<?php
/*
 * StatusNet - the distributed open-source microblogging tool
 * Copyright (C) 2008, 2009, StatusNet, Inc.
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

if (!defined('GNUSOCIAL')) { exit(1); }

/**
 * Table Definition for file_redirection
 */

class File_redirection extends Managed_DataObject
{
    ###START_AUTOCODE
    /* the code below is auto generated do not remove the above tag */

    public $__table = 'file_redirection';                // table name
    public $urlhash;                         // varchar(64) primary_key not_null
    public $url;                             // text
    public $file_id;                         // int(4)
    public $redirections;                    // int(4)
    public $httpcode;                        // int(4)
    public $modified;                        // timestamp()   not_null default_CURRENT_TIMESTAMP

    /* the code above is auto generated do not remove the tag below */
    ###END_AUTOCODE

    protected $file; /* Cache the associated file sometimes */

    public static function schemaDef()
    {
        return array(
            'fields' => array(
                'urlhash' => array('type' => 'varchar', 'length' => 64, 'not null' => true, 'description' => 'sha256 hash of the URL'),
                'url' => array('type' => 'text', 'description' => 'short URL (or any other kind of redirect) for file (id)'),
                'file_id' => array('type' => 'int', 'description' => 'short URL for what URL/file'),
                'redirections' => array('type' => 'int', 'description' => 'redirect count'),
                'httpcode' => array('type' => 'int', 'description' => 'HTTP status code (20x, 30x, etc.)'),
                'modified' => array('type' => 'timestamp', 'not null' => true, 'description' => 'date this record was modified'),
            ),
            'primary key' => array('urlhash'),
            'foreign keys' => array(
                'file_redirection_file_id_fkey' => array('file' => array('file_id' => 'id')),
            ),
        );
    }

    static public function getByUrl($url)
    {
        return self::getByPK(array('urlhash' => File::hashurl($url)));
    }

    static function _commonHttp($url, $redirs) {
        $request = new HTTPClient($url);
        $request->setConfig(array(
            'connect_timeout' => 10, // # seconds to wait
            'max_redirs' => $redirs, // # max number of http redirections to follow
            'follow_redirects' => true, // Follow redirects
            'store_body' => false, // We won't need body content here.
        ));
        return $request;
    }

    /**
     * Check if this URL is a redirect and return redir info.
     *
     * Most code should call File_redirection::where instead, to check if we
     * already know that redirection and avoid extra hits to the web.
     *
     * The URL is hit and any redirects are followed, up to 10 levels or until
     * a protected URL is reached.
     *
     * @param string $in_url
     * @return mixed one of:
     *         string - target URL, if this is a direct link or can't be followed
     *         array - redirect info if this is an *unknown* redirect:
     *              associative array with the following elements:
     *                code: HTTP status code
     *                redirects: count of redirects followed
     *                url: URL string of final target
     *                type (optional): MIME type from Content-Type header
     *                size (optional): byte size from Content-Length header
     *                time (optional): timestamp from Last-Modified header
     */
    static function lookupWhere($short_url, $redirs = 10, $protected = false) {
        if ($redirs < 0) return false;

        if(strpos($short_url,'://') === false){
            return $short_url;
        }
        try {
            $request = self::_commonHttp($short_url, $redirs);
            // Don't include body in output
            $request->setMethod(HTTP_Request2::METHOD_HEAD);
            $response = $request->send();

            if (405 == $response->getStatus() || 204 == $response->getStatus()) {
                // HTTP 405 Unsupported Method
                // Server doesn't support HEAD method? Can this really happen?
                // We'll try again as a GET and ignore the response data.
                //
                // HTTP 204 No Content
                // YFrog sends 204 responses back for our HEAD checks, which
                // seems like it may be a logic error in their servers. If
                // we get a 204 back, re-run it as a GET... if there's really
                // no content it'll be cheap. :)
                $request = self::_commonHttp($short_url, $redirs);
                $response = $request->send();
            }
        } catch (Exception $e) {
            // Invalid URL or failure to reach server
            common_log(LOG_ERR, "Error while following redirects for $short_url: " . $e->getMessage());
            return $short_url;
        }

        if ($response->getRedirectCount() && File::isProtected($response->getUrl())) {
            // Bump back up the redirect chain until we find a non-protected URL
            return self::lookupWhere($short_url, $response->getRedirectCount() - 1, true);
        }

