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                         'uuid' => (object)['@id' => 'http://schema.org/identifier', '@type' => '@id']];
  92
  93                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  94
  95                 $compacted = jsonld_compact($jsonobj, $context);
  96
  97                 return json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
  98         }
  99
 100         /**
 101          * @brief Fetches an element array from a JSON array
 102          *
 103          * @param $array
 104          * @param $element
 105          * @param $key
 106          *
 107          * @return fetched element array
 108          */
 109         public static function fetchElementArray($array, $element, $key = '@id')
 110         {
 111                 if (empty($array)) {
 112                         return null;
 113                 }
 114
 115                 if (!isset($array[$element])) {
 116                         return null;
 117                 }
 118
 119                 // If it isn't an array yet, make it to one
 120                 if (!is_int(key($array[$element]))) {
 121                         $array[$element] = [$array[$element]];
 122                 }
 123
 124                 $elements = [];
 125
 126                 foreach ($array[$element] as $entry) {
 127                         if (!is_array($entry)) {
 128                                 $elements[] = $entry;
 129                         } elseif (!empty($entry[$key])) {
 130                                 $elements[] = $entry[$key];
 131                         } else {
 132                                 $elements[] = $entry;
 133                         }
 134                 }
 135
 136                 return $elements;
 137         }
 138
 139         /**
 140          * @brief Fetches an element from a JSON array
 141          *
 142          * @param $array
 143          * @param $element
 144          * @param $key
 145          * @param $type
 146          * @param $type_value
 147          *
 148          * @return fetched element
 149          */
 150         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 151         {
 152                 if (empty($array)) {
 153                         return null;
 154                 }
 155
 156                 if (!isset($array[$element])) {
 157                         return null;
 158                 }
 159
 160                 if (!is_array($array[$element])) {
 161                         return $array[$element];
 162                 }
 163
 164                 if (is_null($type) || is_null($type_value)) {
 165                         $element_array = self::fetchElementArray($array, $element, $key);
 166                         if (is_null($element_array)) {
 167                                 return null;
 168                         }
 169
 170                         return array_shift($element_array);
 171                 }
 172
 173                 $element_array = self::fetchElementArray($array, $element);
 174                 if (is_null($element_array)) {
 175                         return null;
 176                 }
 177
 178                 foreach ($element_array as $entry) {
 179                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 180                                 return $entry[$key];
 181                         }
 182                 }
 183
 184                 return null;
 185         }
 186 }