const http = require('http');
const https = require('https');
const fs = require('fs');
const path = require('path');
const url = require('url');

const DATA_DIR = process.env.DATA_DIR || './data';
const MUSIC_DIR = process.env.MUSIC_DIR || './music';
const PORT = process.env.PORT || 3001;

// Ensure directories exist
if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR, { recursive: true });
}
if (!fs.existsSync(MUSIC_DIR)) {
    fs.mkdirSync(MUSIC_DIR, { recursive: true });
}

const server = http.createServer((req, res) => {
    // CORS headers
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
    res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

    if (req.method === 'OPTIONS') {
        res.writeHead(204);
        res.end();
        return;
    }

    const parsedUrl = url.parse(req.url, true);
    const pathname = parsedUrl.pathname;
    
    // Path format: /kv/:key?token=...
    const match = pathname.match(/^\/kv\/([a-zA-Z0-9_-]+)$/);
    
    if (!match) {
        res.writeHead(404, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Invalid path' }));
        return;
    }

    const key = match[1];
    const token = parsedUrl.query.token;

    if (!token) {
        res.writeHead(401, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Token required' }));
        return;
    }

    // Simple file-based storage: data/{token}_{key}.json
    // Using token in filename ensures isolation between users
    const safeToken = token.replace(/[^a-zA-Z0-9]/g, '');
    const filePath = path.join(DATA_DIR, `${safeToken}_${key}.json`);

    if (req.method === 'GET') {
        if (fs.existsSync(filePath)) {
            const data = fs.readFileSync(filePath);
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(data);
        } else {
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify(null)); // Key not found returns null
        }
    } else if (req.method === 'POST') {
        let body = '';
        req.on('data', chunk => body += chunk.toString());
        req.on('end', () => {
            try {
                // Validate JSON
                const data = JSON.parse(body);
                fs.writeFileSync(filePath, body);

                // Try to handle background download if data looks like a song list
                // Execute in background
                tryDownloadSongs(data).catch(err => console.error('Download Manager Error:', err));

                res.writeHead(200, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ success: true }));
            } catch (e) {
                console.error(e);
                res.writeHead(400, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({ error: 'Invalid JSON' }));
            }
        });
    } else {
        res.writeHead(405);
        res.end();
    }
});

server.listen(PORT, () => {
    console.log(`Sync Server running on port ${PORT}`);
    console.log(`Data directory: ${DATA_DIR}`);
    console.log(`Music directory: ${MUSIC_DIR}`);
});

// --- Download Manager ---

async function tryDownloadSongs(data) {
    // Detect if data is a song list
    // Must be an array, and items must have id, name, and (source or platform)
    if (!Array.isArray(data) || data.length === 0) return;
    
    const isSongList = data.every(item =>
        item &&
        typeof item === 'object' &&
        item.id &&
        item.name &&
        (item.source || item.platform)
    );

    if (!isSongList) return;

    console.log(`[Sync] Detected song list. Starting background processing for ${data.length} songs...`);
    
    for (const song of data) {
        try {
            await processSong(song);
        } catch (e) {
            console.error(`[Sync] Error processing ${song.name}:`, e.message);
        }
    }
}

function processSong(song) {
    return new Promise((resolve) => {
        // Basic sanitization
        const safeName = (song.name || 'unknown').replace(/[\\/:*?"<>|]/g, '_');
        const safeArtist = (song.artist || 'unknown').replace(/[\\/:*?"<>|]/g, '_');
        const source = song.platform || song.source;
        // Filename: Artist - Name [source_id]
        const baseName = `${safeArtist} - ${safeName} [${source}_${song.id}]`;
        
        // Check if file exists (fuzzy match for extension)
        try {
            const files = fs.readdirSync(MUSIC_DIR);
            // Check for standard format OR manual rename (Song Name.ext)
            const exists = files.some(f => {
                // 1. Standard format: Artist - Name [source_id].ext
                if (f.startsWith(baseName)) return true;
                
                // 2. Manual rename: Name.ext (ignoring extension)
                // We check if the file starts with the song name followed by a dot
                if (f.startsWith(`${safeName}.`)) return true;

                return false;
            });

            if (exists) {
                resolve();
                return;
            }
        } catch (e) {
            console.error('Error reading music dir:', e);
        }

        // Get URL (prefer FLAC)
        const apiUrl = `https://music-dl.sayqz.com/api/?source=${source}&id=${song.id}&type=url&br=flac`;
        
        https.get(apiUrl, (res) => {
            let data = '';
            res.on('data', chunk => data += chunk);
            res.on('end', () => {
                try {
                    const apiRes = JSON.parse(data);
                    const url = apiRes.url;
                    
                    if (!url) {
                        console.log(`[Sync] No URL found for ${song.name}`);
                        resolve();
                        return;
                    }

                    // Determine extension
                    let ext = 'mp3';
                    if (url.includes('.flac')) ext = 'flac';
                    else if (url.includes('.m4a')) ext = 'm4a';
                    else if (url.includes('.ogg')) ext = 'ogg';
                    else if (url.includes('.wav')) ext = 'wav';

                    const dest = path.join(MUSIC_DIR, `${baseName}.${ext}`);
                    downloadFile(url, dest)
                        .then(() => {
                            console.log(`[Sync] Downloaded: ${baseName}.${ext}`);
                            resolve();
                        })
                        .catch(err => {
                            console.error(`[Sync] Download failed for ${song.name}:`, err.message);
                            resolve();
                        });
                } catch (e) {
                    console.error('[Sync] API Parse Error:', e);
                    resolve();
                }
            });
        }).on('error', (e) => {
            console.error(`[Sync] API Request Error: ${e.message}`);
            resolve();
        });
    });
}

function downloadFile(url, dest) {
    return new Promise((resolve, reject) => {
        const protocol = url.startsWith('https') ? https : http;
        protocol.get(url, (res) => {
            // Handle Redirects
            if (res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
                downloadFile(res.headers.location, dest).then(resolve).catch(reject);
                return;
            }
            if (res.statusCode !== 200) {
                reject(new Error(`Status code ${res.statusCode}`));
                return;
            }
            const file = fs.createWriteStream(dest);
            res.pipe(file);
            file.on('finish', () => {
                file.close(() => resolve());
            });
            file.on('error', (err) => {
                fs.unlink(dest, () => {});
                reject(err);
            });
        }).on('error', (err) => {
            fs.unlink(dest, () => {});
            reject(err);
        });
    });
}