/*!
// Infinite Scroll jQuery plugin
// copyright Paul Irish, licensed GPL & MIT
// version 1.5.110408

// 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) {

            if (path.match(/^(.*?)\b2\b(.*?$)/)) {
                path = path.match(/^(.*?)\b2\b(.*?$)/).slice(1);

                // if there is any 2 in the url at all.    
            } else 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;
                }

                if ($.isFunction(opts.pathParse)) {
                    return [path];
                } else {
                    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;
        }
        
        
        // determine filtering nav for multiple instances
        function filterNav() {
            opts.isFiltered = true;
            return binder.trigger("error.infscr." + opts.infid, [302]);
        }
        
        
        // Calculate internal height (used for local scroll)
        function hiddenHeight(element) {
            var height = 0;
            $(element).children().each(function () {
                height = height + $(this).outerHeight(false);
            });
            return height;
        }
        
        
        //Generate InstanceID based on random data (to give consistent but different ID's)
        function generateInstanceID(element) {
            var number = $(element).length + $(element).html().length + $(element).attr("class").length
			+ $(element).attr("id").length;
            opts.infid = number;
        }
        
        
        function isNearBottom() {
            // distance remaining in the scroll
            // computed as: document height - distance already scroll - viewport height - buffer

            if (opts.container.nodeName == "HTML") {
                var pixelsFromWindowBottomToBottom = 0
                + $(document).height()
                // have to do this bs because safari doesnt report a scrollTop on the html element
                - ($(opts.container).scrollTop() || $(opts.container.ownerDocument.body).scrollTop())
                - $(window).height();
            }
            else {
                var pixelsFromWindowBottomToBottom = 0
                + hiddenHeight(opts.container) - $(opts.container).scrollTop() - $(opts.container).height();

            }

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

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

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

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

        function infscrSetup() {
            if (opts.isDuringAjax || opts.isInvalidPage || opts.isDone || opts.isFiltered || opts.isPaused) return;

            if (!isNearBottom(opts, props)) return;
            $(document).trigger('retrieve.infscr.' + opts.infid);

        }  // end of infscrSetup()



        function kickOffAjax() {

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

            // show the loading message quickly
            // then hide the previous/next links after we're
            // sure the loading message was visible
            props.loadingMsg.appendTo(opts.loadMsgSelector).show(opts.loadingMsgRevealSpeed, function () {
                $(opts.navSelector).hide();

                // increment the URL bit. e.g. /page/3/
                opts.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();


                if ($.isFunction(opts.pathParse)) {
                    // if we got a custom path parsing function, pass in our path guess and page iteration
                    desturl = opts.pathParse(path.join('2'), opts.currPage);
                } else {
                    desturl = path.join(opts.currPage);
                }
                box.load(desturl + ' ' + opts.itemSelector, null, loadCallback);

            });

        }

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

            } else {

                var children = box.children();

                // if it didn't return anything
                if (children.length == 0 || children.hasClass('error404')) {
                    // trigger a 404 error so we can quit.
                    return infscrError([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 () { opts.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.get());

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

        function initPause(pauseValue) {
            
            // if pauseValue is not 'pause' or 'resume', toggle it's value
            pauseValue = (pauseValue && (pauseValue == 'pause' || pauseValue == 'resume')) ? pauseValue : 'toggle';
            
            switch (pauseValue) {
                case 'pause':
                    opts.isPaused = true;
                break;

                case 'resume':
                    opts.isPaused = false;
                break;

                case 'toggle':
                    opts.isPaused = !opts.isPaused;
                break;
            }

            debug('Paused: ' + opts.isPaused);
            return false;
        }

        function infscrError(xhr) {
            if (!opts.isDone && xhr == 404) {
                // die if we're out of pages.
                debug('Page not found. Self-destructing...');
                showDoneMsg();
                opts.isDone = true;
                opts.currPage = 1; // if you need to go back to this instance
                binder.unbind('smartscroll.infscr.' + opts.infid);
                $(document).unbind('retrieve.infscr.' + opts.infid);
            }
            if (opts.isFiltered && xhr == 302) {
                // die if filtered.
                debug('Filtered. Going to next instance...');
                opts.isDone = true;
                opts.currPage = 1; // if you need to go back to this instance
                opts.isPaused = false;
                binder.unbind('smartscroll.infscr.' + opts.infid, infscrSetup)
	    	  .unbind('pause.infscr.' + opts.infid)
	    	  .unbind('filter.infscr.' + opts.infid)
	    	  .unbind('error.infscr.' + opts.infid);
                $(document).unbind('retrieve.infscr.' + opts.infid, kickOffAjax);
            }
        }
        

