i18n: Show translation levels for each language in the UI

In the user settings page, in the language selector, now the user will
have visibility of the approximate % of translation each language have.

app/helpers/preferences_helper.rb

@@ -4,8 +4,8 @@
 module PreferencesHelper
   def layout_choices
     [
-        ['Fixed', :fixed],
-        ['Fluid', :fluid]
+      ['Fixed', :fixed],
+      ['Fluid', :fluid]
     ]
   end
 
@@ -76,7 +76,7 @@ module PreferencesHelper
 
   def language_choices
     options_for_select(
-      Gitlab::I18n.selectable_locales.map(&:reverse).sort,
+      selectable_locales_with_translation_level.sort,
       current_user.preferred_language
     )
   end
@@ -107,6 +107,18 @@ module PreferencesHelper
   def default_first_day_of_week
     first_day_of_week_choices.rassoc(Gitlab::CurrentSettings.first_day_of_week).first
   end
+
+  def selectable_locales_with_translation_level
+    Gitlab::I18n.selectable_locales.map do |code, language|
+      [
+        s_("i18n|%{language} (%{percent_translated}%% translated)") % {
+          language: language,
+          percent_translated: Gitlab::I18n.percentage_translated_for(code)
+        },
+        code
+      ]
+    end
+  end
 end
 
 PreferencesHelper.prepend_if_ee('EE::PreferencesHelper')

app/models/user.rb

@@ -425,7 +425,7 @@ class User < ApplicationRecord
 
   def preferred_language
     read_attribute('preferred_language') ||
-      I18n.default_locale.to_s.presence_in(Gitlab::I18n::AVAILABLE_LANGUAGES.keys) ||
+      I18n.default_locale.to_s.presence_in(Gitlab::I18n.available_locales) ||
       'en'
   end
 

changelogs/unreleased/trans-levels-master-patch-26507.yml

+---
+title: Add the translation level for each language in the user profile language selector
+merge_request: 59420
+author:
+type: changed

doc/development/i18n/merging_translations.md

@@ -78,3 +78,10 @@ recreate it with the following steps:
 1. Select the `gitlab-org/gitlab` repository.
 1. In `Select Branches for Translation`, select `master`.
 1. Ensure the `Service Branch Name` is `master-i18n`.
+
+## Manually update the translation levels
+
+There's no automated way to pull the translation levels from CrowdIn, to display
+this information in the language selection dropdown. Therefore, the translation
+levels are hard-coded in the `TRANSLATION_LEVELS` constant in [`i18n.rb`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/i18n.rb),
+and must be regularly updated.

lib/gitlab/i18n.rb

@@ -4,20 +4,6 @@ module Gitlab
   module I18n
     extend self
 
-    # Languages with less then 2% of available translations will not
-    # be available in the UI.
-    # https://gitlab.com/gitlab-org/gitlab/-/issues/221012
-    NOT_AVAILABLE_IN_UI = %w[
-      fil_PH
-      pl_PL
-      nl_NL
-      id_ID
-      cs_CZ
-      bg
-      eo
-      gl_ES
-    ].freeze
-
     AVAILABLE_LANGUAGES = {
       'bg' => 'Bulgarian - български',
       'cs_CZ' => 'Czech - čeština',
@@ -42,9 +28,49 @@ module Gitlab
       'zh_HK' => 'Chinese, Traditional (Hong Kong) - 繁體中文 (香港)',
       'zh_TW' => 'Chinese, Traditional (Taiwan) - 繁體中文 (台灣)'
     }.freeze
+    private_constant :AVAILABLE_LANGUAGES
+
+    # Languages with less then MINIMUM_TRANSLATION_LEVEL% of available translations will not
+    # be available in the UI.
+    # https://gitlab.com/gitlab-org/gitlab/-/issues/221012
+    MINIMUM_TRANSLATION_LEVEL = 2
+
+    # Currently monthly updated manually by ~group::import PM.
+    # https://gitlab.com/gitlab-org/gitlab/-/issues/18923
+    TRANSLATION_LEVELS = {
+      'bg' => 1,
+      'cs_CZ' => 1,
+      'de' => 20,
+      'en' => 100,
+      'eo' => 1,
+      'es' => 44,
+      'fil_PH' => 1,
+      'fr' => 14,
+      'gl_ES' => 1,
+      'id_ID' => 0,
+      'it' => 3,
+      'ja' => 49,
+      'ko' => 15,
+      'nl_NL' => 1,
+      'pl_PL' => 1,
+      'pt_BR' => 23,
+      'ru' => 34,
+      'tr_TR' => 18,
+      'uk' => 46,
+      'zh_CN' => 78,
+      'zh_HK' => 3,
+      'zh_TW' => 4
+    }.freeze
+    private_constant :TRANSLATION_LEVELS
 
