var nodemcu = nodemcu || {};

(function () {
  'use strict';
  //var languageCodeToNameMap = {en: 'English', de: 'Deutsch'};
  var languageCodeToNameMap = {en: 'English'};
  var languageNames = values(languageCodeToNameMap);
  var defaultLanguageCode = 'en';

  $(document).ready(function () {
    addToc();
    hideNavigationForAllButSelectedLanguage();
    addLanguageSelectorToRtdFlyOutMenu();
    replaceRelativeLinksWithStaticGitHubUrl();
  });

  /**
   * Adds a TOC-style table to each page in the 'Modules' section.
   */
  function addToc() {
    var func, intro, tocHtmlTable;
    if (isModulePage()) {
      tocHtmlTable = '<table class="docutils">';
      $('h2').each(function (index) {
        // 'slice' cuts off the single permalink character at the end of the text (e.g. '¶')
        func = $(this).text().slice(0, -1);
        // get the first sentence of the paragraph directly below h2
        intro = $(this).next().text();
        intro = intro.substring(0, intro.indexOf('.') + 1);
        tocHtmlTable += createTocTableRow(func, intro);
      });
      tocHtmlTable += '</table>';
      $(tocHtmlTable).insertBefore($('h2').first())
    }
    function isModulePage() {
      // if the breadcrumb contains 'Modules »' it must be an API page
      return $("ul.wy-breadcrumbs li:contains('Modules »')").size() > 0;
    }
    function createTocTableRow(func, intro) {
      // fragile attempt to auto-create the in-page anchor
      // good tests: file.md,
      var href = func.replace(/[\.:\(\)]/g, '').replace(/ --|, | /g, '-');
      var link = '<a href="#' + href.toLowerCase() + '">' + func + '</a>';
      return '<tr><td>' + link + '</td><td>' + intro + '</td></tr>';
    }
  }

  function hideNavigationForAllButSelectedLanguage() {
    var selectedLanguageCode = determineSelectedLanguageCode();
    var selectedLanguageName = languageCodeToNameMap[selectedLanguageCode];
    // Finds all subnav elements and hides them if they're /language/ subnavs. Hence, all 'Modules' subnav elements
    // won't be hidden.
    // <ul class="subnav">
    //   <li><span>Modules</span></li>
    //   <li class="toctree-l1 ">
    //     <a class="" href="EN/modules/node/">node</a>
    //   </li>
    $('.subnav li span').not(':contains(' + selectedLanguageName + ')').each(function (index) {
      var spanElement = $(this);
      if ($.inArray(spanElement.text(), languageNames) > -1) {
        spanElement.parent().parent().hide();
      }
    });
  }

  /**
   * Adds a language selector to the RTD fly-out menu found bottom left. Example:
   *
   * <dl>
   *   <dt>Languages</dt>
   *   <dd><a href="http://nodemcu.readthedocs.io/en/<branch>/de/">de</a></dd>
   *   <strong>
   *     <dd><a href="http://nodemcu.readthedocs.io/en/<branch>/en/">en</a></dd>
   *   </strong>
   * </dl>
   *
   * UGLY! That fly-out menu is added by RTD with an AJAX call after page load. Hence, we need to
   * react to the subsequent DOM manipulation using a DOM4 MutationObserver. The provided structure
   * is as follows:
   *
   * <div class="rst-other-versions">
   *   <!-- Inserted RTD Footer -->
   *   <div class="injected">
   */
  function addLanguageSelectorToRtdFlyOutMenu() {
    var flyOutWrapper = $('.rst-other-versions');
    // only relevant on RTD
    if (flyOutWrapper.size() > 0) {
      var observer = new MutationObserver(function (mutations) {
        // since mutation on the target node was triggered we can safely assume the injected RTD div has now been added
        var injectedDiv = $('.rst-other-versions .injected');
        var selectedLanguageCode = determineSelectedLanguageCode();
        var dl = document.createElement('dl');
        var dt = document.createElement('dt');
        dl.appendChild(dt);
        dt.appendChild(document.createTextNode('Languages'));
        for (var languageCode in languageCodeToNameMap) {
          dl.appendChild(createLanguageLinkFor(languageCode, selectedLanguageCode === languageCode));
        }
        injectedDiv.prepend(dl);
        // no need for that observer anymore
        observer.disconnect();
      });

