const fs = require('fs');
const net = require('net');
const path = require('path');

const MARKER = path.join(__dirname, '..', '..', '.audio_bridge');
const FRAME_MAX = 4 * 1024 * 1024;

const bridgePort = () => {
  try {
    const port = Number(String(fs.readFileSync(MARKER, 'utf8')).trim());
    return Number.isFinite(port) && port > 0 ? port : 0;
  } catch (_) {
    return 0;
  }
};

module.exports = () => ({
  open(file, { onJpeg, onPcm, onEnd }) {
    let ended = false;
    const finish = () => {
      if (ended) return;
      ended = true;
      try { onEnd(); } catch (_) {}
    };
    const port = bridgePort();
    if (!port) {
      setImmediate(finish);
      return { stop() { ended = true; } };
    }
    const sock = net.connect(port, '127.0.0.1');
    let buf = Buffer.alloc(0);
    sock.setNoDelay(true);
    sock.on('error', finish);
    sock.on('close', finish);
    sock.on('connect', () => sock.write(Buffer.concat([Buffer.from('S'), Buffer.from(`${file}\n`, 'utf8')])));
    sock.on('data', (chunk) => {
      buf = buf.length ? Buffer.concat([buf, chunk]) : chunk;
      while (buf.length >= 5) {
        const len = buf.readUInt32BE(1);
        if (len > FRAME_MAX) { sock.destroy(); return; }
        if (buf.length < 5 + len) return;
        const type = buf[0];
        const payload = Buffer.from(buf.subarray(5, 5 + len));
        buf = buf.subarray(5 + len);
        if (ended) continue;
        if (type === 0x4a) onJpeg(payload);
        else if (type === 0x41) onPcm(payload);
        else if (type === 0x45) { finish(); sock.destroy(); return; }
      }
    });
    return { stop() { ended = true; try { sock.destroy(); } catch (_) {} } };
  }
});