let A_RTC = new WebSocket("ws://127.0.0.1:8080/RTC");

A_RTC.onopen = function(event) {
    console.log("RTC: Connected");
    createOffer().then(r => {

    });
}

A_RTC.onmessage = function(event) {
    console.log("RTC: Received: " + event.data);
    try {
        const data = JSON.parse(event.data);
        if(data.type === "answer"){
            handleAnswer(data).then(r => {

            });
        }
        else if(data.type === "candidate"){
            handleCandidate(data)
        }
    }
    catch (e){
        console.log(e);
    }
}

A_RTC.onclose = function(event) {
    console.log("RTC: Close");
}

// 创建PeerConnection
let peerConnection;
let dataChannel;

function createPeerConnection() {
    peerConnection = new RTCPeerConnection({
        iceServers: [
            // {
            //     urls: ['stun:stun.l.google.com:19302']
            // }
        ]
    });

    // 监听 ICE 状态变化
    peerConnection.oniceconnectionstatechange = () => {
        console.log('ICE connection state:', peerConnection.iceConnectionState);
        if (peerConnection.iceConnectionState === 'connected') {
            console.log('ICE 连接成功！');
            // 在 ICE 连接成功后再创建数据通道
            dataChannel = peerConnection.createDataChannel('DataChannel');
            setupDataChannel();
        }
        else if (peerConnection.iceConnectionState === 'failed') {
            console.error('ICE 连接失败，尝试重新协商...');
        }
    };

}

function setupDataChannel() {
    console.log('Setting up DataChannel...');
    dataChannel.onopen = () => {
        console.log('Data channel is open and ready to be used.');
        // 发送初始数据
        sendData('Hello from DataChannel!');
        sendData(JSON.stringify({ command: 'start', time: Date.now() }));
    };

    dataChannel.onmessage = event => {
        console.log('Received message:', event.data);
    };

    dataChannel.onclose = () => {
        console.log('Data channel closed.');
    };
}

// 创建Offer
async function createOffer() {
    createPeerConnection();
    const offer = await peerConnection.createOffer({
        offerToReceiveAudio: true,
        offerToReceiveVideo: false, // 如果不需要视频，可以设置为 false
    });
    await peerConnection.setLocalDescription(offer);
    console.log('Local Description:', peerConnection.localDescription);
    A_RTC.send(JSON.stringify({ type: 'offer', offer: peerConnection.localDescription }));
}

// 处理Answer
async function handleAnswer(answer) {
    try {
        // 确保传递完整的 RTCSessionDescription 对象
        const remoteDesc = new RTCSessionDescription({
            type: "answer",
            sdp: answer.sdp
        });
        await peerConnection.setRemoteDescription(remoteDesc);
        console.log('Remote Description set successfully.');
        peerConnection.onicecandidate = e => {
            if (e.candidate) {
                A_RTC.send(JSON.stringify({
                    type: 'candidate',
                    candidate: e.candidate
                }));
                console.log('Candidate sent:', e.candidate);
            }
        };

    } catch (e) {
        console.error('Failed to set remote description:', e);
    }
}

// 处理Offer
async function handleOffer(offer) {
    createPeerConnection();
    await peerConnection.setRemoteDescription(new RTCSessionDescription(offer));
    const answer = await peerConnection.createAnswer();
    await peerConnection.setLocalDescription(answer);
    console.log('Local Description:', peerConnection.localDescription);
    A_RTC.send(JSON.stringify({ type: 'answer', answer: peerConnection.localDescription }));
}

// 处理ICE候选
function handleCandidate(candidate) {
    if (peerConnection) {
        const iceCandidate = new RTCIceCandidate({
                candidate: candidate.candidate,
                sdpMid: candidate.sdpMid,
                sdpMLineIndex: candidate.sdpMLineIndex,
                usernameFragment: candidate.usernameFragment
        });
        peerConnection.addIceCandidate(iceCandidate).then(r => {
            console.log('Candidate added successfully.');
        });
    }
}

// 处理来自DataChannel的数据
function handleData(data) {
    if (dataChannel) {
        console.log('Received data:', data)
    }
}

// 发送数据到DataChannel
function sendData(data) {
    if (dataChannel && dataChannel.readyState === 'open') {
        dataChannel.send(data);
    } else {
        console.error('Data channel is not open.');
    }
}