/**
 * jCarouselLite - jQuery plugin to navigate images/any content in a carousel style widget.
 * @requires jQuery v1.2 or above
 *
 * http://gmarwaha.com/jquery/jcarousellite/
 *
 * Copyright (c) 2007 Ganeshji Marwaha (gmarwaha.com)
 * Dual licensed under the MIT and GPL licenses:
 * http://www.opensource.org/licenses/mit-license.php
 * http://www.gnu.org/licenses/gpl.html
 *
 * Version: 1.0.1
 * Note: Requires jquery 1.2 or above from version 1.0.1
 */
/**
btnPrev : 上一张按钮
btnNext : 下一张按钮
btnGo : 标签控制，也就是用’1,2,3,4…’来控制
mouseWheel : 是否支持鼠标滑轮滚动，属性值：false / true；默认为false 打开此项需要jQuery UI插件支持
auto : 设置自动播放的速度，默认自动播放是关闭的，格式 auto: 800 (为播放速度)
speed : 动画效果速度
easing : 动画效果优化，姑且这么里面 需要外部插件支持
vertical : 动画方向，如果设置为true，则表示垂直滚动，默认为false
circular : 是否重复播放，如果设置为false，则到最后一个下一张按钮就点不动了，到第一张上一张按钮就点不动
visible : 设置默认显示几个li，默认是3个
start : 效果从第几个开始，默认为0
scroll : 一次滑动几个li，默认是2
beforeStart : 这个是接口，每次滑动效果执行之前执行的自定义函数
afterEnd : 这个是接口，每次滑动效果执行之后执行的自定义函数
 */
 
