/**
 * Helper function to get track artists string
 */
function getTrackArtists(track) {
    if (track.artists && track.artists.length > 0) {
        return track.artists.map((artist) => artist.name).join(', ');
    }
    return track.artist?.name || 'Unknown Artist';
}

/**
 * Generates CSV playlist export
 * @param {Object} playlist - Playlist metadata
 * @param {Array} tracks - Array of track objects
 * @returns {string} CSV content
 */
export function generateCSV(playlist, tracks) {
    const headers = ['Track Name', 'Artist Name(s)', 'Album', 'Duration'];
    let content = headers.map((h) => `"${h}"`).join(',') + '\n';

    tracks.forEach((track) => {
        const title = (track.title || '').replace(/"/g, '""');
        const artist = getTrackArtists(track).replace(/"/g, '""');
        const album = (track.album?.title || '').replace(/"/g, '""');
        const duration = formatDuration(track.duration || 0);

        content += `"${title}","${artist}","${album}","${duration}"\n`;
    });

    return content;
}

/**
 * Generates XSPF (XML Shareable Playlist Format) export
 * @param {Object} playlist - Playlist metadata
 * @param {Array} tracks - Array of track objects
 * @returns {string} XSPF XML content
 */
export function generateXSPF(playlist, tracks) {
    const date = new Date().toISOString();

    let xml = '<?xml version="1.0" encoding="UTF-8"?>\n';
    xml += '<playlist xmlns="http://xspf.org/ns/0/" version="1">\n';
    xml += `  <title>${escapeXml(playlist.title || 'Unknown Playlist')}</title>\n`;
    xml += `  <creator>${escapeXml(playlist.artist || 'Various Artists')}</creator>\n`;
    xml += `  <date>${date}</date>\n`;
    xml += '  <trackList>\n';

    tracks.forEach((track) => {
        xml += '    <track>\n';
        xml += `      <title>${escapeXml(track.title || 'Unknown Title')}</title>\n`;
        xml += `      <creator>${escapeXml(getTrackArtists(track))}</creator>\n`;
        if (track.album?.title) {
            xml += `      <album>${escapeXml(track.album.title)}</album>\n`;
        }
        if (track.duration) {
            xml += `      <duration>${Math.round(track.duration * 1000)}</duration>\n`;
        }
        xml += '    </track>\n';
    });

    xml += '  </trackList>\n';
    xml += '</playlist>\n';

    return xml;
}

/**
 * Generates generic XML playlist export
 * @param {Object} playlist - Playlist metadata
 * @param {Array} tracks - Array of track objects
 * @returns {string} XML content
 */
export function generateXML(playlist, tracks) {
    const date = new Date().toISOString();

    let xml = '<?xml version="1.0" encoding="UTF-8"?>\n';
    xml += '<playlist>\n';
    xml += `  <name>${escapeXml(playlist.title || 'Unknown Playlist')}</name>\n`;
    xml += `  <creator>${escapeXml(playlist.artist || 'Various Artists')}</creator>\n`;
    xml += `  <created>${date}</created>\n`;
    xml += `  <trackCount>${tracks.length}</trackCount>\n`;
    xml += '  <tracks>\n';

    tracks.forEach((track, index) => {
        xml += '    <track>\n';
        xml += `      <position>${index + 1}</position>\n`;
        xml += `      <title>${escapeXml(track.title || '')}</title>\n`;
        xml += `      <artist>${escapeXml(getTrackArtists(track) || '')}</artist>\n`;
        xml += `      <album>${escapeXml(track.album?.title || '')}</album>\n`;
        xml += `      <duration>${Math.round(track.duration || 0)}</duration>\n`;
        xml += '    </track>\n';
    });

    xml += '  </tracks>\n';
    xml += '</playlist>\n';

    return xml;
}

/**
 * Parses CSV playlist format
 * @param {string} csvText - CSV content
 * @param {Function} api - API instance for searching tracks
 * @param {Function} onProgress - Progress callback
 * @returns {Promise<{tracks: Array, missingTracks: Array}>}
 */
export async function parseCSV(csvText, api, onProgress) {
    const lines = csvText.trim().split('\n');
    if (lines.length < 2) return { tracks: [], missingTracks: [] };

