/**
 * Serendipity
 * 
 * Endows Wikipedia with the “sense of wonder” and “serendipitous discoveries”
 * that proud owners of the print Encyclopædia Britannica find sorely lacking on
 * the Internet. Now, whenever you look up an entry in this ephemeral reference,
 * “lose yourself” in the alphabetically adjacent bounty of knowledge that any
 * self-respecting encyclopedia should offer by default.
 * 
 * :-P
 */

if (mw.config.get("wgAction") == "view" && mw.config.get("wgNamespaceNumber") == 0) {
    mw.loader.using("mediawiki.api", function () {
        var api = new mw.Api();
        
        /**
         * Retrieves the rendered HTML content of an alphabetically adjacent
         * article and passes the content to a callback function.
         * 
         * @param forward   {boolean}   True to get the next page; false to get
         *                              the previous one.
         * @param ok        {function}  A callback function that takes two
         *                              arguments: title, html.
         */
        function fetchAdjacentArticle(forward, ok) {
            api.get({
                list: "allpages",
                apfrom: mw.config.get("wgPageName"),
                apnamespace: 0,
                apfilterredir: "nonredirects",
                aplimit: 2,
                apdir: forward ? "ascending" : "descending",
            }).done(function (data) {
                var pages = data.query && data.query.allpages;
                var page = pages && data.query.allpages[1];
                if(!page) return;
                
                $.get(mw.util.wikiScript("index"), {
                    title: page.title,
                    action: "render",
                }, function (html) {
                    if (ok) ok(page.title, html);
                }, "html");
            });
        }
        
        /**
         * Hides content features that facilitate user contributions, multimedia
         * experiences, non-linear navigation, or fact-checking.
         */
        function hideNewFangledFeatures() {
            // Links
            $("#bodyContent a").unbind("click").click(function (evt) {
                evt.preventDefault();
                evt.stopPropagation();
            });
            var extLinkHeadings = $("h2:contains('xternal link')");
            extLinkHeadings.hide().nextAll("ul").hide();
            if (extLinkHeadings) {
                $(".toctext:contains('xternal link')").parent().hide();
            }
            
            // Cite extension
            var refHeadings = $(".reflist").prev("h2:contains('eference')");
            refHeadings.hide();
            if (refHeadings) $(".toctext:contains('eference')").parent().hide();
            
            // WikiMiniAtlas
            wma_settings = {enabled: false};
            
            // Stylesheets only need to be applied once.
            if (hideNewFangledFeatures.stylesAdded) return;
            hideNewFangledFeatures.stylesAdded = true;
            
            // Links
            mw.util.addCSS("#bodyContent a {" +
                           "background: transparent !important; cursor: inherit;" +
                           "color: inherit; padding-right: 0 !important;" +
                           "text-decoration: inherit;" +
                           "}");
            
            // Abbreviations
            mw.util.addCSS("#bodyContent abbr, #bodyContent acronym," +
                           "#bodyContent .explain {" +
                           "border-bottom: none; cursor: inherit;" +
                           "}");
            
            // Software-powered features
            mw.util.addCSS("#mw-articlefeedback, #catlinks, .mw-editsection," +
                           ".magnify, .toctoggle {display: none;}");
            
            // Cite extension
            mw.util.addCSS(".reference, .reflist {display: none;}");
            
            // Template-powered features
            mw.util.addCSS("#coordinates, img[alt='play'], .navbox, .stub" +
                            "{display: none;}");
        }
        
        /**
         * Inserts the contents of the previous article above the original one.
         */
        function insertPreviousArticle(title, html) {
            // Stuff the main article’s title inside its body element.
            $("#bodyContent").prepend($("#firstHeading"));
            $("#firstHeading").css({
                "font-size": 1.25 * parseFloat($("#firstHeading").css("font-size")),
            });
            
            $("#bodyContent").prepend("<div class='visualClear'></div>")
                             .prepend($(html).wrap("<div id='prevBodyContent'></div>"))
                             .prepend("<h1 id='prevFirstHeading' class='firstHeading'>" +
                                      "<span dir='auto'>" + title + "</span>" +
                                      "</h1>");
            hideNewFangledFeatures();
        };
        
        /**
         * Inserts the contents of the next article above the original one.
         */
        function insertNextArticle(title, html) {
            $("#bodyContent").append("<h1 id='nextFirstHeading' class='firstHeading'>" +
                                     "<span dir='auto'>" + title + "</span>" +
                                     "</h1>")
                             .append($(html).wrap("<div id='nextBodyContent'></div>"))
                             .append("<div class='visualClear'></div>");
            hideNewFangledFeatures();
        };
        
        $(function () {
            fetchAdjacentArticle(false, insertPreviousArticle);
            fetchAdjacentArticle(true, insertNextArticle);
        });
    });
}