const { numericPriority, sortEpgSources } = require('./epgSourceOrdering');

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

function candidateScore(channel, epgChannel) {
    const variantIds = new Set((channel.variants || []).flatMap(variant => [variant.tvgId, variant.epg_channel_id]).filter(Boolean).map(String));
    if (variantIds.has(String(epgChannel.id))) return 100;
    const wantedNames = new Set([channel.standardName, channel.displayName, ...(channel.variants || []).map(variant => variant.name)].map(normalize).filter(Boolean));
    const candidateName = normalize(epgChannel.name);
    if (wantedNames.has(candidateName)) return 90;
    if (candidateName && [...wantedNames].some(name => name.includes(candidateName) || candidateName.includes(name))) return 50;
    return 0;
}

function chooseBestMatch(channel, candidates, epgSources) {
    const language = channel.language?.code;
    const eligible = sortEpgSources(epgSources, { enabledOnly: true }).filter(source =>
        !source.language || !language || language === 'und' || source.language === language
    );
    const priorities = new Map(eligible.map(source => [source.id, numericPriority(source)]));
    return candidates
        .filter(candidate => priorities.has(candidate.sourceId))
        .map(candidate => ({ ...candidate, matchConfidence: candidateScore(channel, candidate) }))
        .filter(candidate => candidate.matchConfidence > 0)
        .sort((left, right) => right.matchConfidence - left.matchConfidence ||
            priorities.get(left.sourceId) - priorities.get(right.sourceId) || left.sourceId - right.sourceId)[0] || null;
}

function findBestMatch(database, channel, epgSources, now = Date.now()) {
    const language = channel.language?.code;
    const enabled = sortEpgSources(epgSources, { enabledOnly: true }).filter(source =>
        !source.language || !language || language === 'und' || source.language === language
    );
    if (!enabled.length) return null;
    const ids = enabled.map(source => source.id);
    const placeholders = ids.map(() => '?').join(',');
    const epgChannels = database.prepare(`
        SELECT source_id AS sourceId, item_id AS id, name
        FROM playlist_items
        WHERE type = 'epg_channel' AND source_id IN (${placeholders})
    `).all(...ids);
    const best = chooseBestMatch(channel, epgChannels, enabled);
    if (!best) return null;
    const current = database.prepare(`
        SELECT title, description, start_time AS startTime, end_time AS endTime
        FROM epg_programs
        WHERE source_id = ? AND channel_id = ? AND start_time <= ? AND end_time > ?
        ORDER BY start_time DESC LIMIT 1
    `).get(best.sourceId, best.id, now, now);
    return {
        sourceId: best.sourceId,
        channelId: best.id,
        matchConfidence: best.matchConfidence,
        currentProgram: current || undefined
    };
}

function rebuildPersistedEpgMatches(database, epgSources, now = Date.now()) {
    const rows = database.prepare(`
        SELECT p.*, l.display_name, c.name AS category_name
        FROM playlist_items p
        JOIN logical_channels l ON l.id = p.logical_channel_id
        LEFT JOIN categories c ON c.source_id = p.source_id AND c.type = 'live' AND c.category_id = p.category_id
        WHERE p.type = 'live' AND p.logical_channel_id IS NOT NULL
        ORDER BY p.logical_channel_id, p.language_code, p.variant_rank
    `).all();
    const groups = new Map();
    for (const row of rows) {
        const languageCode = row.language_code || 'und';
        const key = `${row.logical_channel_id}\0${languageCode}`;
        if (!groups.has(key)) groups.set(key, {
            logicalChannelId: row.logical_channel_id,
            displayName: row.display_name,
            standardName: row.display_name,
            language: { code: languageCode },
            variants: []
        });
        let data = {};
        try { data = row.data ? JSON.parse(row.data) : {}; } catch {}
        groups.get(key).variants.push({
            name: row.name,
            tvgId: data.tvgId || data.tvg_id || null,
            epg_channel_id: data.epg_channel_id || null
        });
    }
    const replace = database.prepare(`
        INSERT INTO live_epg_matches
            (logical_channel_id, language_code, source_id, channel_id, match_confidence, data, updated_at)
        VALUES (?, ?, ?, ?, ?, ?, ?)
        ON CONFLICT(logical_channel_id, language_code) DO UPDATE SET
            source_id = excluded.source_id, channel_id = excluded.channel_id,
            match_confidence = excluded.match_confidence, data = excluded.data,
            updated_at = excluded.updated_at
    `);
    const persist = database.transaction(() => {
        database.prepare('DELETE FROM live_epg_matches').run();
        for (const channel of groups.values()) {
            const match = findBestMatch(database, channel, epgSources, now);
            replace.run(channel.logicalChannelId, channel.language.code,
                match?.sourceId ?? null, match?.channelId ?? null,
                match?.matchConfidence ?? 0, match ? JSON.stringify(match) : null, now);
        }
    });
    persist();
    return { matched: [...groups.values()].length };
}

module.exports = { candidateScore, chooseBestMatch, findBestMatch, normalize, rebuildPersistedEpgMatches };