FEATURE: Show an indicator for posts not originally written in the user's language

assets/javascripts/discourse/components/translated-post-indicator.gjs

@@ -0,0 +1,19 @@
+import Component from "@glimmer/component";
+import { i18n } from "discourse-i18n";
+import DTooltip from "float-kit/components/d-tooltip";
+
+export default class TranslatedPostIndicator extends Component {
+  get tooltip() {
+    return i18n("translator.originally_written_in", {
+      language: this.args.data.detectedLanguage,
+    });
+  }
+
+  <template>
+    <DTooltip
+      @identifier="discourse-translator_translated-post-indicator"
+      @icon="language"
+      @content={{this.tooltip}}
+    />
+  </template>
+}

assets/javascripts/discourse/initializers/extend-for-translate-button.js

@@ -1,8 +1,10 @@
 import { withPluginApi } from "discourse/lib/plugin-api";
+import RenderGlimmer from "discourse/widgets/render-glimmer";
 import LanguageSwitcher from "../components/language-switcher";
 import ToggleTranslationButton from "../components/post-menu/toggle-translation-button";
 import ShowOriginalContent from "../components/show-original-content";
 import TranslatedPost from "../components/translated-post";
+import TranslatedPostIndicator from "../components/translated-post-indicator";
 
 function initializeTranslation(api) {
   const siteSettings = api.container.lookup("service:site-settings");
@@ -46,6 +48,18 @@ function initializeTranslation(api) {
         });
       }
     );
+
+    api.includePostAttributes("is_translated", "detected_language");
+    api.decorateWidget("post-date:before", (dec) => {
+      if (dec.attrs.is_translated && dec.attrs.detected_language) {
+        return new RenderGlimmer(
+          dec.widget,
+          "div.post-info.post-translated-indicator",
+          TranslatedPostIndicator,
+          { detectedLanguage: dec.attrs.detected_language }
+        );
+      }
+    });
   }
 
   customizePostMenu(api);

assets/stylesheets/common/common.scss

@@ -22,3 +22,11 @@
     color: var(--tertiary);
   }
 }
+
+.post-info .post-info.post-translated-indicator {
+  display: inline;
+
+  svg {
+    color: var(--primary-med-or-secondary-med);
+  }
+}

config/locales/client.en.yml

@@ -12,3 +12,4 @@ en:
       content_translated: "Page is machine-translated. Click to view original"
       translated_from: "Translated from %{language} by %{translator}"
       translating: "Translating"
+      originally_written_in: "This post was originally written in %{language}"

lib/discourse_translator/inline_translation.rb

@@ -63,9 +63,16 @@ def inject(plugin)
       plugin.add_to_serializer(:basic_post, :is_translated) do
         SiteSetting.experimental_inline_translation &&
           !object.locale_matches?(InlineTranslation.effective_locale) &&
+          !scope&.request&.cookies&.key?(SHOW_ORIGINAL_COOKIE) &&
           object.translation_for(InlineTranslation.effective_locale).present?
       end
 
+      plugin.add_to_serializer(:basic_post, :detected_language) do
+        if SiteSetting.experimental_inline_translation && object.detected_locale.present?
+          LocaleToLanguage.get_language(object.detected_locale)
+        end
+      end
+
       plugin.add_to_serializer(:topic_view, :is_translated) do
         SiteSetting.experimental_inline_translation &&
           !object.topic.locale_matches?(InlineTranslation.effective_locale) &&

lib/discourse_translator/locale_to_language.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module DiscourseTranslator
+  class LocaleToLanguage
+    def self.get_language(locale)
+      LocaleSiteSetting.values.find { |v| v[:value] == locale.to_s.sub("-", "_") }&.[](:name)
+    end
+  end
+end

spec/lib/locale_to_language_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+describe DiscourseTranslator::LocaleToLanguage do
+  describe ".get_language" do
+    it "returns the language name for a valid locale" do
+      expect(DiscourseTranslator::LocaleToLanguage.get_language("en")).to eq("English (US)")
+      expect(DiscourseTranslator::LocaleToLanguage.get_language("es")).to eq("Español")
+    end
+
+    it "returns nil for a locale that doesn't exist" do
+      expect(DiscourseTranslator::LocaleToLanguage.get_language("xx")).to be_nil
+    end
+
+    it "handles symbol locales" do
+      expect(DiscourseTranslator::LocaleToLanguage.get_language(:en_GB)).to eq("English (UK)")
+    end
+  end
+end

spec/system/full_page_translation_spec.rb

@@ -12,6 +12,7 @@
   fab!(:post_2) do
     Fabricate(:post, topic: topic, raw: "The greatest victory is that which requires no battle")
   end
+  fab!(:post_3) { Fabricate(:post, topic: topic, raw: "将とは、智・信・仁・勇・厳なり。") }
 
   let(:topic_page) { PageObjects::Pages::Topic.new }
   let(:topic_list) { PageObjects::Components::TopicList.new }
@@ -21,11 +22,13 @@
     topic.set_detected_locale("en")
     post_1.set_detected_locale("en")
     post_2.set_detected_locale("en")
+    post_3.set_detected_locale("ja")
 
     topic.set_translation("ja", "孫子兵法からの人生戦略")
     topic.set_translation("es", "Estrategias de vida de El arte de la guerra")
     post_1.set_translation("ja", "傑作は単なる軍事戦略についてではありません")
     post_2.set_translation("ja", "最大の勝利は戦いを必要としないものです")
+    post_3.set_translation("en", "A general is one who possesses wisdom, sincerity...")
   end
 
   context "when the feature is enabled" do
@@ -37,6 +40,7 @@
       SiteSetting.experimental_inline_translation = true
       SiteSetting.automatic_translation_backfill_rate = 1
       SiteSetting.automatic_translation_target_languages = "ja"
+      SiteSetting.experimental_anon_language_switcher = true
     end
 
     it "shows the correct language based on the selected language and login status" do
@@ -49,6 +53,13 @@
       expect(find(topic_page.post_by_number_selector(1))).to have_content(
         "The masterpiece isn’t just about military strategy",
       )
+      expect(find(topic_page.post_by_number_selector(3))).to have_css(
+        "div.post-translated-indicator",
+      )
+      find("#{topic_page.post_by_number_selector(3)} .post-translated-indicator").hover
+      expect(
+        PageObjects::Components::Tooltips.new("discourse-translator_translated-post-indicator"),
+      ).to be_present(text: "This post was originally written in 日本語")
 
       sign_in(japanese_user)
       visit("/")