/**
 * Creates a carousel-style navigation widget for images/any-content from a simple HTML markup.
 *
 * The HTML markup that is used to build the carousel can be as simple as...
 *
 *  <div class="carousel">
 *      <ul>
 *          <li><img src="image/1.jpg" alt="1"></li>
 *          <li><img src="image/2.jpg" alt="2"></li>
 *          <li><img src="image/3.jpg" alt="3"></li>
 *      </ul>
 *  </div>
 *
 * As you can see, this snippet is nothing but a simple div containing an unordered list of images.
 * You don't need any special "class" attribute, or a special "css" file for this plugin.
 * I am using a class attribute just for the sake of explanation here.
 *
 * To navigate the elements of the carousel, you need some kind of navigation buttons.
 * For example, you will need a "previous" button to go backward, and a "next" button to go forward.
 * This need not be part of the carousel "div" itself. It can be any element in your page.
 * Lets assume that the following elements in your document can be used as next, and prev buttons...
 *
 * <button class="prev">&lt;&lt;</button>
 * <button class="next">&gt;&gt;</button>
 *
 * Now, all you need to do is call the carousel component on the div element that represents it, and pass in the
 * navigation buttons as options.
 *
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev"
 * });
 *
 * That's it, you would have now converted your raw div, into a magnificient carousel.
 *
 * There are quite a few other options that you can use to customize it though.
 * Each will be explained with an example below.
 *
 * @param an options object - You can specify all the options shown below as an options object param.
 *
 * @option btnPrev, btnNext : string - no defaults
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev"
 * });
 * @desc Creates a basic carousel. Clicking "btnPrev" navigates backwards and "btnNext" navigates forward.
 *
 * @option btnGo - array - no defaults
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      btnGo: [".0", ".1", ".2"]
 * });
 * @desc If you don't want next and previous buttons for navigation, instead you prefer custom navigation based on
 * the item number within the carousel, you can use this option. Just supply an array of selectors for each element
 * in the carousel. The index of the array represents the index of the element. What i mean is, if the
 * first element in the array is ".0", it means that when the element represented by ".0" is clicked, the carousel
 * will slide to the first element and so on and so forth. This feature is very powerful. For example, i made a tabbed
 * interface out of it by making my navigation elements styled like tabs in css. As the carousel is capable of holding
 * any content, not just images, you can have a very simple tabbed navigation in minutes without using any other plugin.
 * The best part is that, the tab will "slide" based on the provided effect. :-)
 *
 * @option mouseWheel : boolean - default is false
 * @example
 * $(".carousel").jCarouselLite({
 *      mouseWheel: true
 * });
 * @desc The carousel can also be navigated using the mouse wheel interface of a scroll mouse instead of using buttons.
 * To get this feature working, you have to do 2 things. First, you have to include the mouse-wheel plugin from brandon.
 * Second, you will have to set the option "mouseWheel" to true. That's it, now you will be able to navigate your carousel
 * using the mouse wheel. Using buttons and mouseWheel or not mutually exclusive. You can still have buttons for navigation
 * as well. They complement each other. To use both together, just supply the options required for both as shown below.
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      mouseWheel: true
 * });
 *
 * @option auto : number - default is null, meaning autoscroll is disabled by default
 * @example
 * $(".carousel").jCarouselLite({
 *      auto: 800,
 *      speed: 500
 * });
 * @desc You can make your carousel auto-navigate itself by specfying a millisecond value in this option.
 * The value you specify is the amount of time between 2 slides. The default is null, and that disables auto scrolling.
 * Specify this value and magically your carousel will start auto scrolling.
 *
 * @option speed : number - 200 is default
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      speed: 800
 * });
 * @desc Specifying a speed will slow-down or speed-up the sliding speed of your carousel. Try it out with
 * different speeds like 800, 600, 1500 etc. Providing 0, will remove the slide effect.
 *
 * @option easing : string - no easing effects by default.
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      easing: "bounceout"
 * });
 * @desc You can specify any easing effect. Note: You need easing plugin for that. Once specified,
 * the carousel will slide based on the provided easing effect.
 *
 * @option vertical : boolean - default is false
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      vertical: true
 * });
 * @desc Determines the direction of the carousel. true, means the carousel will display vertically. The next and
 * prev buttons will slide the items vertically as well. The default is false, which means that the carousel will
 * display horizontally. The next and prev items will slide the items from left-right in this case.
 *
 * @option circular : boolean - default is true
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      circular: false
 * });
 * @desc Setting it to true enables circular navigation. This means, if you click "next" after you reach the last
 * element, you will automatically slide to the first element and vice versa. If you set circular to false, then
 * if you click on the "next" button after you reach the last element, you will stay in the last element itself
 * and similarly for "previous" button and first element.
 *
 * @option visible : number - default is 3
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      visible: 4
 * });
 * @desc This specifies the number of items visible at all times within the carousel. The default is 3.
 * You are even free to experiment with real numbers. Eg: "3.5" will have 3 items fully visible and the
 * last item half visible. This gives you the effect of showing the user that there are more images to the right.
 *
 * @option start : number - default is 0
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      start: 2
 * });
 * @desc You can specify from which item the carousel should start. Remember, the first item in the carousel
 * has a start of 0, and so on.
 *
 * @option scrool : number - default is 1
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      scroll: 2
 * });
 * @desc The number of items that should scroll/slide when you click the next/prev navigation buttons. By
 * default, only one item is scrolled, but you may set it to any number. Eg: setting it to "2" will scroll
 * 2 items when you click the next or previous buttons.
 *
 * @option beforeStart, afterEnd : function - callbacks
 * @example
 * $(".carousel").jCarouselLite({
 *      btnNext: ".next",
 *      btnPrev: ".prev",
 *      beforeStart: function(a) {
 *          alert("Before animation starts:" + a);
 *      },
 *      afterEnd: function(a) {
 *          alert("After animation ends:" + a);
 *      }
 * });
 * @desc If you wanted to do some logic in your page before the slide starts and after the slide ends, you can
 * register these 2 callbacks. The functions will be passed an argument that represents an array of elements that
 * are visible at the time of callback.
 *
 *
 * @cat Plugins/Image Gallery
 * @author Ganeshji Marwaha/ganeshread@gmail.com
 */

(function($) {                                          // Compliant with jquery.noConflict()
$.fn.jCarouselLite = function(o) {
    o = $.extend({
        btnPrev: null,
        btnNext: null,
        btnGo: null,
        mouseWheel: false,
        auto: null,

        speed: 200,
        easing: null,

        vertical: false,
        circular: true,
        visible: 3,
        start: 0,
        scroll: 1,

        beforeStart: null,
        afterEnd: null
    }, o || {});

    return this.each(function() {                           // Returns the element collection. Chainable.