    // Robust CSV line parser that respects quotes
    const parseLine = (text) => {
        const values = [];
        let current = '';
        let inQuote = false;

        for (let i = 0; i < text.length; i++) {
            const char = text[i];

            if (char === '"') {
                inQuote = !inQuote;
            } else if (char === ',' && !inQuote) {
                values.push(current);
                current = '';
            } else {
                current += char;
            }
        }
        values.push(current);

        // Clean up quotes: remove surrounding quotes and unescape double quotes if any
        return values.map((v) => v.trim().replace(/^"|"$/g, '').replace(/""/g, '"').trim());
    };

    const headers = parseLine(lines[0]);
    const rows = lines.slice(1);

    const tracks = [];
    const missingTracks = [];
    const totalTracks = rows.length;

    for (let i = 0; i < rows.length; i++) {
        const row = rows[i];
        if (!row.trim()) continue;

        const values = parseLine(row);

        if (values.length >= headers.length) {
            let trackTitle = '';
            let artistNames = '';
            let albumName = '';

            headers.forEach((header, index) => {
                const value = values[index];
                if (!value) return;

                switch (header.toLowerCase()) {
                    case 'track name':
                    case 'title':
                    case 'song':
                    case 'name':
                        trackTitle = value;
                        break;
                    case 'artist name(s)':
                    case 'artist name':
                    case 'artist':
                    case 'artists':
                    case 'creator':
                        artistNames = value;
                        break;
                    case 'album':
                    case 'album name':
                        albumName = value;
                        break;
                }
            });

            if (onProgress) {
                onProgress({
                    current: i,
                    total: totalTracks,
                    currentTrack: trackTitle || 'Unknown track',
                    currentArtist: artistNames || '',
                });
            }

            // Search for the track
            if (trackTitle && artistNames) {
                await new Promise((resolve) => setTimeout(resolve, 300));

                try {
                    const searchQuery = `"${trackTitle}" ${artistNames}`.trim();
                    const searchResult = await api.searchTracks(searchQuery);

                    if (searchResult.items && searchResult.items.length > 0) {
                        tracks.push(searchResult.items[0]);
                    } else {
                        missingTracks.push({ title: trackTitle, artist: artistNames, album: albumName });
                    }
                } catch {
                    missingTracks.push({ title: trackTitle, artist: artistNames, album: albumName });
                }
            }
        }
    }

    return { tracks, missingTracks };
}

/**
 * Parses JSPF (JSON Shareable Playlist Format)
 * @param {string} jspfText - JSPF JSON content
 * @param {Function} api - API instance for searching tracks
 * @param {Function} onProgress - Progress callback
 * @returns {Promise<{tracks: Array, missingTracks: Array}>}
 */
export async function parseJSPF(jspfText, api, onProgress) {
    try {
        const jspfData = JSON.parse(jspfText);

        if (!jspfData.playlist || !Array.isArray(jspfData.playlist.track)) {
            throw new Error('Invalid JSPF format: missing playlist or track array');
        }

        const playlist = jspfData.playlist;
        const tracks = [];
        const missingTracks = [];
        const totalTracks = playlist.track.length;

        for (let i = 0; i < playlist.track.length; i++) {
            const jspfTrack = playlist.track[i];
            const trackTitle = jspfTrack.title;
            const trackCreator = jspfTrack.creator;
            const trackAlbum = jspfTrack.album;

            if (onProgress) {
                onProgress({
                    current: i,
                    total: totalTracks,
                    currentTrack: trackTitle || 'Unknown track',
                    currentArtist: trackCreator || '',
                });
            }

            if (trackTitle && trackCreator) {
                await new Promise((resolve) => setTimeout(resolve, 300));

