FEATURE: Show full topic translations

Author: nattsw

config/locales/server.en.yml

@@ -20,6 +20,7 @@ en:
     experimental_anon_language_switcher: "Enable experimental language switcher for anonymous users. This will allow anonymous users to switch between translated versions of Discourse and user-contributed content in topics."
     errors:
       set_locale_cookie_requirements: "The experimental language switcher for anonymous users requires the `set locale from cookie` site setting to be enabled."
+    experimental_topic_translation: "Enable experimental topic translation feature. This replaces existing post in-line translation with a button that allows users to translate the entire topic."
   translator:
     failed: "The translator is unable to translate this content (%{source_locale}) to the default language of this site (%{target_locale})."
     not_supported: "This language is not supported by the translator."

config/settings.yml

@@ -106,3 +106,6 @@ discourse_translator:
     default: false
     client: true
     validator: "LanguageSwitcherSettingValidator"
+  experimental_topic_translation:
+    default: false
+    client: true

plugin.rb

@@ -47,4 +47,17 @@ module ::DiscourseTranslator
   add_to_serializer :post, :can_translate do
     scope.can_translate?(object)
   end
+
+  add_to_class :post, :has_translation? do |language|
+    translated = custom_fields[::DiscourseTranslator::TRANSLATED_CUSTOM_FIELD]
+    !(language.blank? || translated.blank? || translated[language].blank?)
+  end
+
+  add_to_serializer :post, :cooked, false do
+    return super() if !SiteSetting.experimental_topic_translation
+    return super() if scope.request.params["show-original"].present?
+    return super() if !object.has_translation?(I18n.locale)
+    translated = object.custom_fields[::DiscourseTranslator::TRANSLATED_CUSTOM_FIELD]
+    translated[I18n.locale]
+  end
 end