/*
 * jQuery.appear
 * https://github.com/bas2k/jquery.appear/
 * http://code.google.com/p/jquery-appear/
 * http://bas2k.ru/
 *
 * Copyright (c) 2009 Michael Hixson
 * Copyright (c) 2012-2014 Alexander Brovikov
 * Licensed under the MIT license (http://www.opensource.org/licenses/mit-license.php)
 */
(function ($) {
    $.fn.appear = function (fn, options) {
        var settings = $.extend({data: undefined, one: true, accX: 0, accY: 0}, options);
        return this.each(function () {
            var t = $(this);
            t.appeared = false;
            if (!fn) {
                t.trigger('appear', settings.data);
                return;
            }
            var w = $(window);
            var check = function () {
                if (!t.is(':visible')) {
                    t.appeared = false;
                    return;
                }
                var a = w.scrollLeft();
                var b = w.scrollTop();
                var o = t.offset();
                var x = o.left;
                var y = o.top;
                var ax = settings.accX;
                var ay = settings.accY;
                var th = t.height();
                var wh = w.height();
                var tw = t.width();
                var ww = w.width();
                if (y + th + ay >= b && y <= b + wh + ay && x + tw + ax >= a && x <= a + ww + ax) {
                    if (!t.appeared) t.trigger('appear', settings.data);
                } else {
                    t.appeared = false;
                }
            };
            var modifiedFn = function () {
                t.appeared = true;
                if (settings.one) {
                    w.unbind('scroll', check);
                    var i = $.inArray(check, $.fn.appear.checks);
                    if (i >= 0) $.fn.appear.checks.splice(i, 1);
                }
                fn.apply(this, arguments);
            };
            if (settings.one) t.one('appear', settings.data, modifiedFn); else t.bind('appear', settings.data, modifiedFn);
            w.scroll(check);
            $.fn.appear.checks.push(check);
            (check)();
        });
    };
    $.extend($.fn.appear, {
        checks: [], timeout: null, checkAll: function () {
            var length = $.fn.appear.checks.length;
            if (length > 0) while (length--) ($.fn.appear.checks[length])();
        }, run: function () {
            if ($.fn.appear.timeout) clearTimeout($.fn.appear.timeout);
            $.fn.appear.timeout = setTimeout($.fn.appear.checkAll, 20);
        }
    });
    $.each(['append', 'prepend', 'after', 'before', 'attr', 'removeAttr', 'addClass', 'removeClass', 'toggleClass', 'remove', 'css', 'show', 'hide'], function (i, n) {
        var old = $.fn[n];
        if (old) {
            $.fn[n] = function () {
                var r = old.apply(this, arguments);
                $.fn.appear.run();
                return r;
            }
        }
    });
})(jQuery);