// 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) {


    // 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
            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;
                        }
                    }, 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: true, 					//
        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);