                try {
                    const searchQuery = `${trackTitle} ${trackCreator}`;
                    const searchResults = await api.searchTracks(searchQuery);

                    if (searchResults.items && searchResults.items.length > 0) {
                        tracks.push(searchResults.items[0]);
                    } else {
                        missingTracks.push({ title: trackTitle, artist: trackCreator, album: trackAlbum });
                    }
                } catch {
                    missingTracks.push({ title: trackTitle, artist: trackCreator, album: trackAlbum });
                }
            }
        }

        return { tracks, missingTracks };
    } catch (error) {
        throw new Error('Failed to parse JSPF: ' + error.message);
    }
}

/**
 * Parses XSPF (XML Shareable Playlist Format)
 * @param {string} xspfText - XSPF XML content
 * @param {Function} api - API instance for searching tracks
 * @param {Function} onProgress - Progress callback
 * @returns {Promise<{tracks: Array, missingTracks: Array}>}
 */
export async function parseXSPF(xspfText, api, onProgress) {
    // Validate input to prevent potential XXE attacks
    if (!xspfText || typeof xspfText !== 'string' || xspfText.length > 10 * 1024 * 1024) {
        throw new Error('Invalid XSPF content');
    }
    // Reject potential XXE payloads
    if (xspfText.includes('<!ENTITY') || xspfText.includes('<!DOCTYPE')) {
        throw new Error('XSPF content contains potentially dangerous declarations');
    }

    const parser = new DOMParser();
    const xmlDoc = parser.parseFromString(xspfText, 'application/xml');

    const trackList = xmlDoc.getElementsByTagName('track');
    const tracks = [];
    const missingTracks = [];
    const totalTracks = trackList.length;

    for (let i = 0; i < trackList.length; i++) {
        const trackEl = trackList[i];
        const title = trackEl.getElementsByTagName('title')[0]?.textContent || '';
        const creator = trackEl.getElementsByTagName('creator')[0]?.textContent || '';
        const album = trackEl.getElementsByTagName('album')[0]?.textContent || '';

        if (onProgress) {
            onProgress({
                current: i,
                total: totalTracks,
                currentTrack: title || 'Unknown track',
                currentArtist: creator || '',
            });
        }

        if (title && creator) {
            await new Promise((resolve) => setTimeout(resolve, 300));

            try {
                const searchQuery = `${title} ${creator}`;
                const searchResults = await api.searchTracks(searchQuery);

                if (searchResults.items && searchResults.items.length > 0) {
                    tracks.push(searchResults.items[0]);
                } else {
                    missingTracks.push({ title, artist: creator, album });
                }
            } catch {
                missingTracks.push({ title, artist: creator, album });
            }
        }
    }

    return { tracks, missingTracks };
}

/**
 * Parses generic XML playlist format
 * @param {string} xmlText - XML content
 * @param {Function} api - API instance for searching tracks
 * @param {Function} onProgress - Progress callback
 * @returns {Promise<{tracks: Array, missingTracks: Array}>}
 */
export async function parseXML(xmlText, api, onProgress) {
    // Validate input to prevent potential XXE attacks
    if (!xmlText || typeof xmlText !== 'string' || xmlText.length > 10 * 1024 * 1024) {
        throw new Error('Invalid XML content');
    }
    // Reject potential XXE payloads
    if (xmlText.includes('<!ENTITY') || xmlText.includes('<!DOCTYPE')) {
        throw new Error('XML content contains potentially dangerous declarations');
    }

    const parser = new DOMParser();
    const xmlDoc = parser.parseFromString(xmlText, 'application/xml');

    // Try different track element names
    let trackElements = xmlDoc.getElementsByTagName('track');
    if (trackElements.length === 0) {
        trackElements = xmlDoc.getElementsByTagName('song');
    }
    if (trackElements.length === 0) {
        trackElements = xmlDoc.getElementsByTagName('item');
    }

    const tracks = [];
    const missingTracks = [];
    const totalTracks = trackElements.length;

    for (let i = 0; i < trackElements.length; i++) {
        const trackEl = trackElements[i];

