Simplify language lists

- SUPPORTED_SUB_LANGUAGE_CODES[] that I introduced was pretty redundant when SUPPORTED_LANGUAGES[] already hold the information. The logic to ignore sub-languages (i.e. reduce the locale's "en-GB" to "en" is now located in getDefaultLanguage()).

- SUPPORTED_BROWSER_LANGUAGES[] and SUPPORTED_LANGUAGES[] look so similar and hard to tell what the former is for at first glance. The functionality to map 'zh-CN' to 'zh-Hans' is now handled by resolveLanguageAlias(), which makes the intention clearer.

This leaves us with a single list -- SUPPORTED_LANGUAGES[], whose key also tells us the desired language code to use.
Also, clients now need to call `resolveLanguageAlias` to map any language code aliases, as they differ depending on how it is queried (e.g. `navigator.language` vs. `app.getLocal()` uses different standards).

I think we no longer need to explicitly migrate existing user's 'zh-CN' into 'zh-Hans' because the rest of the system will always use the desired language code as long as 'resolveLanguageAlias' is called appropriately. e.g. the system uses `selectLanguage` and `selectLanguage` calls `resolveLanguageAlias`.

ui/component/app/view.jsx

@@ -37,7 +37,6 @@ import {
   STATUS_DOWN,
 } from 'web/effects/use-degraded-performance';
 // @endif
-import LANGUAGE_MIGRATIONS from 'constants/language-migrations';
 export const MAIN_WRAPPER_CLASS = 'main-wrapper';
 export const IS_MAC = navigator.userAgent.indexOf('Mac OS X') !== -1;
 
@@ -145,7 +144,6 @@ function App(props: Props) {
   const useCustomScrollbar = !IS_MAC;
   const hasMyChannels = myChannelUrls && myChannelUrls.length > 0;
   const hasNoChannels = myChannelUrls && myChannelUrls.length === 0;
-  const shouldMigrateLanguage = LANGUAGE_MIGRATIONS[language];
   const hasActiveChannelClaim = activeChannelClaim !== undefined;
 
   let uri;
@@ -259,12 +257,6 @@ function App(props: Props) {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [language, languages]);
 
-  useEffect(() => {
-    if (shouldMigrateLanguage) {
-      setLanguage(shouldMigrateLanguage);
-    }
-  }, [shouldMigrateLanguage, setLanguage]);
-
   useEffect(() => {
     // Check that previousHasVerifiedEmail was not undefined instead of just not truthy
     // This ensures we don't fire the emailVerified event on the initial user fetch

ui/constants/language-migrations.js

@@ -1,6 +0,0 @@
-const LANGUAGE_MIGRATIONS = {
-  'zh-CN': 'zh-Hans',
-  'zh-TW': 'zh-Hant',
-};
-
-export default LANGUAGE_MIGRATIONS;

ui/constants/supported_browser_languages.js

@@ -1,39 +0,0 @@
-const SUPPORTED_BROWSER_LANGUAGES = {
-  en: 'en',
-  da: 'da',
-  'zh-CN': 'zh-Hans',
-  'zh-TW': 'zh-Hant',
-  'zh-Hans': 'zh-Hans',
-  'zh-Hant': 'zh-Hant',
-  hr: 'hr',
-  nl: 'nl',
-  no: 'no',
-  fi: 'fi',
-  fr: 'fr',
-  de: 'de',
-  gu: 'gu',
-  hi: 'hi',
-  id: 'id',
-  jv: 'jv',
-  it: 'it',
-  ms: 'ms',
-  ml: 'ml',
-  mr: 'mr',
-  pa: 'pa',
-  pl: 'pl',
-  pt: 'pt',
-  ro: 'ro',
-  ru: 'ru',
-  sr: 'sr',
-  sk: 'sk',
-  ur: 'ur',
-  ca: 'ca',
-  es: 'es',
-  sv: 'sv',
-  tr: 'tr',
-  cs: 'cs',
-  kn: 'kn',
-  uk: 'uk',
-};
-
-export default SUPPORTED_BROWSER_LANGUAGES;

ui/constants/supported_languages.js

@@ -1,5 +1,5 @@
 import LANGUAGES from './languages';
-// supported_browser_languages
+
 const SUPPORTED_LANGUAGES = {
   en: LANGUAGES.en[1],
   da: LANGUAGES.da[1],

ui/constants/supported_sub_languages.js

@@ -1,8 +0,0 @@
-// https://www.electronjs.org/docs/api/locales
-
-export const SUB_LANG_CODE_LEN = 5;
-
-export const SUPPORTED_SUB_LANGUAGE_CODES = [
-  'zh-CN',
-  'zh-TW',
-];

ui/i18n.js

@@ -1,3 +1,5 @@
+import { getDefaultLanguage, resolveLanguageAlias } from './util/default-languages';
+
 // @if TARGET='app'
 let fs = require('fs');
 // @endif
@@ -31,7 +33,7 @@ function saveMessageDesktop(message) {
     knownMessages[message] = removeContextMetadata(message);
     knownMessages[END] = END;
 
