/*jshint undef: true */
/*global jQuery: true */

/*
   --------------------------------
   Infinite Scroll
   --------------------------------
   + https://github.com/paulirish/infinite-scroll
   + version 2.0b2.120519
   + Copyright 2011/12 Paul Irish & Luke Shumard
   + Licensed under the MIT license

   + Documentation: /infinite-scroll.com/
*/

(function (window, $, undefined) {
	"use strict";

    $.infinitescroll = function infscr(options, callback, element) {
        this.element = $(element);

        // Flag the object in the event of a failed creation
        if (!this._create(options, callback)) {
            this.failed = true;
        }
    };

    $.infinitescroll.defaults = {
        loading: {
            finished: undefined,
            finishedMsg: "<em>已经加载到底部，无法提供更多数据......</em>",
			img: "data:image/gif;base64, ",
            msg: null,
            msgText: "<em>加载更多数据，请稍等......</em>",
            selector: null,
            speed: 'fast',
            start: undefined
        },
        state: {
            isDuringAjax: false,
            isInvalidPage: false,
            isDestroyed: false,
            isDone: false, // For when it goes all the way through the archive.
            isPaused: false,
            isBeyondMaxPage: false,
            currPage: 1
        },
        debug: false,
		behavior: undefined,
        binder: $(window), // used to cache the selector
        nextSelector: "div.navigation a:first",
        navSelector: "div.navigation",
        contentSelector: null, // rename to pageFragment
        extraScrollPx: 150,
        itemSelector: "div.post",
        animate: false,
        pathParse: undefined,
        dataType: 'html',
        appendCallback: true,
        bufferPx: 40,
        errorCallback: function () { },
        infid: 0, //Instance ID
        pixelsFromNavToBottom: undefined,
        path: undefined, // Either parts of a URL as an array (e.g. ["/page/", "/"] or a function that takes in the page number and returns a URL
		prefill: false, // When the document is smaller than the window, load data until the document is larger or links are exhausted
        maxPage: undefined // to manually control maximum page (when maxPage is undefined, maximum page limitation is not work)
	};

    $.infinitescroll.prototype = {

        /*	
            ----------------------------
            Private methods
            ----------------------------
            */

        // Bind or unbind from scroll
        _binding: function infscr_binding(binding) {

            var instance = this,
            opts = instance.options;

            opts.v = '2.0b2.120520';

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_binding_'+opts.behavior] !== undefined) {
                this['_binding_'+opts.behavior].call(this);
                return;
            }

            if (binding !== 'bind' && binding !== 'unbind') {
                this._debug('Binding value  ' + binding + ' not valid');
                return false;
            }

            if (binding === 'unbind') {
                (this.options.binder).unbind('smartscroll.infscr.' + instance.options.infid);
            } else {
                (this.options.binder)[binding]('smartscroll.infscr.' + instance.options.infid, function () {
                    instance.scroll();
                });
            }

            this._debug('Binding', binding);
        },

        // Fundamental aspects of the plugin are initialized
        _create: function infscr_create(options, callback) {

            // Add custom options to defaults
            var opts = $.extend(true, {}, $.infinitescroll.defaults, options);
			this.options = opts;
			var $window = $(window);
			var instance = this;

			// Validate selectors
            if (!instance._validate(options)) {
				return false;
			}

            // Validate page fragment path
            var path = $(opts.nextSelector).attr('href');
            if (!path) {
                this._debug('Navigation selector not found');
                return false;
            }

            // Set the path to be a relative URL from root.
            opts.path = opts.path || this._determinepath(path);

            // contentSelector is 'page fragment' option for .load() / .ajax() calls
            opts.contentSelector = opts.contentSelector || this.element;

            // loading.selector - if we want to place the load message in a specific selector, defaulted to the contentSelector
            opts.loading.selector = opts.loading.selector || opts.contentSelector;

            // Define loading.msg
            opts.loading.msg = opts.loading.msg || $('<div id="infscr-loading"><img alt="Loading..." src="' + opts.loading.img + '" /><div>' + opts.loading.msgText + '</div></div>');

            // Preload loading.img
            (new Image()).src = opts.loading.img;

            // distance from nav links to bottom
            // computed as: height of the document + top offset of container - top offset of nav link
            if(opts.pixelsFromNavToBottom === undefined) {
				opts.pixelsFromNavToBottom = $(document).height() - $(opts.navSelector).offset().top;
				this._debug("pixelsFromNavToBottom: " + opts.pixelsFromNavToBottom);
			}

			var self = this;

            // determine loading.start actions
            opts.loading.start = opts.loading.start || function() {
                $(opts.navSelector).hide();
                opts.loading.msg
                .appendTo(opts.loading.selector)
                .show(opts.loading.speed, $.proxy(function() {
					this.beginAjax(opts);
				}, self));
            };

