
         * Create the envelope for a message
         *
         * @param string $msg     The message that is to be transmitted
         * @param array  $user    The record of the sender
         * @param array  $contact Target of the communication
         * @param string $prvkey  The private key of the sender
         * @param string $pubkey  The public key of the receiver
         * @param bool   $public  Is the message public?
         *
         * @return string The message that will be transmitted to other servers
         * @throws \Exception
         */
        public static function buildMessage($msg, array $user, array $contact, $prvkey, $pubkey, $public = false)
        {
                // The message is put into an envelope with the sender's signature
                $envelope = self::buildMagicEnvelope($msg, $user);

                // Private messages are put into a second envelope, encrypted with the receivers public key
                if (!$public) {
                        $envelope = self::encodePrivateData($envelope, $user, $contact, $prvkey, $pubkey);
                }

                return $envelope;
        }

        /**
         * Creates a signature for a message
         *
         * @param array $owner   the array of the owner of the message
         * @param array $message The message that is to be signed
         *
         * @return string The signature
         */
        private static function signature($owner, $message)
        {
                $sigmsg = $message;
                unset($sigmsg["author_signature"]);
                unset($sigmsg["parent_author_signature"]);

                $signed_text = implode(";", $sigmsg);

                return base64_encode(Crypto::rsaSign($signed_text, $owner["uprvkey"], "sha256"));
        }

        /**
         * Transmit a message to a target server
         *
         * @param array  $owner        the array of the item owner
         * @param array  $contact      Target of the communication
         * @param string $envelope     The message that is to be transmitted
         * @param bool   $public_batch Is it a public post?
         * @param string $guid         message guid
         *
         * @return int Result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function transmit(array $owner, array $contact, $envelope, $public_batch, $guid = "")
        {
                $enabled = intval(DI::config()->get("system", "diaspora_enabled"));
                if (!$enabled) {
                        return 200;
                }

                $logid = Strings::getRandomHex(4);

                // We always try to use the data from the fcontact table.
                // This is important for transmitting data to Friendica servers.
                if (!empty($contact['addr'])) {
                        $fcontact = self::personByHandle($contact['addr']);
                        if (!empty($fcontact)) {
                                $dest_url = ($public_batch ? $fcontact["batch"] : $fcontact["notify"]);
                        }
                }

                if (empty($dest_url)) {
                        $dest_url = ($public_batch ? $contact["batch"] : $contact["notify"]);
                }

                if (!$dest_url) {
                        Logger::log("no url for contact: ".$contact["id"]." batch mode =".$public_batch);
                        return 0;
                }

                Logger::log("transmit: ".$logid."-".$guid." ".$dest_url);

                if (!intval(DI::config()->get("system", "diaspora_test"))) {
                        $content_type = (($public_batch) ? "application/magic-envelope+xml" : "application/json");

                        $postResult = Network::post($dest_url."/", $envelope, ["Content-Type: ".$content_type]);
                        $return_code = $postResult->getReturnCode();
                } else {
                        Logger::log("test_mode");
                        return 200;
                }

                Logger::log("transmit: ".$logid."-".$guid." to ".$dest_url." returns: ".$return_code);

                return $return_code ? $return_code : -1;
        }


        /**
         * Build the post xml
         *
         * @param string $type    The message type
         * @param array  $message The message data
         *
         * @return string The post XML
         */
        public static function buildPostXml($type, $message)
        {
                $data = [$type => $message];

                return XML::fromArray($data, $xml);
        }

        /**
         * Builds and transmit messages
         *
         * @param array  $owner        the array of the item owner
         * @param array  $contact      Target of the communication
         * @param string $type         The message type
         * @param array  $message      The message data
         * @param bool   $public_batch Is it a public post?
         * @param string $guid         message guid
         *
         * @return int Result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        private static function buildAndTransmit(array $owner, array $contact, $type, $message, $public_batch = false, $guid = "")
        {
                $msg = self::buildPostXml($type, $message);

                Logger::log('message: '.$msg, Logger::DATA);
                Logger::log('send guid '.$guid, Logger::DEBUG);

                // Fallback if the private key wasn't transmitted in the expected field
                if (empty($owner['uprvkey'])) {
                        $owner['uprvkey'] = $owner['prvkey'];
                }

                $envelope = self::buildMessage($msg, $owner, $contact, $owner['uprvkey'], $contact['pubkey'], $public_batch);

                $return_code = self::transmit($owner, $contact, $envelope, $public_batch, $guid);

