define(["./kernel", "./config", /*===== "./declare", =====*/ "./lang", "../Evented", "./Color", "../aspect", "../sniff", "../dom", "../dom-style"],
	function(dojo, config, /*===== declare, =====*/ lang, Evented, Color, aspect, has, dom, style){
	// module:
	//		dojo/_base/fx
	// notes:
	//		Animation loosely package based on Dan Pupius' work, contributed under CLA; see
	//		http://pupius.co.uk/js/Toolkit.Drawing.js

	var _mixin = lang.mixin;

	// Module export
	var basefx = {
		// summary:
		//		This module defines the base dojo/_base/fx implementation.
	};

	var _Line = basefx._Line = function(/*int*/ start, /*int*/ end){
		// summary:
		//		Object used to generate values from a start value to an end value
		// start: int
		//		Beginning value for range
		// end: int
		//		Ending value for range
		this.start = start;
		this.end = end;
	};

	_Line.prototype.getValue = function(/*float*/ n){
		// summary:
		//		Returns the point on the line
		// n:
		//		a floating point number greater than 0 and less than 1
		return ((this.end - this.start) * n) + this.start; // Decimal
	};

	var Animation = basefx.Animation = function(args){
		// summary:
		//		A generic animation class that fires callbacks into its handlers
		//		object at various states.
		// description:
		//		A generic animation class that fires callbacks into its handlers
		//		object at various states. Nearly all dojo animation functions
		//		return an instance of this method, usually without calling the
		//		.play() method beforehand. Therefore, you will likely need to
		//		call .play() on instances of `Animation` when one is
		//		returned.
		// args: Object
		//		The 'magic argument', mixing all the properties into this
		//		animation instance.

		_mixin(this, args);
		if(lang.isArray(this.curve)){
			this.curve = new _Line(this.curve[0], this.curve[1]);
		}

	};
	Animation.prototype = new Evented();

	lang.extend(Animation, {
		// duration: Integer
		//		The time in milliseconds the animation will take to run
		duration: 350,

	/*=====
		// curve: _Line|Array
		//		A two element array of start and end values, or a `_Line` instance to be
		//		used in the Animation.
		curve: null,

		// easing: Function?
		//		A Function to adjust the acceleration (or deceleration) of the progress
		//		across a _Line
		easing: null,
	=====*/

		// repeat: Integer?
		//		The number of times to loop the animation
		repeat: 0,

		// rate: Integer?
		//		the time in milliseconds to wait before advancing to next frame
		//		(used as a fps timer: 1000/rate = fps)
		rate: 20 /* 50 fps */,

	/*=====
		// delay: Integer?
		//		The time in milliseconds to wait before starting animation after it
		//		has been .play()'ed
		delay: null,

		// beforeBegin: Event?
		//		Synthetic event fired before a Animation begins playing (synchronous)
		beforeBegin: null,

		// onBegin: Event?
		//		Synthetic event fired as a Animation begins playing (useful?)
		onBegin: null,

		// onAnimate: Event?
		//		Synthetic event fired at each interval of the Animation
		onAnimate: null,

		// onEnd: Event?
		//		Synthetic event fired after the final frame of the Animation
		onEnd: null,

		// onPlay: Event?
		//		Synthetic event fired any time the Animation is play()'ed
		onPlay: null,

		// onPause: Event?
		//		Synthetic event fired when the Animation is paused
		onPause: null,

		// onStop: Event
		//		Synthetic event fires when the Animation is stopped
		onStop: null,

	=====*/

		_percent: 0,
		_startRepeatCount: 0,

		_getStep: function(){
			var _p = this._percent,
				_e = this.easing
			;
			return _e ? _e(_p) : _p;
		},
		_fire: function(/*Event*/ evt, /*Array?*/ args){
			// summary:
			//		Convenience function.  Fire event "evt" and pass it the
			//		arguments specified in "args".
			// description:
			//		Convenience function.  Fire event "evt" and pass it the
			//		arguments specified in "args".
			//		Fires the callback in the scope of this Animation
			//		instance.
			// evt:
			//		The event to fire.
			// args:
			//		The arguments to pass to the event.
			var a = args||[];
			if(this[evt]){
				if(config.debugAtAllCosts){
					this[evt].apply(this, a);
				}else{
					try{
						this[evt].apply(this, a);
					}catch(e){
						// squelch and log because we shouldn't allow exceptions in
						// synthetic event handlers to cause the internal timer to run
						// amuck, potentially pegging the CPU. I'm not a fan of this
						// squelch, but hopefully logging will make it clear what's
						// going on
						console.error("exception in animation handler for:", evt);
						console.error(e);
					}
				}
			}
			return this; // Animation
		},

