(function () {
    var readyListeners = [];
    var readyPlayers = [];

    var PlayerJsReady = window.PlayerJsReady = {};

    /**
     * Add listener for a 'ready' event coming from a specified element.
     *
     * @todo This should be optimized so that performance doesn't degrade if
     *       many iframes and many event listeners are used.
     *
     * @param {DOMElement} iframeEl iFrame element from which to listen for
     *                              'ready' event
     * @param {Function} callback Listener's callback
     */
    PlayerJsReady.listen = function (iframeEl, callback) {
        /**
         * Player inside requested iframe might have already called ready
         * event and in that case we will invoke callback immediately.
         */
        for (var i in readyPlayers) {
            if (iframeEl.contentWindow === readyPlayers[i].source) {
                return callback(readyPlayers[i].message);
            }
        }

        /**
         * If player inside requested iframe is not yet ready then we will
         * register a listener for 'ready' event.
         */
        readyListeners.push({target: iframeEl, callback: callback});
    };

    /**
     * Calls all listeners of given 'ready' event.
     *
     * @param {object} ready 'ready' event
     */
    function callReadyListeners(ready) {
        for (var i in readyListeners) {
            if (readyListeners[i].target.contentWindow === ready.source) {
                readyListeners[i].callback(ready.message);
            }
        }
    }

    /**
     * Listen to 'ready' event from player.js and call all of its listeners.
     */
    window.addEventListener('message', function (e) {
        var message = PlayerJsCommon.getPlayerJsMessage(e);
        var ready;

        if (!message) {
            return;
        }

        if (message.event === 'ready' && message.value && message.value.src) {
            console.log('Ready');

            ready = {source: e.source, message: message};

            readyPlayers.push(ready);

            callReadyListeners({source: e.source, message: message});
        }
    });
}());