        /* 
		* smartscroll: debounced scroll event for jQuery *
		* https://github.com/lukeshumard/smartscroll
		* Based on smartresize by @louis_remi: https://github.com/lrbabe/jquery.smartresize.js *
		* Copyright 2011 Louis-Remi & Luke Shumard * Licensed under the MIT license. *
		*/
		
		var event = $.event,
			scrollTimeout;
		
		event.special.smartscroll = {
			setup: function() {
			  $(this).bind( "scroll", event.special.smartscroll.handler );
			},
			teardown: function() {
			  $(this).unbind( "scroll", event.special.smartscroll.handler );
			},
			handler: function( event, execAsap ) {
			  // Save the context
			  var context = this,
			      args = arguments;
			
			  // set correct event type
			  event.type = "smartscroll";
			
			  if (scrollTimeout) { clearTimeout(scrollTimeout); }
			  scrollTimeout = setTimeout(function() {
			    jQuery.event.handle.apply( context, args );
			  }, execAsap === "execAsap"? 0 : 100);
			}
		};
		
		$.fn.smartscroll = function( fn ) {
			return fn ? this.bind( "smartscroll", fn ) : this.trigger( "smartscroll", ["execAsap"] );
		};



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

        var opts = $.extend({}, $.infinitescroll.defaults, options),
        props = $.infinitescroll, // shorthand
        box, frag, desturl, thisPause, errorStatus;
        callback = callback || function () { };

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

        
        opts.container = opts.container || document.documentElement;

        
        // contentSelector we'll use for our .load()
        opts.contentSelector = opts.contentSelector || this;
        
        // Generate unique instance ID
        if (opts.infid == 0)
            generateInstanceID(opts.contentSelector);
        
        // loadMsgSelector - if we want to place the load message in a specific selector, defaulted to the contentSelector
        opts.loadMsgSelector = opts.loadMsgSelector || opts.contentSelector;

        
        // 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);

        
        // 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;
        
        
        //Check if its HTML (window scroll)
        if (opts.container.nodeName == "HTML") {
            debug("Window Scroll");
            var innerContainerHeight = $(document).height();
            var binder = $(window);
        } else {
            debug("Local Scroll");
            var innerContainerHeight = hiddenHeight(opts.container);
            var binder = $(opts.container);
        }
        
        
        // distance from nav links to bottom
        // computed as: height of the document + top offset of container - top offset of nav link
        opts.pixelsFromNavToBottom = innerContainerHeight +
                                     (opts.container == document.documentElement ? 0 : $(opts.container).offset().top) -
                                     $(opts.navSelector).offset().top;

        
        // set up our bindings
        // bind scroll handler to element (if its a local scroll) or window 
        binder
	        .bind('smartscroll.infscr.' + opts.infid, function () { infscrSetup(); }, 600, false)
	        .bind('filter.infscr.' + opts.infid, filterNav)
	        .bind('error.infscr.' + opts.infid, function (event, errorStatus) { infscrError(errorStatus); })
	        .bind('pause.infscr.' + opts.infid, function (event, thisPause) { initPause(thisPause); })
	        .trigger('smartscroll.infscr.' + opts.infid); // trigger the event, in case it's a short page

        $(document).bind('retrieve.infscr.' + opts.infid, 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..
            loadMsgSelector: null,
            loadingMsgRevealSpeed: 'fast', // controls how fast you want the loading message to come in, ex: 'fast', 'slow', 200 (milliseconds)
            extraScrollPx: 150,
            itemSelector: "div.post",
            animate: false,
            pathParse: undefined,
            bufferPx: 40,
            orientation: 'height',
            errorCallback: function () { },
            currPage: 1,
            infid: 0, //Instance ID (Generated at setup)
            isDuringAjax: false,
            isInvalidPage: false,
            isFiltered: false,
            isDone: false,  // for when it goes all the way through the archive.
            isPaused: false,
            container: undefined, //If left undefined uses window scroll, set as container for local scroll
            pixelsFromNavToBottom: undefined
        },
        loadingImg: undefined,
        loadingMsg: undefined,
        currDOMChunk: null  // defined in setup()'s load()
    };



})(jQuery);