Extract model to handle locales settings

This way we can simplify the view, particularly the form. However, we're
still adding some complexity to the form so inputs are inside labels and
so the collection is easier to style with CSS.

app/components/admin/locales/form_component.html.erb

@@ -1,37 +1,36 @@
-<%= form_tag admin_locales_path, method: :patch, class: "locales-form" do %>
+<%= form_for locales_settings, url: admin_locales_path, html: { class: "locales-form" } do |f| %>
   <% if many_available_locales? %>
-    <%= label_tag "default_locale", t("admin.locales.default") %>
-    <p class="help-text"><%= sanitize(t("admin.locales.default_help_text")) %></p>
-    <%= select_tag "default_locale", locales_options %>
+    <%= f.select :default, locales_options, hint: sanitize(t("admin.locales.default_help_text")) %>
   <% else %>
     <fieldset>
-      <legend><%= t("admin.locales.default") %></legend>
+      <legend><%= attribute_name(:default) %></legend>
       <p class="help-text"><%= sanitize(t("admin.locales.default_help_text")) %></p>
 
       <div class="collection-radio-buttons">
-        <% available_locales.each do |locale| %>
-          <%= label_tag "default_locale_#{locale}" do %>
-            <%= radio_button_tag "default_locale", locale, locale == default %>
-            <%= name_for_locale(locale) %>
-          <% end %>
+        <%= f.collection_radio_buttons(
+          :default,
+          available_locales,
+          :to_sym,
+          ->(locale) { name_for_locale(locale) }
+        ) do |b| %>
+          <%= b.label { b.radio_button + b.text } %>
         <% end %>
       </div>
     </fieldset>
   <% end %>
 
   <fieldset>
-    <legend><%= t("admin.locales.enabled") %></legend>
+    <legend><%= attribute_name(:enabled) %></legend>
     <p class="help-text"><%= t("admin.locales.enabled_help_text") %></p>
 
     <div class="collection-check-boxes">
-      <% available_locales.each do |locale| %>
-        <%= label_tag "enabled_locales_#{locale}" do %>
-          <%= check_box_tag "enabled_locales[]",
-                            locale,
-                            enabled_locales.include?(locale),
-                            id: "enabled_locales_#{locale}" %>
-          <%= name_for_locale(locale) %>
-        <% end %>
+      <%= f.collection_check_boxes(
+        :enabled,
+        available_locales,
+        :to_sym,
+        ->(locale) { name_for_locale(locale) }
+      ) do |b| %>
+        <%= b.label { b.check_box + b.text } %>
       <% end %>
     </div>
   </fieldset>

app/components/admin/locales/form_component.rb

@@ -1,10 +1,9 @@
 class Admin::Locales::FormComponent < ApplicationComponent
-  attr_reader :enabled_locales, :default
+  attr_reader :locales_settings
   use_helpers :name_for_locale
 
-  def initialize(enabled_locales, default:)
-    @enabled_locales = enabled_locales
-    @default = default
+  def initialize(locales_settings)
+    @locales_settings = locales_settings
   end
 
   private
@@ -18,13 +17,14 @@ class Admin::Locales::FormComponent < ApplicationComponent
     end
 
     def locales_options
-      options_for_select(
-        available_locales.map { |locale| [name_for_locale(locale), locale] },
-        default
-      )
+      available_locales.map { |locale| [name_for_locale(locale), locale] }
     end
 
     def select_field_threshold
       10
     end
+
+    def attribute_name(...)
+      locales_settings.class.human_attribute_name(...)
+    end
 end

app/components/admin/locales/show_component.html.erb

@@ -1,4 +1,4 @@
 <%= header %>
 <% provide :main_class, "admin-locales-show" %>
 
-<%= render Admin::Locales::FormComponent.new(locales, default: default) %>
+<%= render Admin::Locales::FormComponent.new(locales_settings) %>

app/components/admin/locales/show_component.rb

@@ -1,10 +1,9 @@
 class Admin::Locales::ShowComponent < ApplicationComponent
   include Header
-  attr_reader :locales, :default
+  attr_reader :locales_settings
 
-  def initialize(locales, default:)
-    @locales = locales
-    @default = default
+  def initialize(locales_settings)
+    @locales_settings = locales_settings
   end
 
   def title