// jquery.jparallax.js
// 0.9.1
// Stephen Band
//
// Dependencies:
// jQuery 1.2.6 (jquery.com)
//
// Project and documentation site:
// http://webdev.stephband.info/parallax.html


// CLOSURE

(function(jQuery){

	var _ct = 0;
	
	// PRIVATE FUNCTIONS
	
	function stripFiletype(ref){
		var x = ref.replace('.html', '');
		return x.replace('#', '');
	}
	
	function initOrigin(l){
		if (l.xorigin == 'left') {
			l.xorigin = 0;
		} else if (l.xorigin == 'middle' || l.xorigin == 'centre' || l.xorigin == 'center') {
			l.xorigin = 0.5;
		} else if (l.xorigin == 'right') {
			l.xorigin = 1;
		}
		if (l.yorigin == 'top') {
			l.yorigin = 0;
		} else if (l.yorigin == 'middle' || l.yorigin == 'centre' || l.yorigin == 'center') {
			l.yorigin = 0.5;
		} else if (l.yorigin == 'bottom') {
			l.yorigin = 1;
		}
	}
	
	function positionMouse(mouseport, localmouse, virtualmouse){
	
		var difference = {
			x: 0,
			y: 0,
			sum: 0
		};
		
		// Set where the virtual mouse is, if not on target
		if (!mouseport.ontarget) {
		
			// Calculate difference
			difference.x = virtualmouse.x - localmouse.x;
			difference.y = virtualmouse.y - localmouse.y;
			difference.sum = Math.sqrt(difference.x * difference.x + difference.y * difference.y);
			
			// Reset virtualmouse
			virtualmouse.x = localmouse.x + difference.x * mouseport.takeoverFactor;
			virtualmouse.y = localmouse.y + difference.y * mouseport.takeoverFactor;
			
			// If mouse is inside the takeoverThresh set ontarget to true
			//  Commented out by PP (12-24-2009)
			
			
			//if (difference.sum < mouseport.takeoverThresh && difference.sum > mouseport.takeoverThresh * -1) {
			//	mouseport.ontarget = true;
			//}
		}  // Set where the layer is if on target
		else {
			virtualmouse.x = localmouse.x;
			virtualmouse.y = localmouse.y;
		}
	}
	
	function setupPorts(viewport, mouseport){
	
		var offset = mouseport.element.offset();
		
		jQuery.extend(viewport, {
			width: viewport.element.width(),
			height: viewport.element.height()
		});
		
		jQuery.extend(mouseport, {
			width: mouseport.element.width(),
			height: mouseport.element.height(),
			top: offset.top,
			left: offset.left
		});
	}
	
	function parseTravel(travel, origin, dimension){
	
		var offset;
		var cssPos;
		
		if (typeof(travel) === 'string') {
			if (travel.search(/^\d+\s?px$/) != -1) {
				travel = travel.replace('px', '');
				travel = parseInt(travel, 10);
				// Set offset constant used in moveLayers()
				offset = origin * (dimension - travel);
				// Set origin now because it won't get altered in moveLayers()
				cssPos = origin * 100 + '%';
				return {
					travel: travel,
					travelpx: true,
					offset: offset,
					cssPos: cssPos
				};
			} else if (travel.search(/^\d+\s?%$/) != -1) {
				travel.replace('%', '');
				travel = parseInt(travel, 10) / 100;
			} else {
				travel = 1;
			}
		}
		// Set offset constant used in moveLayers()
		offset = origin * (1 - travel);
		return {
			travel: travel,
			travelpx: false,
			offset: offset
		}
	}
	
	function setupLayer(layer, i, mouseport){
	
		var xStuff;
		var yStuff;
		var cssObject = {};
		
		layer[i] = jQuery.extend({}, {
			width: layer[i].element.width(),
			height: layer[i].element.height()
		}, layer[i]);
		
		xStuff = parseTravel(layer[i].xtravel, layer[i].xorigin, layer[i].width);
		yStuff = parseTravel(layer[i].ytravel, layer[i].yorigin, layer[i].height);
		
		jQuery.extend(layer[i], {
			// Used in triggerResponse
			diffxrat: mouseport.width / (layer[i].width - mouseport.width),
			diffyrat: mouseport.height / (layer[i].height - mouseport.height),
			// Used in moveLayers
			xtravel: xStuff.travel,
			ytravel: yStuff.travel,
			xtravelpx: xStuff.travelpx,
			ytravelpx: yStuff.travelpx,
			xoffset: xStuff.offset,
			yoffset: yStuff.offset
		});
		
		// Set origin now if it won't be altered in moveLayers()
		if (xStuff.travelpx) {
			cssObject.left = xStuff.cssPos;
		}
		if (yStuff.travelpx) {
			cssObject.top = yStuff.cssPos;
		}
		if (xStuff.travelpx || yStuff.travelpx) {
			layer[i].element.css(cssObject);
		}
	}
	
	function setupLayerContents(layer, i, viewportOffset){
	
		var contentOffset;
		
