prevent changing locales on accepting amendments

decidim-core/app/commands/decidim/amendable/accept.rb

@@ -57,8 +57,20 @@ def update_amendable!
           visibility: "public-only"
         ) do
           @amendable.assign_attributes(form.emendation_params)
-          @amendable.title = { I18n.locale => form.emendation_params.with_indifferent_access[:title] }
-          @amendable.body = { I18n.locale => form.emendation_params.with_indifferent_access[:body] }
+          if @amendable.official?
+            # official proposals can be translated, when amending them, we want to keep the translations
+            # (admins will have to update it afterwards if needed) so we assign the original attributes first
+            @amendable.title = @emendation.amendable.title
+            @amendable.title[I18n.locale.to_s] = form.emendation_params.with_indifferent_access[:title]
+            @amendable.body = @emendation.amendable.body
+            @amendable.body[I18n.locale.to_s] = form.emendation_params.with_indifferent_access[:body]
+          else
+            # For non-official proposals, we only allow one locale, so we just assign the new values.
+            # Note that this will trigger the automatic translation if enabled 
+            # effectively changing the original language in what the proposal was writen
+            @amendable.title = { I18n.locale => form.emendation_params.with_indifferent_access[:title] }
+            @amendable.body = { I18n.locale => form.emendation_params.with_indifferent_access[:body] }
+          end
           @amendable.save!
           @amendable
         end

decidim-core/app/controllers/concerns/decidim/amendments_controller.rb

@@ -11,6 +11,8 @@ class AmendmentsController < Decidim::ApplicationController
     helper_method :amendment, :amendable, :emendation, :similar_emendations
     before_action :ensure_is_draft_from_user, only: [:compare_draft, :edit_draft, :update_draft, :destroy_draft, :preview_draft, :publish_draft]
 
+    around_action :ensure_locale_on_review, only: [:review]
+
     def new
       raise ActionController::RoutingError, "Not Found" unless amendable
 
@@ -192,6 +194,16 @@ def withdraw
 
     private
 
+    def ensure_locale_on_review
+      emendation_locale = (emendation.title.keys - ["machine_translations"]).first
+      if current_locale.to_s != emendation_locale
+        flash[:alert] = t("locale_changed", scope: "decidim.amendments.review", lang: t("locale.name", locale: emendation_locale))
+      end
+      I18n.with_locale(emendation_locale) do
+        yield
+      end
+    end
+
     # GlobalID::SignedGlobalID parameter to locate the amendable resource.
     # Needed for actions :new and :create, when there is no amendment yet.
     def amendable_gid

decidim-core/app/views/decidim/amendments/_edit_form_fields.html.erb

@@ -1,6 +1,6 @@
 <%= form.fields_for :emendation_params, form.object.emendation_params do |emendation_form| %>
   <%= form_required_explanation %>
-
+<% console %>
   <% amendable.attributes.each do |key, value| %>
     <% key = key.to_sym %>
     <% if amendable.amendable_fields.include?(key) %>

decidim-core/config/locales/en.yml

@@ -322,6 +322,7 @@ en:
         back: Back
         heading: Review the amendment
         help_text: You are reviewing an amendment to the %{model_name}
+        locale_changed: This amendment is being made for the "%{lang}" language. The display language has been changed to prevent misunderstandings.
         send: Accept amendment
       update_draft:
         error: There was a problem updating the amendment draft.