/*!
// Infinite Scroll jQuery plugin
// copyright Paul Irish, licensed GPL & MIT
// version 1.5.100504

// home and docs: http://www.infinite-scroll.com
*/

;
(function($){

  $.fn.infinitescroll = function(options,callback){

    // console log wrapper.
    function debug(){
      if (opts.debug) {
        window.console && console.log.call(console,arguments)
        }
    }

    // grab each selector option and see if any fail.
    function areSelectorsValid(opts){
      for (var key in opts){
        if (key.indexOf && key.indexOf('Selector') > -1 && $(opts[key]).length === 0){
          debug('Your ' + key + ' found no elements.');
          return false;
        }
        return true;
      }
    }


    // find the number to increment in the path.
    function determinePath(path){

      path.match(relurl) ? path.match(relurl)[2] : path;

      // there is a 2 in the url surrounded by slashes, e.g. /page/2/
      if ( path.match(/^(.*?)\b2\b(.*?$)/) ){
        path = path.match(/^(.*?)\b2\b(.*?$)/).slice(1);
      } else
      // if there is any 2 in the url at all.
      if (path.match(/^(.*?)2(.*?$)/)){

        // page= is used in django:
        //   http://www.infinite-scroll.com/changelog/comment-page-1/#comment-127
        if ( path.match(/^(.*?page=)2(\/.*|$)/) ){
          path = path.match(/^(.*?page=)2(\/.*|$)/).slice(1);
          return path;
        }

        debug('Trying backup next selector parse technique. Treacherous waters here, matey.');
        path = path.match(/^(.*?)2(.*?$)/).slice(1);
      } else {

        // page= is used in drupal too but second page is page=1 not page=2:
        // thx Jerod Fritz, vladikoff
        if (path.match(/^(.*?page=)1(\/.*|$)/)) {
          path = path.match(/^(.*?page=)1(\/.*|$)/).slice(1);
          return path;
        }

        debug('Sorry, we couldn\'t parse your Next (Previous Posts) URL. Verify your the css selector points to the correct A tag. If you still get this error: yell, scream, and kindly ask for help at infinite-scroll.com.');
        props.isInvalidPage = true;  //prevent it from running on this page.
      }

      return path;
    }


    // 'document' means the full document usually, but sometimes the content of the overflow'd div in local mode
    function getDocumentHeight(){
      // weird doubletouch of scrollheight because http://soulpass.com/2006/07/24/ie-and-scrollheight/
      return opts.localMode ? ($(props.container)[0].scrollHeight && $(props.container)[0].scrollHeight)
      // needs to be document's height. (not props.container's) html's height is wrong in IE.
      : $(document).height()
    }



    function isNearBottom(){

      // distance remaining in the scroll
      // computed as: document height - distance already scroll - viewport height - buffer
      var pixelsFromWindowBottomToBottom = 0 +
      getDocumentHeight()  - (
        opts.localMode ? $(props.container).scrollTop() :
        // have to do this bs because safari doesnt report a scrollTop on the html element
        ($(props.container).scrollTop() || $(props.container.ownerDocument.body).scrollTop())
        ) - $(opts.localMode ? props.container : window).height();

      debug('math:',pixelsFromWindowBottomToBottom, props.pixelsFromNavToBottom);

      // if distance remaining in the scroll (including buffer) is less than the orignal nav to bottom....
      return (pixelsFromWindowBottomToBottom  - opts.bufferPx < props.pixelsFromNavToBottom);
    }

    function showDoneMsg(){
      props.loadingMsg
      .find('img').hide()
      .parent()
      .find('div').html(opts.donetext).animate({
        opacity: 1
      },2000).fadeOut('normal');

      // user provided callback when done
      opts.errorCallback();
    }

    function infscrSetup(){

      if (props.isDuringAjax || props.isInvalidPage || props.isDone) return;

      if ( !isNearBottom(opts,props) ) return;

      $(document).trigger('retrieve.infscr');


    }  // end of infscrSetup()



    function kickOffAjax(){

      // we dont want to fire the ajax multiple times
      props.isDuringAjax = true;

      // show the loading message and hide the previous/next links
      props.loadingMsg.appendTo( opts.contentSelector ).show();
      $( opts.navSelector ).hide();

      // increment the URL bit. e.g. /page/3/
      props.currPage++;

      debug('heading into ajax',path);

      // if we're dealing with a table we can't use DIVs
      box = $(opts.contentSelector).is('table') ? $('<tbody/>') : $('<div/>');
      frag = document.createDocumentFragment();


      box.load( path.join( props.currPage ) + ' ' + opts.itemSelector,null,loadCallback);

    }

    function loadCallback(){
      // if we've hit the last page...
      if (props.isDone){
        showDoneMsg();
        return false;

      } else {

        var children = box.children().get();