     def selectable_locales
-      AVAILABLE_LANGUAGES.reject { |key, _value| NOT_AVAILABLE_IN_UI.include? key }
+      @selectable_locales ||= AVAILABLE_LANGUAGES.reject do |code, _name|
+        percentage_translated_for(code) < MINIMUM_TRANSLATION_LEVEL
+      end
+    end
+
+    def percentage_translated_for(code)
+      TRANSLATION_LEVELS.fetch(code, 0)
     end
 
     def available_locales

locale/gitlab.pot

@@ -37786,6 +37786,9 @@ msgstr ""
 msgid "https://your-bitbucket-server"
 msgstr ""
 
+msgid "i18n|%{language} (%{percent_translated}%% translated)"
+msgstr ""
+
 msgid "image diff"
 msgstr ""
 

spec/features/profiles/user_edit_preferences_spec.rb

 # frozen_string_literal: true
+
 require 'spec_helper'
 
 RSpec.describe 'User edit preferences profile', :js do
@@ -63,17 +64,4 @@ RSpec.describe 'User edit preferences profile', :js do
       expect(page).to have_content('Failed to save preferences.')
     end
   end
-
-  describe 'User language' do
-    let(:user) { create(:user, preferred_language: :es) }
-
-    it 'shows the user preferred language by default' do
-      expect(page).to have_select(
-        'user[preferred_language]',
-        selected: 'Spanish - español',
-        options: Gitlab::I18n.selectable_locales.values,
-        visible: :all
-      )
-    end
-  end
 end

spec/helpers/preferences_helper_spec.rb

@@ -121,6 +121,23 @@ RSpec.describe PreferencesHelper do
     end
   end
 
+  describe '#language_choices' do
+    it 'lists all the selectable language options with their translation percent' do
+      stub_const(
+        'Gitlab::I18n::TRANSLATION_LEVELS',
+        'en' => 100,
+        'es' => 65
+      )
+
+      stub_user(preferred_language: :en)
+
+      expect(helper.language_choices).to eq([
+        '<option selected="selected" value="en">English (100% translated)</option>',
+        '<option value="es">Spanish - español (65% translated)</option>'
+      ].join("\n"))
+    end
+  end
+
   def stub_user(messages = {})
     if messages.empty?
       allow(helper).to receive(:current_user).and_return(nil)

spec/lib/gitlab/i18n_spec.rb

@@ -3,13 +3,21 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::I18n do
-  let(:user) { create(:user, preferred_language: 'es') }
+  let(:user) { create(:user, preferred_language: :es) }
 
   describe '.selectable_locales' do
-    it 'does not return languages that should not be available in the UI' do
-      Gitlab::I18n::NOT_AVAILABLE_IN_UI.each do |language|
-        expect(described_class.selectable_locales).not_to include(language)
-      end
+    it 'does not return languages with low translation levels' do
+      stub_const(
+        'Gitlab::I18n::TRANSLATION_LEVELS',
+        'pt_BR' => 0,
+        'en' => 100,
+        'es' => 65
+      )
+
+      expect(described_class.selectable_locales).to eq({
+        'en' => 'English',
+        'es' => 'Spanish - español'
+      })
     end
   end