/**
 * Slideshow Lite plugin for jQuery
 *
 * v0.8.1
 *
 * Copyright (c) 2009 Fred Wu
 *
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
 */

/**
 * Usage:
 *
 * // using default options
 * $("#slideshow").slideshow();
 *
 * // using some custom options
 * $("#slideshow2").slideshow({
 *   pauseSeconds: 4,
 *   height: 200,
 *   caption: false
 * });
 *
 * Configuration options:
 *
 * pauseSeconds  float    number of seconds between each photo to be displayed
 * fadeSpeed     float    number of seconds for the fading transition, the value should not exceed `pauseSeconds`
 * width         integer  width of the slideshow, in pixels
 * height        integer  height of the slideshow, in pixels
 * caption       boolean  display photo caption?
 * cssClass      string   name of the CSS class, defaults to `slideshowlite`
 * anchorTarget  string   name for the target="_xxx" attribute, defaults to `_self`
 */

(function($){
  $.fn.slideshow = function(options){

    var defaults = {
      pauseSeconds: 2,
      fadeSpeed: 0.5,
      width: 468,
      height: 120,
      caption: true,
      cssClass: 'slideshowlite',
      anchorTarget: '_self'
    };

    var options = $.extend(defaults, options);

    // ----------------------------------------
    // slideshow instance
    // ----------------------------------------

    var runInstance = function(target) {
      var items  = $("a", target);
      var instance;

      // ----------------------------------------
      // some mandontory styling
      // ----------------------------------------

      if ( ! $(target).hasClass(options.cssClass)) $(target).addClass(options.cssClass);

      $(target).css({
        width: options.width + "px",
        height: options.height + "px"
      });

      // ----------------------------------------
      // create anchor links to make the structure simpler for manupilation
      // ----------------------------------------

      $("> img", target).wrap(document.createElement("a"));
      $("a", target).attr("target", options.anchorTarget);

      // ----------------------------------------
      // add item sequence markups
      // ----------------------------------------

      var i = 1;
      $("a", target).each(function(){
        $(this).attr("data-seq", i++);
      });

      // ----------------------------------------
      // create pagination and caption
      // ----------------------------------------
      // ----------------------------------------
      // shortcuts
      // ----------------------------------------

      var firstItem   = $("> a:first", target);
      var lastItem    = $("> a:last", target);
      var currentItem = firstItem;


      // ----------------------------------------
      // slideshow logic
      // ----------------------------------------

      var makeSlideshow = function(){

        currentItem.css("z-index", 2);

        // show the current slide
        currentItem.fadeIn(options.fadeSpeed*1000, function(){
          $("> a", target).hide();
          $(this).show().css("z-index", 1);
        });

        // prepare for the next slide
        // determines the next item (or we need to rewind to the first item?)
        if ($("img", currentItem).attr("src") == $("img", lastItem).attr("src"))
        {
          currentItem = firstItem;
        }
        else
        {
          currentItem = currentItem.next();
        }

        currentItem.css("z-index", 1);
      };

      var startSlideshow = function(){
        clearInterval(instance);
        makeSlideshow();
        instance = setInterval(makeSlideshow, options.pauseSeconds*1000);
      };

      // ----------------------------------------
      // start the slideshow!
      // ----------------------------------------

      startSlideshow();
    }

    // ----------------------------------------
    // run the slideshow instances!
    // ----------------------------------------

    if (this.length > 1) {
      this.each(function() {
        runInstance(this);
      });
    } else {
      runInstance(this);
    }

  };
})(jQuery);