            // determine loading.finished actions
            opts.loading.finished = opts.loading.finished || function() {
                if (!opts.state.isBeyondMaxPage)
                    opts.loading.msg.fadeOut(opts.loading.speed);
            };

			// callback loading
            opts.callback = function(instance, data, url) {
                if (!!opts.behavior && instance['_callback_'+opts.behavior] !== undefined) {
                    instance['_callback_'+opts.behavior].call($(opts.contentSelector)[0], data, url);
                }

                if (callback) {
                    callback.call($(opts.contentSelector)[0], data, opts, url);
                }

				if (opts.prefill) {
					$window.bind("resize.infinite-scroll", instance._prefill);
				}
            };

			if (options.debug) {
				// Tell IE9 to use its built-in console
				if (Function.prototype.bind && (typeof console === 'object' || typeof console === 'function') && typeof console.log === "object") {
					["log","info","warn","error","assert","dir","clear","profile","profileEnd"]
						.forEach(function (method) {
							console[method] = this.call(console[method], console);
						}, Function.prototype.bind);
				}
			}

            this._setup();

			// Setups the prefill method for use
			if (opts.prefill) {
				this._prefill();
			}

            // Return true to indicate successful creation
            return true;
        },

		_prefill: function infscr_prefill() {
			var instance = this;
			var $window = $(window);

			function needsPrefill() {
				return (instance.options.contentSelector.height() <= $window.height());
			}

			this._prefill = function() {
				if (needsPrefill()) {
					instance.scroll();
				}

				$window.bind("resize.infinite-scroll", function() {
					if (needsPrefill()) {
						$window.unbind("resize.infinite-scroll");
						instance.scroll();
					}
				});
			};

			// Call self after setting up the new function
			this._prefill();
		},

        // Console log wrapper
        _debug: function infscr_debug() {
			if (true !== this.options.debug) {
				return;
			}

			if (typeof console !== 'undefined' && typeof console.log === 'function') {
				// Modern browsers
				// Single argument, which is a string
				if ((Array.prototype.slice.call(arguments)).length === 1 && typeof Array.prototype.slice.call(arguments)[0] === 'string') {
					console.log( (Array.prototype.slice.call(arguments)).toString() );
				} else {
					console.log( Array.prototype.slice.call(arguments) );
				}
			} else if (!Function.prototype.bind && typeof console !== 'undefined' && typeof console.log === 'object') {
				// IE8
				Function.prototype.call.call(console.log, console, Array.prototype.slice.call(arguments));
			}
        },

        // find the number to increment in the path.
        _determinepath: function infscr_determinepath(path) {

            var opts = this.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_determinepath_'+opts.behavior] !== undefined) {
                return this['_determinepath_'+opts.behavior].call(this,path);
            }

            if (!!opts.pathParse) {

                this._debug('pathParse manual');
                return opts.pathParse(path, this.options.state.currPage+1);

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

                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;
                } else {
                    this._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.');
                    // Get rid of isInvalidPage to allow permalink to state
                    opts.state.isInvalidPage = true;  //prevent it from running on this page.
                }
            }
            this._debug('determinePath', path);
            return path;

        },

        // Custom error
        _error: function infscr_error(xhr) {

            var opts = this.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_error_'+opts.behavior] !== undefined) {
                this['_error_'+opts.behavior].call(this,xhr);
                return;
            }

            if (xhr !== 'destroy' && xhr !== 'end') {
                xhr = 'unknown';
            }

            this._debug('Error', xhr);

            if (xhr === 'end') {
                this._showdonemsg();
                
            }
            
            if (opts.state.isBeyondMaxPage) {
                opts.loading.msg.find('img').hide();
            }

            opts.state.isDone = true;
            opts.state.currPage = 1; // if you need to go back to this instance
            opts.state.isPaused = false;
            opts.state.isBeyondMaxPage = false;
            this._binding('unbind');

        },

        // Load Callback
        _loadcallback: function infscr_loadcallback(box, data, url) {
            var opts = this.options,
            callback = this.options.callback, // GLOBAL OBJECT FOR CALLBACK
            result = (opts.state.isDone) ? 'done' : (!opts.appendCallback) ? 'no-append' : 'append',
            frag;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_loadcallback_'+opts.behavior] !== undefined) {
                this['_loadcallback_'+opts.behavior].call(this,box,data);
                return;
            }

			switch (result) {
				case 'done':
					this._showdonemsg();
					return false;

				case 'no-append':
					if (opts.dataType === 'html') {
						data = '<div>' + data + '</div>';
						data = $(data).find(opts.itemSelector);
					}
					break;

				case 'append':
					var children = box.children();
					// if it didn't return anything
					if (children.length == 0) {
						return this._error('end');
					}

