Merge pull request #258 from jairo-bc/STRF-9553

STRF-9553 Fallback languages in the chain
bigcommerce · Dec 20, 2021 · ff3383c · ff3383c
2 parents cf416f8 + 1878dd0
commit ff3383c
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Showing 4 changed files with 124 additions and 13 deletions.
diff --git a/lib/translator/index.js b/lib/translator/index.js
@@ -24,16 +24,16 @@ const DEFAULT_LOCALE = 'en';
  * @param {Object} logger
  * @param {Boolean} omitTransforming
  */
-function Translator(acceptLanguage, allTranslations, logger = console, omitTransforming = false) {
+function Translator(acceptLanguage, allTranslations, logger = console) {
     this.logger = logger;
-    this.omitTransforming = omitTransforming;
 
-    const languages = this.omitTransforming ? allTranslations : Transformer.transform(allTranslations, DEFAULT_LOCALE, this.logger);
+    const locales = LocaleParser.getLocales(acceptLanguage);
+    const languages = Transformer.transform(allTranslations, locales, DEFAULT_LOCALE, this.logger);
     /**
      * @private
      * @type {string}
      */
-    this._locale = LocaleParser.getPreferredLocale(acceptLanguage, languages, DEFAULT_LOCALE);
+    this._locale = LocaleParser.getPreferredLocale(locales, languages, DEFAULT_LOCALE);
 
     this.setLanguage(languages);
 

diff --git a/lib/translator/locale-parser.js b/lib/translator/locale-parser.js
@@ -8,13 +8,13 @@ const MessageFormat = require('messageformat');
 
 /**
  * Get preferred locale
- * @param {string} acceptLanguage
+ * @param {string[]} locales
  * @param {Object} languages
  * @param {string} defaultLocale
  * @returns {string}
  */
-function getPreferredLocale(acceptLanguage, languages, defaultLocale) {
-    const locale = getLocales(acceptLanguage).find(locale => languages[locale]) || defaultLocale;
+function getPreferredLocale(locales, languages, defaultLocale) {
+    const locale = locales.find(locale => languages[locale]) || defaultLocale;
     try {
         new MessageFormat(locale);
 

diff --git a/lib/translator/transformer.js b/lib/translator/transformer.js
@@ -7,12 +7,13 @@
 /**
  * Transform translations
  * @param {Object} allTranslations
+ * @param {string[]} locales
  * @param {string} defaultLocale
  * @param {Object} logger
  * @returns {Object.<string, Object>} Transformed translations
  */
-function transform(allTranslations, defaultLocale, logger = console) {
-    return cascade(flatten(allTranslations, logger), defaultLocale);
+function transform(allTranslations, locales, defaultLocale, logger = console) {
+    return cascade(flatten(allTranslations, logger), locales, defaultLocale);
 }
 
 /**
@@ -41,11 +42,14 @@ function flatten(allTranslations, logger = console) {
 
 /**
  * Cascade translations
+ * 
  * @param {Object} allTranslations Flattened translations
+ * @param {string[]} locales
  * @param {string} defaultLocale
  * @returns {Object.<string, Object>} Language objects
  */
-function cascade(allTranslations, defaultLocale) {
+function cascade(allTranslations, locales, defaultLocale) {
+    const availableLocales = addDefaultLocale(locales, defaultLocale);
     return Object.entries(allTranslations)
         .reduce(
             (result, [locale, translations]) => {
@@ -55,6 +59,7 @@ function cascade(allTranslations, defaultLocale) {
 
                 const regionCodes = locale.split('-');
                 for (let regionIndex = regionCodes.length - 1; regionIndex >= 0; regionIndex--) {
+                    // keeping parent locale logic as a source of truth to track "available" keys 
                     const parentLocale = getParentLocale(regionCodes, regionIndex, defaultLocale);
                     const parentTranslations = allTranslations[parentLocale] || {};
 
