<?php
/**
 * Relationship class.
 *
 * @package    Elgg.Core
 * @subpackage Core
 * 
 * @property int    $id           The unique identifier (read-only)
 * @property int    $guid_one     The GUID of the subject of the relationship
 * @property string $relationship The name of the relationship
 * @property int    $guid_two     The GUID of the object of the relationship
 * @property int    $time_created A UNIX timestamp of when the relationship was created (read-only, set on first save)
 */
class ElggRelationship extends ElggData implements
	Importable
{

	/**
	 * Create a relationship object, optionally from a given id value or row.
	 *
	 * @param mixed $id ElggRelationship id, database row, or null for new relationship
	 */
	function __construct($id = null) {
		$this->initializeAttributes();

		if (!empty($id)) {
			if ($id instanceof stdClass) {
				$relationship = $id; // Create from db row
			} else {
				$relationship = get_relationship($id);
			}

			if ($relationship) {
				$objarray = (array) $relationship;
				foreach ($objarray as $key => $value) {
					$this->attributes[$key] = $value;
				}
			}
		}
	}

	/**
	 * Class member get overloading
	 *
	 * @param string $name Name
	 *
	 * @return mixed
	 */
	function get($name) {
		if (array_key_exists($name, $this->attributes)) {
			return $this->attributes[$name];
		}

		return null;
	}

	/**
	 * Class member set overloading
	 *
	 * @param string $name  Name
	 * @param mixed  $value Value
	 *
	 * @return mixed
	 */
	function set($name, $value) {
		$this->attributes[$name] = $value;
		return true;
	}

	/**
	 * Save the relationship
	 *
	 * @return int the relationship id
	 * @throws IOException
	 */
	public function save() {
		if ($this->id > 0) {
			delete_relationship($this->id);
		}

		$this->id = add_entity_relationship($this->guid_one, $this->relationship, $this->guid_two);
		if (!$this->id) {
			throw new IOException(elgg_echo('IOException:UnableToSaveNew', array(get_class())));
		}

		return $this->id;
	}

	/**
	 * Delete a given relationship.
	 *
	 * @return bool
	 */
	public function delete() {
		return delete_relationship($this->id);
	}

	/**
	 * Get a URL for this relationship.
	 *
	 * @return string
	 */
	public function getURL() {
		return get_relationship_url($this->id);
	}

	// EXPORTABLE INTERFACE ////////////////////////////////////////////////////////////

	/**
	 * Return an array of fields which can be exported.
	 *
	 * @return array
	 */
	public function getExportableValues() {
		return array(
			'id',
			'guid_one',
			'relationship',
			'guid_two'
		);
	}

	/**
	 * Export this relationship
	 *
	 * @return array
	 */
	public function export() {
		$uuid = get_uuid_from_object($this);
		$relationship = new ODDRelationship(
			guid_to_uuid($this->guid_one),
			$this->relationship,
			guid_to_uuid($this->guid_two)
		);

		$relationship->setAttribute('uuid', $uuid);

		return $relationship;
	}

	// IMPORTABLE INTERFACE ////////////////////////////////////////////////////////////

	/**
	 * Import a relationship
	 *
	 * @param ODD $data ODD data

	 * @return bool
	 * @throws ImportException|InvalidParameterException
	 */
	public function import(ODD $data) {
		if (!($data instanceof ODDRelationship)) {
			throw new InvalidParameterException(elgg_echo('InvalidParameterException:UnexpectedODDClass'));
		}

		$uuid_one = $data->getAttribute('uuid1');
		$uuid_two = $data->getAttribute('uuid2');

		// See if this entity has already been imported, if so then we need to link to it
		$entity1 = get_entity_from_uuid($uuid_one);
		$entity2 = get_entity_from_uuid($uuid_two);
		if (($entity1) && ($entity2)) {
			// Set the item ID
			$this->attributes['guid_one'] = $entity1->getGUID();
			$this->attributes['guid_two'] = $entity2->getGUID();

			// Map verb to relationship
			//$verb = $data->getAttribute('verb');
			//$relationship = get_relationship_from_verb($verb);
			$relationship = $data->getAttribute('type');

			if ($relationship) {
				$this->attributes['relationship'] = $relationship;
				// save
				$result = $this->save();
				if (!$result) {
					throw new ImportException(elgg_echo('ImportException:ProblemSaving', array(get_class())));
				}

				return true;
			}
		}

		return false;
	}

	// SYSTEM LOG INTERFACE ////////////////////////////////////////////////////////////

	/**
	 * Return an identification for the object for storage in the system log.
	 * This id must be an integer.
	 *
	 * @return int
	 */
	public function getSystemLogID() {
		return $this->id;
	}

	/**
	 * For a given ID, return the object associated with it.
	 * This is used by the river functionality primarily.
	 * This is useful for checking access permissions etc on objects.
	 *
	 * @param int $id ID
	 *
	 * @return ElggRelationship
	 */
	public function getObjectFromID($id) {
		return get_relationship($id);
	}

	/**
	 * Return a type of the object - eg. object, group, user, relationship, metadata, annotation etc
	 *
	 * @return string 'relationship'
	 */
	public function getType() {
		return 'relationship';
	}

	/**
	 * Return a subtype. For metadata & annotations this is the 'name' and for relationship this
	 * is the relationship type.
	 *
	 * @return string
	 */
	public function getSubtype() {
		return $this->relationship;
	}

}