        // if it didn't return anything
        if (children.length == 0){
          // fake an ajaxError so we can quit.
          return $.event.trigger( "ajaxError", [{
            status:404
          }] );
        }

        // use a documentFragment because it works when content is going into a table or UL
        while (box[0].firstChild){
          frag.appendChild(  box[0].firstChild );
        }

        $(opts.contentSelector)[0].appendChild(frag);

        // fadeout currently makes the <em>'d text ugly in IE6
        props.loadingMsg.fadeOut('normal' );

        // smooth scroll to ease in the new content
        if (opts.animate){
          var scrollTo = $(window).scrollTop() + $('#infscr-loading').height() + opts.extraScrollPx + 'px';
          $('html,body').animate({
            scrollTop: scrollTo
          }, 800,function(){
            props.isDuringAjax = false;
          });
        }

        // previously, we would pass in the new DOM element as context for the callback
        // however we're now using a documentfragment, which doesnt havent parents or children,
        // so the context is the contentContainer guy, and we pass in an array
        //   of the elements collected as the first argument.
        callback.call( $(opts.contentSelector)[0], children );

        if (!opts.animate) props.isDuringAjax = false; // once the call is done, we can allow it again.
      }
    }

    /*
     * MODIFIED BY JÓN HELGI
     * This is my only modification. Unbinds stuff so that it does not fetch for all categories that
     * was clicked at some point and can be called from outside the plugin.
     */
    this.resetPlugin = function() {
      
      //$(opts.localMode ? this : window)
      //.unbind('scroll.infscr', infscrSetup)
      //.trigger('scroll.infscr'); // trigger the event, in case it's a short page

      $(document).unbind('retrieve.infscr',kickOffAjax);

      props.currPage = 1;

    };



    // lets get started.
    $.browser.ie6 = $.browser.msie && $.browser.version < 7;

    var opts    = $.extend({}, $.infinitescroll.defaults, options),
    props   = $.infinitescroll, // shorthand
    box, frag;

    callback    = callback || function(){};

    if (!areSelectorsValid(opts)){
      return false;
    }

    // we doing this on an overflow:auto div?
    props.container   =  opts.localMode ? this : document.documentElement;

    // contentSelector we'll use for our .load()
    opts.contentSelector = opts.contentSelector || this;


    // get the relative URL - everything past the domain name.
    var relurl        = /(.*?\/\/).*?(\/.*)/,
    path          = $(opts.nextSelector).attr('href');


    if (!path) {
      debug('Navigation selector not found');
      return;
    }

    // set the path to be a relative URL from root.
    path          = determinePath(path);


    // reset scrollTop in case of page refresh:
    if (opts.localMode) $(props.container)[0].scrollTop = 0;

    // distance from nav links to bottom
    // computed as: height of the document + top offset of container - top offset of nav link
    props.pixelsFromNavToBottom =  getDocumentHeight()  +
    (props.container == document.documentElement ? 0 : $(props.container).offset().top )-
    $(opts.navSelector).offset().top;

    // define loading msg
    props.loadingMsg = $('<div id="infscr-loading" style="text-align: center;"><img alt="Loading..." src="'+
      opts.loadingImg+'" /><div>'+opts.loadingText+'</div></div>');
    // preload the image
    (new Image()).src    = opts.loadingImg;



    // set up our bindings
    $(document).ajaxError(function(e,xhr,opt){
      debug('Page not found. Self-destructing...');

      // die if we're out of pages.
      if (xhr.status == 404){
        showDoneMsg();
        props.isDone = true;
        $(opts.localMode ? this : window).unbind('scroll.infscr');
      }
    });

    // bind scroll handler to element (if its a local scroll) or window
    $(opts.localMode ? this : window)
    .bind('scroll.infscr', infscrSetup)
    .trigger('scroll.infscr'); // trigger the event, in case it's a short page

    $(document).bind('retrieve.infscr',kickOffAjax);

    return this;

  }  // end of $.fn.infinitescroll()



  // options and read-only properties object

  $.infinitescroll = {
    defaults      : {
      debug           : false,
      preload         : false,
      nextSelector    : "div.navigation a:first",
      loadingImg      : "http://www.infinite-scroll.com/loading.gif",
      loadingText     : "<em>Loading the next set of posts...</em>",
      donetext        : "<em>Congratulations, you've reached the end of the internet.</em>",
      navSelector     : "div.navigation",
      contentSelector : null,           // not really a selector. :) it's whatever the method was called on..
      extraScrollPx   : 150,
      itemSelector    : "div.post",
      animate         : false,
      localMode      : false,
      bufferPx        : 40,
      errorCallback   : function(){}
    },
    loadingImg    : undefined,
    loadingMsg    : undefined,
    container     : undefined,
    currPage      : 1,
    currDOMChunk  : null,  // defined in setup()'s load()
    isDuringAjax  : false,
    isInvalidPage : false,
    isDone        : false  // for when it goes all the way through the archive.
  };



})(jQuery);