src/Util/JsonLD.php

   1 <?php
   2 /**
   3  * @file src/Util/JsonLD.php
   4  */
   5 namespace Friendica\Util;
   6
   7 use Friendica\Core\Cache;
   8 use Exception;
   9
  10 /**
  11  * @brief This class contain methods to work with JsonLD data
  12  */
  13 class JsonLD
  14 {
  15         /**
  16          * @brief Loader for LD-JSON validation
  17          *
  18          * @param $url
  19          *
  20          * @return the loaded data
  21          */
  22         public static function documentLoader($url)
  23         {
  24                 $recursion = 0;
  25
  26                 $x = debug_backtrace();
  27                 if ($x) {
  28                         foreach ($x as $n) {
  29                                 if ($n['function'] === __FUNCTION__)  {
  30                                         $recursion ++;
  31                                 }
  32                         }
  33                 }
  34
  35                 if ($recursion > 5) {
  36                         logger('jsonld bomb detected at: ' . $url);
  37                         exit();
  38                 }
  39
  40                 $result = Cache::get('documentLoader:' . $url);
  41                 if (!is_null($result)) {
  42                         return $result;
  43                 }
  44
  45                 $data = jsonld_default_document_loader($url);
  46                 Cache::set('documentLoader:' . $url, $data, CACHE_DAY);
  47                 return $data;
  48         }
  49
  50         /**
  51          * @brief Normalises a given JSON array
  52          *
  53          * @param array $json
  54          *
  55          * @return normalized JSON string
  56          */
  57         public static function normalize($json)
  58         {
  59                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  60
  61                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  62
  63                 try {
  64                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
  65                 }
  66                 catch (Exception $e) {
  67                         $normalized = false;
  68                         logger('normalise error:' . print_r($e, true), LOGGER_DEBUG);
  69                 }
  70
  71                 return $normalized;
  72         }
  73
  74         /**
  75          * @brief Compacts a given JSON array
  76          *
  77          * @param array $json
  78          *
  79          * @return comacted JSON array
  80          */
  81         public static function compact($json)
  82         {
  83                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  84
  85                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
  86                         'w3id' => 'https://w3id.org/security#',
  87                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
  88                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
  89                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
  90                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
  91                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
  92                         'uuid' => (object)['@id' => 'http://schema.org/identifier', '@type' => '@id']];
  93
  94                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  95
  96                 $compacted = jsonld_compact($jsonobj, $context);
  97
  98                 return json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
  99         }
 100
 101         /**
 102          * @brief Fetches an element array from a JSON array
 103          *
 104          * @param $array
 105          * @param $element
 106          * @param $key
 107          *
 108          * @return fetched element array
 109          */
 110         public static function fetchElementArray($array, $element, $key = '@id')
 111         {
 112                 if (empty($array)) {
 113                         return null;
 114                 }
 115
 116                 if (!isset($array[$element])) {
 117                         return null;
 118                 }
 119
 120                 // If it isn't an array yet, make it to one
 121                 if (!is_int(key($array[$element]))) {
 122                         $array[$element] = [$array[$element]];
 123                 }
 124
 125                 $elements = [];
 126
 127                 foreach ($array[$element] as $entry) {
 128                         if (!is_array($entry)) {
 129                                 $elements[] = $entry;
 130                         } elseif (!empty($entry[$key])) {
 131                                 $elements[] = $entry[$key];
 132                         } else {
 133                                 $elements[] = $entry;
 134                         }
 135                 }
 136
 137                 return $elements;
 138         }
 139
 140         /**
 141          * @brief Fetches an element from a JSON array
 142          *
 143          * @param $array
 144          * @param $element
 145          * @param $key
 146          * @param $type
 147          * @param $type_value
 148          *
 149          * @return fetched element
 150          */
 151         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 152         {
 153                 if (empty($array)) {
 154                         return null;
 155                 }
 156
 157                 if (!isset($array[$element])) {
 158                         return null;
 159                 }
 160
 161                 if (!is_array($array[$element])) {
 162                         return $array[$element];
 163                 }
 164
 165                 if (is_null($type) || is_null($type_value)) {
 166                         $element_array = self::fetchElementArray($array, $element, $key);
 167                         if (is_null($element_array)) {
 168                                 return null;
 169                         }
 170
 171                         return array_shift($element_array);
 172                 }
 173
 174                 $element_array = self::fetchElementArray($array, $element);
 175                 if (is_null($element_array)) {
 176                         return null;
 177                 }
 178
 179                 foreach ($element_array as $entry) {
 180                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 181                                 return $entry[$key];
 182                         }
 183                 }
 184
 185                 return null;
 186         }
 187 }