var ditto = {
    // page element ids
    content_id: "#content",
    sidebar_id: "#sidebar",
    edit_id: "#edit",
    back_to_top_id: "#back_to_top",
    loading_id: "#loading",
    error_id: "#error",

    // display elements
    sidebar: true,
    edit_button: true,
    back_to_top_button: true,

    // initialize function
    run: initialize
};

var disqusCode = '<h3>留言</h3><div id="disqus_thread"></div>'; 

function initialize() {
    // initialize sidebar and buttons
    if (ditto.sidebar) {
        init_sidebar_section();
    }

    if (ditto.back_to_top_button) {
        init_back_to_top_button();
    }

    if (ditto.edit_button) {
        init_edit_button();
    }

    // page router
    router();
    $(window).on('hashchange', router);
	var flip = document.querySelector('#flip');
    var hasTouch = 'ontouchstart' in window;

        if (!hasTouch) {
            Veil(flip, {
                prop: 'bottom'
            });
        }
}

function init_sidebar_section() {
    $.get(ditto.sidebar_file, function(data) {
        $(ditto.sidebar_id).html(marked(data));
    }, "text").fail(function() {
        alert("Opps! can't find the sidebar file to display!");
    });

}

function init_back_to_top_button() {
    $(ditto.back_to_top_id).show();
    $(ditto.back_to_top_id).on("click", function() {
        $("html body").animate({
            scrollTop: 0
        }, 200);
    });
}

function init_edit_button() {
    if (ditto.base_url === null) {
        alert("Error! You didn't set 'base_url' when calling ditto.run()!");

    } else {
        $(ditto.edit_id).show();
        $(ditto.edit_id).on("click", function() {
            var hash = location.hash.replace("#", "/");

            if (hash === "") {
                hash = "/" + ditto.index.replace(".md", "");
            }

            window.open(ditto.base_url + hash + ".md");
            // open is better than redirecting, as the previous page history
            // with redirect is a bit messed up
        });
    }
}

function replace_symbols(text) {
    // replace symbols with underscore
    return text.replace(/[&\/\\#,+=()$~%.'":*?<>{}\ \]\[]/g, "_");
}

function li_create_linkage(li_tag, header_level) {
    // add custom id and class attributes
    html_safe_tag = replace_symbols(li_tag.text());
    li_tag.attr("id", html_safe_tag);
    li_tag.attr("class", "link");

    // add click listener - on click scroll to relevant header section
    $(ditto.content_id + " li#" + li_tag.attr("id")).click(function() {
        // scroll to relevant section
        var header = $(
            ditto.content_id + " h" + header_level + "." + li_tag.attr("id")
        );
        $('html, body').animate({
            scrollTop: header.offset().top
        }, 200);

        // highlight the relevant section
        original_color = header.css("color");
        header.animate({ color: "#ED1C24", }, 500, function() {
            // revert back to orig color
            $(this).animate({color: original_color}, 2500);
        });
    });
}

function create_page_anchors() {
    // create page anchors by matching li's to headers
    // if there is a match, create click listeners
    // and scroll to relevant sections

    // go through header level 1 to 3
    for (var i = 1; i <= 4; i++) {
        // parse all headers
        var headers = [];
        $('#content h' + i).map(function() {
            headers.push($(this).text());
            $(this).addClass(replace_symbols($(this).text()));
			this.id = 'h'+i+'-'+replace_symbols($(this).text());
        });

        if ((i === 2) && headers.length !== 0){
			var ul_tag = $('<ol></ol>')
				.insertAfter('#content h1')
				.addClass("content-toc")
				.attr('id','content-toc');
			for (var j = 0; j < headers.length; j++) {
                var li_tag = $('<li></li>').text(headers[j]);
				ul_tag.append(li_tag);
                li_create_linkage(li_tag, i);
			}
		}
    }
}

function normalize_paths() {
    // images
    $(ditto.content_id + " img").map(function() {
        var src = $(this).attr("src").replace("./", "");
        if ($(this).attr("src").slice(0, 5) !== "http") {
            var url = location.hash.replace("#", "");

            // split and extract base dir
            url = url.split("/");
            var base_dir = url.slice(0, url.length - 1).toString();

