Allow selecting both default flavour and theme

Fixes #672

app/controllers/admin/settings_controller.rb

@@ -18,6 +18,7 @@ module Admin
       bootstrap_timeline_accounts
       flavour
       skin
+      flavour_and_skin
       thumbnail
       hero
       mascot
@@ -54,7 +55,13 @@ module Admin
     def update
       authorize :settings, :update?
 
-      settings_params.each do |key, value|
+      settings = settings_params
+      flavours_and_skin = settings.delete('flavour_and_skin')
+      if flavours_and_skin
+        settings['flavour'], settings['skin'] = flavours_and_skin.split('/', 2)
+      end
+
+      settings.each do |key, value|
         if UPLOAD_SETTINGS.include?(key)
           upload = SiteUpload.where(var: key).first_or_initialize(var: key)
           upload.update(file: value)

app/lib/themes.rb

@@ -80,4 +80,10 @@ class Themes
   def skins_for(name)
     @conf[name]['skin'].keys
   end
+
+  def flavours_and_skins
+    flavours.map do |flavour|
+      [flavour, skins_for(flavour).map{ |skin| [flavour, skin] }]
+    end
+  end
 end

app/models/form/admin_settings.rb

@@ -48,4 +48,8 @@ class Form::AdminSettings
     :custom_css=,
     to: Setting
   )
+
+  def flavour_and_skin
+    "#{Setting.flavour}/#{Setting.skin}"
+  end
 end

app/views/admin/settings/edit.html.haml

@@ -7,7 +7,7 @@
     = f.input :site_title, wrapper: :with_label, label: t('admin.settings.site_title')
 
   .fields-group
-    = f.input :flavour, collection: Themes.instance.flavours, label_method: lambda { |flavour| I18n.t("flavours.#{flavour}.name", default: flavour) }, wrapper: :with_label, include_blank: false
+    = f.input :flavour_and_skin, collection: Themes.instance.flavours_and_skins, group_label_method: lambda { |(flavour, _)| I18n.t("flavours.#{flavour}.name", default: flavour) }, wrapper: :with_label, include_blank: false, as: :grouped_select, label_method: :last, value_method: lambda { |value| value.join('/') }, group_method: :last
 
   .fields-row
     .fields-row__column.fields-row__column-6.fields-group