        $ret = array('code' => $response->getStatus()
                , 'redirects' => $response->getRedirectCount()
                , 'url' => $response->getUrl());

        $type = $response->getHeader('Content-Type');
        if ($type) $ret['type'] = $type;
        if ($protected) $ret['protected'] = true;
        $size = $response->getHeader('Content-Length'); // @fixme bytes?
        if ($size) $ret['size'] = $size;
        $time = $response->getHeader('Last-Modified');
        if ($time) $ret['time'] = strtotime($time);
        return $ret;
    }

    /**
     * Check if this URL is a redirect and return redir info.
     * If a File record is present for this URL, it is not considered a redirect.
     * If a File_redirection record is present for this URL, the recorded target is returned.
     *
     * If no File or File_redirect record is present, the URL is hit and any
     * redirects are followed, up to 10 levels or until a protected URL is
     * reached.
     *
     * @param string $in_url
     * @param boolean $discover true to attempt dereferencing the redirect if we don't know it already
     * @return File_redirection
     */
    static function where($in_url, $discover=true) {
        $redir = new File_redirection();
        $redir->url = $in_url;
        $redir->urlhash = File::hashurl($redir->url);
        $redir->redirections = 0;

        try {
            $r = File_redirection::getByUrl($in_url);
            if($r instanceof File_redirection) {
                return $r;
            }
        } catch (NoResultException $e) {
            try {
                $f = File::getByUrl($in_url);
                $redir->file_id = $f->id;
                $redir->file = $f;
                return $redir;
            } catch (NoResultException $e) {
                // Oh well, let's keep going
            }
        }

        if ($discover) {
            $redir_info = File_redirection::lookupWhere($in_url);
            if(is_string($redir_info)) {
                $redir_info = array('url' => $redir_info);
            }

            // Double check that we don't already have the resolved URL
            $r = self::where($redir_info['url'], false);
            if (!empty($r->file_id)) {
                return $r;
            }

            $redir->httpcode = $redir_info['code'];
            $redir->redirections = intval($redir_info['redirects']);
            $redir->file = new File();
            $redir->file->url = $redir_info ? $redir_info['url'] : $in_url;
            $redir->file->mimetype = $redir_info['type'];
            $redir->file->size = $redir_info['size'];
            $redir->file->date = $redir_info['time'];
            if ($redir_info['protected']) {
                $redir->file->protected = true;
            }
        }

        return $redir;
    }

    /**
     * Shorten a URL with the current user's configured shortening
     * options, if applicable.
     *
     * If it cannot be shortened or the "short" URL is longer than the
     * original, the original is returned.
     *
     * If the referenced item has not been seen before, embedding data
     * may be saved.
     *
     * @param string $long_url
     * @param User $user whose shortening options to use; defaults to the current web session user
     * @return string
     */
    static function makeShort($long_url, $user=null)
    {
        $canon = File_redirection::_canonUrl($long_url);

        $short_url = File_redirection::_userMakeShort($canon, $user);

        // Did we get one? Is it shorter?

        return !empty($short_url) ? $short_url : $long_url;
    }

    /**
     * Shorten a URL with the current user's configured shortening
     * options, if applicable.
     *
     * If it cannot be shortened or the "short" URL is longer than the
     * original, the original is returned.
     *
     * If the referenced item has not been seen before, embedding data
     * may be saved.
     *
     * @param string $long_url
     * @return string
     */

    static function forceShort($long_url, $user)
    {
        $canon = File_redirection::_canonUrl($long_url);

        $short_url = File_redirection::_userMakeShort($canon, $user, true);

