import type { Language } from '@/contexts/language';

const loaded = new Set<Language>();

/**
 * Lazy-load the script-specific display font for the active locale (CJK +
 * Devanagari).
 *
 * The Thai (Kanit), Japanese (Noto Sans JP), Korean (Noto Sans KR) and Hindi
 * (Noto Sans Devanagari) font families are large and only needed for users on
 * those locales — but they were imported statically in main.tsx, so every
 * visitor downloaded them. They are now loaded on demand, once per locale, and
 * other users never fetch them. Text briefly falls back to a system font until
 * the stylesheet resolves.
 */
export function loadLocaleFont(language: Language): void {
  if (loaded.has(language)) return;
  loaded.add(language);

  if (language === 'ja') {
    void Promise.all([
      import('@fontsource/noto-sans-jp/400.css'),
      import('@fontsource/noto-sans-jp/500.css'),
      import('@fontsource/noto-sans-jp/700.css'),
    ]).catch(() => {});
  } else if (language === 'ko') {
    void Promise.all([
      import('@fontsource/noto-sans-kr/400.css'),
      import('@fontsource/noto-sans-kr/500.css'),
      import('@fontsource/noto-sans-kr/700.css'),
    ]).catch(() => {});
  } else if (language === 'th') {
    void Promise.all([
      import('@fontsource/kanit/400.css'),
      import('@fontsource/kanit/500.css'),
      import('@fontsource/kanit/600.css'),
      import('@fontsource/kanit/700.css'),
    ]).catch(() => {});
  } else if (language === 'hi') {
    void Promise.all([
      import('@fontsource/noto-sans-devanagari/400.css'),
      import('@fontsource/noto-sans-devanagari/500.css'),
      import('@fontsource/noto-sans-devanagari/700.css'),
    ]).catch(() => {});
  }
}