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
    };
}

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