                Logger::log("guid: ".$guid." result ".$return_code, Logger::DEBUG);

                return $return_code;
        }

        /**
         * sends a participation (Used to get all further updates)
         *
         * @param array $contact Target of the communication
         * @param array $item    Item array
         *
         * @return int The result of the transmission
         * @throws \Exception
         */
        private static function sendParticipation(array $contact, array $item)
        {
                // Don't send notifications for private postings
                if ($item['private'] == Item::PRIVATE) {
                        return;
                }

                $cachekey = "diaspora:sendParticipation:".$item['guid'];

                $result = DI::cache()->get($cachekey);
                if (!is_null($result)) {
                        return;
                }

                // Fetch some user id to have a valid handle to transmit the participation.
                // In fact it doesn't matter which user sends this - but it is needed by the protocol.
                // If the item belongs to a user, we take this user id.
                if ($item['uid'] == 0) {
                        $condition = ['verified' => true, 'blocked' => false, 'account_removed' => false, 'account_expired' => false];
                        $first_user = DBA::selectFirst('user', ['uid'], $condition);
                        $owner = User::getOwnerDataById($first_user['uid']);
                } else {
                        $owner = User::getOwnerDataById($item['uid']);
                }

                $author = self::myHandle($owner);

                $message = ["author" => $author,
                                "guid" => System::createUUID(),
                                "parent_type" => "Post",
                                "parent_guid" => $item["guid"]];

                Logger::log("Send participation for ".$item["guid"]." by ".$author, Logger::DEBUG);

                // It doesn't matter what we store, we only want to avoid sending repeated notifications for the same item
                DI::cache()->set($cachekey, $item["guid"], Duration::QUARTER_HOUR);

                return self::buildAndTransmit($owner, $contact, "participation", $message);
        }

        /**
         * sends an account migration
         *
         * @param array $owner   the array of the item owner
         * @param array $contact Target of the communication
         * @param int   $uid     User ID
         *
         * @return int The result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function sendAccountMigration(array $owner, array $contact, $uid)
        {
                $old_handle = DI::pConfig()->get($uid, 'system', 'previous_addr');
                $profile = self::createProfileData($uid);

                $signed_text = 'AccountMigration:'.$old_handle.':'.$profile['author'];
                $signature = base64_encode(Crypto::rsaSign($signed_text, $owner["uprvkey"], "sha256"));

                $message = ["author" => $old_handle,
                                "profile" => $profile,
                                "signature" => $signature];

                Logger::log("Send account migration ".print_r($message, true), Logger::DEBUG);

                return self::buildAndTransmit($owner, $contact, "account_migration", $message);
        }

        /**
         * Sends a "share" message
         *
         * @param array $owner   the array of the item owner
         * @param array $contact Target of the communication
         *
         * @return int The result of the transmission
         * @throws \Exception
         */
        public static function sendShare(array $owner, array $contact)
        {
                /**
                 * @todo support the different possible combinations of "following" and "sharing"
                 * Currently, Diaspora only interprets the "sharing" field
                 *
                 * Before switching this code productive, we have to check all "sendShare" calls if "rel" is set correctly
                 */

                /*
                switch ($contact["rel"]) {
                        case Contact::FRIEND:
                                $following = true;
                                $sharing = true;

                        case Contact::SHARING:
                                $following = false;
                                $sharing = true;

                        case Contact::FOLLOWER:
                                $following = true;
                                $sharing = false;
                }
                */

                $message = ["author" => self::myHandle($owner),
                                "recipient" => $contact["addr"],
                                "following" => "true",
                                "sharing" => "true"];

                Logger::log("Send share ".print_r($message, true), Logger::DEBUG);

                return self::buildAndTransmit($owner, $contact, "contact", $message);
        }

        /**
         * sends an "unshare"
         *
         * @param array $owner   the array of the item owner
         * @param array $contact Target of the communication
         *
         * @return int The result of the transmission
         * @throws \Exception
         */
        public static function sendUnshare(array $owner, array $contact)
        {
                $message = ["author" => self::myHandle($owner),
                                "recipient" => $contact["addr"],
                                "following" => "false",
                                "sharing" => "false"];

                Logger::log("Send unshare ".print_r($message, true), Logger::DEBUG);

                return self::buildAndTransmit($owner, $contact, "contact", $message);
        }

        /**
         * Checks a message body if it is a reshare
         *
         * @param string $body     The message body that is to be check
         * @param bool   $complete Should it be a complete check or a simple check?
         *
         * @return array|bool Reshare details or "false" if no reshare
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function isReshare($body, $complete = true)
        {
                $body = trim($body);

                $reshared = Item::getShareArray(['body' => $body]);
                if (empty($reshared)) {
                        return false;
                }

