const displayMediaOptions = {
    video: {
      displaySurface: "browser",
    },
    audio: {
      suppressLocalAudioPlayback: false,
    },
    preferCurrentTab: false,
    selfBrowserSurface: "exclude",
    systemAudio: "include",
    surfaceSwitching: "include",
    monitorTypeSurfaces: "include",
};

const peerConnection = new RTCPeerConnection();
const broadcast = new BroadcastChannel("screen_sharing");

function main() {
    peerConnection.onconnectionstatechange = (evt) => {
        console.log("Connection state changed", evt)
    }

    peerConnection.oniceconnectionstatechange = () => {
        console.log('ICE state: ',peerConn.iceConnectionState);
    }

    peerConnection.ontrack = function (e) {
        var vid = document.createElement("video");
        document.body.appendChild(vid);
        vid.srcObject = e.streams[0];
    };

    broadcast.onmessage = (evt) => {
        const message = JSON.parse(evt.data);
        console.log("Received message", message)
        if (message.type === "answer") {
            peerConnection.setRemoteDescription(
                new RTCSessionDescription(message.payload),
                () => {},
                error,
            );
        }
    };

    const urlParams = new URLSearchParams(window.location.search);
    const b64Offer = urlParams.get('offer');
    if (!b64Offer) return;

    const offer = JSON.parse(atob(b64Offer));
    peerConnection.setRemoteDescription(
        new RTCSessionDescription(offer),
        () => {
            peerConnection.createAnswer(function (answer) {
            peerConnection.setLocalDescription(
              answer,
              function () {
                broadcast.postMessage(JSON.stringify({
                    type: 'answer',
                    payload: answer
                }))
              },
              error,
            );
          }, error);
        },
        error,
    );
}

function shareScreen() {
    return navigator.mediaDevices
        .getDisplayMedia(displayMediaOptions)
        .then(captureStream => {
            peerConnection.addStream(captureStream);

            peerConnection.createOffer(function (offer) {
                peerConnection.setLocalDescription(
                  offer,
                  () => {
                    const b64Offer = btoa(JSON.stringify(offer))
                    const url = "https://127.0.0.1:" + window.location.port + "?offer=" + encodeURIComponent(b64Offer)
                    console.log(url)
                    fetch("/api/v1/cast", {
                        method: 'POST',
                        headers: {
                            "Content-Type": "application/json"
                        },
                        body: JSON.stringify({
                            "url": url,
                        })
                    })
                  },
                  error,
                );
            }, error);
        })
        .catch(err => {
            console.error(err)
        })
}

function endCall() {
    var videos = document.getElementsByTagName("video");
    for (var i = 0; i < videos.length; i++) {
      videos[i].pause();
    }
  
    peerConnection.close();
}

function error(err) {
    console.error(err);
    endCall();
}

main()