<?php
	/**
	 * Listen for events and update their timestamps
	 */
	class Tribe__Cache_Listener {

		/**
		 * The name of the trigger that will be fired when rewrite rules are generated.
		 */
		const TRIGGER_GENERATE_REWRITE_RULES = 'generate_rewrite_rules';

		/**
		 * The name of the trigger that will be fired when a post is saved.
		 */
		const TRIGGER_SAVE_POST = 'save_post';

		/**
		 * The singleton instance of the class.
		 *
		 * @var Tribe__Cache_Listener|null
		 */
		private static $instance;

		/**
		 * An instance of the cache object.
		 *
		 * @var Tribe__Cache|null
		 */
		private $cache;

		/**
		 * Class constructor.
		 *
		 * @return void
		 */
		public function __construct() {
			$this->cache = new Tribe__Cache();
		}

		/**
		 * Run the init functionality (like add_hooks).
		 *
		 * @return void
		 */
		public function init() {
			$this->add_hooks();
		}

		/**
		 * Add the hooks necessary.
		 *
		 * @return void
		 */
		private function add_hooks() {
			add_action( 'save_post', [ $this, 'save_post' ], 0, 2 );
			add_action( 'updated_option', [ $this, 'update_last_save_post' ], 10, 3 );
			add_action( 'generate_rewrite_rules', [ $this, 'generate_rewrite_rules' ] );
		}

		/**
		 * Run the caching functionality that is executed on save post.
		 *
		 * @param int     $post_id The post_id.
		 * @param WP_Post $post    The current post object being saved.
		 */
		public function save_post( $post_id, $post ) {
			if ( in_array( $post->post_type, Tribe__Main::get_post_types() ) ) {
				$this->cache->set_last_occurrence( self::TRIGGER_SAVE_POST );
			}
		}

		/**
		 * Run the caching functionality that is executed on saving tribe calendar options.
		 *
		 * @see 'updated_option'
		 *
	     * @param string $option_name    Name of the updated option.
	     * @param mixed  $old_value The old option value.
	     * @param mixed  $value     The new option value.
		 */
		public function update_last_save_post( $option_name, $old_value, $value ) {
			$triggers = array(
				'tribe_events_calendar_options',
				'permalink_structure',
				'rewrite_rules',
			);
			if ( in_array( $option_name, $triggers, true ) ) {
				$this->cache->set_last_occurrence( self::TRIGGER_SAVE_POST );
			}
		}

		/**
		 * For any hook that doesn't need any additional filtering
		 *
		 * @param $method
		 * @param $args
		 */
		public function __call( $method, $args ) {
			$this->cache->set_last_occurrence( $method );
		}

		/**
		 * Instance method of the cache listener.
		 *
		 * @return Tribe__Cache_Listener
		 */
		public static function instance() {
			if ( empty( self::$instance ) ) {
				self::$instance = self::create_listener();
			}

			return self::$instance;
		}

		/**
		 * Create a cache listener.
		 *
		 * @return Tribe__Cache_Listener
		 */
		private static function create_listener() {
			$listener = new self();
			$listener->init();

			return $listener;
		}

		/**
		 * Run the caching functionality that is executed when rewrite rules are generated.
		 *
		 * @since TBD
		 */
		public function generate_rewrite_rules() {
			$this->cache->set_last_occurrence( self::TRIGGER_GENERATE_REWRITE_RULES );
		}
	}