                // Skip if it isn't a pure repeated messages
                // Does it start with a share?
                if (!empty($reshared['comment']) && $complete) {
                        return false;
                }

                if (!empty($reshared['guid']) && $complete) {
                        $condition = ['guid' => $reshared['guid'], 'network' => [Protocol::DFRN, Protocol::DIASPORA]];
                        $item = Item::selectFirst(['contact-id'], $condition);
                        if (DBA::isResult($item)) {
                                $ret = [];
                                $ret["root_handle"] = self::handleFromContact($item["contact-id"]);
                                $ret["root_guid"] = $reshared['guid'];
                                return $ret;
                        } elseif ($complete) {
                                // We are resharing something that isn't a DFRN or Diaspora post.
                                // So we have to return "false" on "$complete" to not trigger a reshare.
                                return false;
                        }
                } elseif (empty($reshared['guid']) && $complete) {
                        return false;
                }

                $ret = [];

                if (!empty($reshared['profile']) && ($cid = Contact::getIdForURL($reshared['profile']))) {
                        $contact = DBA::selectFirst('contact', ['addr'], ['id' => $cid]);
                        if (!empty($contact['addr'])) {
                                $ret['root_handle'] = $contact['addr'];
                        }
                }

                if (empty($ret) && !$complete) {
                        return true;
                }

                return $ret;
        }

        /**
         * Create an event array
         *
         * @param integer $event_id The id of the event
         *
         * @return array with event data
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function buildEvent($event_id)
        {
                $r = q("SELECT `guid`, `uid`, `start`, `finish`, `nofinish`, `summary`, `desc`, `location`, `adjust` FROM `event` WHERE `id` = %d", intval($event_id));
                if (!DBA::isResult($r)) {
                        return [];
                }

                $event = $r[0];

                $eventdata = [];

                $r = q("SELECT `timezone` FROM `user` WHERE `uid` = %d", intval($event['uid']));
                if (!DBA::isResult($r)) {
                        return [];
                }

                $user = $r[0];

                $r = q("SELECT `addr`, `nick` FROM `contact` WHERE `uid` = %d AND `self`", intval($event['uid']));
                if (!DBA::isResult($r)) {
                        return [];
                }

                $owner = $r[0];

                $eventdata['author'] = self::myHandle($owner);

                if ($event['guid']) {
                        $eventdata['guid'] = $event['guid'];
                }

                $mask = DateTimeFormat::ATOM;

                /// @todo - establish "all day" events in Friendica
                $eventdata["all_day"] = "false";

                $eventdata['timezone'] = 'UTC';
                if (!$event['adjust'] && $user['timezone']) {
                        $eventdata['timezone'] = $user['timezone'];
                }

                if ($event['start']) {
                        $eventdata['start'] = DateTimeFormat::convert($event['start'], "UTC", $eventdata['timezone'], $mask);
                }
                if ($event['finish'] && !$event['nofinish']) {
                        $eventdata['end'] = DateTimeFormat::convert($event['finish'], "UTC", $eventdata['timezone'], $mask);
                }
                if ($event['summary']) {
                        $eventdata['summary'] = html_entity_decode(BBCode::toMarkdown($event['summary']));
                }
                if ($event['desc']) {
                        $eventdata['description'] = html_entity_decode(BBCode::toMarkdown($event['desc']));
                }
                if ($event['location']) {
                        $event['location'] = preg_replace("/\[map\](.*?)\[\/map\]/ism", '$1', $event['location']);
                        $coord = Map::getCoordinates($event['location']);

                        $location = [];
                        $location["address"] = html_entity_decode(BBCode::toMarkdown($event['location']));
                        if (!empty($coord['lat']) && !empty($coord['lon'])) {
                                $location["lat"] = $coord['lat'];
                                $location["lng"] = $coord['lon'];
                        } else {
                                $location["lat"] = 0;
                                $location["lng"] = 0;
                        }
                        $eventdata['location'] = $location;
                }

                return $eventdata;
        }

        /**
         * Create a post (status message or reshare)
         *
         * @param array $item  The item that will be exported
         * @param array $owner the array of the item owner
         *
         * @return array
         * 'type' -> Message type ("status_message" or "reshare")
         * 'message' -> Array of XML elements of the status
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function buildStatus(array $item, array $owner)
        {
                $cachekey = "diaspora:buildStatus:".$item['guid'];

                $result = DI::cache()->get($cachekey);
                if (!is_null($result)) {
                        return $result;
                }

                $myaddr = self::myHandle($owner);

                $public = ($item["private"] == Item::PRIVATE ? "false" : "true");
                $created = DateTimeFormat::utc($item['received'], DateTimeFormat::ATOM);
                $edited = DateTimeFormat::utc($item["edited"] ?? $item["created"], DateTimeFormat::ATOM);

