// 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() {
    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 **********************************************************************

    $.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) {
                $(document).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
            /*$(window).resize(function() {
                setupPorts(viewport, mouseport);

                for (var i=0; i<layer.length; i++) {
                    setupLayer(layer, i, mouseport);
                }
            });*/


        });
    };

    // END OF PLUGIN DEFINITION **********************************************************************

    // PLUGIN DEFAULTS

    $.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
    };

    initOrigin($.fn.jparallax.settings);
})();