		play: function(/*int?*/ delay, /*Boolean?*/ gotoStart){
			// summary:
			//		Start the animation.
			// delay:
			//		How many milliseconds to delay before starting.
			// gotoStart:
			//		If true, starts the animation from the beginning; otherwise,
			//		starts it from its current position.
			// returns: Animation
			//		The instance to allow chaining.

			var _t = this;
			if(_t._delayTimer){ _t._clearTimer(); }
			if(gotoStart){
				_t._stopTimer();
				_t._active = _t._paused = false;
				_t._percent = 0;
			}else if(_t._active && !_t._paused){
				return _t;
			}

			_t._fire("beforeBegin", [_t.node]);

			var de = delay || _t.delay,
				_p = lang.hitch(_t, "_play", gotoStart);

			if(de > 0){
				_t._delayTimer = setTimeout(_p, de);
				return _t;
			}
			_p();
			return _t;	// Animation
		},

		_play: function(gotoStart){
			var _t = this;
			if(_t._delayTimer){ _t._clearTimer(); }
			_t._startTime = new Date().valueOf();
			if(_t._paused){
				_t._startTime -= _t.duration * _t._percent;
			}

			_t._active = true;
			_t._paused = false;
			var value = _t.curve.getValue(_t._getStep());
			if(!_t._percent){
				if(!_t._startRepeatCount){
					_t._startRepeatCount = _t.repeat;
				}
				_t._fire("onBegin", [value]);
			}

			_t._fire("onPlay", [value]);

			_t._cycle();
			return _t; // Animation
		},

		pause: function(){
			// summary:
			//		Pauses a running animation.
			var _t = this;
			if(_t._delayTimer){ _t._clearTimer(); }
			_t._stopTimer();
			if(!_t._active){ return _t; /*Animation*/ }
			_t._paused = true;
			_t._fire("onPause", [_t.curve.getValue(_t._getStep())]);
			return _t; // Animation
		},

		gotoPercent: function(/*Decimal*/ percent, /*Boolean?*/ andPlay){
			// summary:
			//		Sets the progress of the animation.
			// percent:
			//		A percentage in decimal notation (between and including 0.0 and 1.0).
			// andPlay:
			//		If true, play the animation after setting the progress.
			var _t = this;
			_t._stopTimer();
			_t._active = _t._paused = true;
			_t._percent = percent;
			if(andPlay){ _t.play(); }
			return _t; // Animation
		},

		stop: function(/*boolean?*/ gotoEnd){
			// summary:
			//		Stops a running animation.
			// gotoEnd:
			//		If true, the animation will end.
			var _t = this;
			if(_t._delayTimer){ _t._clearTimer(); }
			if(!_t._timer){ return _t; /* Animation */ }
			_t._stopTimer();
			if(gotoEnd){
				_t._percent = 1;
			}
			_t._fire("onStop", [_t.curve.getValue(_t._getStep())]);
			_t._active = _t._paused = false;
			return _t; // Animation
		},

		destroy: function(){
			// summary:
			//		cleanup the animation
			this.stop();
		},

		status: function(){
			// summary:
			//		Returns a string token representation of the status of
			//		the animation, one of: "paused", "playing", "stopped"
			if(this._active){
				return this._paused ? "paused" : "playing"; // String
			}
			return "stopped"; // String
		},

		_cycle: function(){
			var _t = this;
			if(_t._active){
				var curr = new Date().valueOf();
				// Allow durations of 0 (instant) by setting step to 1 - see #13798
				var step = _t.duration === 0 ? 1 : (curr - _t._startTime) / (_t.duration);

				if(step >= 1){
					step = 1;
				}
				_t._percent = step;