                // Detect a share element and do a reshare
                if (($item['private'] != Item::PRIVATE) && ($ret = self::isReshare($item["body"]))) {
                        $message = ["author" => $myaddr,
                                        "guid" => $item["guid"],
                                        "created_at" => $created,
                                        "root_author" => $ret["root_handle"],
                                        "root_guid" => $ret["root_guid"],
                                        "provider_display_name" => $item["app"],
                                        "public" => $public];

                        $type = "reshare";
                } else {
                        $title = $item["title"];
                        $body = $item["body"];

                        // Fetch the title from an attached link - if there is one
                        if (empty($item["title"]) && DI::pConfig()->get($owner['uid'], 'system', 'attach_link_title')) {
                                $page_data = BBCode::getAttachmentData($item['body']);
                                if (!empty($page_data['type']) && !empty($page_data['title']) && ($page_data['type'] == 'link')) {
                                        $title = $page_data['title'];
                                }
                        }

                        if ($item['author-link'] != $item['owner-link']) {
                                require_once 'mod/share.php';
                                $body = share_header($item['author-name'], $item['author-link'], $item['author-avatar'],
                                        "", $item['created'], $item['plink']) . $body . '[/share]';
                        }

                        // convert to markdown
                        $body = html_entity_decode(BBCode::toMarkdown($body));

                        // Adding the title
                        if (strlen($title)) {
                                $body = "### ".html_entity_decode($title)."\n\n".$body;
                        }

                        if ($item["attach"]) {
                                $cnt = preg_match_all('/href=\"(.*?)\"(.*?)title=\"(.*?)\"/ism', $item["attach"], $matches, PREG_SET_ORDER);
                                if ($cnt) {
                                        $body .= "\n".DI::l10n()->t("Attachments:")."\n";
                                        foreach ($matches as $mtch) {
                                                $body .= "[".$mtch[3]."](".$mtch[1].")\n";
                                        }
                                }
                        }

                        $location = [];

                        if ($item["location"] != "")
                                $location["address"] = $item["location"];

                        if ($item["coord"] != "") {
                                $coord = explode(" ", $item["coord"]);
                                $location["lat"] = $coord[0];
                                $location["lng"] = $coord[1];
                        }

                        $message = ["author" => $myaddr,
                                        "guid" => $item["guid"],
                                        "created_at" => $created,
                                        "edited_at" => $edited,
                                        "public" => $public,
                                        "text" => $body,
                                        "provider_display_name" => $item["app"],
                                        "location" => $location];

                        // Diaspora rejects messages when they contain a location without "lat" or "lng"
                        if (!isset($location["lat"]) || !isset($location["lng"])) {
                                unset($message["location"]);
                        }

                        if ($item['event-id'] > 0) {
                                $event = self::buildEvent($item['event-id']);
                                if (count($event)) {
                                        $message['event'] = $event;

                                        if (!empty($event['location']['address']) &&
                                                !empty($event['location']['lat']) &&
                                                !empty($event['location']['lng'])) {
                                                $message['location'] = $event['location'];
                                        }

                                        /// @todo Once Diaspora supports it, we will remove the body and the location hack above
                                        // $message['text'] = '';
                                }
                        }

                        $type = "status_message";
                }

                $msg = ["type" => $type, "message" => $message];

                DI::cache()->set($cachekey, $msg, Duration::QUARTER_HOUR);

                return $msg;
        }

        private static function prependParentAuthorMention($body, $profile_url)
        {
                $profile = Contact::getDetailsByURL($profile_url);
                if (!empty($profile['addr'])
                        && $profile['contact-type'] != Contact::TYPE_COMMUNITY
                        && !strstr($body, $profile['addr'])
                        && !strstr($body, $profile_url)
                ) {
                        $body = '@[url=' . $profile_url . ']' . $profile['name'] . '[/url] ' . $body;
                }

                return $body;
        }

        /**
         * Sends a post
         *
         * @param array $item         The item that will be exported
         * @param array $owner        the array of the item owner
         * @param array $contact      Target of the communication
         * @param bool  $public_batch Is it a public post?
         *
         * @return int The result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function sendStatus(array $item, array $owner, array $contact, $public_batch = false)
        {
                $status = self::buildStatus($item, $owner);

                return self::buildAndTransmit($owner, $contact, $status["type"], $status["message"], $public_batch, $item["guid"]);
        }

        /**
         * Creates a "like" object
         *
         * @param array $item  The item that will be exported
         * @param array $owner the array of the item owner
         *
         * @return array The data for a "like"
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function constructLike(array $item, array $owner)
        {
                $parent = Item::selectFirst(['guid', 'uri', 'parent-uri'], ['uri' => $item["thr-parent"]]);
                if (!DBA::isResult($parent)) {
                        return false;
                }