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

					this._debug('contentSelector', $(opts.contentSelector)[0]);
					$(opts.contentSelector)[0].appendChild(frag);
					// previously, we would pass in the new DOM element as context for the callback
					// however we're now using a documentfragment, which doesn't have parents or children,
					// so the context is the contentContainer guy, and we pass in an array
					// of the elements collected as the first argument.

					data = children.get();
					break;
			}

            // loadingEnd function
            opts.loading.finished.call($(opts.contentSelector)[0],opts);

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

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

            callback(this, data, url);

			if (opts.prefill) {
				this._prefill();
			}
		},

        _nearbottom: function infscr_nearbottom() {

            var opts = this.options,
            pixelsFromWindowBottomToBottom = 0 + $(document).height() - (opts.binder.scrollTop()) - $(window).height();

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_nearbottom_'+opts.behavior] !== undefined) {
                return this['_nearbottom_'+opts.behavior].call(this);
            }

            this._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);

        },

        // Pause / temporarily disable plugin from firing
        _pausing: function infscr_pausing(pause) {

            var opts = this.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_pausing_'+opts.behavior] !== undefined) {
                this['_pausing_'+opts.behavior].call(this,pause);
                return;
            }

            // If pause is not 'pause' or 'resume', toggle it's value
            if (pause !== 'pause' && pause !== 'resume' && pause !== null) {
                this._debug('Invalid argument. Toggling pause value instead');
            }

            pause = (pause && (pause === 'pause' || pause === 'resume')) ? pause : 'toggle';

            switch (pause) {
                case 'pause':
                    opts.state.isPaused = true;
                break;

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

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

            this._debug('Paused', opts.state.isPaused);
            return false;

        },

        // Behavior is determined
        // If the behavior option is undefined, it will set to default and bind to scroll
        _setup: function infscr_setup() {

            var opts = this.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_setup_'+opts.behavior] !== undefined) {
                this['_setup_'+opts.behavior].call(this);
                return;
            }

            this._binding('bind');

            return false;

        },

        // Show done message
        _showdonemsg: function infscr_showdonemsg() {

            var opts = this.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['_showdonemsg_'+opts.behavior] !== undefined) {
                this['_showdonemsg_'+opts.behavior].call(this);
                return;
            }

            opts.loading.msg
            .find('img')
            .hide()
            .parent()
            .find('div').html(opts.loading.finishedMsg).animate({ opacity: 1 }, 2000, function () {
                $(this).parent().fadeOut(opts.loading.speed);
            });

            // user provided callback when done    
            opts.errorCallback.call($(opts.contentSelector)[0],'done');
        },

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

            return true;
        },

        /*	
            ----------------------------
            Public methods
            ----------------------------
            */

        // Bind to scroll
        bind: function infscr_bind() {
            this._binding('bind');
        },

        // Destroy current instance of plugin
        destroy: function infscr_destroy() {
            this.options.state.isDestroyed = true;
			this.options.loading.finished();
            return this._error('destroy');
        },

        // Set pause value to false
        pause: function infscr_pause() {
            this._pausing('pause');
        },

        // Set pause value to false
        resume: function infscr_resume() {
            this._pausing('resume');
        },

		beginAjax: function infscr_ajax(opts) {
			var instance = this,
				path = opts.path,
				box, desturl, method, condition;

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

            // Manually control maximum page 
            if ( opts.maxPage != undefined && opts.state.currPage > opts.maxPage ){
                opts.state.isBeyondMaxPage = true;
                this.destroy();
                return;
            }

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

			desturl = (typeof path === 'function') ? path(opts.state.currPage) : path.join(opts.state.currPage);
			instance._debug('heading into ajax', desturl);

			method = (opts.dataType === 'html' || opts.dataType === 'json' ) ? opts.dataType : 'html+callback';
			if (opts.appendCallback && opts.dataType === 'html') {
				method += '+callback';
			}

			switch (method) {
				case 'html+callback':
					instance._debug('Using HTML via .load() method');
					box.load(desturl + ' ' + opts.itemSelector, undefined, function infscr_ajax_callback(responseText) {
						instance._loadcallback(box, responseText, desturl);
					});

					break;

				case 'html':
					instance._debug('Using ' + (method.toUpperCase()) + ' via $.ajax() method');
					$.ajax({
						// params
						url: desturl,
						dataType: opts.dataType,
						complete: function infscr_ajax_callback(jqXHR, textStatus) {
							condition = (typeof (jqXHR.isResolved) !== 'undefined') ? (jqXHR.isResolved()) : (textStatus === "success" || textStatus === "notmodified");
							if (condition) {
								instance._loadcallback(box, jqXHR.responseText, desturl);
							} else {
								instance._error('end');
							}
						}
					});

