<?php
/**
 *
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright	  Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link		  http://cakephp.org CakePHP(tm) Project
 * @package		  Baser.Event
 * @since		  CakePHP(tm) v 2.1
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */

App::uses('CakeEventListener', 'Event');

/**
 * The event manager is responsible for keeping track of event listeners, passing the correct
 * data to them, and firing them in the correct order, when associated events are triggered. You
 * can create multiple instances of this object to manage local events or keep a single instance
 * and pass it around to manage all events in your app.
 *
 * @package Cake.Event
 */
class CakeEventManager {

/**
 * The default priority queue value for new, attached listeners
 *
 * @var integer
 */
	public static $defaultPriority = 10;

/**
 * The globally available instance, used for dispatching events attached from any scope
 *
 * @var CakeEventManager
 */
	protected static $_generalManager = null;

/**
 * List of listener callbacks associated to
 *
 * @var object $Listeners
 */
	protected $_listeners = array();

/**
 * Internal flag to distinguish a common manager from the singleton
 *
 * @var boolean
 */
	protected $_isGlobal = false;

/**
 * Returns the globally available instance of a CakeEventManager
 * this is used for dispatching events attached from outside the scope
 * other managers were created. Usually for creating hook systems or inter-class
 * communication
 *
 * If called with the first parameter, it will be set as the globally available instance
 *
 * @param CakeEventManager $manager
 * @return CakeEventManager the global event manager
 */
	public static function instance($manager = null) {
		if ($manager instanceof CakeEventManager) {
			self::$_generalManager = $manager;
		}
		if (empty(self::$_generalManager)) {
			self::$_generalManager = new CakeEventManager();
		}

		self::$_generalManager->_isGlobal = true;
		return self::$_generalManager;
	}

/**
 * Adds a new listener to an event. Listeners
 *
 * @param callback|CakeEventListener $callable PHP valid callback type or instance of CakeEventListener to be called
 * when the event named with $eventKey is triggered. If a CakeEventListener instance is passed, then the `implementedEvents`
 * method will be called on the object to register the declared events individually as methods to be managed by this class.
 * It is possible to define multiple event handlers per event name.
 *
 * @param string $eventKey The event unique identifier name with which the callback will be associated. If $callable
 * is an instance of CakeEventListener this argument will be ignored
 *
 * @param array $options used to set the `priority` and `passParams` flags to the listener.
 * Priorities are handled like queues, and multiple attachments added to the same priority queue will be treated in
 * the order of insertion. `passParams` means that the event data property will be converted to function arguments
 * when the listener is called. If $called is an instance of CakeEventListener, this parameter will be ignored
 *
 * @return void
 * @throws InvalidArgumentException When event key is missing or callable is not an
 *   instance of CakeEventListener.
 */
	public function attach($callable, $eventKey = null, $options = array()) {
		if (!$eventKey && !($callable instanceof CakeEventListener)) {
			throw new InvalidArgumentException(__d('cake_dev', 'The eventKey variable is required'));
		}
		if ($callable instanceof CakeEventListener) {
			$this->_attachSubscriber($callable);
			return;
		}
		$options = $options + array('priority' => self::$defaultPriority, 'passParams' => false);
		$this->_listeners[$eventKey][$options['priority']][] = array(
			'callable' => $callable,
			'passParams' => $options['passParams'],
		);
	}

/**
 * Auxiliary function to attach all implemented callbacks of a CakeEventListener class instance
 * as individual methods on this manager
 *
 * @param CakeEventListener $subscriber
 * @return void
 */
	protected function _attachSubscriber(CakeEventListener $subscriber) {
		foreach ((array)$subscriber->implementedEvents() as $eventKey => $function) {
			$options = array();
			$method = $function;
			if (is_array($function) && isset($function['callable'])) {
				list($method, $options) = $this->_extractCallable($function, $subscriber);
			} elseif (is_array($function) && is_numeric(key($function))) {
				foreach ($function as $f) {
					list($method, $options) = $this->_extractCallable($f, $subscriber);
					$this->attach($method, $eventKey, $options);
				}
				continue;
			}
			if (is_string($method)) {
				$method = array($subscriber, $function);
			}
			$this->attach($method, $eventKey, $options);
		}
	}

/**
 * Auxiliary function to extract and return a PHP callback type out of the callable definition
 * from the return value of the `implementedEvents` method on a CakeEventListener
 *
 * @param array $function the array taken from a handler definition for an event
 * @param CakeEventListener $object The handler object
 * @return callback
 */
	protected function _extractCallable($function, $object) {
		$method = $function['callable'];
		$options = $function;
		unset($options['callable']);
		if (is_string($method)) {
			$method = array($object, $method);
		}
		return array($method, $options);
	}