                $target_type = ($parent["uri"] === $parent["parent-uri"] ? "Post" : "Comment");
                $positive = null;
                if ($item['verb'] === Activity::LIKE) {
                        $positive = "true";
                } elseif ($item['verb'] === Activity::DISLIKE) {
                        $positive = "false";
                }

                return(["author" => self::myHandle($owner),
                                "guid" => $item["guid"],
                                "parent_guid" => $parent["guid"],
                                "parent_type" => $target_type,
                                "positive" => $positive,
                                "author_signature" => ""]);
        }

        /**
         * Creates an "EventParticipation" object
         *
         * @param array $item  The item that will be exported
         * @param array $owner the array of the item owner
         *
         * @return array The data for an "EventParticipation"
         * @throws \Exception
         */
        private static function constructAttend(array $item, array $owner)
        {
                $parent = Item::selectFirst(['guid', 'uri', 'parent-uri'], ['uri' => $item["thr-parent"]]);
                if (!DBA::isResult($parent)) {
                        return false;
                }

                switch ($item['verb']) {
                        case Activity::ATTEND:
                                $attend_answer = 'accepted';
                                break;
                        case Activity::ATTENDNO:
                                $attend_answer = 'declined';
                                break;
                        case Activity::ATTENDMAYBE:
                                $attend_answer = 'tentative';
                                break;
                        default:
                                Logger::log('Unknown verb '.$item['verb'].' in item '.$item['guid']);
                                return false;
                }

                return(["author" => self::myHandle($owner),
                                "guid" => $item["guid"],
                                "parent_guid" => $parent["guid"],
                                "status" => $attend_answer,
                                "author_signature" => ""]);
        }

        /**
         * Creates the object for a comment
         *
         * @param array $item  The item that will be exported
         * @param array $owner the array of the item owner
         *
         * @return array|false The data for a comment
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function constructComment(array $item, array $owner)
        {
                $cachekey = "diaspora:constructComment:".$item['guid'];

                $result = DI::cache()->get($cachekey);
                if (!is_null($result)) {
                        return $result;
                }

                $toplevel_item = Item::selectFirst(['guid', 'author-id', 'author-link'], ['id' => $item["parent"], 'parent' => $item["parent"]]);
                if (!DBA::isResult($toplevel_item)) {
                        Logger::error('Missing parent conversation item', ['parent' => $item["parent"]]);
                        return false;
                }

                $thread_parent_item = $toplevel_item;
                if ($item['thr-parent'] != $item['parent-uri']) {
                        $thread_parent_item = Item::selectFirst(['guid', 'author-id', 'author-link'], ['uri' => $item['thr-parent'], 'uid' => $item['uid']]);
                }

                $body = $item["body"];

                // The replied to autor mention is prepended for clarity if:
                // - Item replied isn't yours
                // - Item is public or explicit mentions are disabled
                // - Implicit mentions are enabled
                if (
                        $item['author-id'] != $thread_parent_item['author-id']
                        && (empty($item['uid']) || !Feature::isEnabled($item['uid'], 'explicit_mentions'))
                        && !DI::config()->get('system', 'disable_implicit_mentions')
                ) {
                        $body = self::prependParentAuthorMention($body, $thread_parent_item['author-link']);
                }

                $text = html_entity_decode(BBCode::toMarkdown($body));
                $created = DateTimeFormat::utc($item["created"], DateTimeFormat::ATOM);
                $edited = DateTimeFormat::utc($item["edited"], DateTimeFormat::ATOM);

                $comment = [
                        "author"      => self::myHandle($owner),
                        "guid"        => $item["guid"],
                        "created_at"  => $created,
                        "edited_at"   => $edited,
                        "parent_guid" => $toplevel_item["guid"],
                        "text"        => $text,
                        "author_signature" => ""
                ];

                // Send the thread parent guid only if it is a threaded comment
                if ($item['thr-parent'] != $item['parent-uri']) {
                        $comment['thread_parent_guid'] = $thread_parent_item['guid'];
                }

