/*global JSONP, Faye */
if (window.Transistor === undefined) {
    window.Transistor = {};
}

(function (transistor) {

    var Radio = (function () {

        return function (station_finder, station_uid, token, cache) {
            var jsonp, init_url, bayeux, listeners, turnOn, error, tune, build_channel_path;

            jsonp = JSONP();

            init_url = station_finder + '/init/' + station_uid + '/' + token;
            listeners = [];

            turnOn = function () {
                var initial_value;

                jsonp.get(init_url, {}, function (init) {
                    if (init.error !== undefined) {
                        error(init);
                    }

                    bayeux = new Faye.Client(init.aerial_url, { retry: 3 });

                    for (var i = 0; i < listeners.length; i += 1) {
                        initial_value = init.channels[listeners[i].channel_path];

                        if (initial_value !== undefined) { 
                            listeners[i].callback({
                                event:  'init',
                                args:   initial_value
                            });
                        }

                        bayeux.subscribe(build_channel_path(listeners[i].channel_path), listeners[i].callback);
                    }
                });
            };

            error = function (args) {
                throw "Init error: \"" + args.error + "\"";
            };

            tune = function (channel_path, callback) {
                listeners.push({
                    channel_path: channel_path,
                    callback: function (event) {
                        callback(event.event, event.args);
                    }
                });
            };

            build_channel_path = function (channel_path) {
                return '/' + station_uid + '/' + token + '/' + channel_path;
            };

            return {
                tune: tune,
                turnOn: turnOn
            };
        };
    }());

    transistor.Radio = Radio;

}(window.Transistor));