const socket = io();
const remoteVideo = document.getElementById('remoteVideo');
const overlay = document.getElementById('overlay');

let peerConnection;
const config = {
    iceServers: [
        { urls: "stun:localhost:3478" },
        {
            urls: "turn:localhost:3478",
            username: "myuser",
            credential: "mypassword"
        }
    ]
};

socket.on('offer', (id, description) => {
    peerConnection = new RTCPeerConnection(config);
    
    peerConnection.ontrack = event => {
        remoteVideo.srcObject = event.streams[0];
        remoteVideo.classList.add('active');
        overlay.classList.add('hidden');
    };

    // Auto-unmute when the user interacts with the document to bypass browser autoplay restrictions
    document.addEventListener('click', () => {
        remoteVideo.muted = false;
        // Set sink to max possible volume explicitly avoiding browser gain staging
        remoteVideo.volume = 1.0; 
    }, {once: true});

    peerConnection.onicecandidate = event => {
        if (event.candidate) {
            socket.emit('candidate', id, event.candidate);
        }
    };

    peerConnection
        .setRemoteDescription(description)
        .then(() => peerConnection.createAnswer())
        .then(sdp => {
            let sdpLines = sdp.sdp.split('\r\n');
            let opusPayloadType = null;
            for (let i = 0; i < sdpLines.length; i++) {
                if (sdpLines[i].includes('a=rtpmap:') && sdpLines[i].includes('opus/48000/2')) {
                    const match = sdpLines[i].match(/a=rtpmap:(\d+) /);
                    if (match) opusPayloadType = match[1];
                }
            }
            if (opusPayloadType) {
                let fmtpFound = false;
                for (let i = 0; i < sdpLines.length; i++) {
                    if (sdpLines[i].startsWith(`a=fmtp:${opusPayloadType}`)) {
                        sdpLines[i] = `a=fmtp:${opusPayloadType} minptime=10;useinbandfec=1;maxplaybackrate=48000;stereo=1;sprop-stereo=1;maxaveragebitrate=510000;cbr=1`;
                        fmtpFound = true;
                    }
                }
                if (!fmtpFound) {
                    sdpLines.push(`a=fmtp:${opusPayloadType} minptime=10;useinbandfec=1;maxplaybackrate=48000;stereo=1;sprop-stereo=1;maxaveragebitrate=510000;cbr=1`);
                }
            }
            sdp.sdp = sdpLines.join('\r\n');
            return peerConnection.setLocalDescription(sdp);
        })
        .then(() => {
            socket.emit('answer', id, peerConnection.localDescription);
        });
});

socket.on('candidate', (id, candidate) => {
    if (peerConnection) {
        peerConnection.addIceCandidate(new RTCIceCandidate(candidate))
            .catch(e => console.error(e));
    }
});

socket.on('broadcaster', () => {
    socket.emit('viewer');
});

socket.on('disconnectPeer', () => {
    if (peerConnection) {
        peerConnection.close();
        peerConnection = null;
    }
    remoteVideo.classList.remove('active');
    remoteVideo.srcObject = null;
    
    overlay.classList.remove('hidden');
    overlay.querySelector('h1').innerText = 'Stream Ended';
    overlay.querySelector('.status-indicator span:last-child').innerText = 'Waiting for new stream...';
});

socket.on('connect', () => {
    socket.emit('viewer');
});