        var running = false, animCss=o.vertical?"top":"left", sizeCss=o.vertical?"height":"width";
        var div = $(this), ul = $("ul", div), tLi = $("li", ul), tl = tLi.size(), v = o.visible;

        if(o.circular) {
            ul.prepend(tLi.slice(tl-v-1+1).clone())
              .append(tLi.slice(0,v).clone());
            o.start += v;
        }

        var li = $("li", ul), itemLength = li.size(), curr = o.start;
        div.css("visibility", "visible");

        li.css({overflow: "hidden", float: o.vertical ? "none" : "left"});
        ul.css({margin: "0", padding: "0", position: "relative", "list-style-type": "none", "z-index": "1"});
        div.css({overflow: "hidden", position: "relative", "z-index": "2", left: "0px"});

        var liSize = o.vertical ? height(li) : width(li);   // Full li size(incl margin)-Used for animation
        var ulSize = liSize * itemLength;                   // size of full ul(total length, not just for the visible items)
        var divSize = liSize * v;                           // size of entire div(total length for just the visible items)

        li.css({width: li.width(), height: li.height()});
        ul.css(sizeCss, ulSize+"px").css(animCss, -(curr*liSize));

        div.css(sizeCss, divSize+"px");                     // Width of the DIV. length of visible images

        if(o.btnPrev)
            $(o.btnPrev).click(function() {
                return go(curr-o.scroll);
            });

        if(o.btnNext)
            $(o.btnNext).click(function() {
                return go(curr+o.scroll);
            });

        if(o.btnGo)
            $.each(o.btnGo, function(i, val) {
                $(val).click(function() {
                    return go(o.circular ? o.visible+i : i);
                });
            });

        if(o.mouseWheel && div.mousewheel)
            div.mousewheel(function(e, d) {
                return d>0 ? go(curr-o.scroll) : go(curr+o.scroll);
            });

        if(o.auto)
            setInterval(function() {
                go(curr+o.scroll);
            }, o.auto+o.speed);

        function vis() {
            return li.slice(curr).slice(0,v);
        };

        function go(to) {
            if(!running) {

                if(o.beforeStart)
                    o.beforeStart.call(this, vis());

                if(o.circular) {            // If circular we are in first or last, then goto the other end
                    if(to<=o.start-v-1) {           // If first, then goto last
                        ul.css(animCss, -((itemLength-(v*2))*liSize)+"px");
                        // If "scroll" > 1, then the "to" might not be equal to the condition; it can be lesser depending on the number of elements.
                        curr = to==o.start-v-1 ? itemLength-(v*2)-1 : itemLength-(v*2)-o.scroll;
                    } else if(to>=itemLength-v+1) { // If last, then goto first
                        ul.css(animCss, -( (v) * liSize ) + "px" );
                        // If "scroll" > 1, then the "to" might not be equal to the condition; it can be greater depending on the number of elements.
                        curr = to==itemLength-v+1 ? v+1 : v+o.scroll;
                    } else curr = to;
                } else {                    // If non-circular and to points to first or last, we just return.
                    if(to<0 || to>itemLength-v) return;
                    else curr = to;
                }                           // If neither overrides it, the curr will still be "to" and we can proceed.

                running = true;

                ul.animate(
                    animCss == "left" ? { left: -(curr*liSize) } : { top: -(curr*liSize) } , o.speed, o.easing,
                    function() {
                        if(o.afterEnd)
                            o.afterEnd.call(this, vis());
                        running = false;
                    }
                );
                // Disable buttons when the carousel reaches the last/first, and enable when not
                if(!o.circular) {
                    $(o.btnPrev + "," + o.btnNext).removeClass("disabled");
                    $( (curr-o.scroll<0 && o.btnPrev)
                        ||
                       (curr+o.scroll > itemLength-v && o.btnNext)
                        ||
                       []
                     ).addClass("disabled");
                }

            }
            return false;
        };
    });
};

function css(el, prop) {
    return parseInt($.css(el[0], prop)) || 0;
};
function width(el) {
    return  el[0].offsetWidth + css(el, 'marginLeft') + css(el, 'marginRight');
};
function height(el) {
    return el[0].offsetHeight + css(el, 'marginTop') + css(el, 'marginBottom');
};

})(jQuery);