/**
  * Create a signal collection from JSON string.
  *
  * @param  string $json
  * @return GraphCommons\Graph\SignalCollection
  * @throws GraphCommons\Util\JsonException, \InvalidArgumentException
  */
 public static final function fromJson($json)
 {
     $json = new Json($json);
     if ($json->hasError()) {
         $jsonError = $json->getError();
         throw new JsonException(sprintf('JSON error: code(%d) message(%s)', $jsonError['code'], $jsonError['message']), $jsonError['code']);
     }
     $data = $json->decode(true);
     if (!isset($data['signals'])) {
         throw new \InvalidArgumentException("'signals' field is required!");
     }
     $array = array();
     foreach ($data['signals'] as $i => $signal) {
         if (!isset($signal['action'])) {
             throw new \InvalidArgumentException("Signal 'action' and 'parameters' fields are required!");
         }
         $array[$i]['action'] = Signal::detectAction(Util::arrayPick($signal, 'action'));
         foreach ($signal as $key => $value) {
             $array[$i]['parameters'][$key] = $value;
         }
     }
     return self::fromArray($array);
 }
 /**
  * Fill a lib's graph object.
  *
  * @param  GraphCommons\Graph\Graph $graph
  * @param  array|object $g
  * @return GraphCommons\Graph\Graph
  */
 private final function fillGraph(Graph $graph, $g)
 {
     // force input being an object
     $g = Util::toObject($g);
     if (isset($g->id)) {
         $graph->setId($g->id)->setName($g->name)->setDescription($g->description)->setSubtitle($g->subtitle)->setStatus($g->status)->setCreatedAt($g->created_at);
         // add signals if exists
         if (isset($g->signals)) {
             $array = array();
             foreach ($g->signals as $i => $signal) {
                 $action = $signal->action;
                 unset($signal->action);
                 $array[$i]['action'] = Signal::detectAction($action);
                 $array[$i]['parameters'] = Util::toArray($signal);
             }
             $graph->setSignals(SignalCollection::fromArray($array));
         }
     }
     return $graph;
 }