        // Did we get one? Is it shorter?
        return !empty($short_url) ? $short_url : $long_url;
    }

    static function _userMakeShort($long_url, User $user=null, $force = false) {
        $short_url = common_shorten_url($long_url, $user, $force);
        if (!empty($short_url) && $short_url != $long_url) {
            $short_url = (string)$short_url;
            // store it
            $file = File::getKV('url', $long_url);
            if (!$file instanceof File) {
                // Check if the target URL is itself a redirect...
                $redir = File_redirection::where($long_url);
                $file = $redir->getFile();
                if (empty($file->id)) {
                    $file->saveFile();
                }
            }
            $file_redir = File_redirection::getKV('url', $short_url);
            if (!$file_redir instanceof File_redirection) {
                $file_redir = new File_redirection;
                $file_redir->urlhash = File::hashurl($short_url);
                $file_redir->url = $short_url;
                $file_redir->file_id = $file->id;
                $file_redir->insert();
            }
            return $short_url;
        }
        return null;
    }

    /**
     * Basic attempt to canonicalize a URL, cleaning up some standard variants
     * such as funny syntax or a missing path. Used internally when cleaning
     * up URLs for storage and following redirect chains.
     *
     * Note that despite being on File_redirect, this function DOES NOT perform
     * any dereferencing of redirects.
     *
     * @param string $in_url input URL
     * @param string $default_scheme if given a bare link; defaults to 'http://'
     * @return string
     */
    static function _canonUrl($in_url, $default_scheme = 'http://') {
        if (empty($in_url)) return false;
        $out_url = $in_url;
        $p = parse_url($out_url);
        if (empty($p['host']) || empty($p['scheme'])) {
            list($scheme) = explode(':', $in_url, 2);
            switch (strtolower($scheme)) {
            case 'fax':
            case 'tel':
                $out_url = str_replace('.-()', '', $out_url);
                break;

            case 'mailto':
            case 'magnet':
            case 'aim':
            case 'jabber':
            case 'xmpp':
                // don't touch anything
                break;

            default:
                $out_url = $default_scheme . ltrim($out_url, '/');
                $p = parse_url($out_url);
                if (empty($p['scheme'])) return false;
                break;
            }
        }

        if (('ftp' == $p['scheme']) || ('ftps' == $p['scheme']) || ('http' == $p['scheme']) || ('https' == $p['scheme'])) {
            if (empty($p['host'])) return false;
            if (empty($p['path'])) {
                $out_url .= '/';
            }
        }

        return $out_url;
    }

    static function saveNew($data, $file_id, $url) {
        $file_redir = new File_redirection;
        $file_redir->urlhash = File::hashurl($url);
        $file_redir->url = $url;
        $file_redir->file_id = $file_id;
        $file_redir->redirections = intval($data['redirects']);
        $file_redir->httpcode = intval($data['code']);
        $file_redir->insert();
    }

    static public function beforeSchemaUpdate()
    {
        $table = strtolower(get_called_class());
        $schema = Schema::get();
        $schemadef = $schema->getTableDef($table);

        // 2015-02-19 We have to upgrade our table definitions to have the urlhash field populated
        if (isset($schemadef['fields']['urlhash']) && in_array('urlhash', $schemadef['primary key'])) {
            // We already have the urlhash field, so no need to migrate it.
            return;
        }
        echo "\nFound old $table table, upgrading it to contain 'urlhash' field...";
        // We have to create a urlhash that is _not_ the primary key,
        // transfer data and THEN run checkSchema
        $schemadef['fields']['urlhash'] = array (
                                              'type' => 'varchar',
                                              'length' => 64,
                                              'not null' => true,
                                              'description' => 'sha256 hash of the URL',
                                            );
        $schemadef['fields']['url'] = array (
                                              'type' => 'text',
                                              'description' => 'short URL (or any other kind of redirect) for file (id)',
                                            );
        unset($schemadef['primary key']);
        $schema->ensureTable($table, $schemadef);
        echo "DONE.\n";

        $classname = ucfirst($table);
        $tablefix = new $classname;
        // urlhash is hash('sha256', $url) in the File table
        echo "Updating urlhash fields in $table table...";
        // Maybe very MySQL specific :(
        $tablefix->query(sprintf('UPDATE %1$s SET %2$s=%3$s;',
                            $schema->quoteIdentifier($table),
                            'urlhash',
                            // The line below is "result of sha256 on column `url`"
                            'SHA2(url, 256)'));
        echo "DONE.\n";
        echo "Resuming core schema upgrade...";
    }

    public function getFile() {
        if(empty($this->file) && $this->file_id) {
            $this->file = File::getKV('id', $this->file_id);
        }

        return $this->file;
    }
}