var pc = null;

function negotiate() {
    pc.addTransceiver('video', { direction: 'recvonly' });
    return pc.createOffer().then((offer) => {
        return pc.setLocalDescription(offer);
    }).then(() => {
        // wait for ICE gathering to complete
        return new Promise((resolve) => {
            if (pc.iceGatheringState === 'complete') {
                resolve();
            } else {
                const checkState = () => {
                    if (pc.iceGatheringState === 'complete') {
                        pc.removeEventListener('icegatheringstatechange', checkState);
                        resolve();
                    }
                };
                pc.addEventListener('icegatheringstatechange', checkState);
            }
        });
    }).then(() => {
        var offer = pc.localDescription;
        return fetch('/offer', {
            body: JSON.stringify({
                sdp: offer.sdp,
                type: offer.type,
            }),
            headers: {
                'Content-Type': 'application/json'
            },
            method: 'POST'
        });
    }).then((response) => {
        return response.json();
    }).then((answer) => {
        return pc.setRemoteDescription(answer);
    }).catch((e) => {
        alert(e);
    });
}

function start() {
    console.log('开始执行！');
    var config = {
        sdpSemantics: 'unified-plan'
    };
    //config.iceServers = [{ urls: ['stun:stun.voiparound.com'] }];
    pc = new RTCPeerConnection();
    pc.addEventListener('track', (evt) => {
        if (evt.track.kind == 'video') {
            const video = document.getElementById('video');
            video.srcObject = evt.streams[0];
            //video.play()
//            video.muted = true; // 静音
//            video.play().then(() => {
//                // 如果成功播放，可以选择恢复音量
//                video.muted = false;
//            }).catch((error) => {
//                console.error('Error playing video:', error);
//            });
        }
    });
    document.getElementById('start').style.display = 'none';
    negotiate();
    document.getElementById('stop').style.display = 'inline-block';
}

function stop() {
    document.getElementById('stop').style.display = 'none';
    // close peer connection
    setTimeout(() => {
        pc.close();
    }, 500);
    document.getElementById('start').style.display = 'inline-block';
}

function showView(){
    console.log('status:',document.getElementById('video').paused)
    if (document.getElementById('video').paused) {
        document.getElementById('video').play().catch(error => {
            console.error('Error playing video:', error);
        });
    }
}

// // 监听页面焦点变化
window.addEventListener('focus', () => {
if (document.getElementById('video').paused) {
    document.getElementById('video').play().catch(error => {
        console.error('Error playing video:', error);
    });
}
});

//document.addEventListener('visibilitychange', () => {
//if (document.visibilityState === 'visible') {
//    if (document.getElementById('video').paused) {
//        document.getElementById('video').play().catch(error => {
//            console.error('Error playing video:', error);
//        });
//    }
//}
//});