class WebRtcPlayer {
    /**
     * WebRtc播放器
     * @param {Element} ele 
     */
    constructor(ele) {
        this.ele = ele
        // this.PeerConnection = window.RTCPeerConnection || window.mozRTCPeerConnection || window.webkitRTCPeerConnection;
        this.PeerConnection = window.RTCPeerConnection

    }
    Open (url) {
        if (this.localpc) {
            this.Close()
        }
        this.localpc = new this.PeerConnection(null)
        const AudioTransceiverInit = {
            direction: 'recvonly',
            sendEncodings: []
        }
        const VideoTransceiverInit = {
            direction: 'recvonly',
            sendEncodings: []
        }
        this.localpc.addTransceiver('audio', AudioTransceiverInit)
        this.localpc.addTransceiver('video', VideoTransceiverInit)
        let that = this
        this.localpc.ontrack = function (e) {
            if (!that.localpc.stream) {
                that.localpc.streamId = e.track.id
                that.localpc.stream = new MediaStream()
                that.ele.srcObject = that.localpc.stream
                that.ele.muted = true
                that.ele.autoplay = true
            }
            that.localpc.stream.addTrack(e.track)
        }

        this.localpc.createOffer()
            .then(offer => this.localpc.setLocalDescription(offer))
            .then(() => {
                that.getSdp(url, this.localpc.localDescription.sdp, function (data) {
                    data = JSON.parse(data)
                    if (data.code != 0) return
                    let anwser = {}
                    anwser.sdp = data.sdp
                    anwser.type = 'answer'
                    that.localpc.setRemoteDescription(anwser).then(() => {
                        console.log("播放成功")
                    }).catch(e => {
                        console.error("播放错误:" + e)
                    })
                })
            })
            .catch(e => "添加ICE候选人过程错误: " + e)
    }
    Close () {
        if (this.localpc) {
            this.localpc.close()
            this.localpc = null
        }
    }
    getSdp (url, body, success) {
        let xhr = new XMLHttpRequest()
        xhr.open('POST', url)
        xhr.setRequestHeader('Content-Type', 'text/plain;charset=utf-8')
        xhr.onreadystatechange = function () {
            if (xhr.responseText.length < 1) return
            if (xhr.status === 200) {
                success(xhr.responseText)
            }
        }
        xhr.send(body)
    }
}