Add translations support (#116)

docs/.vitepress/theme/index.js

@@ -1,14 +1,50 @@
-import DefaultTheme from 'vitepress/theme'
+import { localeDefinitions } from '@modrinth/omorphia-dev/locales/index.js'
+import { createPlugin } from '@vintl/vintl/plugin'
 import Omorphia from 'omorphia'
+import DefaultTheme from 'vitepress/theme'
+import { createVNode } from 'vue'
 import DemoContainer from './DemoContainer.vue'
+import LanguageSwitcher from './LanguageSwitcher.vue'
 
 import './compat.scss'
 import './style.scss'
 
+/** @type {import('vitepress').Theme} */
 export default {
   ...DefaultTheme,
   enhanceApp(ctx) {
     ctx.app.use(Omorphia)
     ctx.app.component('DemoContainer', DemoContainer)
+    ctx.app.use(
+      createPlugin({
+        controllerOpts: {
+          locales: Object.keys(localeDefinitions).map((tag) => ({ tag })),
+          listen: {
+            async localeload(event) {
+              const locale = event.locale.tag
+              if (!Object.hasOwn(localeDefinitions, locale)) {
+                throw new Error(`Unknown locale: ${locale}`)
+              }
+
+              try {
+                const { messages } = await localeDefinitions[locale].importFunction()
+                event.addMessages(messages)
+              } catch (err) {
+                console.error(`Failed to load locale: ${locale}`, err)
+              }
+            },
+          },
+          defaultMessageOrder: ['locale', 'descriptor'],
+        },
+        globalMixin: false,
+      })
+    )
+  },
+  Layout() {
+    return createVNode(DefaultTheme.Layout, null, {
+      'sidebar-nav-before'() {
+        return createVNode(LanguageSwitcher)
+      },
+    })
   },
 }