		// Give layer a content object
		jQuery.extend(layer[i], {
			content: []
		});
		// Layer content: get positions, dimensions and calculate element offsets for centering children of layers
		for (var n = 0; n < layer[i].element.children().length; n++) {
		
			if (!layer[i].content[n]) 
				layer[i].content[n] = {};
			if (!layer[i].content[n].element) 
				layer[i].content[n]['element'] = layer[i].element.children().eq(n);
			
			// Store the anchor name if one has not already been specified.  You can specify anchors in Layer Options rather than html if you want.
			if (!layer[i].content[n].anchor && layer[i].content[n].element.children('a').attr('name')) {
				layer[i].content[n]['anchor'] = layer[i].content[n].element.children('a').attr('name');
			}
			
			// Only bother to store child's dimensions if child has an anchor.  What's the point otherwise?
			if (layer[i].content[n].anchor) {
				contentOffset = layer[i].content[n].element.offset();
				jQuery.extend(layer[i].content[n], {
					width: layer[i].content[n].element.width(),
					height: layer[i].content[n].element.height(),
					x: contentOffset.left - viewportOffset.left,
					y: contentOffset.top - viewportOffset.top
				});
				jQuery.extend(layer[i].content[n], {
					posxrat: (layer[i].content[n].x + layer[i].content[n].width / 2) / layer[i].width,
					posyrat: (layer[i].content[n].y + layer[i].content[n].height / 2) / layer[i].height
				});
			}
		}
	}
	
	function moveLayers(layer, xratio, yratio){
	
		var xpos;
		var ypos;
		var cssObject;
		
		for (var i = 0; i < layer.length; i++) {
		
			// Calculate the moving factor
			xpos = layer[i].xtravel * xratio + layer[i].xoffset;
			ypos = layer[i].ytravel * yratio + layer[i].yoffset;
			cssObject = {};
			// Do the moving by pixels or by ratio depending on travelpx
			if (layer[i].xparallax) {
				if (layer[i].xtravelpx) {
					cssObject.marginLeft = xpos * -1 + 'px';
				} else {
					cssObject.left = xpos * 100 + '%';
					cssObject.marginLeft = xpos * layer[i].width * -1 + 'px';
				}
			}
			if (layer[i].yparallax) {
				if (layer[i].ytravelpx) {
					cssObject.marginTop = ypos * -1 + 'px';
				} else {
					cssObject.top = ypos * 100 + '%';
					cssObject.marginTop = ypos * layer[i].height * -1 + 'px';
				}
			}
			layer[i].element.css(cssObject);
		}
	}
	
	// PLUGIN DEFINITION **********************************************************************
	
	jQuery.fn.jparallax = function(options){
	
		// Organise settings into objects (Is this a bit of a mess, or is it efficient?)
		var settings = jQuery().extend({}, jQuery.fn.jparallax.settings, options);
		var settingsLayer = {
			xparallax: settings.xparallax,
			yparallax: settings.yparallax,
			xorigin: settings.xorigin,
			yorigin: settings.yorigin,
			xtravel: settings.xtravel,
			ytravel: settings.ytravel
		};
		var settingsMouseport = {
			element: settings.mouseport,
			takeoverFactor: settings.takeoverFactor,
			takeoverThresh: settings.takeoverThresh
		};
		if (settings.mouseport) 
			settingsMouseport['element'] = settings.mouseport;
		
		// Populate layer array with default settings
		var layersettings = [];
		for (var a = 1; a < arguments.length; a++) {
			layersettings.push(jQuery.extend({}, settingsLayer, arguments[a]));
		}
		
		// Iterate matched elements
		return this.each(function(){
		
			// VAR
			
			var localmouse = {
				x: 0.5,
				y: 0.5
			};
			
			var virtualmouse = {
				x: 0.5,
				y: 0.5
			};
			
			var timer = {
				running: false,
				frame: settings.frameDuration,
				fire: function(x, y){
					positionMouse(mouseport, localmouse, virtualmouse);
					moveLayers(layer, virtualmouse.x, virtualmouse.y);
					this.running = setTimeout(function(){
						if (localmouse.x != x || localmouse.y != y || !mouseport.ontarget) {
							timer.fire(localmouse.x, localmouse.y);
						} else if (timer.running) {
							timer.running = false;
							mouseport.ontarget = false;
						}
					}, timer.frame);
				}
			};
			
			var viewport = {
				element: jQuery(this)
			};
			
			var mouseport = jQuery.extend({}, {
				element: viewport.element
			}, settingsMouseport, {
				xinside: false, // is the mouse inside the mouseport's dimensions?
				yinside: false,
				active: false, // are the mouse coordinates still being read?
				ontarget: false // is the top layer inside the takeoverThresh?
			});
			
			var layer = [];
			
