hugo-theme-even/layouts/partials/header/language-selector.html

<!--
  Language selector.

  If current page has version in another language, language link will lead
  to the translated page. If not, the link will be to the home page of the site
  with specified language.
-->
{{ if (and (.Site.IsMultiLingual) ($.Site.Params.showLanguageSelector)) }}
  <div class="language-selector">
    <ul class="languages-list">
      {{ range $homeTranslation := .Site.Home.AllTranslations }}
        {{ $active := eq $homeTranslation.Language $.Site.Language }}
        {{ $pageTranslation := (index (where $.Page.AllTranslations "Language.Lang"  "eq" $homeTranslation.Language.Lang) 0) }}

        <li class="language-item {{if $active}}active{{end}}">
          {{ with $pageTranslation }}
            <a href="{{ .Permalink }}">{{ .Language.Lang }}</a>
          {{ else }}
            <a href="{{ $homeTranslation.Permalink }}">{{ .Language.Lang }}</a>
          {{ end }}
        </li>
      {{ end }}
    </ul>
  </div>
{{ end }}