Bug 1820259 - Add strategy for matching records for a language; r=nor…

…dzilla

Differential Revision: https://phabricator.services.mozilla.com/D176187

toolkit/components/translations/actors/TranslationsParent.sys.mjs

@@ -433,23 +433,19 @@ export class TranslationsParent extends JSWindowActorParent {
     if (TranslationsParent.#mockedLanguagePairs) {
       return TranslationsParent.#mockedLanguagePairs;
     }
+
     const records = await this.#getTranslationModelRecords();
-    const languagePairKeys = new Set();
+    const languagePairMap = new Map();
+
     for (const { fromLang, toLang, version } of records.values()) {
       const isBeta = Services.vc.compare(version, "1.0") < 0;
-      languagePairKeys.add({ key: fromLang + toLang, isBeta });
-    }
-
-    const languagePairs = [];
-    for (const { key, isBeta } of languagePairKeys) {
-      languagePairs.push({
-        fromLang: key[0] + key[1],
-        toLang: key[2] + key[3],
-        isBeta,
-      });
+      const key = `${fromLang},${toLang}`;
+      if (!languagePairMap.has(key)) {
+        languagePairMap.set(key, { fromLang, toLang, isBeta });
+      }
     }
 
-    return languagePairs;
+    return Array.from(languagePairMap.values());
   }
 
   /**
@@ -837,6 +833,72 @@ export class TranslationsParent extends JSWindowActorParent {
     return buffer;
   }
 
+  /**
+   * Get the necessary files for translating to and from the app language and a
+   * requested language. This may require the files for a pivot language translation
+   * if there is no language model for a direct translation.
+   *
+   * @param {string} requestedLanguage The BCP 47 language tag.
+   * @param {boolean} isForDeletion - Return a more restrictive set of languages, as
+   *                  these files are marked for deletion. We don't want to remove
+   *                  files that are needed for some other language's pivot translation.
+   * @returns {Set<TranslationModelRecord>}
+   */
+  async getRecordsForTranslatingToAndFromAppLanguage(
+    requestedLanguage,
+    isForDeletion = false
+  ) {
+    const records = await this.#getTranslationModelRecords();
+    const appLanguage = new Intl.Locale(Services.locale.appLocaleAsBCP47)
+      .language;
+
+    let matchedRecords = new Set();
+
+    if (requestedLanguage === appLanguage) {
+      // There are no records if the requested language and app language are the same.
+      return matchedRecords;
+    }
+
+    const addLanguagePair = (fromLang, toLang) => {
+      let matchFound = false;
+      for (const record of records.values()) {
+        if (record.fromLang === fromLang && record.toLang === toLang) {
+          matchedRecords.add(record);
+          matchFound = true;
+        }
+      }
+      return matchFound;
+    };
+
+    if (
+      // Is there a direct translation?
+      !addLanguagePair(requestedLanguage, appLanguage)
+    ) {
+      // This is no direct translation, get the pivot files.
+      addLanguagePair(requestedLanguage, PIVOT_LANGUAGE);
+      // These files may be required for other pivot translations, so don't remove
+      // them if we are deleting records.
+      if (!isForDeletion) {
+        addLanguagePair(PIVOT_LANGUAGE, appLanguage);
+      }
+    }
+
+    if (
+      // Is there a direct translation?
+      !addLanguagePair(appLanguage, requestedLanguage)
+    ) {
+      // This is no direct translation, get the pivot files.
+      addLanguagePair(PIVOT_LANGUAGE, requestedLanguage);
+      // These files may be required for other pivot translations, so don't remove
+      // them if we are deleting records.
+      if (!isForDeletion) {
+        addLanguagePair(appLanguage, PIVOT_LANGUAGE);
+      }
+    }
+
+    return matchedRecords;
+  }
+
   /**
    * Gets the language model files in an array buffer by downloading attachments from
    * Remote Settings, or retrieving them from the local cache. Each translation

