// Make filtering div appear to float to the right of the results div
$('#filters').custFloat({width_guide_id: 'filters-width-guide', height_guide_el: '#results'});

// Custom float (note: relies on underscore.js for throttling and debounce)
(function ($, _) {
    $.fn.custFloat = function (options) {
        var opts = _.extend({
                width_guide_id: 'float-width-guide', // Should be a valid id string
                height_guide_el: 'body', // Should be a jquery selector
                pin_boundary_adjust_offset: 0,
                outer_height_adjust_offset: 100,
                scroll_throttle_ms: 15,
                debounce_timer_ms: 25
            }, options);

        return this.each(function () {
            var $this               = $(this),
                $parent             = $this.offsetParent(),
                $window             = $(window),
                $width_guide_el     = $('<div id=' + opts.width_guide_id + '></div>').insertBefore($this),
                top                 = Math.floor($this.offset().top - parseFloat($this.css('marginTop').replace(/auto/, 0))),
                floating            = false,
                pinned              = false,

                scroll = function() {
                    var y                   = $window.scrollTop(),
                        height              = $this.outerHeight(true) + opts.outer_height_adjust_offset;
                        parent_height       = $parent.height(),
                        available_height    = $(opts.height_guide_el).height(),
                        parent_top_offset   = $parent.offset().top,
                        pin_boundary        = Math.ceil(parent_top_offset + parent_height - height - opts.pin_boundary_adjust_offset);

                    if (height < available_height) {
                        if ((y >= top) && (y < pin_boundary) && (floating === false) && (pinned === false)) {
                            floatIt();
                        } else if ((y >= pin_boundary) && (pinned === false)) {
                            pinIt();
                        } else if ((y < pin_boundary) && (pinned)) {
                            floatIt();
                        } else if ((y < top) && (floating)) {
                            restoreIt();
                        } else {
                            // Noop
                        }
                    } else {
                        restoreIt();
                    }
                },

                resize = function() {
                    var width = $width_guide_el.width();
                    $this.css({width: width});
                };

            function floatIt() {
                var width = $width_guide_el.width();

                floating = true;
                pinned = false;

                $this.css({
                    position: 'fixed',
                    top: 0,
                    pin_boundary: '',
                    width: width
                });
            }

            function pinIt() {
                var width = $width_guide_el.width(),
                    height = $this.outerHeight(true) + opts.outer_height_adjust_offset;

                pinned = true;
                floating = false;

                $this.css({
                    position: 'absolute',
                    top: $parent.height() - height - opts.pin_boundary_adjust_offset,
                    pin_boundary: '',
                    width: width
                });
            }

            function restoreIt() {
                floating = false;
                pinned = false;

                $this.css({
                    position: '',
                    top: '',
                    pin_boundary: '',
                    width: ''
                });
            }

            $window.scroll(_.throttle(scroll, opts.scroll_throttle_ms));
            $window.resize(_.debounce(resize, opts.debounce_timer_ms));

        });
    };
})(jQuery, _);