FEATURE: Make site texts controller handle pages and locales (#8408)

Some endpoints are returning i18n keys instead of translated messages
and with these changes, the site_texts endpoint can help translating
those.

Pagination part is needed for better wildcard support. For example,
looking for 'js.notifications' would set 'has_more' to true, but return
only the first 50 messages with no way of fetching the remaining.

app/controllers/admin/site_texts_controller.rb

@@ -20,11 +20,15 @@ class Admin::SiteTextsController < Admin::AdminController
     extras = {}
 
     query = params[:q] || ""
+
+    locale = params[:locale] || I18n.locale
+    raise Discourse::InvalidParameters.new(:locale) if !I18n.locale_available?(locale)
+
     if query.blank? && !overridden
       extras[:recommended] = true
-      results = self.class.preferred_keys.map { |k| record_for(k) }
+      results = I18n.with_locale(locale) { self.class.preferred_keys.map { |k| record_for(k) } }
     else
-      results = find_translations(query, overridden)
+      results = I18n.with_locale(locale) { find_translations(query, overridden) }
 
       if results.any?
         extras[:regex] = I18n::Backend::DiscourseI18n.create_search_regexp(query, as_string: true)
@@ -41,8 +45,15 @@ class Admin::SiteTextsController < Admin::AdminController
       end
     end
 
-    extras[:has_more] = true if results.size > 50
-    render_serialized(results[0..49], SiteTextSerializer, root: 'site_texts', rest_serializer: true, extras: extras, overridden_keys: overridden_keys)
+    page = params[:page].to_i
+    raise Discourse::InvalidParameters.new(:page) if page < 0
+
+    per_page = 50
+    first = page * per_page
+    last = first + per_page
+
+    extras[:has_more] = true if results.size > last
+    render_serialized(results[first..last - 1], SiteTextSerializer, root: 'site_texts', rest_serializer: true, extras: extras, overridden_keys: overridden_keys)
   end
 
   def show

spec/requests/admin/site_texts_controller_spec.rb

@@ -58,6 +58,33 @@ RSpec.describe Admin::SiteTextsController do
         expect(JSON.parse(response.body)['extras']['has_more']).to be_truthy
       end
 
+      it 'works with pages' do
+        texts = Set.new
+
+        get "/admin/customize/site_texts.json", params: { q: 'e' }
+        JSON.parse(response.body)['site_texts'].each { |text| texts << text['id'] }
+        expect(texts.size).to eq(50)
+
+        get "/admin/customize/site_texts.json", params: { q: 'e', page: 1 }
+        JSON.parse(response.body)['site_texts'].each { |text| texts << text['id'] }
+        expect(texts.size).to eq(100)
+      end
+
+      it 'works with locales' do
+        get "/admin/customize/site_texts.json", params: { q: 'yes_value', locale: 'en' }
+        value = JSON.parse(response.body)['site_texts'].find { |text| text['id'] == 'js.yes_value' }['value']
+        expect(value).to eq(I18n.with_locale(:en) { I18n.t('js.yes_value') })
+
+        get "/admin/customize/site_texts.json", params: { q: 'yes_value', locale: 'de' }
+        value = JSON.parse(response.body)['site_texts'].find { |text| text['id'] == 'js.yes_value' }['value']
+        expect(value).to eq(I18n.with_locale(:de) { I18n.t('js.yes_value') })
+      end
+
+      it 'returns an error on invalid locale' do
+        get "/admin/customize/site_texts.json", params: { locale: '?' }
+        expect(response.status).to eq(400)
+      end
+
       it 'normalizes quotes during search' do
         value = %q|“That’s a ‘magic’ sock.”|
         put "/admin/customize/site_texts/title.json", params: { site_text: { value: value } }