perfect-postcode/frontend/src/i18n/index.ts
2026-05-14 22:07:14 +01:00

146 lines
4.3 KiB
TypeScript

import i18n from 'i18next';
import { initReactI18next } from 'react-i18next';
import en from './locales/en';
export const SUPPORTED_LANGUAGES = [
{ code: 'en', label: 'English', flag: '\uD83C\uDDEC\uD83C\uDDE7' },
{ code: 'fr', label: 'Fran\u00E7ais', flag: '\uD83C\uDDEB\uD83C\uDDF7' },
{ code: 'de', label: 'Deutsch', flag: '\uD83C\uDDE9\uD83C\uDDEA' },
{ code: 'zh', label: '\u4E2D\u6587', flag: '\uD83C\uDDE8\uD83C\uDDF3' },
{ code: 'hi', label: '\u0939\u093F\u0928\u094D\u0926\u0940', flag: '\uD83C\uDDEE\uD83C\uDDF3' },
{ code: 'hu', label: 'Magyar', flag: '\uD83C\uDDED\uD83C\uDDFA' },
] as const;
export type LanguageCode = (typeof SUPPORTED_LANGUAGES)[number]['code'];
const supportedCodes: Set<string> = new Set(SUPPORTED_LANGUAGES.map((l) => l.code));
function toSupportedLanguage(value: string): LanguageCode | null {
const lower = value.toLowerCase();
if (supportedCodes.has(lower)) return lower as LanguageCode;
const prefix = lower.split('-')[0];
if (supportedCodes.has(prefix)) return prefix as LanguageCode;
return null;
}
function getStoredLanguage(): LanguageCode | null {
try {
const stored = localStorage.getItem('language');
return stored ? toSupportedLanguage(stored) : null;
} catch {
return null;
}
}
function getUrlLanguage(): LanguageCode | null {
try {
if (typeof window === 'undefined') return null;
const value = new URLSearchParams(window.location.search).get('lang');
return value ? toSupportedLanguage(value) : null;
} catch {
return null;
}
}
function getBrowserLanguages(): readonly string[] {
if (typeof navigator === 'undefined') return [];
return navigator.languages?.length ? navigator.languages : [navigator.language];
}
function detectLanguage(): LanguageCode {
// 1. Explicit URL language, used by generated screenshot/OG image URLs.
const urlLanguage = getUrlLanguage();
if (urlLanguage) return urlLanguage;
// 2. Explicit user choice (persisted from the language dropdown)
const stored = getStoredLanguage();
if (stored) return stored;
// 3. Browser preference (navigator.languages falls back to navigator.language)
for (const tag of getBrowserLanguages()) {
const language = toSupportedLanguage(tag);
if (language) return language;
}
return 'en';
}
export const INITIAL_LANGUAGE = detectLanguage();
type TranslationResource = Record<string, unknown>;
const localeLoaders: Record<
Exclude<LanguageCode, 'en'>,
() => Promise<{ default: TranslationResource }>
> = {
fr: () => import('./locales/fr'),
de: () => import('./locales/de'),
hu: () => import('./locales/hu'),
zh: () => import('./locales/zh'),
hi: () => import('./locales/hi'),
};
async function getLanguageResource(
code: Exclude<LanguageCode, 'en'>
): Promise<TranslationResource> {
const module = await localeLoaders[code]();
return module.default;
}
function setDocumentLanguage(code: LanguageCode) {
if (typeof document !== 'undefined') {
document.documentElement.lang = code;
}
}
export async function loadLanguage(code: LanguageCode): Promise<void> {
if (code === 'en' || i18n.hasResourceBundle(code, 'translation')) return;
const resource = await getLanguageResource(code);
i18n.addResourceBundle(code, 'translation', resource, true, true);
}
export async function changeLanguage(code: LanguageCode): Promise<void> {
await loadLanguage(code);
await i18n.changeLanguage(code);
setDocumentLanguage(code);
}
export const i18nReady = (async () => {
const resources: Record<string, { translation: TranslationResource }> = {
en: { translation: en },
};
let language = INITIAL_LANGUAGE;
if (language !== 'en') {
try {
resources[language] = { translation: await getLanguageResource(language) };
} catch (error) {
console.error(`Failed to load ${language} translations`, error);
language = 'en';
}
}
await i18n.use(initReactI18next).init({
resources,
lng: language,
fallbackLng: 'en',
interpolation: {
escapeValue: false, // React already escapes
},
});
setDocumentLanguage(language);
})();
/**
* Translate a key that is computed at runtime (not a literal).
* Bypasses the strict type checking on t() for dynamic key construction.
*/
export function tDynamic(key: string): string {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
return (i18n.t as any)(key);
}
export default i18n;