feat: init i18n features

src/components/helper/i18n/LanguagePicker.astro

@@ -0,0 +1,14 @@
+---
+import { languages } from '../../../i18n/ui';
+import { getLangFromUrl, useTranslatedPath } from '../../../i18n/utils';
+
+const lang = getLangFromUrl(Astro.url);
+const translatePath = useTranslatedPath(lang);
+---
+<ul>
+    {Object.entries(languages).map(([lang, label]) => (
+            <li>
+                <a href={translatePath('/', lang)}>{label}</a>
+            </li>
+    ))}
+</ul>

src/i18n/ui.ts

@@ -0,0 +1,19 @@
+export const languages = {
+    en: 'English',
+    zh_hans: '中文（简体）',
+};
+
+export const defaultLang = 'en';
+export const showDefaultLang = false;
+
+export const ui = {
+    en: {
+        'nav.home': 'Home',
+        'nav.about': 'About',
+        'nav.twitter': 'Twitter',
+    },
+    zh_hans: {
+        'nav.home': '首页',
+        'nav.about': '关于',
+    },
+} as const;

src/i18n/utils.ts

@@ -0,0 +1,19 @@
+import {ui, defaultLang, showDefaultLang} from './ui';
+
+export function getLangFromUrl(url: URL) {
+    const [, lang] = url.pathname.split('/');
+    if (lang in ui) return lang as keyof typeof ui;
+    return defaultLang;
+}
+
+export function useTranslations(lang: keyof typeof ui) {
+    return function t(key: keyof typeof ui[typeof defaultLang]) {
+        return ui[lang][key] || ui[defaultLang][key];
+    }
+}
+
+export function useTranslatedPath(lang: keyof typeof ui) {
+    return function translatePath(path: string, l: string = lang) {
+        return !showDefaultLang && l === defaultLang ? path : `/${l}${path}`
+    }
+}