				// Perform easing
				if(_t.easing){
					step = _t.easing(step);
				}

				_t._fire("onAnimate", [_t.curve.getValue(step)]);

				if(_t._percent < 1){
					_t._startTimer();
				}else{
					_t._active = false;

					if(_t.repeat > 0){
						_t.repeat--;
						_t.play(null, true);
					}else if(_t.repeat == -1){
						_t.play(null, true);
					}else{
						if(_t._startRepeatCount){
							_t.repeat = _t._startRepeatCount;
							_t._startRepeatCount = 0;
						}
					}
					_t._percent = 0;
					_t._fire("onEnd", [_t.node]);
					!_t.repeat && _t._stopTimer();
				}
			}
			return _t; // Animation
		},

		_clearTimer: function(){
			// summary:
			//		Clear the play delay timer
			clearTimeout(this._delayTimer);
			delete this._delayTimer;
		}

	});

	// the local timer, stubbed into all Animation instances
	var ctr = 0,
		timer = null,
		runner = {
			run: function(){}
		};

	lang.extend(Animation, {

		_startTimer: function(){
			if(!this._timer){
				this._timer = aspect.after(runner, "run", lang.hitch(this, "_cycle"), true);
				ctr++;
			}
			if(!timer){
				timer = setInterval(lang.hitch(runner, "run"), this.rate);
			}
		},

		_stopTimer: function(){
			if(this._timer){
				this._timer.remove();
				this._timer = null;
				ctr--;
			}
			if(ctr <= 0){
				clearInterval(timer);
				timer = null;
				ctr = 0;
			}
		}

	});

	var _makeFadeable =
		has("ie") ? function(node){
			// only set the zoom if the "tickle" value would be the same as the
			// default
			var ns = node.style;
			// don't set the width to auto if it didn't already cascade that way.
			// We don't want to f anyones designs
			if(!ns.width.length && style.get(node, "width") == "auto"){
				ns.width = "auto";
			}
		} :
		function(){};

	basefx._fade = function(/*Object*/ args){
		// summary:
		//		Returns an animation that will fade the node defined by
		//		args.node from the start to end values passed (args.start
		//		args.end) (end is mandatory, start is optional)

		args.node = dom.byId(args.node);
		var fArgs = _mixin({ properties: {} }, args),
			props = (fArgs.properties.opacity = {});

		props.start = !("start" in fArgs) ?
			function(){
				return +style.get(fArgs.node, "opacity")||0;
			} : fArgs.start;
		props.end = fArgs.end;

		var anim = basefx.animateProperty(fArgs);
		aspect.after(anim, "beforeBegin", lang.partial(_makeFadeable, fArgs.node), true);

		return anim; // Animation
	};

	/*=====
	var __FadeArgs = declare(null, {
		// node: DOMNode|String
		//		The node referenced in the animation
		// duration: Integer?
		//		Duration of the animation in milliseconds.
		// easing: Function?
		//		An easing function.
	});
	=====*/

	basefx.fadeIn = function(/*__FadeArgs*/ args){
		// summary:
		//		Returns an animation that will fade node defined in 'args' from
		//		its current opacity to fully opaque.
		return basefx._fade(_mixin({ end: 1 }, args)); // Animation
	};

	basefx.fadeOut = function(/*__FadeArgs*/ args){
		// summary:
		//		Returns an animation that will fade node defined in 'args'
		//		from its current opacity to fully transparent.
		return basefx._fade(_mixin({ end: 0 }, args)); // Animation
	};

	basefx._defaultEasing = function(/*Decimal?*/ n){
		// summary:
		//		The default easing function for Animation(s)
		return 0.5 + ((Math.sin((n + 1.5) * Math.PI)) / 2);	// Decimal
	};

	var PropLine = function(properties){
		// PropLine is an internal class which is used to model the values of
		// an a group of CSS properties across an animation lifecycle. In
		// particular, the "getValue" function handles getting interpolated
		// values between start and end for a particular CSS value.
		this._properties = properties;
		for(var p in properties){
			var prop = properties[p];
			if(prop.start instanceof Color){
				// create a reusable temp color object to keep intermediate results
				prop.tempColor = new Color();
			}
		}
	};

