Add support for multiple interface languages

1 files changed, 22 insertions, 4 deletions

diff --git a/src/i18n/messages.js b/src/i18n/messages.js
index 74a89ca8..849d98fd 100644
--- a/src/i18n/messages.js
+++ b/src/i18n/messages.js
@@ -7,8 +7,11 @@
 // sed -i -e "s/'//gm" -e 's/"/\\"/gm' -re 's/^( +)(.+?): ((.+?))?(,?)(\{?)$/\1"\2": "\4"/gm' -e 's/\"\{\"/{/g' -e 's/,"$/",/g' file.json
 // There's only problem that apostrophe character ' gets replaced by \\ so you have to fix it manually, sorry.
 
+import { isEqual } from 'lodash'
 import { languages, langCodeToJsonName } from './languages.js'
 
+const ULTIMATE_FALLBACK_LOCALE = 'en'
+
 const hasLanguageFile = (code) => languages.includes(code)
 
 const loadLanguageFile = (code) => {
@@ -25,11 +28,26 @@ const messages = {
     en: require('./en.json').default
   },
   setLanguage: async (i18n, language) => {
-    if (hasLanguageFile(language)) {
-      const messages = await loadLanguageFile(language)
-      i18n.setLocaleMessage(language, messages.default)
+    const languages = (Array.isArray(language) ? language : [language]).filter(k => k)
+
+    if (!languages.includes(ULTIMATE_FALLBACK_LOCALE)) {
+      languages.push(ULTIMATE_FALLBACK_LOCALE)
+    }
+    const [first, ...rest] = languages
+
+    if (first === i18n.locale && isEqual(rest, i18n.fallbackLocale)) {
+      return
     }
-    i18n.locale = language
+
+    for (const lang of languages) {
+      if (hasLanguageFile(lang)) {
+        const messages = await loadLanguageFile(lang)
+        i18n.setLocaleMessage(lang, messages.default)
+      }
+    }
+
+    i18n.fallbackLocale = rest
+    i18n.locale = first
   }
 }