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

const loaded = new Set<Language>();

/**
 * Lazy-load the CJK display font for the active locale.
 *
 * The Thai (Kanit), Japanese (Noto Sans JP) and Korean (Noto Sans KR) 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 non-CJK users never fetch them.
 * Text briefly falls back to a system font until the stylesheet resolves.
 */
export function loadCjkFont(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(() => {});
  }
}