import { IANA_ISO3166 } from '@/lib/iso3166-iana';

/** ISO 3166-1 alpha-2 → regional indicator symbols (flag emoji). */
export function flagEmojiFromCode(code) {
    if (!code || typeof code !== 'string' || code.length !== 2) return '🏳️';
    const u = code.toUpperCase();
    if (u.length !== 2 || /[^A-Z]/.test(u)) return '🏳️';
    return String.fromCodePoint(...[...u].map((c) => 127397 + c.charCodeAt(0)));
}

let cached = null;

/**
 * Full country list: IANA iso3166.tab (every ISO alpha-2 region), display names
 * upgraded via {@link Intl.DisplayNames} when available.
 *
 * @returns {{ code: string, name: string }[]}
 */
export function getAllCountries() {
    if (cached) return cached;
    const dn =
        typeof Intl !== 'undefined' && typeof Intl.DisplayNames === 'function'
            ? new Intl.DisplayNames(['en'], { type: 'region' })
            : null;

    cached = IANA_ISO3166.map(({ code, name: ianaName }) => {
        let name = ianaName;
        try {
            if (dn) {
                const intl = dn.of(code);
                if (intl && intl !== code) name = intl;
            }
        } catch {
            /* keep IANA label */
        }
        return { code, name };
    }).sort((a, b) => a.name.localeCompare(b.name));

    return cached;
}

/**
 * Match stored deal.country (full name or code) to a row.
 * @param {string} stored
 * @param {{ code: string, name: string }[]} countries
 */
export function matchCountry(stored, countries) {
    if (!stored || typeof stored !== 'string') return null;
    const s = stored.trim();
    if (!s) return null;
    const lower = s.toLowerCase();

    const byName = countries.find((c) => c.name.toLowerCase() === lower);
    if (byName) return byName;

    const byCode = countries.find((c) => c.code.toLowerCase() === lower);
    if (byCode) return byCode;

    const iana = IANA_ISO3166.find((c) => c.name.toLowerCase() === lower);
    if (iana) {
        return countries.find((c) => c.code === iana.code) || iana;
    }

    const fuzzy = countries.find((c) => c.name.toLowerCase().includes(lower));
    if (fuzzy) return fuzzy;

    const ianaFuzzy = IANA_ISO3166.find((c) => c.name.toLowerCase().includes(lower));
    if (ianaFuzzy) {
        return countries.find((c) => c.code === ianaFuzzy.code) || ianaFuzzy;
    }

    return null;
}