/*
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2011 Jerry Luk
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Modified after Mika Tuupola's lazyload:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Version:  1.0.2
 *
 */
(function($) {

   $.fn.lazyload = function(options) {
       var settings = {
           threshold: 0,
           failurelimit: 0,
           delay: 100,
           container: window
       },
       elements = this,
       timeout = null,
       $lastElement;

       if (options) {
           $.extend(settings, options);
       }

       function checkElements(event) {
           var counter = 0;
           var containerOffsets = getOffsets(settings.container);
           elements.each(function() {
               if ($(this).attr("data-src") && $(this).is(":visible")) {
                   var elementOffsets = getOffsets($(this));
                   if (aboveTheTop(containerOffsets, elementOffsets, settings) ||
                   leftOfBegin(containerOffsets, elementOffsets, settings)) {
                       /* Nothing. */
                   } else if (!belowTheFold(containerOffsets, elementOffsets, settings) &&
                   !rightOfFold(containerOffsets, elementOffsets, settings)) {
                       $(this).trigger("appear");
                   } else {
                       if (counter++>settings.failurelimit) {
                           return false;
                       }
                   }
               }
           });
       }

       function getOffsets(element) {
           var elementTop,
           elementLeft,
           elementWidth,
           elementHeight;
           if (element == undefined || element == window) {
               elementTop = $(window).scrollTop();
               elementHeight = $(window).height();
               elementLeft = $(window).scrollLeft();
               elementWidth = $(window).width();
           } else {
               elementTop = $(element).offset().top;
               elementHeight = $(element).height();
               elementLeft = $(element).offset().left;
               elementWidth = $(element).width();
           }
           return {
               top: elementTop,
               height: elementHeight,
               left: elementLeft,
               width: elementWidth
           };
       }

       function belowTheFold(containerOffsets, elementOffsets, settings) {
           var fold = containerOffsets.top + containerOffsets.height;
           return fold <= elementOffsets.top - settings.threshold;
       }

       function rightOfFold(containerOffsets, elementOffsets, settings) {
           var fold = containerOffsets.left + containerOffsets.width;
           return fold <= elementOffsets.left - settings.threshold;
       }

       function aboveTheTop(containerOffsets, elementOffsets, settings) {
           var fold = containerOffsets.top;
           return fold >= elementOffsets.top + settings.threshold + elementOffsets.height;
       }

       function leftOfBegin(containerOffsets, elementOffsets, settings) {
           var fold = containerOffsets.left;
           return fold >= elementOffsets.left + settings.threshold + elementOffsets.width;
       }
        
       this.each(function() {
           var $this = $(this);
           $lastElement = $this;
           if (settings.placeholder) {
               $this.attr("src", settings.placeholder);
           }
           $this.one("appear",
           function(e) {
               $this.attr("src", $this.attr("data-src"));
               $this.removeAttr("data-src");
           });
       });


       /*$lastElement.one("load",
       function() {*/
       $(settings.container).bind("scroll lazyload",
         function(e) {
             if (timeout) {
                 clearTimeout(timeout);
             }
             timeout = setTimeout(function() {
                 checkElements();
             },
             settings.delay);
         }
       );
       /* Force initial check if images should appear. */
       checkElements();
       /*});*/
        
       return this;
   };

   })(jQuery);