{{- /*
  Send readers to the docs in their own language.

  Only English pages that have a translation get this script. When a reader
  arrives on one from outside the site (a search result, a link, a bookmark),
  we pick a language in this order:

    1. The language they last chose in the header language menu.
    2. Their browser's preferred languages, in order. If English comes first
       in that list we stop and keep English.

  If that language has a translation of this page we replace the URL, keeping
  the query string and anchor, so the back button never bounces between the
  two versions.

  We never redirect when the reader got here by clicking within the docs. A
  translated page links to English for the sections we don't translate
  (releases, supported_tools), and a reader who picks English in the language
  menu must be able to stay there. Picking any language in that menu is saved
  and wins over the browser setting from then on.

  Crawlers are left alone: every version is listed through hreflang links and
  the per-language sitemaps, so search engines index each language on its own
  URL.
*/ -}}
{{- if and (eq .Lang "en") .IsTranslated }}
{{- $translations := dict }}
{{- range .Translations }}
{{- $translations = merge $translations (dict .Lang .RelPermalink) }}
{{- end }}
<script>
  (function () {
    var KEY = 'dd-docs-lang';
    var translations = {{ $translations | jsonify | safeJS }};

    // Map a browser language tag (de-AT, pt-BR, zh-CN) to a docs language, or
    // "en" for English. Traditional Chinese has no docs translation, so it
    // gets nothing rather than Simplified.
    function docsLang(tag) {
      tag = String(tag || '').toLowerCase();
      var base = tag.split('-')[0];
      if (base === 'en') return 'en';
      if (base === 'pt') return 'pt-br';
      if (base === 'zh') {
        return /^zh(-hans)?(-(cn|sg))?$|^zh-hans-/.test(tag) ? 'zh-hans' : null;
      }
      return base;
    }

    function saved() {
      try { return localStorage.getItem(KEY); } catch (e) { return null; }
    }

    function fromBrowser() {
      var list = navigator.languages && navigator.languages.length
        ? navigator.languages : [navigator.language];
      for (var i = 0; i < list.length; i++) {
        var lang = docsLang(list[i]);
        if (lang === 'en') return null;
        if (lang && translations[lang]) return lang;
      }
      return null;
    }

    function cameFromDocs() {
      try {
        return !!document.referrer && new URL(document.referrer).host === location.host;
      } catch (e) { return false; }
    }

    var bot = navigator.webdriver ||
      /bot|crawl|spider|slurp|lighthouse|headless|preview/i.test(navigator.userAgent);
    if (bot || cameFromDocs()) return;

    var lang = saved() || fromBrowser();
    if (!lang || lang === 'en' || !translations[lang]) return;
    location.replace(translations[lang] + location.search + location.hash);
  })();
</script>
{{- end }}
<script>
  // Remember the language a reader picks in the header language menu, so the
  // redirect above follows their choice instead of the browser setting.
  document.addEventListener('click', function (event) {
    var link = event.target.closest && event.target.closest('[aria-labelledby="doks-languages"] a[hreflang]');
    if (!link) return;
    try { localStorage.setItem('dd-docs-lang', link.getAttribute('hreflang')); } catch (e) {}
  });
</script>