        // Try different element names for title/artist
        const title =
            trackEl.getElementsByTagName('title')[0]?.textContent ||
            trackEl.getElementsByTagName('name')[0]?.textContent ||
            '';
        const artist =
            trackEl.getElementsByTagName('artist')[0]?.textContent ||
            trackEl.getElementsByTagName('creator')[0]?.textContent ||
            trackEl.getElementsByTagName('performer')[0]?.textContent ||
            '';
        const album = trackEl.getElementsByTagName('album')[0]?.textContent || '';

        if (onProgress) {
            onProgress({
                current: i,
                total: totalTracks,
                currentTrack: title || 'Unknown track',
                currentArtist: artist || '',
            });
        }

        if (title && artist) {
            await new Promise((resolve) => setTimeout(resolve, 300));

            try {
                const searchQuery = `${title} ${artist}`;
                const searchResults = await api.searchTracks(searchQuery);

                if (searchResults.items && searchResults.items.length > 0) {
                    tracks.push(searchResults.items[0]);
                } else {
                    missingTracks.push({ title, artist, album });
                }
            } catch {
                missingTracks.push({ title, artist, album });
            }
        }
    }

    return { tracks, missingTracks };
}

/**
 * Parses M3U/M3U8 playlist format
 * @param {string} m3uText - M3U content
 * @param {Function} api - API instance for searching tracks
 * @param {Function} onProgress - Progress callback
 * @returns {Promise<{tracks: Array, missingTracks: Array}>}
 */
export async function parseM3U(m3uText, api, onProgress) {
    const lines = m3uText.trim().split('\n');
    const tracks = [];
    const missingTracks = [];

    const trackInfo = [];
    let currentInfo = null;

    // Parse M3U format
    for (const line of lines) {
        const trimmed = line.trim();
        if (!trimmed || trimmed.startsWith('#EXTM3U')) continue;

        if (trimmed.startsWith('#EXTINF:')) {
            // Parse EXTINF line: #EXTINF:duration,Artist - Title
            const match = trimmed.match(/#EXTINF:(-?\d+)?,(.+)/);
            if (match) {
                const displayName = match[2];
                const parts = displayName.split(' - ');
                currentInfo = {
                    title: parts.length > 1 ? parts.slice(1).join(' - ') : displayName,
                    artist: parts.length > 1 ? parts[0] : '',
                };
            }
        } else if (!trimmed.startsWith('#')) {
            // This is a file path line
            if (currentInfo) {
                trackInfo.push(currentInfo);
                currentInfo = null;
            }
        }
    }

    const totalTracks = trackInfo.length;

    for (let i = 0; i < trackInfo.length; i++) {
        const info = trackInfo[i];

        if (onProgress) {
            onProgress({
                current: i,
                total: totalTracks,
                currentTrack: info.title || 'Unknown track',
                currentArtist: info.artist || '',
            });
        }

        if (info.title) {
            await new Promise((resolve) => setTimeout(resolve, 300));

            try {
                const searchQuery = info.artist ? `${info.title} ${info.artist}` : info.title;
                const searchResults = await api.searchTracks(searchQuery);

                if (searchResults.items && searchResults.items.length > 0) {
                    tracks.push(searchResults.items[0]);
                } else {
                    missingTracks.push({ title: info.title, artist: info.artist, album: '' });
                }
            } catch {
                missingTracks.push({ title: info.title, artist: info.artist, album: '' });
            }
        }
    }

    return { tracks, missingTracks };
}

/**
 * Formats duration in MM:SS format
 * @param {number} seconds - Duration in seconds
 * @returns {string} Formatted duration
 */
function formatDuration(seconds) {
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return `${mins}:${secs.toString().padStart(2, '0')}`;
}

/**
 * Helper function to escape XML special characters
 */
function escapeXml(text) {
    if (!text) return '';
    return text
        .toString()
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#39;');
}

// Export all functions
export { getTrackArtists };