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                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id']];
  92
  93                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  94
  95
  96                 try {
  97                         $compacted = jsonld_compact($jsonobj, $context);
  98                 }
  99                 catch (Exception $e) {
 100                         $compacted = false;
 101                         logger('compacting error:' . print_r($e, true), LOGGER_DEBUG);
 102                 }
 103
 104                 return json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 105         }
 106
 107         /**
 108          * @brief Fetches an element array from a JSON array
 109          *
 110          * @param $array
 111          * @param $element
 112          * @param $key
 113          *
 114          * @return fetched element array
 115          */
 116         public static function fetchElementArray($array, $element, $key = '@id')
 117         {
 118                 if (empty($array)) {
 119                         return null;
 120                 }
 121
 122                 if (!isset($array[$element])) {
 123                         return null;
 124                 }
 125
 126                 // If it isn't an array yet, make it to one
 127                 if (!is_int(key($array[$element]))) {
 128                         $array[$element] = [$array[$element]];
 129                 }
 130
 131                 $elements = [];
 132
 133                 foreach ($array[$element] as $entry) {
 134                         if (!is_array($entry)) {
 135                                 $elements[] = $entry;
 136                         } elseif (!empty($entry[$key])) {
 137                                 $elements[] = $entry[$key];
 138                         } elseif (!empty($entry) || !is_array($entry)) {
 139                                 $elements[] = $entry;
 140                         }
 141                 }
 142
 143                 return $elements;
 144         }
 145
 146         /**
 147          * @brief Fetches an element from a JSON array
 148          *
 149          * @param $array
 150          * @param $element
 151          * @param $key
 152          * @param $type
 153          * @param $type_value
 154          *
 155          * @return fetched element
 156          */
 157         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 158         {
 159                 if (empty($array)) {
 160                         return null;
 161                 }
 162
 163                 if (!isset($array[$element])) {
 164                         return null;
 165                 }
 166
 167                 if (!is_array($array[$element])) {
 168                         return $array[$element];
 169                 }
 170
 171                 if (is_null($type) || is_null($type_value)) {
 172                         $element_array = self::fetchElementArray($array, $element, $key);
 173                         if (is_null($element_array)) {
 174                                 return null;
 175                         }
 176
 177                         return array_shift($element_array);
 178                 }
 179
 180                 $element_array = self::fetchElementArray($array, $element);
 181                 if (is_null($element_array)) {
 182                         return null;
 183                 }
 184
 185                 foreach ($element_array as $entry) {
 186                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 187                                 return $entry[$key];
 188                         }
 189                 }
 190
 191                 return null;
 192         }
 193 }