Adding a "System Language" option to the "Locale Preference" (#1241)

Closes: #1205

* Added "Follow System" option to
`Settings -> General Settings -> Locale Preference`
and set it to default

* Changed double quotes to single quotes

* Removed unnecessary comment

* Changed `app` accessing method

* Cleaned up if/else statements

* Checks similar locales as fallback

* Changed label to "System Language"

* Changed locale filtering logic to use the filter() method

src/renderer/components/general-settings/general-settings.js

@@ -103,6 +103,10 @@ export default Vue.extend({
       const names = []
 
       Object.keys(this.$i18n.messages).forEach((locale) => {
+        if (locale === 'system') {
+          names.push('System Language')
+          return
+        }
         const localeName = this.$i18n.messages[locale]['Locale Name']
         if (typeof localeName !== 'undefined') {
           names.push(localeName)

src/renderer/main.js

@@ -27,26 +27,36 @@ Vue.component('FontAwesomeIcon', FontAwesomeIcon)
 Vue.use(VueI18n)
 
 // List of locales approved for use
-const activeLocales = ['en-US', 'en_GB', 'ar', 'bg', 'cs', 'da', 'de-DE', 'el', 'es', 'es-MX', 'fi', 'fr-FR', 'gl', 'he', 'hu', 'hr', 'id', 'is', 'it', 'ja', 'nb_NO', 'nl', 'nn', 'pl', 'pt', 'pt-BR', 'pt-PT', 'ru', 'sk', 'sl', 'sv', 'tr', 'uk', 'vi', 'zh-CN', 'zh-TW']
+const activeLocales = ['system', 'en-US', 'en_GB', 'ar', 'bg', 'cs', 'da', 'de-DE', 'el', 'es', 'es-MX', 'fi', 'fr-FR', 'gl', 'he', 'hu', 'hr', 'id', 'is', 'it', 'ja', 'nb_NO', 'nl', 'nn', 'pl', 'pt', 'pt-BR', 'pt-PT', 'ru', 'sk', 'sl', 'sv', 'tr', 'uk', 'vi', 'zh-CN', 'zh-TW']
 const messages = {}
 /* eslint-disable-next-line */
 const fileLocation = isDev ? 'static/locales/' : `${__dirname}/static/locales/`
 
 // Take active locales and load respective YAML file
 activeLocales.forEach((locale) => {
+  // Import elctrons app object to access getLocale function
+  const { app } = require('@electron/remote')
   try {
     // File location when running in dev
+    if (locale === 'system') {
+      const systemsLocale = activeLocales.filter((currentValue) => { return currentValue.startsWith(app.getLocale()) })
+      if (systemsLocale.length) {
+        const doc = yaml.load(fs.readFileSync(`${fileLocation}${systemsLocale[0]}.yaml`))
+        messages[locale] = doc
+      }
+    } else {
       const doc = yaml.load(fs.readFileSync(`${fileLocation}${locale}.yaml`))
       messages[locale] = doc
+    }
   } catch (e) {
     console.log(e)
   }
 })
 
 const i18n = new VueI18n({
-  locale: 'en-US', // set locale
+  locale: 'system', // set locale standard is to follow the systems locale
   fallbackLocale: {
-    default: 'en-US'
+    default: 'en-US' // for the case systems locale has no corresponding .yaml file en-US gets set
   },
   messages // set locale messages
 })