// 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:      false,                 // 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:                 0.0,              // Sets default alignment - only comes into play when travel is not 1
   yorigin:                 0.0,              //
   xtravel:              1,              // Factor by which travel is amplified
   ytravel:              0.1,              //
   takeoverFactor:          0.65,                  // Sets rate of decay curve for catching up with target mouse position
   takeoverThresh:          0.000,              // 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);