/**
* @author       Richard Davey <rich@photonstorm.com>
* @copyright    2013 Photon Storm Ltd.
* @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/

/**
* Time constructor.
*
* @class Phaser.Time
* @classdesc This is the core internal game clock. It manages the elapsed time and calculation of elapsed values, used for game object motion and tweens.
* @constructor
* @param {Phaser.Game} game A reference to the currently running game.
*/
Phaser.Time = function (game) {

	/**
	* @property {Phaser.Game} game - Local reference to game.
	*/
	this.game = game;

	/**
	* @property {number} _started - The time at which the Game instance started.
	* @private
	*/
	this._started = 0;

	/**
	* @property {number} _timeLastSecond - The time (in ms) that the last second counter ticked over.
	* @private
	*/
	this._timeLastSecond = 0;

	/**
	* @property {number} _pauseStarted - The time the game started being paused.
	* @private
	*/
	this._pauseStarted = 0;

	/**
	* @property {number} physicsElapsed - The elapsed time calculated for the physics motion updates.
	*/
	this.physicsElapsed = 0;

	/**
	* @property {number} time - Game time counter.
	*/
	this.time = 0;

	/**
	* @property {number} pausedTime - Records how long the game has been paused for. Is reset each time the game pauses.
	*/
	this.pausedTime = 0;

	/**
	* @property {number} now - The time right now.
	*/
	this.now = 0;

	/**
	* @property {number} elapsed - Elapsed time since the last frame (in ms).
	*/
	this.elapsed = 0;

	/**
	* @property {number} fps - Frames per second.
	*/
	this.fps = 0;

	/**
	* @property {number} fpsMin - The lowest rate the fps has dropped to.
	*/
	this.fpsMin = 1000;

	/**
	* @property {number} fpsMax - The highest rate the fps has reached (usually no higher than 60fps).
	*/
	this.fpsMax = 0;

	/**
	* @property {number} msMin - The minimum amount of time the game has taken between two frames.
	* @default
	*/
	this.msMin = 1000;

	/**
	* @property {number} msMax - The maximum amount of time the game has taken between two frames.
	*/
	this.msMax = 0;

	/**
	* @property {number} frames - The number of frames record in the last second.
	*/
	this.frames = 0;

	/**
	* @property {number} pauseDuration - Records how long the game was paused for in miliseconds.
	*/
	this.pauseDuration = 0;

	/**
	* @property {number} timeToCall - The value that setTimeout needs to work out when to next update
	*/
	this.timeToCall = 0;

	/**
	* @property {number} lastTime - Internal value used by timeToCall as part of the setTimeout loop
	*/
	this.lastTime = 0;

	/**
	* @property {Phaser.Timer} _timer - Internal Phaser.Timer object.
	* @private
	*/
	this._timer = new Phaser.Timer(this.game, false);

	/**
	* @property {boolean} _justResumed - Internal value used to recover from the game pause state.
    * @private
	*/
	this._justResumed = false;

	/**
	* @property {array} _timers - Internal store of Phaser.Timer objects.
    * @private
	*/
	this._timers = [];

	//	Listen for game pause/resume events
	this.game.onPause.add(this.gamePaused, this);
	this.game.onResume.add(this.gameResumed, this);

};

Phaser.Time.prototype = {

    /**
    * @method Phaser.Time#boot
    */
	boot: function () {

		this._timer.start();

	},

    /**
    * Adds a new Event to this Timer. The event will fire after the given amount of 'delay' in milliseconds has passed, once the Timer has started running.
    * Call Timer.start() once you have added all of the Events you require for this Timer. The delay is in relation to when the Timer starts, not the time it was added.
    * @method Phaser.Time#addEvent
    * @param {number} delay - The number of milliseconds that should elapse before the Timer will call the given callback.
    * @param {function} callback - The callback that will be called when the Timer event occurs.
    * @param {object} callbackContext - The context in which the callback will be called.
    * @param {...} arguments - The values to be sent to your callback function when it is called.
    */
    addEvent: function (delay, callback, callbackContext) {

        this._timer.create(delay, false, 0, callback, callbackContext, Array.prototype.splice.call(arguments, 3));

    },

    /**
    * Adds a new Event to this Timer that will repeat for the given number of iterations.
    * The event will fire after the given amount of 'delay' milliseconds has passed once the Timer has started running.
    * Call Timer.start() once you have added all of the Events you require for this Timer. The delay is in relation to when the Timer starts, not the time it was added.
    * @method Phaser.Time#repeatEvent
    * @param {number} delay - The number of milliseconds that should elapse before the Timer will call the given callback.
    * @param {number} repeatCount - The number of times to repeat the event.
    * @param {function} callback - The callback that will be called when the Timer event occurs.
    * @param {object} callbackContext - The context in which the callback will be called.
    * @param {...} arguments - The values to be sent to your callback function when it is called.
    */
    repeatEvent: function (delay, repeatCount, callback, callbackContext) {

        this._timer.create(delay, false, repeatCount, callback, callbackContext, Array.prototype.splice.call(arguments, 4));

