/*!
 * This is a jQuery port of Drew Diller's excellent Belated PNG script
 * Original script here: http://www.dillerdesign.com/experiment/DD_belatedPNG/
 * @author: Rodrigo Saboya
 * Version: 0.0.7a
 */
(function($) {
	ns = 'DD_belatedPNG';
	imgSize = {}
	styleSheet = null;

	/**
	* This is the method to use in a document.
	* @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'
	**/
	$.extend({
		fix: function(selector) {
			var selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */
			for (var i=0; i<selectors.length; i++) {
				styleSheet.addRule(selectors[i], 'behavior:expression(jQuery.belate(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */
			}
		},
		belate: function(el) {
			$(el).belated();
		}
	});

	$.fn.belated = function() {
		if(!jQuery.browser.msie || !/^6/.test(jQuery.browser.version)) {
			return this;
		}
		return this.each(function() {
			this.style.behavior = 'none';
			if (this.nodeName == 'BODY' || this.nodeName == 'TD' || this.nodeName == 'TR') { //this elements not supported yet
				return;
			}
			this.isImg = false;
			if (this.nodeName == 'IMG') {
				if(this.src.toLowerCase().search(/\.png$/) != -1) {
					this.isImg = true;
					this.style.visibility = 'hidden';
				}
				else {
					return;
				}
			}
			else if (this.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {
				return;
			}
			this.vml = {color: {}, image: {}};
			var els = {shape: {}, fill: {}};
			for (var r in this.vml) {
				for (var e in els) {
					var nodeStr = ns + ':' + e;
					this.vml[r][e] = document.createElement(nodeStr);
				}
				this.vml[r].shape.stroked = false;
				this.vml[r].shape.appendChild(this.vml[r].fill);
				this.parentNode.insertBefore(this.vml[r].shape, this);
			}
			this.vml.image.shape.fillcolor = 'none'; // Don't show blank white shapeangle when waiting for image to load.
			this.vml.image.fill.type = 'tile'; // Ze magic!! Makes image show up.
			this.vml.color.fill.on = false; // Actually going to apply vml element's style.backgroundColor, so hide the whiteness.
	
			attachHandlers(this);
	
			giveLayout(this);
			giveLayout(this.offsetParent);
	
			// set up element
			applyVML(this);
		});
	}

	function createVmlNameSpace() { /* enable VML */
		if (document.namespaces && !document.namespaces[ns]) {
		  document.namespaces.add(ns, 'urn:schemas-microsoft-com:vml');
		}
	};

	function createVmlStyleSheet() { /* style VML, enable behaviors */
		/*
			Just in case lots of other developers have added
			lots of other stylesheets using document.createStyleSheet
			and hit the 31-limit mark, let's not use that method!
			further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx
		*/
		var style = document.createElement('style');
		document.documentElement.firstChild.insertBefore(style, document.documentElement.firstChild.firstChild);
		var _styleSheet = style.styleSheet;
		_styleSheet.addRule(ns + '\\:*', '{behavior:url(#default#VML)}');
		_styleSheet.addRule(ns + '\\:shape', 'position:absolute;');
		_styleSheet.addRule('img.' + ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */
		styleSheet = _styleSheet;
	};

	function readPropertyChange() {
		var el = event.srcElement;
		if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {
			applyVML(el);
		}
		if (event.propertyName == 'style.display') {
			var display = (el.currentStyle.display == 'none') ? 'none' : 'block';
			for (var v in el.vml) {
				el.vml[v].shape.style.display = display;
			}
		}
		if (event.propertyName.search('filter') != -1) {
			vmlOpacity(el);
		}
	};

	 function vmlOpacity(el) {
		if (el.currentStyle.filter.search('lpha') != -1) {
			var trans = el.currentStyle.filter;
			trans = parseInt(trans.substring(trans.lastIndexOf('=')+1, trans.lastIndexOf(')')), 10)/100;
			el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */
			el.vml.image.fill.opacity = trans; /* complete guesswork */
		}
	};

	function handlePseudoHover(el) {
		setTimeout(function() { /* wouldn't work as intended without setTimeout */
			applyVML(el);
		}, 1);
	};

	function applyVML(el) {
		el.runtimeStyle.cssText = '';
		vmlFill(el);
		vmlOffsets(el);
		vmlOpacity(el);
		if (el.isImg) {
			copyImageBorders(el);
		}
	};

	function attachHandlers(el) {
		if (el.nodeName == 'A') {
			el.attachEvent('onmouseleave', function() {
				handlePseudoHover(el);
			});
			el.attachEvent('onmouseenter', function() {
				handlePseudoHover(el);
			});
			el.attachEvent('onfocus', function() {
				handlePseudoHover(el);
			});
			el.attachEvent('onblur', function() {
				handlePseudoHover(el);
			});
		}
		el.attachEvent('onresize', function() {
			vmlOffsets(el);
		});
		el.attachEvent('onmove', function() {
			vmlOffsets(el);
		});
		el.attachEvent('onpropertychange', readPropertyChange);
	};

	function giveLayout(el) {
		el.style.zoom = 1;
		if (el.currentStyle.position == 'static') {
			el.style.position = 'relative';
		}
	};