            // normalize the path (i.e. make it absolute)
            $(this).attr("src", base_dir + "/" + src);
        }
    });

}

function show_error() {
    console.log("SHOW ERORR!");
    $(ditto.error_id).show();
}

function show_loading() {
    $(ditto.loading_id).show();
    $(ditto.content_id).html("");  // clear content

    // infinite loop until clearInterval() is called on loading
    var loading = setInterval(function() {
        $(ditto.loading_id).fadeIn(1000).fadeOut(1000);
    }, 2000);

    return loading;
}

function router() {

    var path = location.hash.replace("#", "./");

    // default page if hash is empty
    if (location.pathname === "/index.html") {
        path = location.pathname.replace("index.html", ditto.index);
        normalize_paths();
    } else if (path === "") {
        path = window.location + ditto.index;
        normalize_paths();
    } else {
        path = path + ".md";
    }

    // otherwise get the markdown and render it
    var loading = show_loading();
    $.get(path , function(data) {
        $(ditto.error_id).hide();
        $(ditto.content_id).html(marked(data)+disqusCode);
		if ($(ditto.content_id+" h1").text() === ditto.document_title){
			document.title = ditto.document_title;
		} else {
			document.title = $(ditto.content_id+" h1").text() + " - " + ditto.document_title;
		}
        normalize_paths();
        create_page_anchors();

		// 完成代码高亮
		$('#content code').map(function() {
            Prism.highlightElement(this);
        });

		// 加载disqus
		(function () {
			// http://docs.disqus.com/help/2/
			window.disqus_shortname = 'es6';
			window.disqus_identifier = (location.hash?location.hash.replace("#", ""):'READEME');
			window.disqus_title =$(ditto.content_id+" h1").text();
			window.disqus_url = 'http://es6.ruanyifeng.com/' + (location.hash?location.hash.replace("#", ""):'README');

			// http://docs.disqus.com/developers/universal/
			(function() {
				var dsq = document.createElement('script'); dsq.type = 'text/javascript'; dsq.async = true;
				dsq.src = 'http://'+window.disqus_shortname+'.disqus.com/embed.js';
				(document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(dsq);
			})();
		})();

		if(location.hash !== ''){
			$('html, body').animate({
				scrollTop: $('#content').offset().top
			}, 200);
		}

    }).fail(function() {
        show_error();

    }).always(function() {
        clearInterval(loading);
        $(ditto.loading_id).hide();
	});
}

// veil.js

(function (window, document, $) {

    window.Veil = function (elem, options) {

        var defaults = {
            offset: 0,
            prop: 'top',
            onScroll: function (elem, threshold) {},
            isHidden: function (elem, threshold) {},
            isVisible: function (elem, threshold) {}
        };

        var lastScroll = 0;
        var treshold = 0;

        // merge the defaults with the passed options
        for (var key in options) {
            defaults[key] = options[key];
        }

        // if the defaults.prop is 'top' or 'bottom'
        // we need the height, otherwise the width
        var sizeProp = /to/i.test(defaults.prop) ? 'offsetHeight' : 'offsetWidth';

        Veil.scroll = function () {
            var scrollOffset = document.documentElement.scrollTop || document.body.scrollTop,
                elemSize = elem[sizeProp] + defaults.offset,
                diff = scrollOffset - lastScroll;

            treshold = (treshold + diff > elemSize) ? elemSize : (scrollOffset < 0) ? 0 : treshold + diff;
            treshold = (treshold < 0) ? 0 : treshold;

            elem.style[defaults.prop] = (-treshold) + 'px';
            defaults.onScroll(elem, treshold);
            if (!treshold) defaults.isVisible(elem, treshold);
            if (treshold === elemSize) defaults.isHidden(elem, treshold);

            lastScroll = scrollOffset;
        };

        Veil.scroll();

        // modern browsers
        if (window.addEventListener) return window.addEventListener('scroll', Veil.scroll);

        // ie8 and below
        window.attachEvent('onscroll', Veil.scroll);
    };

    // if jquery or zepto is present,
    // add a function to their prototype
    if ($) $.fn.veil = function (options) {
        return this.each(function () {
            Veil(this, options);
        });
    };

}(this, document, this.jQuery || this.Zepto));