			// FUNCTIONS
			
			function matrixSearch(layer, ref, callback){
				for (var i = 0; i < layer.length; i++) {
					var gotcha = false;
					for (var n = 0; n < layer[i].content.length; n++) {
						if (layer[i].content[n].anchor == ref) {
							callback(i, n);
							return [i, n];
						}
					}
				}
				return false;
			}
			
			// RUN
			
			setupPorts(viewport, mouseport);
			
			// Cycle through and create layers
			for (var i = 0; i < viewport.element.children().length; i++) {
				// Create layer from settings if it doesn't exist
				layer[i] = jQuery.extend({}, settingsLayer, layersettings[i], {
					element: viewport.element.children('*:eq(' + i + ')')
				});
				
				setupLayer(layer, i, mouseport);
				
				if (settings.triggerResponse) {
					setupLayerContents(layer, i, viewport.element.offset());
				}
			}
			
			
			
			// Set up layers CSS and initial position
			viewport.element.children().css('position', 'absolute');
			moveLayers(layer, 0.5, 0.5);
			
			// Mouse Response
			if (settings.mouseResponse) {
				jQuery().mousemove(function(mouse){
					// Is mouse inside?
					mouseport.xinside = (mouse.pageX >= mouseport.left && mouse.pageX < mouseport.width + mouseport.left) ? true : false;
					mouseport.yinside = (mouse.pageY >= mouseport.top && mouse.pageY < mouseport.height + mouseport.top) ? true : false;
					// Then switch active on.
					if (mouseport.xinside && mouseport.yinside && !mouseport.active) {
						mouseport.ontarget = false;
						mouseport.active = true;
					}
					// If active is on give localmouse coordinates
					if (mouseport.active) {
						if (mouseport.xinside) {
							localmouse.x = (mouse.pageX - mouseport.left) / mouseport.width;
						} else {
							localmouse.x = (mouse.pageX < mouseport.left) ? 0 : 1;
						}
						if (mouseport.yinside) {
							localmouse.y = (mouse.pageY - mouseport.top) / mouseport.height;
						} else {
							localmouse.y = (mouse.pageY < mouseport.top) ? 0 : 1;
						}
					}
					
					// If mouse is inside, fire timer
					if (mouseport.xinside && mouseport.yinside) {
						if (!timer.running) {
							timer.fire(localmouse.x, localmouse.y);
						}
					} else if (mouseport.active) {
						mouseport.active = false;
					}
				});
			}
			
			// Trigger Response
			if (settings.triggerResponse) {
				viewport.element.bind("jparallax", function(event, ref){
				
					ref = stripFiletype(ref);
					
					matrixSearch(layer, ref, function(i, n){
						localmouse.x = layer[i].content[n].posxrat * (layer[i].diffxrat + 1) - (0.5 * layer[i].diffxrat);
						localmouse.y = layer[i].content[n].posyrat * (layer[i].diffyrat + 1) - (0.5 * layer[i].diffyrat);
						
						if (!settings.triggerExposesEdges) {
							if (localmouse.x < 0) 
								localmouse.x = 0;
							if (localmouse.x > 1) 
								localmouse.x = 1;
							if (localmouse.y < 0) 
								localmouse.y = 0;
							if (localmouse.y > 1) 
								localmouse.y = 1;
						}
						
						mouseport.ontarget = false;
						
						if (!timer.running) 
							timer.fire(localmouse.x, localmouse.y);
					});
				});
			}
			
			// Window Resize Response
			jQuery(window).resize(function(){
			
				setupPorts(viewport, mouseport);
				for (var i = 0; i < layer.length; i++) {
					setupLayer(layer, i, mouseport);
				}
			});
			
			
		});
	};
	
	// END OF PLUGIN DEFINITION **********************************************************************
	
	// PLUGIN DEFAULTS
	
	jQuery.fn.jparallax.settings = {
		mouseResponse: true, // Sets mouse response
		mouseActiveOutside: false, // Makes mouse affect layers from outside of the mouseport. 
		triggerResponse: true, // Sets trigger response
		triggerExposesEdges: false, // Sets whether the trigger pulls layer edges into view in trying to centre layer content.
		xparallax: true, // Sets directions to move in
		yparallax: false, //
		xorigin: 0.5, // Sets default alignment - only comes into play when travel is not 1
		yorigin: 0.5, //
		xtravel: 1, // Factor by which travel is amplified
		ytravel: 1, //
		takeoverFactor: 0.65, // Sets rate of decay curve for catching up with target mouse position
		takeoverThresh: 0.002, // Sets the distance within which virtualmouse is considered to be on target, as a multiple of mouseport width.
		frameDuration: 25 // In milliseconds
	};
	
	// RUN
	
	initOrigin(jQuery.fn.jparallax.settings);
	
	jQuery(function(){
	
	});
	
	
	// END CLOSURE

})(jQuery);