					break;
				case 'json':
					instance._debug('Using ' + (method.toUpperCase()) + ' via $.ajax() method');
					$.ajax({
						dataType: 'json',
						type: 'GET',
						url: desturl,
						success: function (data, textStatus, jqXHR) {
							condition = (typeof (jqXHR.isResolved) !== 'undefined') ? (jqXHR.isResolved()) : (textStatus === "success" || textStatus === "notmodified");
							if (opts.appendCallback) {
								// if appendCallback is true, you must defined template in options.
								// note that data passed into _loadcallback is already an html (after processed in opts.template(data)).
								if (opts.template !== undefined) {
									var theData = opts.template(data);
									box.append(theData);
									if (condition) {
										instance._loadcallback(box, theData);
									} else {
										instance._error('end');
									}
								} else {
									instance._debug("template must be defined.");
									instance._error('end');
								}
							} else {
								// if appendCallback is false, we will pass in the JSON object. you should handle it yourself in your callback.
								if (condition) {
									instance._loadcallback(box, data, desturl);
								} else {
									instance._error('end');
								}
							}
						},
						error: function() {
							instance._debug("JSON ajax request failed.");
							instance._error('end');
						}
					});

					break;
			}
		},

        // Retrieve next set of content items
        retrieve: function infscr_retrieve(pageNum) {
			pageNum = pageNum || null;

			var instance = this,
            opts = instance.options;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['retrieve_'+opts.behavior] !== undefined) {
                this['retrieve_'+opts.behavior].call(this,pageNum);
                return;
            }

            // for manual triggers, if destroyed, get out of here
            if (opts.state.isDestroyed) {
                this._debug('Instance is destroyed');
                return false;
            }

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

            opts.loading.start.call($(opts.contentSelector)[0],opts);
        },

        // Check to see next page is needed
        scroll: function infscr_scroll() {

            var opts = this.options,
            state = opts.state;

            // if behavior is defined and this function is extended, call that instead of default
            if (!!opts.behavior && this['scroll_'+opts.behavior] !== undefined) {
                this['scroll_'+opts.behavior].call(this);
                return;
            }

            if (state.isDuringAjax || state.isInvalidPage || state.isDone || state.isDestroyed || state.isPaused) {
				return;
			}

            if (!this._nearbottom()) {
				return;
			}

            this.retrieve();

        },

        // Toggle pause value
        toggle: function infscr_toggle() {
            this._pausing();
        },

        // Unbind from scroll
        unbind: function infscr_unbind() {
            this._binding('unbind');
        },

        // update options
        update: function infscr_options(key) {
            if ($.isPlainObject(key)) {
                this.options = $.extend(true,this.options,key);
            }
        }
    };


    /*	
        ----------------------------
        Infinite Scroll function
        ----------------------------

        Borrowed logic from the following...

        jQuery UI
        - https://github.com/jquery/jquery-ui/blob/master/ui/jquery.ui.widget.js

        jCarousel
        - https://github.com/jsor/jcarousel/blob/master/lib/jquery.jcarousel.js

        Masonry
        - https://github.com/desandro/masonry/blob/master/jquery.masonry.js		

*/

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


        var thisCall = typeof options;

        switch (thisCall) {

            // method 
            case 'string':
                var args = Array.prototype.slice.call(arguments, 1);

				this.each(function () {
					var instance = $.data(this, 'infinitescroll');

					if (!instance) {
						// not setup yet
						// return $.error('Method ' + options + ' cannot be called until Infinite Scroll is setup');
						return false;
					}

					if (!$.isFunction(instance[options]) || options.charAt(0) === "_") {
						// return $.error('No such method ' + options + ' for Infinite Scroll');
						return false;
					}

					// no errors!
					instance[options].apply(instance, args);
				});

            break;

            // creation 
            case 'object':

                this.each(function () {

                var instance = $.data(this, 'infinitescroll');

                if (instance) {

                    // update options of current instance
                    instance.update(options);

                } else {

                    // initialize new instance
                    instance = new $.infinitescroll(options, callback, this);

                    // don't attach if instantiation failed
                    if (!instance.failed) {
                        $.data(this, 'infinitescroll', instance);
                    }

                }

            });

            break;

        }

        return this;
    };



    /* 
     * 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 () {
                $(context).trigger('smartscroll', args);
            }, execAsap === "execAsap" ? 0 : 100);
        }
    };

    $.fn.smartscroll = function (fn) {
        return fn ? this.bind("smartscroll", fn) : this.trigger("smartscroll", ["execAsap"]);
    };


})(window, jQuery);