	PropLine.prototype.getValue = function(r){
		var ret = {};
		for(var p in this._properties){
			var prop = this._properties[p],
				start = prop.start;
			if(start instanceof Color){
				ret[p] = Color.blendColors(start, prop.end, r, prop.tempColor).toCss();
			}else if(!lang.isArray(start)){
				ret[p] = ((prop.end - start) * r) + start + (p != "opacity" ? prop.units || "px" : 0);
			}
		}
		return ret;
	};

	/*=====
	var __AnimArgs = declare(__FadeArgs, {
		// properties: Object?
		//		A hash map of style properties to Objects describing the transition,
		//		such as the properties of _Line with an additional 'units' property
		properties: {}

		//TODOC: add event callbacks
	});
	=====*/

	basefx.animateProperty = function(/*__AnimArgs*/ args){
		// summary:
		//		Returns an animation that will transition the properties of
		//		node defined in `args` depending how they are defined in
		//		`args.properties`
		//
		// description:
		//		Foundation of most `dojo/_base/fx`
		//		animations. It takes an object of "properties" corresponding to
		//		style properties, and animates them in parallel over a set
		//		duration.
		//
		// example:
		//		A simple animation that changes the width of the specified node.
		//	|	basefx.animateProperty({
		//	|		node: "nodeId",
		//	|		properties: { width: 400 },
		//	|	}).play();
		//		Dojo figures out the start value for the width and converts the
		//		integer specified for the width to the more expressive but
		//		verbose form `{ width: { end: '400', units: 'px' } }` which you
		//		can also specify directly. Defaults to 'px' if omitted.
		//
		// example:
		//		Animate width, height, and padding over 2 seconds... the
		//		pedantic way:
		//	|	basefx.animateProperty({ node: node, duration:2000,
		//	|		properties: {
		//	|			width: { start: '200', end: '400', units:"px" },
		//	|			height: { start:'200', end: '400', units:"px" },
		//	|			paddingTop: { start:'5', end:'50', units:"px" }
		//	|		}
		//	|	}).play();
		//		Note 'paddingTop' is used over 'padding-top'. Multi-name CSS properties
		//		are written using "mixed case", as the hyphen is illegal as an object key.
		//
		// example:
		//		Plug in a different easing function and register a callback for
		//		when the animation ends. Easing functions accept values between
		//		zero and one and return a value on that basis. In this case, an
		//		exponential-in curve.
		//	|	basefx.animateProperty({
		//	|		node: "nodeId",
		//	|		// dojo figures out the start value
		//	|		properties: { width: { end: 400 } },
		//	|		easing: function(n){
		//	|			return (n==0) ? 0 : Math.pow(2, 10 * (n - 1));
		//	|		},
		//	|		onEnd: function(node){
		//	|			// called when the animation finishes. The animation
		//	|			// target is passed to this function
		//	|		}
		//	|	}).play(500); // delay playing half a second
		//
		// example:
		//		Like all `Animation`s, animateProperty returns a handle to the
		//		Animation instance, which fires the events common to Dojo FX. Use `aspect.after`
		//		to access these events outside of the Animation definition:
		//	|	var anim = basefx.animateProperty({
		//	|		node:"someId",
		//	|		properties:{
		//	|			width:400, height:500
		//	|		}
		//	|	});
		//	|	aspect.after(anim, "onEnd", function(){
		//	|		console.log("animation ended");
		//	|	}, true);
		//	|	// play the animation now:
		//	|	anim.play();
		//
		// example:
		//		Each property can be a function whose return value is substituted along.
		//		Additionally, each measurement (eg: start, end) can be a function. The node
		//		reference is passed directly to callbacks.
		//	|	basefx.animateProperty({
		//	|		node:"mine",
		//	|		properties:{
		//	|			height:function(node){
		//	|				// shrink this node by 50%
		//	|				return domGeom.position(node).h / 2
		//	|			},
		//	|			width:{
		//	|				start:function(node){ return 100; },
		//	|				end:function(node){ return 200; }
		//	|			}
		//	|		}
		//	|	}).play();
		//

