var WebRtcStreamer = (function () {

    /**
     * Interface with WebRTC-streamer API
     * @constructor
     * @param {string} videoElement - id of the video element tag
     * @param {string} srvurl -  url of webrtc-streamer (default is current location)
     */
    var WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
        if (typeof videoElement === "string") {
            this.videoElement = document.getElementById(videoElement);
        } else {
            this.videoElement = videoElement;
        }
        this.srvurl = srvurl || location.protocol + "//" + window.location.hostname + ":" + window.location.port;
        this.pc = null;

        this.mediaConstraints = {offerToReceiveAudio: true, offerToReceiveVideo: true};

        this.iceServers = null;
        this.earlyCandidates = [];
    }

    WebRtcStreamer.prototype._handleHttpErrors = function (response) {
        if (!response.ok) {
            throw Error(response.statusText);
        }
        return response;
    }

    /**
     * Connect a WebRTC Stream to videoElement
     * @param {string} videourl - id of WebRTC video stream
     * @param {string} audiourl - id of WebRTC audio stream
     * @param {string} options -  options of WebRTC call
     * @param {string} stream  -  local stream to send
     */
    WebRtcStreamer.prototype.connect = function (videourl, audiourl, options, localstream) {
        this.disconnect();

        // getIceServers is not already received
        if (!this.iceServers) {
            console.log("Get IceServers");

            fetch(this.srvurl + "/api/getIceServers")
                .then(this._handleHttpErrors)
                .then((response) => (response.json()))
                .then((response) => this.onReceiveGetIceServers.call(this, response, videourl, audiourl, options, localstream))
                .catch((error) => this.onError("getIceServers " + error))

        } else {
            this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream);
        }
    }

    /**
     * Disconnect a WebRTC Stream and clear videoElement source
     */
    WebRtcStreamer.prototype.disconnect = function () {
        if (this.videoElement?.srcObject) {
            this.videoElement.srcObject.getTracks().forEach(track => {
                track.stop()
                this.videoElement.srcObject.removeTrack(track);
            });
        }
        if (this.pc) {
            fetch(this.srvurl + "/api/hangup?peerid=" + this.pc.peerid)
                .then(this._handleHttpErrors)
                .catch((error) => this.onError("hangup " + error))


            try {
                this.pc.close();
            } catch (e) {
                console.log("Failure close peer connection:" + e);
            }
            this.pc = null;
        }
    }

    /*
    * GetIceServers callback
    */
    WebRtcStreamer.prototype.onReceiveGetIceServers = function (iceServers, videourl, audiourl, options, stream) {
        this.iceServers = iceServers;
        this.pcConfig = iceServers || {"iceServers": []};
        try {
            this.createPeerConnection();

            var callurl = this.srvurl + "/api/call?peerid=" + this.pc.peerid + "&url=" + encodeURIComponent(videourl);
            if (audiourl) {
                callurl += "&audiourl=" + encodeURIComponent(audiourl);
            }
            if (options) {
                callurl += "&options=" + encodeURIComponent(options);
            }

            if (stream) {
                this.pc.addStream(stream);
            }

            // clear early candidates
            this.earlyCandidates.length = 0;

            // create Offer
            var bind = this;
            this.pc.createOffer(this.mediaConstraints).then(function (sessionDescription) {
                console.log("Create offer:" + JSON.stringify(sessionDescription));

                bind.pc.setLocalDescription(sessionDescription
                    , function () {
                        fetch(callurl, {method: "POST", body: JSON.stringify(sessionDescription)})
                            .then(bind._handleHttpErrors)
                            .then((response) => (response.json()))
                            .catch((error) => bind.onError("call " + error))
                            .then((response) => bind.onReceiveCall.call(bind, response))
                            .catch((error) => bind.onError("call " + error))

                    }
                    , function (error) {
                        console.log("setLocalDescription error:" + JSON.stringify(error));
                    });

            }, function (error) {
                alert("Create offer error:" + JSON.stringify(error));
            });

        } catch (e) {
            this.disconnect();
            alert("connect error: " + e);
        }
    }


    WebRtcStreamer.prototype.getIceCandidate = function () {
        fetch(this.srvurl + "/api/getIceCandidate?peerid=" + this.pc.peerid)
            .then(this._handleHttpErrors)
            .then((response) => (response.json()))
            .then((response) => this.onReceiveCandidate.call(this, response))
            .catch((error) => bind.onError("getIceCandidate " + error))
    }

