function Hara() {
    this.send_message_ids = {};
    this.onopen = this.onclose = this.onerror = this.onmessage = function(){};
}

Hara.prototype.send = function(action, args, callback){
    var id = Hara.uuid();
    var message = Hara.encode({_id: id, action: action, args: args});
    this.send_message_ids[id] = callback;
    this.websocket.send(message);
}

Hara.prototype.connect = function(url, protocol){
    this.websocket = new WebSocket(url, protocol);
    this.setup_callbacks();
}

Hara.prototype.setup_callbacks = function(){
    var that = this;
    this.websocket.onopen = function(){
        that.onopen.apply(that, arguments);
    };
    this.websocket.onclose = function(){
        that.onclose.apply(that, arguments);
    };
    this.websocket.onerror = function(){
        that.onerror.apply(that, arguments);
    };
    this.websocket.onmessage = function(msg){
        var message = Hara.decode(msg.data);
        switch(message.type){
            case 'response':
            that.handle_response(message);
            break;
            case 'push':
            that.handle_push(message);
            break;
            default:
            throw 'Unknown message type'
        }
    };
};

Hara.prototype.handle_response = function(message) {
    var id = message._id;
    var args = message.args;
    var callback = this.send_message_ids[id];
    if(callback) {
        callback.apply(this, [args]);
    }
    delete this.send_message_ids[id];
};

Hara.prototype.handle_push = function(message) {
    var args = message.args;
    this.onmessage(args);
};

Hara.prototype.close = function(){
    this.websocket.close.apply(this.websocket, arguments);
    this.send_message_ids = {};
}

Hara.uuid = function() {
    var uuid = ('xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
        return v.toString(16);
    }));
    return uuid;
}

Hara.encode = function(args) {
    return JSON.stringify(args);
}

Hara.decode = function(args){
    return JSON.parse(args);
}