const express = require('express');
const router = express.Router();
const multer = require('multer');
const { execFile } = require('child_process');
const fs = require('fs');
const os = require('os');
const path = require('path');
const axios = require('axios');

// Configure multer to save files to system temp directory
const upload = multer({ dest: os.tmpdir() });

router.post('/', upload.single('audio'), async (req, res) => {
  if (!req.file) {
    return res.status(400).json({ error: 'No audio file uploaded.' });
  }

  const filePath = req.file.path;
  
  try {
    // 1. Generate fingerprint using fpcalc
    const { duration, fingerprint } = await new Promise((resolve, reject) => {
      execFile('fpcalc', [filePath], (error, stdout, stderr) => {
        if (error) {
          return reject(new Error('fpcalc failed: ' + stderr));
        }
        
        let dur = null;
        let fp = null;
        
        stdout.split('\n').forEach(line => {
          if (line.startsWith('DURATION=')) dur = parseInt(line.split('=')[1], 10);
          if (line.startsWith('FINGERPRINT=')) fp = line.split('=')[1];
        });
        
        if (!dur || !fp) {
          return reject(new Error('Invalid fpcalc output'));
        }
        
        resolve({ duration: dur, fingerprint: fp });
      });
    });

    // 2. Query AcoustID API
    const acoustidKey = process.env.ACOUSTID_API_KEY;
    if (!acoustidKey) {
      throw new Error('Missing ACOUSTID_API_KEY');
    }

    const response = await axios.get('https://api.acoustid.org/v2/lookup', {
      params: {
        client: acoustidKey,
        meta: 'recordings',
        duration: duration,
        fingerprint: fingerprint
      }
    });

    const results = response.data.results;
    if (!results || results.length === 0) {
      return res.json({ status: 'not_found' });
    }

    // Sort results by score (descending)
    results.sort((a, b) => b.score - a.score);
    const bestResult = results[0];
    
    // Find a recording with title and artists
    let title = 'Unknown';
    let artist = 'Unknown';
    
    if (bestResult.recordings && bestResult.recordings.length > 0) {
      const rec = bestResult.recordings[0];
      title = rec.title || 'Unknown';
      if (rec.artists && rec.artists.length > 0) {
        artist = rec.artists.map(a => a.name).join(' & ');
      }
    }

    res.json({
      status: 'success',
      data: {
        title: title,
        artist: artist,
        matchScore: Math.round(bestResult.score * 100) + '%'
      }
    });

  } catch (err) {
    console.error('Recognition error:', err.message);
    res.status(500).json({ error: 'Failed to recognize audio' });
  } finally {
    // Clean up uploaded file
    fs.unlink(filePath, () => {});
  }
});

module.exports = router;