                DI::cache()->set($cachekey, $comment, Duration::QUARTER_HOUR);

                return($comment);
        }

        /**
         * Send a like or a comment
         *
         * @param array $item         The item that will be exported
         * @param array $owner        the array of the item owner
         * @param array $contact      Target of the communication
         * @param bool  $public_batch Is it a public post?
         *
         * @return int The result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function sendFollowup(array $item, array $owner, array $contact, $public_batch = false)
        {
                if (in_array($item['verb'], [Activity::ATTEND, Activity::ATTENDNO, Activity::ATTENDMAYBE])) {
                        $message = self::constructAttend($item, $owner);
                        $type = "event_participation";
                } elseif (in_array($item["verb"], [Activity::LIKE, Activity::DISLIKE])) {
                        $message = self::constructLike($item, $owner);
                        $type = "like";
                } elseif (!in_array($item["verb"], [Activity::FOLLOW, Activity::TAG])) {
                        $message = self::constructComment($item, $owner);
                        $type = "comment";
                }

                if (empty($message)) {
                        return false;
                }

                $message["author_signature"] = self::signature($owner, $message);

                return self::buildAndTransmit($owner, $contact, $type, $message, $public_batch, $item["guid"]);
        }

        /**
         * Creates a message from a signature record entry
         *
         * @param array $item The item that will be exported
         * @return array The message
         */
        private static function messageFromSignature(array $item)
        {
                // Split the signed text
                $signed_parts = explode(";", $item['signed_text']);

                if ($item["deleted"]) {
                        $message = ["author" => $item['signer'],
                                        "target_guid" => $signed_parts[0],
                                        "target_type" => $signed_parts[1]];
                } elseif (in_array($item["verb"], [Activity::LIKE, Activity::DISLIKE])) {
                        $message = ["author" => $signed_parts[4],
                                        "guid" => $signed_parts[1],
                                        "parent_guid" => $signed_parts[3],
                                        "parent_type" => $signed_parts[2],
                                        "positive" => $signed_parts[0],
                                        "author_signature" => $item['signature'],
                                        "parent_author_signature" => ""];
                } else {
                        // Remove the comment guid
                        $guid = array_shift($signed_parts);

                        // Remove the parent guid
                        $parent_guid = array_shift($signed_parts);

                        // Remove the handle
                        $handle = array_pop($signed_parts);

                        $message = [
                                "author" => $handle,
                                "guid" => $guid,
                                "parent_guid" => $parent_guid,
                                "text" => implode(";", $signed_parts),
                                "author_signature" => $item['signature'],
                                "parent_author_signature" => ""
                        ];
                }
                return $message;
        }

        /**
         * Relays messages (like, comment, retraction) to other servers if we are the thread owner
         *
         * @param array $item         The item that will be exported
         * @param array $owner        the array of the item owner
         * @param array $contact      Target of the communication
         * @param bool  $public_batch Is it a public post?
         *
         * @return int The result of the transmission
         * @throws \Exception
         */
        public static function sendRelay(array $item, array $owner, array $contact, $public_batch = false)
        {
                if ($item["deleted"]) {
                        return self::sendRetraction($item, $owner, $contact, $public_batch, true);
                } elseif (in_array($item["verb"], [Activity::LIKE, Activity::DISLIKE])) {
                        $type = "like";
                } else {
                        $type = "comment";
                }

                Logger::log("Got relayable data ".$type." for item ".$item["guid"]." (".$item["id"].")", Logger::DEBUG);

                $msg = json_decode($item['signed_text'], true);

                $message = [];
                if (is_array($msg)) {
                        foreach ($msg as $field => $data) {
                                if (!$item["deleted"]) {
                                        if ($field == "diaspora_handle") {
                                                $field = "author";
                                        }
                                        if ($field == "target_type") {
                                                $field = "parent_type";
                                        }
                                }

                                $message[$field] = $data;
                        }
                } else {
                        Logger::log("Signature text for item ".$item["guid"]." (".$item["id"].") couldn't be extracted: ".$item['signed_text'], Logger::DEBUG);
                }

                $message["parent_author_signature"] = self::signature($owner, $message);

                Logger::log("Relayed data ".print_r($message, true), Logger::DEBUG);

                return self::buildAndTransmit($owner, $contact, $type, $message, $public_batch, $item["guid"]);
        }

        /**
         * Sends a retraction (deletion) of a message, like or comment
         *
         * @param array $item         The item that will be exported
         * @param array $owner        the array of the item owner
         * @param array $contact      Target of the communication
         * @param bool  $public_batch Is it a public post?
         * @param bool  $relay        Is the retraction transmitted from a relay?
         *
         * @return int The result of the transmission
         * @throws \Exception
         */
        public static function sendRetraction(array $item, array $owner, array $contact, $public_batch = false, $relay = false)
        {
                $itemaddr = self::handleFromContact($item["contact-id"], $item["author-id"]);

                $msg_type = "retraction";

                if ($item['id'] == $item['parent']) {
                        $target_type = "Post";
                } elseif (in_array($item["verb"], [Activity::LIKE, Activity::DISLIKE])) {
                        $target_type = "Like";
                } else {
                        $target_type = "Comment";
                }

