(function() {
    var bus = openerp.bus = {};

    bus.ERROR_DELAY = 10000;

    bus.Bus = openerp.Widget.extend({
        init: function(){
            this._super();
            this.options = {};
            this.activated = false;
            this.channels = [];
            this.last = 0;
            this.stop = false;
        },
        start_polling: function(){
            if(!this.activated){
                this.poll();
                this.stop = false;
            }
        },
        stop_polling: function(){
            this.activated = false;
            this.stop = true;
            this.channels = [];
        },
        poll: function() {
            var self = this;
            self.activated = true;
            var data = {'channels': self.channels, 'last': self.last, 'options' : self.options};
            openerp.session.rpc('/longpolling/poll', data, {shadow : true}).then(function(result) {
                _.each(result, _.bind(self.on_notification, self));
                if(!self.stop){
                    self.poll();
                }
            }, function(unused, e) {
                // no error popup if request is interrupted or fails for any reason
                e.preventDefault();
                // random delay to avoid massive longpolling
                setTimeout(_.bind(self.poll, self), bus.ERROR_DELAY + (Math.floor((Math.random()*20)+1)*1000));
            });
        },
        on_notification: function(notification) {
            if (notification.id > this.last) {
                this.last = notification.id;
            }
            this.trigger("notification", [notification.channel, notification.message]);
        },
        add_channel: function(channel){
            if(!_.contains(this.channels, channel)){
                this.channels.push(channel);
            }
        },
        delete_channel: function(channel){
            this.channels = _.without(this.channels, channel);
        },
    });

    // singleton
    bus.bus = new bus.Bus();
    return bus;
})();