toolkit/components/translations/tests/browser/browser_translations_actor.js

@@ -48,3 +48,161 @@ add_task(async function test_pivot_language_behavior() {
 
   return cleanup();
 });
+
+async function usingAppLocale(locale, callback) {
+  info(`Mocking the locale "${locale}", expect missing resource errors.`);
+  const { availableLocales, requestedLocales } = Services.locale;
+  Services.locale.availableLocales = [locale];
+  Services.locale.requestedLocales = [locale];
+
+  if (Services.locale.appLocaleAsBCP47 !== locale) {
+    throw new Error("Unable to change the app locale.");
+  }
+  await callback();
+
+  // Reset back to the originals.
+  Services.locale.availableLocales = availableLocales;
+  Services.locale.requestedLocales = requestedLocales;
+}
+
+add_task(async function test_translating_to_and_from_app_language() {
+  const PIVOT_LANGUAGE = "en";
+
+  const { actor, cleanup } = await setupActorTest({
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "es" },
+      { fromLang: "es", toLang: PIVOT_LANGUAGE },
+      { fromLang: PIVOT_LANGUAGE, toLang: "fr" },
+      { fromLang: "fr", toLang: PIVOT_LANGUAGE },
+      { fromLang: PIVOT_LANGUAGE, toLang: "pl" },
+      { fromLang: "pl", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  /**
+   * Each language pair has multiple models. De-duplicate the language pairs and
+   * return a sorted list.
+   */
+  function getUniqueLanguagePairs(records) {
+    const langPairs = new Set();
+    for (const { fromLang, toLang } of records) {
+      langPairs.add(fromLang + toLang);
+    }
+    return Array.from(langPairs)
+      .sort()
+      .map(langPair => ({
+        fromLang: langPair[0] + langPair[1],
+        toLang: langPair[2] + langPair[3],
+      }));
+  }
+
+  function assertLanguagePairs({
+    app,
+    requested,
+    message,
+    languagePairs,
+    isForDeletion,
+  }) {
+    return usingAppLocale(app, async () => {
+      Assert.deepEqual(
+        getUniqueLanguagePairs(
+          await actor.getRecordsForTranslatingToAndFromAppLanguage(
+            requested,
+            isForDeletion
+          )
+        ),
+        languagePairs,
+        message
+      );
+    });
+  }
+
+  await assertLanguagePairs({
+    message:
+      "When the app locale is the pivot language, download another language.",
+    app: PIVOT_LANGUAGE,
+    requested: "fr",
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "fr" },
+      { fromLang: "fr", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message: "When a pivot language is required, they are both downloaded.",
+    app: "fr",
+    requested: "pl",
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "fr" },
+      { fromLang: PIVOT_LANGUAGE, toLang: "pl" },
+      { fromLang: "fr", toLang: PIVOT_LANGUAGE },
+      { fromLang: "pl", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message:
+      "When downloading the pivot language, only download the one for the app's locale.",
+    app: "es",
+    requested: PIVOT_LANGUAGE,
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "es" },
+      { fromLang: "es", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message:
+      "Delete just the requested language when the app locale is the pivot language",
+    app: PIVOT_LANGUAGE,
+    requested: "fr",
+    isForDeletion: true,
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "fr" },
+      { fromLang: "fr", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message: "Delete just the requested language, and not the pivot.",
+    app: "fr",
+    requested: "pl",
+    isForDeletion: true,
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "pl" },
+      { fromLang: "pl", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message: "Delete just the requested language, and not the pivot.",
+    app: "fr",
+    requested: "pl",
+    isForDeletion: true,
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "pl" },
+      { fromLang: "pl", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message: "Delete just the pivot → app and app → pivot.",
+    app: "es",
+    requested: PIVOT_LANGUAGE,
+    isForDeletion: true,
+    languagePairs: [
+      { fromLang: PIVOT_LANGUAGE, toLang: "es" },
+      { fromLang: "es", toLang: PIVOT_LANGUAGE },
+    ],
+  });
+
+  await assertLanguagePairs({
+    message:
+      "If the app and request language are the same, nothing is returned.",
+    app: "fr",
+    requested: "fr",
+    languagePairs: [],
+  });
+
+  return cleanup();
+});