Feature: Allow custom language pack for webapp

webapp/src/components/LocaleSwitcher.vue

@@ -1,31 +1,24 @@
 <template>
-    <select class="form-select" @change="updateLanguage()" v-model="$i18n.locale">
-        <option v-for="locale in $i18n.availableLocales" :key="`locale-${locale}`" :value="locale">
-            {{ getLocaleName(locale) }}
+    <select class="form-select" @change="setLocale(($event.target as HTMLSelectElement).value)" :value="$i18n.locale">
+        <option v-for="locale in allLocales" :key="`locale-${locale.code}`" :value="locale.code">
+            {{ locale.name }}
         </option>
     </select>
 </template>
 
 <script lang="ts">
 import { defineComponent } from 'vue';
-import { LOCALES } from '@/locales';
+import { allLocales, setLocale } from '@/i18n';
 
 export default defineComponent({
     name: 'LocaleSwitcher',
-    methods: {
-        updateLanguage() {
-            localStorage.setItem('locale', this.$i18n.locale);
-        },
-        getLocaleName(locale: string): string {
-            return LOCALES.find((i) => i.value === locale)?.caption || '';
-        },
+    data() {
+        return {
+            allLocales,
+        };
     },
-    mounted() {
-        if (localStorage.getItem('locale')) {
-            this.$i18n.locale = localStorage.getItem('locale') || 'en';
-        } else {
-            localStorage.setItem('locale', this.$i18n.locale);
-        }
+    methods: {
+        setLocale,
     },
 });
 </script>

webapp/src/i18n.ts

@@ -0,0 +1,145 @@
+import { createI18n } from 'vue-i18n';
+import messages from '@intlify/unplugin-vue-i18n/messages';
+import type { I18nOptions, IntlDateTimeFormat, IntlNumberFormat } from 'vue-i18n';
+
+export const allLocales = [
+    { code: 'en', name: 'English' },
+    { code: 'de', name: 'Deutsch' },
+    { code: 'fr', name: 'Français' },
+];
+
+const dateTimeFormatsTemplate: IntlDateTimeFormat = {
+    datetime: {
+        hour: 'numeric',
+        minute: 'numeric',
+        second: 'numeric',
+        year: 'numeric',
+        month: 'numeric',
+        day: 'numeric',
+        hour12: false,
+    },
+};
+
+const numberFormatTemplate: IntlNumberFormat = {
+    decimal: {
+        style: 'decimal',
+    },
+    decimalNoDigits: {
+        style: 'decimal',
+        minimumFractionDigits: 0,
+        maximumFractionDigits: 0,
+    },
+    decimalOneDigit: {
+        style: 'decimal',
+        minimumFractionDigits: 1,
+        maximumFractionDigits: 1,
+    },
+    decimalTwoDigits: {
+        style: 'decimal',
+        minimumFractionDigits: 2,
+        maximumFractionDigits: 2,
+    },
+    percent: {
+        style: 'percent',
+    },
+    percentOneDigit: {
+        style: 'percent',
+        minimumFractionDigits: 1,
+        maximumFractionDigits: 1,
+    },
+    byte: {
+        style: 'unit',
+        unit: 'byte',
+    },
+    kilobyte: {
+        style: 'unit',
+        unit: 'kilobyte',
+    },
+    megabyte: {
+        style: 'unit',
+        unit: 'megabyte',
+    },
+    celsius: {
+        style: 'unit',
+        unit: 'celsius',
+        maximumFractionDigits: 1,
+    },
+};
+
+export const dateTimeFormats: I18nOptions['datetimeFormats'] = {};
+export const numberFormats: I18nOptions['numberFormats'] = {};
+
+allLocales.forEach((locale) => {
+    dateTimeFormats[locale.code] = dateTimeFormatsTemplate;
+    numberFormats[locale.code] = numberFormatTemplate;
+});
+
+export const i18n = createI18n({
+    legacy: false,
+    globalInjection: true,
+    locale: navigator.language.split('-')[0],
+    fallbackLocale: allLocales[0].code,
+    messages,
+    datetimeFormats: dateTimeFormats,
+    numberFormats: numberFormats,
+});
+
+const dynamicLocales = await loadAvailLocales();
+allLocales.push(...dynamicLocales);
+
+if (localStorage.getItem('locale')) {
+    setLocale(localStorage.getItem('locale') || 'en');
+} else {
+    localStorage.setItem('locale', i18n.global.locale.value);
+}
+
+// Set new locale.
+export async function setLocale(locale: string) {
+    // Load locale if not available yet.
+    if (!i18n.global.availableLocales.includes(locale)) {
+        const messages = await loadLocale(locale);
+
+        // fetch() error occurred.
+        if (messages === undefined) {
+            i18n.global.locale.value = allLocales[0].code;
+            return;
+        }
+
+        // Add locale.
+        i18n.global.setLocaleMessage(locale, messages.webapp);
+        i18n.global.setNumberFormat(locale, numberFormatTemplate);
+        i18n.global.setDateTimeFormat(locale, dateTimeFormatsTemplate);
+    }
+
+    // Set locale.
+    i18n.global.locale.value = locale;
+    localStorage.setItem('locale', i18n.global.locale.value);
+}
+
+// Fetch locale.
+async function loadLocale(locale: string) {
+    return fetch(`/api/i18n/language?code=${locale}`)
+        .then((response) => {
+            if (response.ok) {
+                return response.json();
+            }
+            throw new Error('Something went wrong!');
+        })
+        .catch((error) => {
+            console.error(error);
+        });
+}
+
+// Fetch available locales
+async function loadAvailLocales() {
+    return fetch('/api/i18n/languages')
+        .then((response) => {
+            if (response.ok) {
+                return response.json();
+            }
+            throw new Error('Something went wrong!');
+        })
+        .catch((error) => {
+            console.error(error);
+        });
+}

webapp/src/main.ts

@@ -1,11 +1,9 @@
-import messages from '@intlify/unplugin-vue-i18n/messages';
 import mitt from 'mitt';
 import { createApp } from 'vue';
-import { createI18n } from 'vue-i18n';
 import App from './App.vue';
-import { dateTimeFormats, defaultLocale, numberFormats } from './locales';
 import { tooltip } from './plugins/bootstrap';
 import router from './router';
+import { i18n } from './i18n';
 
 import 'bootstrap';
 import './scss/styles.scss';
@@ -17,16 +15,6 @@ app.config.globalProperties.$emitter = emitter;
 
 app.directive('tooltip', tooltip);
 
-const i18n = createI18n({
-    legacy: false,
-    globalInjection: true,
-    locale: navigator.language.split('-')[0],
-    fallbackLocale: defaultLocale,
-    messages,
-    datetimeFormats: dateTimeFormats,
-    numberFormats: numberFormats,
-});
-
 app.use(router);
 app.use(i18n);
 

webapp/vite.config.ts

@@ -27,6 +27,7 @@ export default defineConfig({
     VueI18nPlugin({
         /* options */
         include: path.resolve(path.dirname(fileURLToPath(import.meta.url)), './src/locales/**.json'),
+        runtimeOnly: false,
         fullInstall: false,
         forceStringify: true,
         strictMessage: false,
@@ -55,6 +56,7 @@ export default defineConfig({
         assetFileNames: "assets/[name].[ext]",
       },
     },
+    target: 'es2022',
   },
   esbuild: {
     drop: ['console', 'debugger'],