      // observed target node is the fly-out wrapper, the only event we care about is when children are modified
      observer.observe(flyOutWrapper[0], {childList: true});
    }
  }

  /**
   * The module doc pages contain relative links to artifacts in the GitHub repository. For those links to work both
   * on GitHub (i.e. when the page is viewed on GitHub) and on RTD they are defined with a relative URL. This function
   * replaces the relative path with an absolute path based on the selected branch.
   */
  function replaceRelativeLinksWithStaticGitHubUrl() {
    var relativePath = isOnRtd() ? "../../../.." : "../../..";
    var gitHubPath = "https://github.com/nodemcu/nodemcu-firmware/tree/" + determineSelectedBranch();
    var gitHubLinks = $("a[href^='" + relativePath + "']").each(function (index) {
      var url = $(this).attr('href');
      $(this).attr('href', url.replace(relativePath, gitHubPath));
    });
  }

  function createLanguageLinkFor(languageCode, isCurrentlySelected) {
    var strong;
    // split[0] is an '' because the path starts with the separator
    var pathSegments = window.location.pathname.split('/');
    var dd = document.createElement("dd");
    var href = document.createElement("a");
    href.setAttribute('href', '/' + pathSegments[1] + '/' + pathSegments[2] + '/' + languageCode);
    href.appendChild(document.createTextNode(languageCode));
    dd.appendChild(href);
    if (isCurrentlySelected) {
      strong = document.createElement("strong");
      strong.appendChild(dd);
      return strong;
    } else {
      return dd;
    }
  }

  /**
   * Analyzes the URL of the current page to find out what the selected language is. It's usually
   * part of the location path. The code needs to distinguish between running MkDocs standalone
   * and docs served from RTD. If no valid language could be determined the default language is
   * returned.
   *
   * @returns 2-char language code
   */
  function determineSelectedLanguageCode() {
    var selectedLanguageCode, path = window.location.pathname;
    if (isOnRtd()) {
      // path is like /en/<branch>/<lang>/build/ -> extract 'lang'
      // split[0] is an '' because the path starts with the separator
      selectedLanguageCode = path.split('/')[3];
    } else if (!window.location.href.startsWith('file://')) {
      // path is like /<lang>/build/ -> extract 'lang'
      selectedLanguageCode = path.substr(1, 2);
    }
    if (!selectedLanguageCode || selectedLanguageCode.length > 2) {
      selectedLanguageCode = defaultLanguageCode;
    }
    return selectedLanguageCode;
  }

  /**
   * Analyzes the URL of the current page to find out what the selected GitHub branch is. It's usually
   * part of the location path. The code needs to distinguish between running MkDocs standalone
   * and docs served from RTD. If no valid branch could be determined 'dev' returned.
   *
   * @returns GitHub branch name
   */
  function determineSelectedBranch() {
    var branch = 'dev', path = window.location.pathname;
    if (isOnRtd()) {
      // path is like /en/<branch>/<lang>/build/ -> extract 'lang'
      // split[0] is an '' because the path starts with the separator
      var thirdPathSegment = path.split('/')[2];
      // 'latest' is an alias on RTD for the 'dev' branch - which is the default for 'branch' here
      if (thirdPathSegment != 'latest') {
        branch = thirdPathSegment;
      }
    }
    return branch;
  }

  function values(associativeArray) {
    var values = [];
    for (var key in associativeArray) {
      if (associativeArray.hasOwnProperty(key)) {
        values.push(associativeArray[key]);
      }
    }
    return values;
  }

  function isOnRtd() {
    return window.location.origin.indexOf('readthedocs') > -1;
  }
}());