// Tab Selection
function SelectTab(tabIndex, pathToBase) {
    var overviewItem = document.getElementById('tabone');
    var macItem = document.getElementById('tabtwo');
    var iphoneItem = document.getElementById('tabfour');
    var ipadItem = document.getElementById('tabthree');
    var tabs = [overviewItem, macItem, ipadItem, iphoneItem];
    for ( var i = 0; i < tabs.length; i++ ) {
    	var depth = Math.abs(tabIndex-i);
        var item = tabs[i];
 
        item.style.zIndex = 5 - depth;
 
 		var tabBackgroundFile = pathToBase + '/images/SideTab' + depth + '.png';
 		anchor = item.childNodes.item(0);
 		anchor.style.backgroundImage = 'url(' + tabBackgroundFile + ')';
    }
}

// Preload images
var imgObjects = [];
function PreloadImages(pathToGeneralImagesDir, extraImages) {
	function LoadImages(prefix, names) {
	    for (var i = imgObjects.length; i < names.length; i++) {
	        imgObjects[i] = new Image(); 
	        imgObjects[i].src = prefix + imgNames[i];
	    }  
	}
	
	// Extra Images
	LoadImages('', extraImages);
	
	// General imagese
	var imgNames = ['ClipboardBackground.jpg', 'WidePageBackground.jpg', 'LetterStripes.png', 'PageSplit.jpg', 'SideTab0.png', 'SideTab1.png', 'SideTab2.png', 'SideTab3.png', 'MacTabLabel.png', 'iPadTabLabel.png', 'iPhoneTabLabel.png', 'OverviewTabLabel.png', 'WrinklyPeaTab.png', 'WrinklyPeaTabLabel.png']; 
	LoadImages(pathToGeneralImagesDir + '/', imgNames);
}

// Rotate Screenshots
var currentScreenshotIndex = 0;
var lastScreenshotIndex = 0;
function RotateScreenshots() {
	var screenshotElement = document.getElementById('screenshots');
	var imageElements = screenshotElement.getElementsByTagName('img');
	var numberOfImages = imageElements.length;
	if ( numberOfImages <= 1 ) return;
	currentScreenshotIndex = (currentScreenshotIndex + 1) % numberOfImages;
	for ( var imageIndex = 0; imageIndex < numberOfImages; imageIndex++ ) {
		var image = imageElements.item(imageIndex);
		if ( imageIndex == currentScreenshotIndex ) {
			Effect.Appear(image, {to:1.0, duration:1.0});   
		}
		else if ( lastScreenshotIndex == imageIndex ) {
			Effect.Fade(image, {duration:1.0});		
		}
	}
	lastScreenshotIndex = currentScreenshotIndex;
}

// Get parameters
function GetQueryParam(name) {
	var params={};	
	document.location.search.replace(/\??(?:([^=]+)=([^&]*)&?)/g, function () {
	    function decode(s) {
	        return decodeURIComponent(s.split("+").join(" "));
	    }
	    params[decode(arguments[1])] = decode(arguments[2]);
	});
	return params[name];
}