88 lines
3.2 KiB
TypeScript
88 lines
3.2 KiB
TypeScript
 
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// Pure language-code helpers for the on-device translation feature. No DOM / no
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// engine — unit-testable in isolation (langUtils.test.ts).
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/**
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* Normalize a BCP-47 tag to the base language subtag, lowercased:
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* "en-US" -> "en", "ZH" -> "zh", "pt-BR" -> "pt".
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* Chinese is a common exception where script matters (zh-Hant vs zh-Hans); we
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* keep the script subtag for `zh` so a Traditional/Simplified distinction isn't
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* flattened. Everything else collapses to the primary subtag.
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*/
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export function normalizeLang(code: string | undefined | null): string {
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if (!code) return '';
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const lower = code.trim().toLowerCase();
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if (!lower) return '';
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const parts = lower.split(/[-_]/);
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const base = parts[0];
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if (base === 'zh' && (parts[1] === 'hant' || parts[1] === 'hans')) {
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return `zh-${parts[1]}`;
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}
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return base;
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}
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/** True when two language tags refer to the same base language. */
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export function sameLanguage(a: string | undefined | null, b: string | undefined | null): boolean {
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const na = normalizeLang(a);
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const nb = normalizeLang(b);
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return na !== '' && na === nb;
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}
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/**
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* Curated list of target languages offered in the "Translate messages into"
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* setting — the common languages the on-device engine can produce. Codes are the
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* normalized base tags passed to the engine.
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*/
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export const TRANSLATE_TARGET_LANGUAGES: ReadonlyArray<{ code: string; name: string }> = [
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{ code: 'en', name: 'English' },
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{ code: 'es', name: 'Spanish' },
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{ code: 'fr', name: 'French' },
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{ code: 'de', name: 'German' },
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{ code: 'it', name: 'Italian' },
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{ code: 'pt', name: 'Portuguese' },
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{ code: 'nl', name: 'Dutch' },
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{ code: 'pl', name: 'Polish' },
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{ code: 'ru', name: 'Russian' },
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{ code: 'uk', name: 'Ukrainian' },
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{ code: 'tr', name: 'Turkish' },
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{ code: 'ar', name: 'Arabic' },
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{ code: 'he', name: 'Hebrew' },
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{ code: 'hi', name: 'Hindi' },
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{ code: 'bn', name: 'Bengali' },
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{ code: 'ja', name: 'Japanese' },
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{ code: 'ko', name: 'Korean' },
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{ code: 'zh', name: 'Chinese' },
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{ code: 'vi', name: 'Vietnamese' },
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{ code: 'th', name: 'Thai' },
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{ code: 'id', name: 'Indonesian' },
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{ code: 'sv', name: 'Swedish' },
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{ code: 'cs', name: 'Czech' },
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{ code: 'ro', name: 'Romanian' },
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{ code: 'el', name: 'Greek' },
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{ code: 'fa', name: 'Persian' },
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];
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const CURATED_NAME = new Map(TRANSLATE_TARGET_LANGUAGES.map((l) => [l.code, l.name]));
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/**
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* Human-readable language name for a code, e.g. "de" -> "German". Prefers
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* `Intl.DisplayNames` (localized) and falls back to the curated map, then the
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* raw code. `uiLocale` picks the display locale for the name.
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*/
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export function languageName(code: string, uiLocale = 'en'): string {
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const norm = normalizeLang(code);
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if (!norm) return code;
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try {
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const dn = new Intl.DisplayNames([uiLocale], { type: 'language' });
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const name = dn.of(norm);
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if (name && name.toLowerCase() !== norm) return name;
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} catch {
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/* Intl.DisplayNames unsupported or bad code — fall through */
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}
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return CURATED_NAME.get(norm) ?? norm;
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}
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/** Is `code` in the curated target-language list? (validates a persisted setting) */
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export function isSupportedTargetLang(code: string): boolean {
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return CURATED_NAME.has(normalizeLang(code));
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}
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