// Interface language: fr, en, es (Yvv, 2026-10-21). French is the source.
import { en } from './en';
import { es } from './es';
import { fr, type Key, type Messages } from './fr';
import type { Lang } from '../types';

export const LANGS: Lang[] = ['fr', 'en', 'es'];
const CATALOGS: Record<Lang, Messages> = { fr, en, es };
const LOCALES: Record<Lang, string> = { fr: 'fr-FR', en: 'en-GB', es: 'es-ES' };

function initial(): Lang {
  try {
    const saved = localStorage.getItem('ld:lang');
    if (saved === 'fr' || saved === 'en' || saved === 'es') return saved;
  } catch {
    /* no storage */
  }
  const nav = (typeof navigator !== 'undefined' ? navigator.language : 'fr').slice(0, 2);
  return nav === 'en' || nav === 'es' ? nav : 'fr';
}

class I18n {
  lang = $state<Lang>('fr');

  init() {
    this.set(initial());
  }

  set(lang: Lang) {
    this.lang = lang;
    document.documentElement.lang = lang;
    try {
      localStorage.setItem('ld:lang', lang);
    } catch {
      /* no storage */
    }
  }

  t = (key: Key, params: Record<string, string | number> = {}): string => {
    const raw = CATALOGS[this.lang][key] ?? fr[key] ?? key;
    return raw.replace(/\{(\w+)\}/g, (_, k: string) => (k in params ? String(params[k]) : `{${k}}`));
  };

  /** `<key>.one` / `<key>.other` — French says « 0 session », English and Spanish « 0 sessions ». */
  plural = (key: string, n: number, params: Record<string, string | number> = {}): string => {
    const one = this.lang === 'fr' ? n <= 1 : n === 1;
    return this.t(`${key}.${one ? 'one' : 'other'}` as Key, { n, ...params });
  };

  date = (iso: string | null | undefined): string => {
    if (!iso) return '';
    return new Date(iso).toLocaleDateString(LOCALES[this.lang], { day: 'numeric', month: 'long', year: 'numeric' });
  };

  number = (n: number): string => n.toLocaleString(LOCALES[this.lang]);
}

export const i18n = new I18n();
export const t = i18n.t;
export type { Key };