/*
* Lazy Load - jQuery plugin for lazy loading images
*
* Copyright (c) 2007-2011 Mika Tuupola
*
* Licensed under the MIT license:
*   http://www.opensource.org/licenses/mit-license.php
*
* Project home:
*   http://www.appelsiini.net/projects/lazyload
*
* Version:  1.6.0
*
*/
(function ($) {

	$.fn.lazyload = function (options) {
		var settings = {
			threshold: 0,
			failure_limit: 0,
			event: "scroll",
			effect: "show",
			container: window,
			skip_invisible: true
		};

		if (options) {
			/* Maintain BC for a couple of version. */
			if (null !== options.failurelimit) {
				options.failure_limit = options.failurelimit;
				delete options.failurelimit;
			}

			$.extend(settings, options);
		}

		/* Fire one scroll event per scroll. Not one scroll event per image. */
		var elements = this;
		if (0 == settings.event.indexOf("scroll")) {
			$(settings.container).bind(settings.event, function (event) {
				var counter = 0;
				elements.each(function () {
					if (settings.skip_invisible && !$(this).is(":visible")) return;
					if ($.abovethetop(this, settings) ||
                        $.leftofbegin(this, settings)) {
						/* Nothing. */
					} else if (!$.belowthefold(this, settings) &&
                        !$.rightoffold(this, settings)) {
						$(this).trigger("appear");
					} else {
						if (++counter > settings.failure_limit) {
							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;
			self.loaded = false;

			/* When appear is triggered load original image. */
			$(self).one("appear", function () {
				if (!this.loaded) {
					$("<img />")
                        .bind("load", function () {
                        	$(self)
                                .hide()
                                .attr("src", $(self).data("original"))
                                [settings.effect](settings.effectspeed);
                        	self.loaded = true;
                        })
                        .attr("src", $(self).data("original"));
				};
			});

			/* When wanted event is triggered load original image */
			/* by triggering appear.                              */
			if (0 != settings.event.indexOf("scroll")) {
				$(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": function (a) { return $.belowthefold(a, { threshold: 0, container: window }) },
		"above-the-fold": function (a) { return !$.belowthefold(a, { threshold: 0, container: window }) },
		"right-of-fold": function (a) { return $.rightoffold(a, { threshold: 0, container: window }) },
		"left-of-fold": function (a) { return !$.rightoffold(a, { threshold: 0, container: window }) }
	});

})(jQuery);