/**
 * Removes a listener from the active listeners.
 *
 * @param callback|CakeEventListener $callable any valid PHP callback type or an instance of CakeEventListener
 * @param string $eventKey The event unique identifier name with which the callback has been associated
 * @return void
 */
	public function detach($callable, $eventKey = null) {
		if ($callable instanceof CakeEventListener) {
			return $this->_detachSubscriber($callable, $eventKey);
		}
		if (empty($eventKey)) {
			foreach (array_keys($this->_listeners) as $eventKey) {
				$this->detach($callable, $eventKey);
			}
			return;
		}
		if (empty($this->_listeners[$eventKey])) {
			return;
		}
		foreach ($this->_listeners[$eventKey] as $priority => $callables) {
			foreach ($callables as $k => $callback) {
				if ($callback['callable'] === $callable) {
					unset($this->_listeners[$eventKey][$priority][$k]);
					break;
				}
			}
		}
	}

/**
 * Auxiliary function to help detach all listeners provided by an object implementing CakeEventListener
 *
 * @param CakeEventListener $subscriber the subscriber to be detached
 * @param string $eventKey optional event key name to unsubscribe the listener from
 * @return void
 */
	protected function _detachSubscriber(CakeEventListener $subscriber, $eventKey = null) {
		$events = (array)$subscriber->implementedEvents();
		if (!empty($eventKey) && empty($events[$eventKey])) {
			return;
		} elseif (!empty($eventKey)) {
			$events = array($eventKey => $events[$eventKey]);
		}
		foreach ($events as $key => $function) {
			if (is_array($function)) {
				if (is_numeric(key($function))) {
					foreach ($function as $handler) {
						$handler = isset($handler['callable']) ? $handler['callable'] : $handler;
						$this->detach(array($subscriber, $handler), $key);
					}
					continue;
				}
				$function = $function['callable'];
			}
			$this->detach(array($subscriber, $function), $key);
		}
	}

/**
 * Dispatches a new event to all configured listeners
 *
 * @param string|CakeEvent $event the event key name or instance of CakeEvent
 * @return CakeEvent
 * @triggers $event
 */
	public function dispatch($event) {
		if (is_string($event)) {
			$event = new CakeEvent($event);
		}

		$listeners = $this->listeners($event->name());
		if (empty($listeners)) {
			return $event;
		}

		foreach ($listeners as $listener) {
			if ($event->isStopped()) {
				break;
			}
			if ($listener['passParams'] === true) {
				$result = call_user_func_array($listener['callable'], $event->data);
			} else {
				$result = call_user_func($listener['callable'], $event);
			}
			if ($result === false) {
				$event->stopPropagation();
			}
			
			// CUSTOMIZE ADD 2013/09/23 ryuring
			// ObjectCollection を継承しているイベントの場合、
			// 複数のオブジェクトに対するイベントの結果が配列で返ってくるが、
			// 全ての結果がNULLの場合、その前のイベントの結果が上書きされてしまう。
			// 全ての結果がNULLの場合には、結果がNULLとみなし、上書きしない仕様に変更した
			// >>>
			if(is_array($result) && array_key_exists(0, $result)) {
				$notNull = false;
				foreach ($result as $key => $val) {
					if ($val !== null) {
						$notNull = true;
					}
				}
				if(!$notNull) {
					$result = null;
				}
			}
			// <<<
			
			if ($result !== null) {
				$event->result = $result;
			}
		}
		return $event;
	}

/**
 * Returns a list of all listeners for an eventKey in the order they should be called
 *
 * @param string $eventKey
 * @return array
 */
	public function listeners($eventKey) {
		$localListeners = array();
		$priorities = array();
		if (!$this->_isGlobal) {
			$localListeners = $this->prioritisedListeners($eventKey);
			$localListeners = empty($localListeners) ? array() : $localListeners;
		}
		$globalListeners = self::instance()->prioritisedListeners($eventKey);
		$globalListeners = empty($globalListeners) ? array() : $globalListeners;

		$priorities = array_merge(array_keys($globalListeners), array_keys($localListeners));
		$priorities = array_unique($priorities);
		asort($priorities);

		$result = array();
		foreach ($priorities as $priority) {
			if (isset($globalListeners[$priority])) {
				$result = array_merge($result, $globalListeners[$priority]);
			}
			if (isset($localListeners[$priority])) {
				$result = array_merge($result, $localListeners[$priority]);
			}
		}
		return $result;
	}

/**
 * Returns the listeners for the specified event key indexed by priority
 *
 * @param string $eventKey
 * @return array
 */
	public function prioritisedListeners($eventKey) {
		if (empty($this->_listeners[$eventKey])) {
			return array();
		}
		return $this->_listeners[$eventKey];
	}
}