    },

    /**
    * Adds a new looped Event to this Timer that will repeat forever or until the Timer is stopped.
    * The event will fire after the given amount of 'delay' milliseconds has passed once the Timer has started running.
    * Call Timer.start() once you have added all of the Events you require for this Timer. The delay is in relation to when the Timer starts, not the time it was added.
    * @method Phaser.Time#loopEvent
    * @param {number} delay - The number of milliseconds that should elapse before the Timer will call the given callback.
    * @param {function} callback - The callback that will be called when the Timer event occurs.
    * @param {object} callbackContext - The context in which the callback will be called.
    * @param {...} arguments - The values to be sent to your callback function when it is called.
    */
    loopEvent: function (delay, callback, callbackContext) {

        this._timer.create(delay, true, 0, callback, callbackContext, Array.prototype.splice.call(arguments, 3));

    },

    /**
    * Creates a new stand-alone Phaser.Timer object.
    * @method Phaser.Time#create
	* @param {boolean} [autoDestroy=true] - A Timer that is set to automatically destroy itself will do so after all of its events have been dispatched (assuming no looping events).
	* @return {Phaser.Timer} The Timer object that was created.
    */
	create: function (autoDestroy) {

		if (typeof autoDestroy === 'undefined') { autoDestroy = true; }

		var timer = new Phaser.Timer(this.game, autoDestroy);

		this._timers.push(timer);

		return timer;

	},

    /**
    * Remove all Timer objects, regardless of their state.
    * @method Phaser.Time#removeAll
    */
    removeAll: function () {

    	for (var i = 0; i < this._timers.length; i++)
    	{
    		this._timers[i].destroy();
    	}

		this._timers = [];

    },

	/**
	* Updates the game clock and calculate the fps. This is called automatically by Phaser.Game.
	* @method Phaser.Time#update
	* @param {number} time - The current timestamp, either performance.now or Date.now depending on the browser.
	*/
	update: function (time) {

		this.now = time;

		if (this._justResumed)
		{
			this.time = this.now;
			this._justResumed = false;
		}

		this.timeToCall = this.game.math.max(0, 16 - (time - this.lastTime));

		this.elapsed = this.now - this.time;

		this.msMin = this.game.math.min(this.msMin, this.elapsed);
		this.msMax = this.game.math.max(this.msMax, this.elapsed);

		this.frames++;

		if (this.now > this._timeLastSecond + 1000)
		{
			this.fps = Math.round((this.frames * 1000) / (this.now - this._timeLastSecond));
			this.fpsMin = this.game.math.min(this.fpsMin, this.fps);
			this.fpsMax = this.game.math.max(this.fpsMax, this.fps);
			this._timeLastSecond = this.now;
			this.frames = 0;
		}

		this.time = this.now;
        this.lastTime = time + this.timeToCall;
		this.physicsElapsed = 1.0 * (this.elapsed / 1000);

		//	Clamp the delta
		if (this.physicsElapsed > 1)
		{
			this.physicsElapsed = 1;
		}

		//  Paused?
		if (this.game.paused)
		{
			this.pausedTime = this.now - this._pauseStarted;
		}

		//	Our internal timer
		this._timer.update(this.now);

        var i = 0;
        var len = this._timers.length;

        while (i < len)
        {
            if (this._timers[i].update(this.now))
            {
                i++;
            }
            else
            {
                this._timers.splice(i, 1);

                len--;
            }
        }

	},

	/**
	* Called when the game enters a paused state.
	* @method Phaser.Time#gamePaused
	* @private
	*/
	gamePaused: function () {
		
		this._pauseStarted = this.now;

	},

	/**
	* Called when the game resumes from a paused state.
	* @method Phaser.Time#gameResumed
	* @private
	*/
	gameResumed: function () {

		//  Level out the elapsed timer to avoid spikes
		this.time = Date.now();
		this.pauseDuration = this.pausedTime;
		this._justResumed = true;

	},

	/**
	* The number of seconds that have elapsed since the game was started.
	* @method Phaser.Time#totalElapsedSeconds
	* @return {number}
	*/
	totalElapsedSeconds: function() {
		return (this.now - this._started) * 0.001;
	},

	/**
	* How long has passed since the given time.
	* @method Phaser.Time#elapsedSince
	* @param {number} since - The time you want to measure against.
	* @return {number} The difference between the given time and now.
	*/
	elapsedSince: function (since) {
		return this.now - since;
	},

	/**
	* How long has passed since the given time (in seconds).
	* @method Phaser.Time#elapsedSecondsSince
	* @param {number} since - The time you want to measure (in seconds).
	* @return {number} Duration between given time and now (in seconds).
	*/
	elapsedSecondsSince: function (since) {
		return (this.now - since) * 0.001;
	},

	/**
	* Resets the private _started value to now.
	* @method Phaser.Time#reset
	*/
	reset: function () {
		this._started = this.now;
	}

};

Phaser.Time.prototype.constructor = Phaser.Time;