(function($) {
    $.fn.lazyload = function(options) {
        var settings = {
            src: '',
            placeholder: '/leaf_loader.gif',
            threshold: 0,
            failurelimit: 0,
            events: ['scroll'],
            effect: 'show',
            container: window
        };
        if (options) {
            $.extend(settings, options)
        }
        var elements = this;
        $.each(settings.events, 
        function(i, item) {
            $(settings.container).bind(item, 
            function(item) {
                var counter = 0;
                elements.each(function() {
                    if ($.abovethetop(this, settings) || $.leftofbegin(this, settings)) {} else if (!$.belowthefold(this, settings) && !$.rightoffold(this, settings)) {
                        $(this).trigger('appear')
                    } else {
                        if (counter++>settings.failurelimit) {
                            return false
                        }
                    }
                });
                var temp = $.grep(elements, 
                function(element) {
                    return ! element.loaded
                });
                elements = $(temp)
            })
        });
        this.each(function() {
            var self = this;
            if (undefined == $(self).attr('original')) {
                $(self).attr('original', $(self).attr('src'))
            }
            if (undefined == $(self).attr('src') && undefined == $(self).attr('original')) {
                $(self).one('appear', 
                function() {
                    if (!this.loaded || 1 == 1) {
                        $(self).load(settings.src);
                        self.loaded = true
                    }
                })
            } else {
                if (undefined == $(self).attr('src') || '' == $(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
                }
                $(self).one('appear', 
                function() {
                    if (!this.loaded || 1 == 1) {
                        $('<img />').bind('load', 
                        function() {
                            $(self).hide().attr('src', $(self).attr('original'))[settings.effect](settings.effectspeed);
                            self.loaded = true
                        }).attr('src', $(self).attr('original'))
                    }
                })
            }
            $.each(settings.events, 
            function(i, item) {
                $(self).bind(item, 
                function(item) {
                    if (!self.loaded) {
                        $(self).trigger('appear')
                    }
                })
            })
        });
        $(settings.container).trigger(settings.events[0]);
        return this
    };
    $.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()
    };
    $.extend($.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);