                $message = ["author" => $itemaddr,
                                "target_guid" => $item['guid'],
                                "target_type" => $target_type];

                Logger::log("Got message ".print_r($message, true), Logger::DEBUG);

                return self::buildAndTransmit($owner, $contact, $msg_type, $message, $public_batch, $item["guid"]);
        }

        /**
         * Sends a mail
         *
         * @param array $item    The item that will be exported
         * @param array $owner   The owner
         * @param array $contact Target of the communication
         *
         * @return int The result of the transmission
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         * @throws \ImagickException
         */
        public static function sendMail(array $item, array $owner, array $contact)
        {
                $myaddr = self::myHandle($owner);

                $cnv = DBA::selectFirst('conv', [], ['id' => $item["convid"], 'uid' => $item["uid"]]);
                if (!DBA::isResult($cnv)) {
                        Logger::log("conversation not found.");
                        return;
                }

                $body = BBCode::toMarkdown($item["body"]);
                $created = DateTimeFormat::utc($item["created"], DateTimeFormat::ATOM);

                $msg = [
                        "author" => $myaddr,
                        "guid" => $item["guid"],
                        "conversation_guid" => $cnv["guid"],
                        "text" => $body,
                        "created_at" => $created,
                ];

                if ($item["reply"]) {
                        $message = $msg;
                        $type = "message";
                } else {
                        $message = [
                                "author" => $cnv["creator"],
                                "guid" => $cnv["guid"],
                                "subject" => $cnv["subject"],
                                "created_at" => DateTimeFormat::utc($cnv['created'], DateTimeFormat::ATOM),
                                "participants" => $cnv["recips"],
                                "message" => $msg
                        ];

                        $type = "conversation";
                }

                return self::buildAndTransmit($owner, $contact, $type, $message, false, $item["guid"]);
        }

        /**
         * Split a name into first name and last name
         *
         * @param string $name The name
         *
         * @return array The array with "first" and "last"
         */
        public static function splitName($name) {
                $name = trim($name);

                // Is the name longer than 64 characters? Then cut the rest of it.
                if (strlen($name) > 64) {
                        if ((strpos($name, ' ') <= 64) && (strpos($name, ' ') !== false)) {
                                $name = trim(substr($name, 0, strrpos(substr($name, 0, 65), ' ')));
                        } else {
                                $name = substr($name, 0, 64);
                        }
                }

                // Take the first word as first name
                $first = ((strpos($name, ' ') ? trim(substr($name, 0, strpos($name, ' '))) : $name));
                $last = (($first === $name) ? '' : trim(substr($name, strlen($first))));
                if ((strlen($first) < 32) && (strlen($last) < 32)) {
                        return ['first' => $first, 'last' => $last];
                }

                // Take the last word as last name
                $first = ((strrpos($name, ' ') ? trim(substr($name, 0, strrpos($name, ' '))) : $name));
                $last = (($first === $name) ? '' : trim(substr($name, strlen($first))));

                if ((strlen($first) < 32) && (strlen($last) < 32)) {
                        return ['first' => $first, 'last' => $last];
                }

                // Take the first 32 characters if there is no space in the first 32 characters
                if ((strpos($name, ' ') > 32) || (strpos($name, ' ') === false)) {
                        $first = substr($name, 0, 32);
                        $last = substr($name, 32);
                        return ['first' => $first, 'last' => $last];
                }

                $first = trim(substr($name, 0, strrpos(substr($name, 0, 33), ' ')));
                $last = (($first === $name) ? '' : trim(substr($name, strlen($first))));

                // Check if the last name is longer than 32 characters
                if (strlen($last) > 32) {
                        if (strpos($last, ' ') <= 32) {
                                $last = trim(substr($last, 0, strrpos(substr($last, 0, 33), ' ')));
                        } else {
                                $last = substr($last, 0, 32);
                        }
                }

                return ['first' => $first, 'last' => $last];
        }

        /**
         * Create profile data
         *
         * @param int $uid The user id
         *
         * @return array The profile data
         * @throws \Friendica\Network\HTTPException\InternalServerErrorException
         */
        private static function createProfileData($uid)
        {
                $profile = DBA::selectFirst('owner-view', ['uid', 'addr', 'name', 'location', 'net-publish', 'dob', 'about', 'pub_keywords'], ['uid' => $uid]);
                if (!DBA::isResult($profile)) {
                        return [];
                }

                $handle = $profile["addr"];

                $split_name = self::splitName($profile['name']);
                $first = $split_name['first'];
                $last = $split_name['last'];