	function copyImageBorders(el) {
		var styles = {'borderStyle':true, 'borderWidth':true, 'borderColor':true};
		for (var s in styles) {
			el.vml.color.shape.style[s] = el.currentStyle[s];
		}
	};

	function vmlFill(el) {
		if (!el.currentStyle) {
			return;
		} else {
			var elStyle = el.currentStyle;
		}
		for (var v in el.vml) {
			el.vml[v].shape.style.zIndex = elStyle.zIndex;
		}
		el.runtimeStyle.backgroundColor = '';
		el.runtimeStyle.backgroundImage = '';
		var noColor = (elStyle.backgroundColor == 'transparent');
		var noImg = true;
		if (elStyle.backgroundImage != 'none' || el.isImg) {
			if (!el.isImg) {
				el.vmlBg = elStyle.backgroundImage;
				el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")')-5);
			}
			else {
				el.vmlBg = el.src;
			}
			if (!imgSize[el.vmlBg]) { /* determine size of loaded image */
				var img = document.createElement('img');
				imgSize[el.vmlBg] = img;
				img.className = ns + '_sizeFinder';
				img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
				img.attachEvent('onload', function() {
					this.width = this.offsetWidth; /* weird cache-busting requirement! */
					this.height = this.offsetHeight;
					vmlOffsets(el);
				});
				img.src = el.vmlBg;
				img.removeAttribute('width');
				img.removeAttribute('height');
				document.body.insertBefore(img, document.body.firstChild);
			}
			el.vml.image.fill.src = el.vmlBg;
			noImg = false;
		}
		el.vml.image.fill.on = !noImg;
		el.vml.image.fill.color = 'none';
		el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;
		el.runtimeStyle.backgroundImage = 'none';
		el.runtimeStyle.backgroundColor = 'transparent';
	};

	/* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */
	function vmlOffsets(el) {
		var thisStyle = el.currentStyle;
		var size = {'W':el.clientWidth+1, 'H':el.clientHeight+1, 'w':imgSize[el.vmlBg].width, 'h':imgSize[el.vmlBg].height, 'L':el.offsetLeft, 'T':el.offsetTop, 'bLW':el.clientLeft, 'bTW':el.clientTop};
		var fudge = (size.L + size.bLW == 1) ? 1 : 0;
	
		/* vml shape, left, top, width, height, origin */
		var makeVisible = function(vml, l, t, w, h, o) {
			vml.coordsize = w+','+h;
			vml.coordorigin = o+','+o;
			vml.path = 'm0,0l'+w+',0l'+w+','+h+'l0,'+h+' xe';
			vml.style.width = w + 'px';
			vml.style.height = h + 'px';
			vml.style.left = l + 'px';
			vml.style.top = t + 'px';
		};
		makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);
		makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1);
	
		var bg = {'X':0, 'Y':0};
		var figurePercentage = function(axis, position) {
			var fraction = true;
			switch(position) {
				case 'left':
				case 'top':
					bg[axis] = 0;
					break;
				case 'center':
					bg[axis] = .5;
					break;
				case 'right':
				case 'bottom':
					bg[axis] = 1;
					break;
				default:
					if (position.search('%') != -1) {
						bg[axis] = parseInt(position)*.01;
					}
					else {
						fraction = false;
					}
			}
			var horz = (axis == 'X');
			bg[axis] = Math.ceil(fraction ? ( (size[horz?'W': 'H'] * bg[axis]) - (size[horz?'w': 'h'] * bg[axis]) ) : parseInt(position));
			if (bg[axis] == 0) {
				bg[axis]++;
			}
		};
		for (var b in bg) {
			figurePercentage(b, thisStyle['backgroundPosition'+b]);
		}
	
		el.vml.image.fill.position = (bg.X/size.W) + ',' + (bg.Y/size.H);
	
		var bgR = thisStyle.backgroundRepeat;
		var dC = {'T':1, 'R':size.W+fudge, 'B':size.H, 'L':1+fudge}; /* these are defaults for repeat of any kind */
		var altC = { 'X': {'b1': 'L', 'b2': 'R', 'd': 'W'}, 'Y': {'b1': 'T', 'b2': 'B', 'd': 'H'} };
		if (bgR != 'repeat') {
			var c = {'T':(bg.Y), 'R':(bg.X+size.w), 'B':(bg.Y+size.h), 'L':(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */
			if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */
				var v = bgR.split('repeat-')[1].toUpperCase();
				c[altC[v].b1] = 1;
				c[altC[v].b2] = size[altC[v].d];
			}
			if (c.B > size.H) {
				c.B = size.H;
			}
			el.vml.image.shape.style.clip = 'rect('+c.T+'px '+(c.R+fudge)+'px '+c.B+'px '+(c.L+fudge)+'px)';
		}
		else {
			el.vml.image.shape.style.clip = 'rect('+dC.T+'px '+dC.R+'px '+dC.B+'px '+dC.L+'px)';
		}
	};

	if(jQuery.browser.msie && /^6/.test(jQuery.browser.version)) {
		try {
			document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */
		} catch(r) {}
		createVmlNameSpace();
		createVmlStyleSheet();
	}
})(jQuery);