const socket = io();
const chatBox = document.getElementById('chat-box');
const chatInput = document.getElementById('chat-input');
const sendBtn = document.getElementById('send-btn');
const joinBtn = document.getElementById('join-btn');
const statusText = document.getElementById('status');
const audioContainer = document.getElementById('audio-container');

let localStream;
const peers = {}; // Store connections to other users

// --- WebRTC Configuration ---
// Using Google STUN and your dedicated Metered.live TURN server
const rtcConfig = {
    iceServers: [
        { urls: 'stun:stun.l.google.com:19302' },
        { urls: 'stun:stun1.l.google.com:19302' }, // Backup STUN
        {
            urls: 'turn:saman.metered.live:80',
            username: '1bb6c42832c6a26b4db391e4',
            credential: 'axHWrYuQbsBaG5u9'
        },
        {
            urls: 'turn:saman.metered.live:443',
            username: '1bb6c42832c6a26b4db391e4',
            credential: 'axHWrYuQbsBaG5u9'
        },
        {
            urls: 'turn:saman.metered.live:443?transport=tcp',
            username: '1bb6c42832c6a26b4db391e4',
            credential: 'axHWrYuQbsBaG5u9'
        }
    ]
};

// --- CHAT LOGIC ---
sendBtn.onclick = () => {
    const text = chatInput.value.trim();
    if (text) {
        socket.emit('chat-message', text);
        chatInput.value = '';
    }
};

socket.on('chat-message', (data) => {
    const div = document.createElement('div');
    div.className = 'message ' + (data.id === socket.id ? 'self' : '');
    div.innerText = `${data.id === socket.id ? 'You' : data.id.substring(0,4)}: ${data.text}`;
    chatBox.appendChild(div);
    chatBox.scrollTop = chatBox.scrollHeight;
});

// Allow hitting "Enter" to send a chat message
chatInput.addEventListener("keypress", function(event) {
    if (event.key === "Enter") {
        event.preventDefault();
        sendBtn.click();
    }
});

// --- AUDIO/WEBRTC LOGIC ---
joinBtn.onclick = async () => {
    try {
        // Request microphone access
        localStream = await navigator.mediaDevices.getUserMedia({ audio: true, video: false });
        statusText.innerText = "Mic Online - You are in the call";
        joinBtn.disabled = true;
        
        // Let the server know we are ready to connect to others
        socket.emit('join-room');
    } catch (err) {
        alert("Microphone access denied or not found.");
        console.error(err);
    }
};

// When a new user connects, we (if we have our mic on) initiate a call to them
socket.on('user-connected', (userId) => {
    if (!localStream) return; // Don't call if we aren't in the audio room
    
    appendSystemMessage(`User ${userId.substring(0,4)} joined. Attempting connection...`);
    const peer = createPeerConnection(userId, true);
    peers[userId] = peer;
});

// Handle incoming signals (Offers, Answers, ICE candidates)
socket.on('signal', async (data) => {
    if (!localStream) return; 

    const { from, signal } = data;
    
    // If we don't have a peer connection for this user yet, create one
    if (!peers[from]) {
        peers[from] = createPeerConnection(from, false);
    }

    const peer = peers[from];

    try {
        if (signal.type === 'offer') {
            await peer.setRemoteDescription(new RTCSessionDescription(signal));
            const answer = await peer.createAnswer();
            await peer.setLocalDescription(answer);
            socket.emit('signal', { to: from, signal: peer.localDescription });
        } else if (signal.type === 'answer') {
            await peer.setRemoteDescription(new RTCSessionDescription(signal));
        } else if (signal.candidate) {
            await peer.addIceCandidate(new RTCIceCandidate(signal));
        }
    } catch (err) {
        console.error("Signaling error:", err);
    }
});

// Clean up when someone leaves
socket.on('user-disconnected', (userId) => {
    if (peers[userId]) {
        peers[userId].close();
        delete peers[userId];
        
        // Remove their audio element
        const audioEl = document.getElementById(`audio-${userId}`);
        if (audioEl) audioEl.remove();
        
        appendSystemMessage(`User ${userId.substring(0,4)} left.`);
    }
});

// Helper function to create a WebRTC Peer Connection
function createPeerConnection(targetUserId, isInitiator) {
    const peer = new RTCPeerConnection(rtcConfig);

    // Add our local microphone stream to the connection
    localStream.getTracks().forEach(track => peer.addTrack(track, localStream));

    // Send ICE candidates to the other user
    peer.onicecandidate = (event) => {
        if (event.candidate) {
            socket.emit('signal', { to: targetUserId, signal: event.candidate });
        }
    };

    // TRACK THE CONNECTION STATUS
    peer.oniceconnectionstatechange = () => {
        console.log(`Connection state with ${targetUserId}:`, peer.iceConnectionState);
        if (peer.iceConnectionState === 'failed') {
            appendSystemMessage(`❌ Connection to ${targetUserId.substring(0,4)} failed. Firewalls blocked it.`);
        } else if (peer.iceConnectionState === 'connected') {
            appendSystemMessage(`✅ Successfully connected to ${targetUserId.substring(0,4)}! Audio flowing.`);
        } else if (peer.iceConnectionState === 'disconnected') {
            appendSystemMessage(`⚠️ Connection to ${targetUserId.substring(0,4)} lost. Trying to reconnect...`);
        }
    };

    // When we receive their audio stream, play it
    peer.ontrack = (event) => {
        let audioEl = document.getElementById(`audio-${targetUserId}`);
        if (!audioEl) {
            audioEl = document.createElement('audio');
            audioEl.id = `audio-${targetUserId}`;
            audioEl.autoplay = true;
            audioContainer.appendChild(audioEl);
        }
        audioEl.srcObject = event.streams[0];
        
        // Force the browser to play the audio and catch any autoplay errors
        audioEl.play().catch(error => {
            console.error("Browser blocked autoplay:", error);
            appendSystemMessage("Audio blocked by browser. Click anywhere on the page to allow audio.");
        });
    };

    // If we are initiating the call, create an offer
    if (isInitiator) {
        peer.createOffer().then(offer => {
            peer.setLocalDescription(offer);
            socket.emit('signal', { to: targetUserId, signal: offer });
        });
    }

    return peer;
}

function appendSystemMessage(msg) {
    const div = document.createElement('div');
    div.className = 'message system';
    div.innerText = msg;
    chatBox.appendChild(div);
    chatBox.scrollTop = chatBox.scrollHeight;
}