/**
 * 定时器
 * @class Timer
 * @constructor
 * @param {String} id 定时器的唯一标识
 * @param {Number} delay 初次运行的延迟时间
 * @param {Number} interval 每次运行的间隔时间
 * @param {Object} callback 定时执行的方法，参数为Timer本身
 * @param {mix} context 传入回调方法的上下文
 */
var Timer = function(id, delay, interval, callback, context) {
	this.id = id;
	this.delay = delay;
	this.interval = interval;
	this.callback = callback;
	this.context = context;
};

/**
 * 开始执行定时器
 * @method start
 */
Timer.prototype.start = function() {
	if (this.timer !== undefined) {
		clearTimeout(this.timer);
		delete this.timer;
	}

	var _this = this;
	var execute = function() {
		_this.callback(_this);

		//在回调函数中被中止
		if (_this.timer !== undefined) {
			_this.timer = setTimeout(execute, _this.interval);
		}
	};

	this.timer = setTimeout(execute, this.delay);
};

/**
 * 中止定时器
 * @method halt
 */
Timer.prototype.halt = function() {
	clearTimeout(this.timer);
	delete this.timer;
};

/**
 * 定时器是否在运行中
 * @method isRunning
 * @return Boolean
 */
Timer.prototype.isRunning = function() {
	return this.timer !== undefined;
};


/**
 * 定时器管理，这是一个单例
 * @class TimerManager
 * @constructor
 */
var TimerManager = function() {
	var instance = this;
	this.timers = {};

	TimerManager = function() {
		return instance;
	};
};

/**
 * 添加一个定时器
 * @method addTimer
 * @param {Object} 要添加的Timer
 */
TimerManager.prototype.addTimer = function(timer) {
	if (this.timers[timer.id] === undefined) {
		this.timers[timer.id] = timer;
	}
	return this;
};

/**
 * 根据唯一标识获取定时器
 * @method getTimer
 * @param {String} id 定时器的id
 * @return {Object}
 */
TimerManager.prototype.getTimer = function(id) {
	return this.timers[id];
};

/**
 * 删除一个定时器
 * @method halt
 * @param {String} id 定时器的id
 */
TimerManager.prototype.deleteTimer = function(id) {
	if (this.timers[id] !== undefined) {
		this.timers[id].halt();
	}
	delete this.timers[id];
};

/**
 * 定时器全部开始运行
 * @method startAll
 */
TimerManager.prototype.startAll = function() {
	for (id in this.timers) {
		this.timers[id].start();
	}
};

/**
 * 定时器全部中止
 * @method haltAll
 */
TimerManager.prototype.haltAll = function() {
	for (id in this.timers) {
		this.timers[id].halt();
	}
};