@@ -65,8 +70,11 @@ function cascade(allTranslations, defaultLocale) {
                             result[locale].locales[key] = locale;
                             result[locale].translations[key] = translations[key];
                         } else if (!result[locale].translations[key]) {
-                            result[locale].locales[key] = parentLocale;
-                            result[locale].translations[key] = parentTranslations[key];
+                            const preparedLocales = prepareLocales(availableLocales, locale);
+                            const { nextAvailableLocale, nextAvailableTranslation } = getNextLocaleTranslation(preparedLocales, allTranslations, key);
+                             // fallback to old logic in case no languages are present in lang header
+                            result[locale].locales[key] = nextAvailableLocale || parentLocale;
+                            result[locale].translations[key] = nextAvailableTranslation || parentTranslations[key]; 
                         }
                     });
                 }
@@ -77,6 +85,56 @@ function cascade(allTranslations, defaultLocale) {
         );
 }
 
+/**
+ * Adding default locale in case it's absent
+ * 
+ * @param {string[]} locales
+ * @param {string} defaultLocale
+ * @returns {string[]}
+ */
+ function addDefaultLocale(locales, defaultLocale) {
+    // the object will be mutated, so making a copy of it.
+   const copiedLocales = [...locales];
+   if (locales[locales.length - 1] !== defaultLocale) {
+       copiedLocales.push(defaultLocale);
+   }
+   return copiedLocales;
+}
+
+/**
+ * Adding default locale in case it's absent
+ * 
+ * @param {string[]} availableLocales
+ * @param {string} currentLocale
+ * @returns {string[]}
+ */
+function prepareLocales(availableLocales, currentLocale) {
+    const localeIndex = availableLocales.findIndex(locale => locale == currentLocale);
+    const locales = availableLocales.slice(localeIndex + 1);
+    return locales;
+}
+
+/**
+ * Returns next available pair (locale and translation) in the chain
+ * 
+ * @param {string[]} locales
+ * @param {Object} allTranslations Flattened translations
+ * @param {string} key
+ * @returns {Object.<string, string>} selected locale and translation
+ */
+function getNextLocaleTranslation(locales, allTranslations, key) {
+    for (const locale of locales) {
+        if (allTranslations[locale] && allTranslations[locale][key]) {
+            return {
+                nextAvailableLocale: locale,
+                nextAvailableTranslation: allTranslations[locale][key],
+            }
+        }
+    }
+
+    return {};
+}
+
 /**
  * Get parent locale
  * @private

diff --git a/spec/lib/translator.js b/spec/lib/translator.js
@@ -290,6 +290,59 @@ describe('Translator', () => {
             expect(translator.translate(key)).to.equal(translations.fr.level1.level2);
             done();
         })
-    })
+    });
+
+    describe('multiple languages support in accept language header', () => {
+        it('should sucessfully translate phrase and fallback to de', done => {
+            translations = {
+                en: {
+                    search: 'Search',
+                },
+                'es-mx': {
+                    test: 'Test',
+                },
+                de: {
+                    search: 'German translation',
+                },
+            };
+            console.log('before');
+            const translator = Translator.create('es-mx,es,de,en', translations);
+            expect(translator.translate('search')).to.equal(translations.de.search);
+            done();
+        });
+
+        it('should sucessfully translate phrase and fallback to es-mx, when it is presented in header', done => {
+            translations = {
+                en: {
+                    search: 'English translation',
+                },
+                'es-mx': {
+                    search: 'Spanish Mexico Translation',
+                },
+                de: {
+                    search: 'German translation',
+                },
+            };
+            const translator = Translator.create('es,es-mx,de,en', translations);
+            expect(translator.translate('search')).to.equal(translations['es-mx'].search);
+            done();
+        });
 
+        it('should sucessfully translate phrase and fallback to en when no en in header', done => {
+            translations = {
+                en: {
+                    search: 'English translation',
+                },
+                'es-mx': {
+                    Test: 'Spanish Mexico Translation',
+                },
+                pt: {
+                    search: 'Portuguese translation',
+                },
+            };
+            const translator = Translator.create('es-mx,de', translations);
+            expect(translator.translate('search')).to.equal(translations.en.search);
+            done();
+        });
+    });
 });