-    fs.writeFile(messagesFilePath, JSON.stringify(knownMessages, null, 2) + '\n', 'utf-8', err => {
+    fs.writeFile(messagesFilePath, JSON.stringify(knownMessages, null, 2) + '\n', 'utf-8', (err) => {
       if (err) {
         throw err;
       }
@@ -83,9 +85,10 @@ export function __(message, tokens) {
     return '';
   }
 
-  const language = localStorageAvailable
-    ? window.localStorage.getItem('language') || 'en'
-    : window.navigator.language.slice(0, 2) || 'en';
+  const language = resolveLanguageAlias(
+    localStorageAvailable ? window.localStorage.getItem('language') || 'en' : getDefaultLanguage() || 'en'
+  );
+
   if (!isProduction) {
     IS_WEB ? saveMessageWeb(message) : saveMessageDesktop(message);
   }
@@ -97,7 +100,7 @@ export function __(message, tokens) {
     return translatedMessage;
   }
 
-  return translatedMessage.replace(/%([^%]+)%/g, function($1, $2) {
+  return translatedMessage.replace(/%([^%]+)%/g, ($1, $2) => {
     return tokens.hasOwnProperty($2) ? tokens[$2] : $2;
   });
 }

ui/redux/selectors/settings.js

@@ -2,7 +2,7 @@ import { SETTINGS, DAEMON_SETTINGS } from 'lbry-redux';
 import { createSelector } from 'reselect';
 import homepages from 'homepages';
 import { SIMPLE_SITE } from 'config';
-import { getDefaultHomepageKey, getDefaultLanguage } from 'util/default-languages';
+import { resolveLanguageAlias, getDefaultHomepageKey, getDefaultLanguage } from 'util/default-languages';
 
 const selectState = (state) => state.settings || {};
 
@@ -62,7 +62,8 @@ export const selectHomepageCode = createSelector(makeSelectClientSetting(SETTING
 });
 
 export const selectLanguage = createSelector(makeSelectClientSetting(SETTINGS.LANGUAGE), (setting) => {
-  return setting || getDefaultLanguage();
+  const lang = resolveLanguageAlias(setting) || getDefaultLanguage();
+  return lang;
 });
 
 export const selectHomepageData = createSelector(

ui/util/default-languages.js

@@ -1,10 +1,49 @@
 import homepages from 'homepages';
-import SUPPORTED_BROWSER_LANGUAGES from 'constants/supported_browser_languages';
+import SUPPORTED_LANGUAGES from 'constants/supported_languages';
 const DEFAULT_LANG = 'en';
 
+/**
+ * Checks if the given language is an alias of a language that we support, and
+ * returns the version that the rest of the application (lbry-sdk, Transifex)
+ * expects. If the given language is not an expected alias, the original value
+ * is returned.
+ *
+ * @param lang
+ * @returns {*}
+ */
+export function resolveLanguageAlias(lang) {
+  const KNOWN_LANG_ALIASES = {
+    'zh-CN': 'zh-Hans',
+    'zh-TW': 'zh-Hant',
+  };
+  return KNOWN_LANG_ALIASES[lang] ? KNOWN_LANG_ALIASES[lang] : lang;
+}
+
+/**
+ * Returns the native language of the system, filtered/resolved
+ * to the language code format that the application expects.
+ *
+ * @returns {string|*}
+ */
 export const getDefaultLanguage = () => {
-  const browserLanguage = window.navigator.language;
-  return SUPPORTED_BROWSER_LANGUAGES[browserLanguage] || DEFAULT_LANG;
+  const browserLanguage = resolveLanguageAlias(window.navigator.language);
+
+  if (SUPPORTED_LANGUAGES[browserLanguage]) {
+    return browserLanguage;
+  } else {
+    if (browserLanguage.includes('-')) {
+      // Perhaps it is a sub-lang that we are currently not supporting.
+      // See if we support the main one.
+      const mainLang = browserLanguage.substring(0, browserLanguage.indexOf('-'));
+      if (SUPPORTED_LANGUAGES[mainLang]) {
+        return mainLang;
+      } else {
+        return DEFAULT_LANG;
+      }
+    } else {
+      return DEFAULT_LANG;
+    }
+  }
 };
 
 // If homepages has a key "zh-Hant" return that, otherwise return "zh", otherwise "en"