(function($) {

    $.fn.lazyload = function(options) {
        var settings = {
            threshold    : 0,
            failurelimit : 0,
            event        : "scroll",
            effect       : "show",
            container    : window,
			loadDelay    : 30
        };
                
        if(options) {
            $.extend(settings, options);
        }
        /* Fire one scroll event per scroll. Not one scroll event per image. */
        var elements = this;
        if ("scroll" == settings.event) {
            $(settings.container).bind("scroll", function(event) {
                loadImages(elements);
            });
            $(settings.container).bind("resize", function(event) {
                loadImages(elements);
            });
        }
        var loadImages = function(elements) {
			var counter = 0;
			var loadDelay = 0;
			var elementSize = $(elements).size();
			elements.each(function() {
				if ($.abovethetop(this, settings) || $.leftofbegin(this, settings)) {
						/* Nothing. */
				} 
				else if (!$.belowthefold(this, settings) && !$.rightoffold(this, settings)) {
						var $this = $(this);
						setTimeout(function() {
							$this.trigger("appear");
						}, loadDelay);
						loadDelay += settings.loadDelay;
				} 
				else {
					if (counter++ > settings.failurelimit) {
						return false;
					}
				}
			});
			/* Remove image from array so it is not looped next time. */
			var temp = $.grep(elements, function(element) {
				return !element.loaded;
			});
			elements = $(temp);	
		}
		this.each(function() {
            var $self = $(this);
			var self = this;
            
            /* Save original only if it is not defined in HTML. */
            if (undefined == $self.attr("original")) {
                $self.attr("original", $self.attr("src"));     
            }
            if ("scroll" != settings.event || 
                    undefined == $self.attr("src") || 
                    settings.placeholder == $self.attr("src") || 
                    ($.abovethetop(self, settings) ||
                     $.leftofbegin(self, settings) || 
                     $.belowthefold(self, settings) || 
                     $.rightoffold(self, settings) )) {
                        
                if (settings.placeholder) {
                    $self.attr("src", settings.placeholder);      
                } 
				else {
                    $self.removeAttr("src");
                }
                self.loaded = false;
            } 
			else {
                self.loaded = true;
            }
            /* When appear is triggered load original image. */
			$self.one("appear", function() {
				if (!this.loaded) {
					$("<img />")
						.bind("load", function() {
							$self
								.hide()
								.attr("src", $self.attr("original"))
								[settings.effect](settings.effectspeed);
							self.loaded = true;
						})
						.attr("src", $self.attr("original"));
				};
			});

            /* When wanted event is triggered load original image */
            /* by triggering appear.                              */
            if ("scroll" != settings.event) {
                $self.bind(settings.event, function(event) {
                    if (!self.loaded) {
                        $self.trigger("appear");
                    }
                });
            }
        });
        
        /* Force initial check if images should appear. */
        $(settings.container).trigger(settings.event);
        
        return this;

    };
	
	
    /* Convenience methods in jQuery namespace.           */
    /* Use as  $.belowthefold(element, {threshold : 100, container : window}) */

    $.belowthefold = function(element, settings) {
        if (settings.container === undefined || settings.container === window) {
            var fold = $(window).height() + $(window).scrollTop();
        } else {
            var fold = $(settings.container).offset().top + $(settings.container).height();
        }
        return fold <= $(element).offset().top - settings.threshold;
    };
    
    $.rightoffold = function(element, settings) {
        if (settings.container === undefined || settings.container === window) {
            var fold = $(window).width() + $(window).scrollLeft();
        } else {
            var fold = $(settings.container).offset().left + $(settings.container).width();
        }
        return fold <= $(element).offset().left - settings.threshold;
    };
        
    $.abovethetop = function(element, settings) {
        if (settings.container === undefined || settings.container === window) {
            var fold = $(window).scrollTop();
        } else {
            var fold = $(settings.container).offset().top;
        }
        return fold >= $(element).offset().top + settings.threshold  + $(element).height();
    };
    
    $.leftofbegin = function(element, settings) {
        if (settings.container === undefined || settings.container === window) {
            var fold = $(window).scrollLeft();
        } else {
            var fold = $(settings.container).offset().left;
        }
        return fold >= $(element).offset().left + settings.threshold + $(element).width();
    };
    /* Custom selectors for your convenience.   */
    /* Use as $("img:below-the-fold").something() */

    $.extend($.expr[':'], {
        "below-the-fold" : "$.belowthefold(a, {threshold : 0, container: window})",
        "above-the-fold" : "!$.belowthefold(a, {threshold : 0, container: window})",
        "right-of-fold"  : "$.rightoffold(a, {threshold : 0, container: window})",
        "left-of-fold"   : "!$.rightoffold(a, {threshold : 0, container: window})"
    });
    
})(jQuery);