class ServiceReferenceGraph

class ServiceReferenceGraph {
  private $nodes;

  /**
   * Constructor.
   */
  public function __construct() {
    $this->nodes = array();
  }

  /**
   * Checks if the graph has a specific node.
   *
   * @param string $id Id to check
   */
  public function hasNode($id) {
    return isset($this->nodes[$id]);
  }

  /**
   * Gets a node by identifier.
   *
   * @param string $id The id to retrieve
   *
   * @return ServiceReferenceGraphNode The node matching the supplied identifier
   *
   * @throws InvalidArgumentException if no node matches the supplied identifier
   */
  public function getNode($id) {
    if (!isset($this->nodes[$id])) {
      throw new InvalidArgumentException(sprintf('There is no node with id "%s".', $id));
    }
    return $this->nodes[$id];
  }

  /**
   * Returns all nodes.
   *
   * @return array An array of all ServiceReferenceGraphNode objects
   */
  public function getNodes() {
    return $this->nodes;
  }

  /**
   * Clears all nodes.
   */
  public function clear() {
    $this->nodes = array();
  }

  /**
   * Connects 2 nodes together in the Graph.
   *
   * @param string $sourceId
   * @param string $sourceValue
   * @param string $destId
   * @param string $destValue
   * @param string $reference
   */
  public function connect($sourceId, $sourceValue, $destId, $destValue = null, $reference = null) {
    $sourceNode = $this
      ->createNode($sourceId, $sourceValue);
    $destNode = $this
      ->createNode($destId, $destValue);
    $edge = new ServiceReferenceGraphEdge($sourceNode, $destNode, $reference);
    $sourceNode
      ->addOutEdge($edge);
    $destNode
      ->addInEdge($edge);
  }

  /**
   * Creates a graph node.
   *
   * @param string $id
   * @param string $value
   *
   * @return ServiceReferenceGraphNode
   */
  private function createNode($id, $value) {
    if (isset($this->nodes[$id]) && $this->nodes[$id]
      ->getValue() === $value) {
      return $this->nodes[$id];
    }
    return $this->nodes[$id] = new ServiceReferenceGraphNode($id, $value);
  }

}