/*
	Animated miniTabs by frequency decoder (http://www.frequency-decoder.com/)
	Based on an idea by Rob L Glazebrook (http://www.rootarcana.com/test/smartmini/) itself
	derived from the original idea of Stephen Clark (http://www.sgclark.com/sandbox/minislide/)
*/

var miniTab = {
	currentTab:     0,
	activeTab:      0,
	destX:          0,
	destW:          0,
	t:              0,
	b:              0,
	c:              0,
	d:              20,
	animInterval:   null,
	sliderObj:      null,
	aHeight:        0,
	ul:             [],
	liArr:          [],
	aArr:           [],

	init: function() {
		if(!document.getElementById || !document.getElementById("topnavigation")) return;

		miniTab.ul          = document.getElementById("topnavigation").getElementsByTagName("ul")[0];
		miniTab.liArr       = miniTab.ul.getElementsByTagName("li");
		miniTab.aArr        = miniTab.ul.getElementsByTagName("a");

		for(var i = 0, li; li = miniTab.liArr[i]; i++) {
			li.onmouseover = miniTab.aArr[i].onfocus = function(e) {
				var pos = 0;
				var elem = this.nodeName == "LI" ? this : this.parentNode;
				while(elem.previousSibling) {
					elem = elem.previousSibling;
					if(elem.tagName && elem.tagName == "LI") pos++;
				}
				miniTab.initSlide(pos);
			}
		}

		miniTab.ul.onmouseout = function(e) {
			miniTab.initSlide(miniTab.currentTab);
		};

		for(var i = 0, a; a = miniTab.aArr[i]; i++) {
			if(a.className.search("active") != -1) {
				miniTab.activeTab = miniTab.currentTab = i;
			}
		}

		miniTab.slideObj                = miniTab.ul.parentNode.appendChild(document.createElement("div"));
		miniTab.slideObj.appendChild(document.createTextNode(String.fromCharCode(160)));
		miniTab.slideObj.id             = "animated-tab";
		miniTab.slideObj.style.top      = "0";
		miniTab.slideObj.style.left     = (miniTab.ul.offsetLeft + miniTab.liArr[miniTab.activeTab].offsetLeft + miniTab.aArr[miniTab.activeTab].offsetLeft) + "px";
		miniTab.slideObj.style.width    = miniTab.aArr[miniTab.activeTab].offsetWidth + "px";
		miniTab.aHeight                 = miniTab.ul.offsetTop + miniTab.liArr[miniTab.activeTab].offsetTop + miniTab.aArr[miniTab.activeTab].offsetTop;
		
		miniTab.initSlide(miniTab.activeTab, true);

		var intervalMethod = function() { miniTab.slideIt(); }
		miniTab.animInterval = setInterval(intervalMethod,10);
	},

	cleanUp: function() {
		clearInterval(miniTab.animInterval);
		miniTab.animInterval = null;
	},

	initSlide: function(pos, force) {
		if(!force && pos == miniTab.activeTab) return;
		miniTab.activeTab = pos;
		miniTab.initAnim();
	},

	initAnim: function() {
		
		miniTab.destX = parseInt(miniTab.liArr[miniTab.activeTab].offsetLeft + miniTab.liArr[miniTab.activeTab].getElementsByTagName("a")[0].offsetLeft + miniTab.ul.offsetLeft);
		miniTab.destW = parseInt(miniTab.liArr[miniTab.activeTab].getElementsByTagName("a")[0].offsetWidth);
		miniTab.t = 0;
		miniTab.b = miniTab.slideObj.offsetLeft;
		miniTab.c = miniTab.destX - miniTab.b;

		miniTab.bW = miniTab.slideObj.offsetWidth;
		miniTab.cW = miniTab.destW - miniTab.bW;

		miniTab.slideObj.style.top = (miniTab.ul.offsetTop + miniTab.liArr[miniTab.activeTab].offsetTop + miniTab.aArr[miniTab.activeTab].offsetTop) + "px";
		miniTab.slideObj.visibility = "visible";
	},

	slideIt:function() {
		
		// Has the browser text size changed?
		if(miniTab.aHeight != miniTab.ul.offsetTop + miniTab.liArr[miniTab.activeTab].offsetTop + miniTab.aArr[miniTab.activeTab].offsetTop) {
			miniTab.initAnim();
			miniTab.aHeight = miniTab.ul.offsetTop + miniTab.liArr[miniTab.activeTab].offsetTop + miniTab.aArr[miniTab.activeTab].offsetTop
		};

		if(miniTab.t++ < miniTab.d) {
			var x = miniTab.animate(miniTab.t,miniTab.b,miniTab.c,miniTab.d);
			var w = miniTab.animate(miniTab.t,miniTab.bW,miniTab.cW,miniTab.d);

			miniTab.slideObj.style.left = parseInt(x) + "px";
			miniTab.slideObj.style.width = parseInt(w) + "px";
		} else {
			miniTab.slideObj.style.left = miniTab.destX + "px";
			miniTab.slideObj.style.width = miniTab.destW +"px";
		}
	},

	animate: function(t,b,c,d) {
		if ((t/=d/2) < 1) return c/2*t*t + b;
		return -c/2 * ((--t)*(t-2) - 1) + b;
	}
}

window.onload = miniTab.init;
window.onunload = miniTab.cleanUp;