		var n = args.node = dom.byId(args.node);
		if(!args.easing){ args.easing = dojo._defaultEasing; }

		var anim = new Animation(args);
		aspect.after(anim, "beforeBegin", lang.hitch(anim, function(){
			var pm = {};
			for(var p in this.properties){
				// Make shallow copy of properties into pm because we overwrite
				// some values below. In particular if start/end are functions
				// we don't want to overwrite them or the functions won't be
				// called if the animation is reused.
				if(p == "width" || p == "height"){
					this.node.display = "block";
				}
				var prop = this.properties[p];
				if(lang.isFunction(prop)){
					prop = prop(n);
				}
				prop = pm[p] = _mixin({}, (lang.isObject(prop) ? prop: { end: prop }));

				if(lang.isFunction(prop.start)){
					prop.start = prop.start(n);
				}
				if(lang.isFunction(prop.end)){
					prop.end = prop.end(n);
				}
				var isColor = (p.toLowerCase().indexOf("color") >= 0);
				function getStyle(node, p){
					// domStyle.get(node, "height") can return "auto" or "" on IE; this is more reliable:
					var v = { height: node.offsetHeight, width: node.offsetWidth }[p];
					if(v !== undefined){ return v; }
					v = style.get(node, p);
					return (p == "opacity") ? +v : (isColor ? v : parseFloat(v));
				}
				if(!("end" in prop)){
					prop.end = getStyle(n, p);
				}else if(!("start" in prop)){
					prop.start = getStyle(n, p);
				}

				if(isColor){
					prop.start = new Color(prop.start);
					prop.end = new Color(prop.end);
				}else{
					prop.start = (p == "opacity") ? +prop.start : parseFloat(prop.start);
				}
			}
			this.curve = new PropLine(pm);
		}), true);
		aspect.after(anim, "onAnimate", lang.hitch(style, "set", anim.node), true);
		return anim; // Animation
	};

	basefx.anim = function(	/*DOMNode|String*/	node,
							/*Object*/			properties,
							/*Integer?*/		duration,
							/*Function?*/		easing,
							/*Function?*/		onEnd,
							/*Integer?*/		delay){
		// summary:
		//		A simpler interface to `animateProperty()`, also returns
		//		an instance of `Animation` but begins the animation
		//		immediately, unlike nearly every other Dojo animation API.
		// description:
		//		Simpler (but somewhat less powerful) version
		//		of `animateProperty`.  It uses defaults for many basic properties
		//		and allows for positional parameters to be used in place of the
		//		packed "property bag" which is used for other Dojo animation
		//		methods.
		//
		//		The `Animation` object returned will be already playing, so
		//		calling play() on it again is (usually) a no-op.
		// node:
		//		a DOM node or the id of a node to animate CSS properties on
		// duration:
		//		The number of milliseconds over which the animation
		//		should run. Defaults to the global animation default duration
		//		(350ms).
		// easing:
		//		An easing function over which to calculate acceleration
		//		and deceleration of the animation through its duration.
		//		A default easing algorithm is provided, but you may
		//		plug in any you wish. A large selection of easing algorithms
		//		are available in `dojo/fx/easing`.
		// onEnd:
		//		A function to be called when the animation finishes
		//		running.
		// delay:
		//		The number of milliseconds to delay beginning the
		//		animation by. The default is 0.
		// example:
		//		Fade out a node
		//	|	basefx.anim("id", { opacity: 0 });
		// example:
		//		Fade out a node over a full second
		//	|	basefx.anim("id", { opacity: 0 }, 1000);
		return basefx.animateProperty({ // Animation
			node: node,
			duration: duration || Animation.prototype.duration,
			properties: properties,
			easing: easing,
			onEnd: onEnd
		}).play(delay || 0);
	};


	if(has("extend-dojo")){
		_mixin(dojo, basefx);
		// Alias to drop come 2.0:
		dojo._Animation = Animation;
	}

	return basefx;
});