    /*
    * create RTCPeerConnection
    */
    WebRtcStreamer.prototype.createPeerConnection = function () {
        console.log("createPeerConnection  config: " + JSON.stringify(this.pcConfig));
        this.pc = new RTCPeerConnection(this.pcConfig);
        var pc = this.pc;
        pc.peerid = Math.random();

        var bind = this;
        pc.onicecandidate = function (evt) {
            bind.onIceCandidate.call(bind, evt);
        };
        pc.onaddstream = function (evt) {
            bind.onAddStream.call(bind, evt);
        };
        pc.oniceconnectionstatechange = function (evt) {
            console.log("oniceconnectionstatechange  state: " + pc.iceConnectionState);
            if (bind.videoElement) {
                if (pc.iceConnectionState === "connected") {
                    bind.videoElement.style.opacity = "1.0";
                } else if (pc.iceConnectionState === "disconnected") {
                    bind.videoElement.style.opacity = "0.25";
                } else if ((pc.iceConnectionState === "failed") || (pc.iceConnectionState === "closed")) {
                    bind.videoElement.style.opacity = "0.5";
                } else if (pc.iceConnectionState === "new") {
                    bind.getIceCandidate.call(bind)
                }
            }
        }
        pc.ondatachannel = function (evt) {
            console.log("remote datachannel created:" + JSON.stringify(evt));

            evt.channel.onopen = function () {
                console.log("remote datachannel open");
                this.send("remote channel openned");
            }
            evt.channel.onmessage = function (event) {
                console.log("remote datachannel recv:" + JSON.stringify(event.data));
            }
        }
        pc.onicegatheringstatechange = function () {
            if (pc.iceGatheringState === "complete") {
                const recvs = pc.getReceivers();

                recvs.forEach((recv) => {
                    if (recv.track && recv.track.kind === "video") {
                        console.log("codecs:" + JSON.stringify(recv.getParameters().codecs))
                    }
                });
            }
        }

        try {
            var dataChannel = pc.createDataChannel("ClientDataChannel");
            dataChannel.onopen = function () {
                console.log("local datachannel open");
                this.send("local channel openned");
            }
            dataChannel.onmessage = function (evt) {
                console.log("local datachannel recv:" + JSON.stringify(evt.data));
            }
        } catch (e) {
            console.log("Cannor create datachannel error: " + e);
        }

        console.log("Created RTCPeerConnnection with config: " + JSON.stringify(this.pcConfig));
        return pc;
    }


    /*
    * RTCPeerConnection IceCandidate callback
    */
    WebRtcStreamer.prototype.onIceCandidate = function (event) {
        if (event.candidate) {
            if (this.pc.currentRemoteDescription) {
                this.addIceCandidate(this.pc.peerid, event.candidate);
            } else {
                this.earlyCandidates.push(event.candidate);
            }
        } else {
            console.log("End of candidates.");
        }
    }


    WebRtcStreamer.prototype.addIceCandidate = function (peerid, candidate) {
        fetch(this.srvurl + "/api/addIceCandidate?peerid=" + peerid, {method: "POST", body: JSON.stringify(candidate)})
            .then(this._handleHttpErrors)
            .then((response) => (response.json()))
            .then((response) => {
                console.log("addIceCandidate ok:" + response)
            })
            .catch((error) => this.onError("addIceCandidate " + error))
    }

    /*
    * RTCPeerConnection AddTrack callback
    */
    WebRtcStreamer.prototype.onAddStream = function (event) {
        console.log("Remote track added:" + JSON.stringify(event));

        this.videoElement.srcObject = event.stream;
        var promise = this.videoElement.play();
        if (promise !== undefined) {
            var bind = this;
            promise.catch(function (error) {
                console.warn("error:" + error);
                bind.videoElement.setAttribute("controls", true);
            });
        }
    }

    /*
    * AJAX /call callback
    */
    WebRtcStreamer.prototype.onReceiveCall = function (dataJson) {
        var bind = this;
        console.log("offer: " + JSON.stringify(dataJson));
        var descr = new RTCSessionDescription(dataJson);
        this.pc.setRemoteDescription(descr
            , function () {
                console.log("setRemoteDescription ok");
                while (bind.earlyCandidates.length) {
                    var candidate = bind.earlyCandidates.shift();
                    bind.addIceCandidate.call(bind, bind.pc.peerid, candidate);
                }

                bind.getIceCandidate.call(bind)
            }
            , function (error) {
                console.log("setRemoteDescription error:" + JSON.stringify(error));
            });
    }

    /*
    * AJAX /getIceCandidate callback
    */
    WebRtcStreamer.prototype.onReceiveCandidate = function (dataJson) {
        console.log("candidate: " + JSON.stringify(dataJson));
        if (dataJson) {
            for (var i = 0; i < dataJson.length; i++) {
                var candidate = new RTCIceCandidate(dataJson[i]);

                console.log("Adding ICE candidate :" + JSON.stringify(candidate));
                this.pc.addIceCandidate(candidate
                    , function () {
                        console.log("addIceCandidate OK");
                    }
                    , function (error) {
                        console.log("addIceCandidate error:" + JSON.stringify(error));
                    });
            }
            this.pc.addIceCandidate();
        }
    }


    /*
    * AJAX callback for Error
    */
    WebRtcStreamer.prototype.onError = function (status) {
        console.log("onError:" + status);
    }

    return WebRtcStreamer;
})();

if (typeof window !== 'undefined' && typeof window.document !== 'undefined') {
    window.WebRtcStreamer = WebRtcStreamer;
}
if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
    module.exports = WebRtcStreamer;
}