// WebRTC Sdp Player
export default class sdpPlayer {
    private pc: any;
    public player: any;
    private statsTimeoutHandler: any;
    private statsFun: Function = new Function();
    private startFun: Function = new Function();
    private errorFun: Function = (e)=>{
        clearInterval(this.statsTimeoutHandler);
    };

    public setView(id: string): void {
        this.player = document.getElementById(id);
    }

	/** 
	 * video play
	 * @param url .sdp video url
	 */
    public start(url: string): void {
        if (url === '' && !this.player) {
			cc.error("need url and set player ID");
			this.errorFun(`need url and set player ID`); // cahnge to error Fun
			return;
		}
		// cc.log('Start play');
		const offerSdpOption = {
			offerToReceiveAudio: true,
			offerToReceiveVideo: true
		};
		this.pc = new RTCPeerConnection();
		this.pc.addTransceiver("audio", { direction: "recvonly" });
		this.pc.addTransceiver("video", { direction: "recvonly" });
		this.pc.oniceconnectionstatechange = this.onIceStateChange(this.pc);
		this.pc.stream = new MediaStream();
		this.pc.ontrack = this.gotRemoteStream.bind(this);
		this.pc.createOffer(offerSdpOption).then((offer) => {
			this.pc.setLocalDescription(offer);
			const xmlhttp = new XMLHttpRequest();   // new HttpRequest instance 
			xmlhttp.timeout = 6000;
			xmlhttp.onerror = this.errorFun.bind(this); // xmlerror to error Fun
			xmlhttp.ontimeout = this.errorFun.bind(this); // timeout to error Fun
			xmlhttp.onload = () => {
				if (xmlhttp.status == 200) {
					const data = JSON.parse(xmlhttp.responseText);
					const remoteSdp = data.remoteSdp;
					this.pc.setRemoteDescription(
						new RTCSessionDescription(remoteSdp),
						() => {
							cc.log("setRemoteDescription success!");
						}, 
						(e) => {
							stop();
							this.errorFun(e.message); // cahnge to error Fun
							cc.log("setRemoteDescription failed, message:" + e.message);
						}
					);
					this.startFun();
					this.onStatus();
				} else {
                    this.errorFun(`xml status: ${xmlhttp.status}`); // cahnge to error Fun
				}
			};
			xmlhttp.open("POST", url);
			xmlhttp.send(JSON.stringify({ localSdp: offer }));
		}).catch((reason) => {
			this.errorFun(reason); // cahnge to error Fun
		});
    }

    private onIceStateChange(pc): void {
		if (pc) {
			if (pc.iceConnectionState == 'disconnected') stop();
			cc.log('ICE state: ' + pc.iceConnectionState);
		}
	}

    private gotRemoteStream(m): void {
		cc.log("ontrack, kind:" + m.track.kind);
		this.pc.stream.addTrack(m.track);
		this.player.srcObject = this.pc.stream;
	}

    // video status event timer
	private onStatus(): void {
		var checkInterval = 1000; // check every 1s (do not use lower values)
		this.statsTimeoutHandler = setInterval(this.statsFun, checkInterval)
	}

	/** 
	 * video event listener
	 * @param event start,stats,error
	 * @param fn listener callback function
	 */
	public on(event: "start" | "stats" | "error", fn: Function): void {
		this[event + "Fun"] = (event === "error") ? (e) => {
			clearInterval(this.statsTimeoutHandler);
			fn(e);
		} : fn;
	}

	/** video voice (support max and min voice only) */
    public setVolume(num: Number): void {
        if (this.player) {
            if (num == 0) this.player.muted = true;
            else this.player.muted = false;
        }        
    }

	/** video stop */
    public stop(): void {
        clearInterval(this.statsTimeoutHandler);
		try {
			if (this.player) {
				const tracks = this.player.srcObject?.getTracks();
				this.player.load();
				if (tracks) {
					tracks.forEach(track => track.stop());
					this.pc?.removeStream(this.player.srcObject);
				}
			} 
		} catch(ex) {
			cc.log(ex);
		}		
		this.pc?.close();
		this.pc = null;
    }

	/** auto play active (need user touch active) */
	public autoPlayActive(): void {
		if (this.player) {
			this.player.muted = false;
			this.player.controls = false;
			this.player.autoplay = true;
			this.player.playsinline = true;
		}
	}
}