<?php namespace Datafeedr\Api\Wuwei\Event;

/**
 * Class Manager
 *
 * The event manager manages events using the WordPress plugin API.
 *
 * @link https://carlalexander.ca/design-system-wordpress-event-management/
 *
 * @since 2.0.0
 */
class Manager {

	/**
	 * Adds a callback to a specific hook of the WordPress plugin API.
	 *
	 * @since 2.0.0
	 *
	 * @uses add_filter()
	 *
	 * @param string $hook_name
	 * @param callable $callback
	 * @param int $priority
	 * @param int $accepted_args
	 */
	public function add_callback( $hook_name, $callback, $priority = 10, $accepted_args = 1 ) {
		add_filter( $hook_name, $callback, $priority, $accepted_args );
	}

	/**
	 * Add an event subscriber.
	 *
	 * The event manager registers all the hooks that the given subscriber
	 * wants to register with the WordPress Plugin API.
	 *
	 * @since 2.0.0
	 *
	 * @param Subscriber_Interface $subscriber
	 */
	public function add_subscriber( Subscriber_Interface $subscriber ) {
		foreach ( $subscriber->get_subscribed_events() as $hook_name => $parameters ) {
			$this->add_subscriber_callback( $subscriber, $hook_name, $parameters );
		}
	}

	/**
	 * Executes all the callbacks registered with the given hook.
	 *
	 * @since 2.0.0
	 *
	 * @see do_action()
	 *
	 * @return mixed Returns the return value of the callback which for do_action is void.
	 */
	public function execute() {
		return call_user_func_array( 'do_action', func_get_args() );
	}

	/**
	 * Filters the given value by applying all the changes from the callbacks
	 * registered with the given hook. Returns the filtered value.
	 *
	 * @since 2.0.0
	 *
	 * @see apply_filters()
	 *
	 * @return mixed Returns the filtered value.
	 */
	public function filter() {
		return call_user_func_array( 'apply_filters', func_get_args() );
	}

	/**
	 * Get the name of the hook that WordPress plugin API is executing. Returns
	 * false if it isn't executing a hook.
	 *
	 * @since 2.0.0
	 *
	 * @see current_filter()
	 *
	 * @return string|bool
	 */
	public function get_current_hook() {
		return current_filter();
	}

	/**
	 * Checks the WordPress plugin API to see if the given hook has
	 * the given callback. The priority of the callback will be returned
	 * or false. If no callback is given will return true or false if
	 * there's any callbacks registered to the hook.
	 *
	 * @since 2.0.0
	 *
	 * @see has_filter()
	 *
	 * @param string $hook_name
	 * @param mixed $callback
	 *
	 * @return bool|int
	 */
	public function has_callback( $hook_name, $callback = false ) {
		return has_filter( $hook_name, $callback );
	}

	/**
	 * Removes the given callback from the given hook. The WordPress plugin API only
	 * removes the hook if the callback and priority match a registered hook.
	 *
	 * @since 2.0.0
	 *
	 * @see remove_filter()
	 *
	 * @param string $hook_name
	 * @param callable $callback
	 * @param int $priority
	 *
	 * @return bool
	 */
	public function remove_callback( $hook_name, $callback, $priority = 10 ) {
		return remove_filter( $hook_name, $callback, $priority );
	}

	/**
	 * Remove an event subscriber.
	 *
	 * The event manager removes all the hooks that the given subscriber
	 * wants to register with the WordPress Plugin API.
	 *
	 * @since 2.0.0
	 *
	 * @param Subscriber_Interface $subscriber
	 */
	public function remove_subscriber( Subscriber_Interface $subscriber ) {
		foreach ( $subscriber->get_subscribed_events() as $hook_name => $parameters ) {
			$this->remove_subscriber_callback( $subscriber, $hook_name, $parameters );
		}
	}

	/**
	 * Adds the given subscriber's callback to a specific hook
	 * of the WordPress plugin API.
	 *
	 * @since 2.0.0
	 *
	 * @param Subscriber_Interface $subscriber
	 * @param string $hook_name
	 * @param mixed $parameters
	 */
	private function add_subscriber_callback( Subscriber_Interface $subscriber, $hook_name, $parameters ) {
		if ( is_string( $parameters ) ) {
			$this->add_callback( $hook_name, array( $subscriber, $parameters ) );
		} elseif ( is_array( $parameters ) && isset( $parameters[0] ) ) {
			$this->add_callback(
				$hook_name,
				array(
					$subscriber,
					$parameters[0]
				),
				isset( $parameters[1] ) ? $parameters[1] : 10,
				isset( $parameters[2] ) ? $parameters[2] : 1
			);
		}
	}

	/**
	 * Removes the given subscriber's callback to a specific hook
	 * of the WordPress plugin API.
	 *
	 * @since 2.0.0
	 *
	 * @param Subscriber_Interface $subscriber
	 * @param string $hook_name
	 * @param mixed $parameters
	 */
	private function remove_subscriber_callback( Subscriber_Interface $subscriber, $hook_name, $parameters ) {
		if ( is_string( $parameters ) ) {
			$this->remove_callback( $hook_name, array( $subscriber, $parameters ) );
		} elseif ( is_array( $parameters ) && isset( $parameters[0] ) ) {
			$this->remove_callback(
				$hook_name,
				array(
					$subscriber,
					$parameters[0]
				),
				isset( $parameters[1] ) ? $parameters[1] : 10
			);
		}
	}
}