const express = require('express');
const cors = require('cors');
const { spawn } = require('child_process');
const dotenv = require('dotenv');

dotenv.config();

const app = express();
app.use(cors());

const port = process.env.PORT || 3000;
const rtspUrl = process.env.RTSP_URL;

app.get('/stream', (req, res) => {
    if (!rtspUrl) {
        return res.status(500).send('RTSP_URL not configured in .env');
    }

    res.writeHead(200, {
        'Content-Type': 'multipart/x-mixed-replace; boundary=ffserver',
        'Cache-Control': 'no-cache',
        'Connection': 'close',
        'Pragma': 'no-cache'
    });

    const ffmpegArgs = [
        '-rtsp_transport', 'tcp',
        '-i', rtspUrl,
        '-f', 'mpjpeg',
        '-r', '15',           // 15 fps is enough for motion detection
        '-q:v', '5',          // Quality (2-31, lower is better)
        '-s', '1280x720',     // Resize to 720p to save bandwidth and CPU
        '-'                   // Output to stdout
    ];

    console.log('Starting ffmpeg with args:', ffmpegArgs.join(' '));
    const ffmpeg = spawn('ffmpeg', ffmpegArgs);

    ffmpeg.stdout.on('data', (data) => {
        res.write(data);
    });

    ffmpeg.stderr.on('data', (data) => {
        // Uncomment for debugging ffmpeg errors
        // console.error(`ffmpeg stderr: ${data.toString()}`);
    });

    ffmpeg.on('close', (code) => {
        console.log(`ffmpeg process exited with code ${code}`);
        res.end();
    });

    req.on('close', () => {
        console.log('Client disconnected, killing ffmpeg process');
        ffmpeg.kill('SIGKILL');
    });
});

app.listen(port, () => {
    console.log(`Server listening on port ${port}`);
    console.log(`MJPEG Stream available at http://localhost:${port}/stream`);
});