Simplify language selection with a few languages

As mentioned in commit 5214d89c8, using the `change` event of a `select`
field to automatically change location is really annoying for keyboard
users, since the event will trigger when pressing the down key to
navigate through the options or when typing a key to start searching for
an option. This might cause a lot of frustration.

Most multilanguage CONSUL sites enable between 2 and 4 languages. In
these cases, it's easier to just display the list of languages to
simplify the selection.

This way in this situation we also make it clear which languages are
available. If we use a `<select>` tag, users will have to open it in
order to check whether the site is available in their preferred
language.

This is also useful when the current language uses characters users
don't recognize; users will recognize their own language in the list of
available languages, while it might be harder to recognize the language
selector allows them to switch to a different language.

In this case, we're also hiding the label because a list of links with
language names is usually self explanatory for sighted users. We're
still providing it for screen reader users so they immediately know the
list allows them to change the language and if they don't need to do so
they can quickly skip it.

app/assets/stylesheets/layout/locale_switcher.scss

@@ -1,10 +1,14 @@
 .locale {
-  @include has-fa-icon(angle-down, solid, after);
   float: left;
   margin-bottom: $line-height / 4;
   margin-top: $line-height / 4;
   position: relative;
 
+  .locale-form {
+    @include has-fa-icon(angle-down, solid, after);
+    display: inline-block;
+    position: relative;
+
     &::after {
       color: #808080;
       font-size: $small-font-size;
@@ -16,10 +20,6 @@
       transform: translateY(-50%);
     }
 
-  .locale-form {
-    display: inline-block;
-    position: relative;
-
     label {
       color: #fff;
       font-size: $tiny-font-size;
@@ -51,4 +51,31 @@
       }
     }
   }
+
+  p {
+    @include element-invisible;
+  }
+
+  ul {
+    $gap: 0.75em;
+    display: flex;
+    flex-wrap: wrap;
+    margin-left: -$gap;
+
+    > * {
+      margin-left: $gap;
+    }
+
+    li::after {
+      content: none;
+    }
+
+    a {
+      margin-left: 0;
+    }
+
+    [aria-current] {
+      font-weight: bold;
+    }
+  }
 }

app/components/layout/locale_switcher_component.html.erb

@@ -1,10 +1,14 @@
 <div class="locale">
+  <% if many_locales? %>
     <form class="locale-form">
-    <label class="inline-block" for="locale-switcher">
+      <label class="inline-block" for="locale-switcher"><%= label %></label>
-      <%= t("layouts.header.locale") %>
-    </label>
       <select class="js-location-changer locale-switcher inline-block" name="locale-switcher" id="locale-switcher">
         <%= options_for_select(language_options, current_path_with_query_params(locale: I18n.locale)) %>
       </select>
     </form>
+  <% else %>
+    <p id="<%= label_id %>"><%= label %></p>
+
+    <%= link_list(*language_links, "aria-labelledby": label_id) %>
+  <% end %>
 </div>

app/components/layout/locale_switcher_component.rb

@@ -1,5 +1,5 @@
 class Layout::LocaleSwitcherComponent < ApplicationComponent
-  delegate :name_for_locale, :current_path_with_query_params, to: :helpers
+  delegate :name_for_locale, :link_list, :current_path_with_query_params, to: :helpers
 
   def render?
     locales.size > 1
@@ -7,13 +7,36 @@ class Layout::LocaleSwitcherComponent < ApplicationComponent
 
   private
 
+    def many_locales?
+      locales.size > 4
+    end
+
     def locales
       I18n.available_locales
     end
 
-    def language_options
+    def label
+      t("layouts.header.locale")
+    end
+
+    def label_id
+      "locale_switcher_label"
+    end
+
+    def language_links
       locales.map do |locale|
-        [name_for_locale(locale), current_path_with_query_params(locale: locale), lang: locale]
+        [
+          name_for_locale(locale),
+          current_path_with_query_params(locale: locale),
+          locale == I18n.locale,
+          lang: locale
+        ]
+      end
+    end
+
+    def language_options
+      language_links.map do |text, path, _, options|
+        [text, path, options]
       end
     end
 end

spec/components/layout/locale_switcher_component_spec.rb

@@ -28,6 +28,7 @@ describe Layout::LocaleSwitcherComponent, type: :component do
 
       expect(page).to have_css "form"
       expect(page).to have_select "Language:", options: %w[Deutsch English Español Français Nederlands]
+      expect(page).not_to have_css "ul"
     end
 
     it "selects the current locale" do
@@ -53,4 +54,27 @@ describe Layout::LocaleSwitcherComponent, type: :component do
       end
     end
   end
+
+  context "with a few languages" do
+    before do
+      allow(I18n).to receive(:available_locales).and_return(%i[en es fr])
+    end
+
+    it "renders a list of links" do
+      render_inline component
+
+      expect(page).to have_css "ul"
+      expect(page).to have_link "English", href: "/?locale=en"
+      expect(page).to have_link "Español", href: "/?locale=es"
+      expect(page).to have_link "Français", href: "/?locale=fr"
+      expect(page).not_to have_css "form"
+    end
+
+    it "marks the current locale" do
+      render_inline component
+
+      expect(page).to have_css "[aria-current]", count: 1
+      expect(page).to have_css "[aria-current]", exact_text: "English"
+    end
+  end
 end