                $large = DI::baseUrl().'/photo/custom/300/'.$profile['uid'].'.jpg';
                $medium = DI::baseUrl().'/photo/custom/100/'.$profile['uid'].'.jpg';
                $small = DI::baseUrl().'/photo/custom/50/'  .$profile['uid'].'.jpg';
                $searchable = ($profile['net-publish'] ? 'true' : 'false');

                $dob = null;
                $about = null;
                $location = null;
                $tags = null;
                if ($searchable === 'true') {
                        $dob = '';

                        if ($profile['dob'] && ($profile['dob'] > '0000-00-00')) {
                                list($year, $month, $day) = sscanf($profile['dob'], '%4d-%2d-%2d');
                                if ($year < 1004) {
                                        $year = 1004;
                                }
                                $dob = DateTimeFormat::utc($year . '-' . $month . '-'. $day, 'Y-m-d');
                        }

                        $about = BBCode::toMarkdown($profile['about']);

                        $location = $profile['location'];
                        $tags = '';
                        if ($profile['pub_keywords']) {
                                $kw = str_replace(',', ' ', $profile['pub_keywords']);
                                $kw = str_replace('  ', ' ', $kw);
                                $arr = explode(' ', $kw);
                                if (count($arr)) {
                                        for ($x = 0; $x < 5; $x ++) {
                                                if (!empty($arr[$x])) {
                                                        $tags .= '#'. trim($arr[$x]) .' ';
                                                }
                                        }
                                }
                        }
                        $tags = trim($tags);
                }

                return ["author" => $handle,
                                "first_name" => $first,
                                "last_name" => $last,
                                "image_url" => $large,
                                "image_url_medium" => $medium,
                                "image_url_small" => $small,
                                "birthday" => $dob,
                                "bio" => $about,
                                "location" => $location,
                                "searchable" => $searchable,
                                "nsfw" => "false",
                                "tag_string" => $tags];
        }

        /**
         * Sends profile data
         *
         * @param int  $uid    The user id
         * @param bool $recips optional, default false
         * @return void
         * @throws \Exception
         */
        public static function sendProfile($uid, $recips = false)
        {
                if (!$uid) {
                        return;
                }

                $owner = User::getOwnerDataById($uid);
                if (!$owner) {
                        return;
                }

                if (!$recips) {
                        $recips = q(
                                "SELECT `id`,`name`,`network`,`pubkey`,`notify` FROM `contact` WHERE `network` = '%s'
                                AND `uid` = %d AND `rel` != %d",
                                DBA::escape(Protocol::DIASPORA),
                                intval($uid),
                                intval(Contact::SHARING)
                        );
                }

                if (!$recips) {
                        return;
                }

                $message = self::createProfileData($uid);

                // @ToDo Split this into single worker jobs
                foreach ($recips as $recip) {
                        Logger::log("Send updated profile data for user ".$uid." to contact ".$recip["id"], Logger::DEBUG);
                        self::buildAndTransmit($owner, $recip, "profile", $message);
                }
        }

        /**
         * Creates the signature for likes that are created on our system
         *
         * @param integer $uid  The user of that comment
         * @param array   $item Item array
         *
         * @return array Signed content
         * @throws \Exception
         */
        public static function createLikeSignature($uid, array $item)
        {
                $owner = User::getOwnerDataById($uid);
                if (empty($owner)) {
                        Logger::log("No owner post, so not storing signature", Logger::DEBUG);
                        return false;
                }

                if (!in_array($item["verb"], [Activity::LIKE, Activity::DISLIKE])) {
                        return false;
                }

                $message = self::constructLike($item, $owner);
                if ($message === false) {
                        return false;
                }

                $message["author_signature"] = self::signature($owner, $message);

                return $message;
        }

        /**
         * Creates the signature for Comments that are created on our system
         *
         * @param integer $uid  The user of that comment
         * @param array   $item Item array
         *
         * @return array Signed content
         * @throws \Exception
         */
        public static function createCommentSignature($uid, array $item)
        {
                $owner = User::getOwnerDataById($uid);
                if (empty($owner)) {
                        Logger::log("No owner post, so not storing signature", Logger::DEBUG);
                        return false;
                }

                // This is a workaround for the behaviour of the "insert" function, see mod/item.php
                $item['thr-parent'] = $item['parent-uri'];

                $parent = Item::selectFirst(['parent-uri'], ['uri' => $item['parent-uri']]);
                if (!DBA::isResult($parent)) {
                        return;
                }

                $item['parent-uri'] = $parent['parent-uri'];

                $message = self::constructComment($item, $owner);
                if ($message === false) {
                        return false;
                }

                $message["author_signature"] = self::signature($owner, $message);

                return $message;
        }
}