const API_ROOT = 'https://iptv-org.github.io/api';

function normalize(value) {
    return String(value || '').normalize('NFKD').replace(/[\u0300-\u036f]/g, '')
        .toLowerCase().replace(/[^a-z0-9]+/g, ' ').trim();
}

function parseJson(value, fallback = []) {
    try { return JSON.parse(value); } catch { return fallback; }
}

async function refresh(database, fetchImpl = globalThis.fetch) {
    if (typeof fetchImpl !== 'function') throw new Error('A fetch implementation is required');
    const [channelsResponse, feedsResponse] = await Promise.all([
        fetchImpl(`${API_ROOT}/channels.json`), fetchImpl(`${API_ROOT}/feeds.json`)
    ]);
    if (!channelsResponse.ok || !feedsResponse.ok) throw new Error('iptv-org API refresh failed');
    const channels = await channelsResponse.json();
    const feeds = await feedsResponse.json();
    const feedLanguages = new Map();
    for (const feed of feeds) {
        const list = feedLanguages.get(feed.channel) || new Set();
        for (const language of feed.languages || []) list.add(String(language).toLowerCase());
        feedLanguages.set(feed.channel, list);
    }
    const write = database.transaction(() => {
        database.prepare('DELETE FROM iptv_org_channels').run();
        const insert = database.prepare(`
            INSERT INTO iptv_org_channels
                (id, name, normalized_name, alt_names, country, languages, data, updated_at)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?)
        `);
        const now = Date.now();
        for (const channel of channels) {
            insert.run(channel.id, channel.name, normalize(channel.name), JSON.stringify(channel.alt_names || []),
                channel.country || null, JSON.stringify([...feedLanguages.get(channel.id) || []]), JSON.stringify(channel), now);
        }
        database.prepare(`
            INSERT INTO iptv_org_cache_state (resource, refreshed_at, item_count) VALUES ('catalog', ?, ?)
            ON CONFLICT(resource) DO UPDATE SET refreshed_at = excluded.refreshed_at, item_count = excluded.item_count
        `).run(now, channels.length);
    });
    write();
    return { refreshedAt: Date.now(), itemCount: channels.length };
}

function findMatch(database, channel) {
    const names = new Set([channel.displayName, channel.fingerprint, ...(channel.variants || []).map(variant => variant.name)].map(normalize).filter(Boolean));
    if (!names.size) return null;
    const direct = database.prepare(`SELECT * FROM iptv_org_channels WHERE normalized_name IN (${[...names].map(() => '?').join(',')})`).all(...names);
    const candidates = direct.length ? direct : database.prepare('SELECT * FROM iptv_org_channels').all().filter(row =>
        parseJson(row.alt_names).some(name => names.has(normalize(name)))
    );
    const language = channel.language?.code;
    const compatible = candidates.find(row => language === 'und' || parseJson(row.languages).includes(language)) || candidates[0];
    if (!compatible) return null;
    return {
        channelId: compatible.id,
        name: compatible.name,
        country: compatible.country,
        confidence: names.has(compatible.normalized_name) ? 100 : 90
    };
}

module.exports = { API_ROOT, findMatch, normalize, refresh };