interface SFUMessage {
  type: string;
  data?: any;
}

class SFUPublisher {
  private ws: WebSocket | null = null;
  private peerConnection: RTCPeerConnection | null = null;
  private localStream: MediaStream | null = null;
  private isStreaming = false;

  private rtcConfiguration: RTCConfiguration = {
    iceServers: [
      { urls: 'stun:stun.l.google.com:19302' },
      { urls: 'stun:stun1.l.google.com:19302' }
    ]
  };

  // UI Elements
  private statusElement: HTMLElement;
  private subscribersCountElement: HTMLElement;
  private producersCountElement: HTMLElement;
  private startButton: HTMLButtonElement;
  private stopButton: HTMLButtonElement;
  private localVideo: HTMLVideoElement;

  constructor() {
    this.statusElement = document.getElementById('status')!;
    this.subscribersCountElement = document.getElementById('subscribersCount')!;
    this.producersCountElement = document.getElementById('producersCount')!;
    this.startButton = document.getElementById('startBtn') as HTMLButtonElement;
    this.stopButton = document.getElementById('stopBtn') as HTMLButtonElement;
    this.localVideo = document.getElementById('localVideo') as HTMLVideoElement;

    this.setupEventHandlers();
  }

  private setupEventHandlers(): void {
    this.startButton.addEventListener('click', () => this.startBroadcasting());
    this.stopButton.addEventListener('click', () => this.stopBroadcasting());
  }

  private async startBroadcasting(): Promise<void> {
    try {
      this.updateStatus('Connecting to SFU server...', 'waiting');
      this.setButtonStates(false, false);

      await this.connectToServer();
      await this.getLocalStream();
      await this.createPeerConnection();
      await this.startSFUNegotiation();

      this.isStreaming = true;
      this.updateStatus('Broadcasting via SFU - Optimized for scalability!', 'connected');
      this.setButtonStates(false, true);
      this.updateStats();

    } catch (error) {
      console.error('Error starting broadcast:', error);
      this.updateStatus('Failed to start broadcast: ' + error.message, 'disconnected');
      this.setButtonStates(true, false);
    }
  }

  private async stopBroadcasting(): Promise<void> {
    this.isStreaming = false;

    if (this.peerConnection) {
      this.peerConnection.close();
      this.peerConnection = null;
    }

    if (this.localStream) {
      this.localStream.getTracks().forEach(track => track.stop());
      this.localStream = null;
    }

    if (this.localVideo) {
      this.localVideo.srcObject = null;
    }

    if (this.ws) {
      this.ws.close();
      this.ws = null;
    }

    this.updateStatus('Broadcast stopped', 'disconnected');
    this.setButtonStates(true, false);
    this.resetStats();
  }

  private async connectToServer(): Promise<void> {
    return new Promise((resolve, reject) => {
      this.ws = new WebSocket('ws://localhost:3001?role=publisher');

      this.ws.onopen = () => resolve();
      this.ws.onerror = (error) => reject(error);
      
      this.ws.onmessage = async (event) => {
        try {
          const message: SFUMessage = JSON.parse(event.data);
          await this.handleServerMessage(message);
        } catch (error) {
          console.error('Failed to parse message:', error);
        }
      };

      this.ws.onclose = () => {
        if (this.isStreaming) {
          this.updateStatus('Connection to server lost', 'disconnected');
        }
      };
    });
  }

  private async handleServerMessage(message: SFUMessage): Promise<void> {
    console.log('Received message:', message.type);
    
    switch (message.type) {
      case 'join':
        console.log('Joined as publisher:', message.data);
        break;
      case 'routerRtpCapabilities':
        console.log('Received router capabilities');
        // In a full SFU implementation, this would configure the device
        break;
      case 'webRtcTransportCreated':
        console.log('Transport created, connecting...');
        break;
      case 'webRtcTransportConnected':
        console.log('Transport connected, starting to produce');
        break;
      case 'produced':
        console.log('Producer created:', message.data.producerId);
        break;
      case 'error':
        console.error('Server error:', message.data.message);
        break;
      default:
        console.log('Unknown message type:', message.type);
    }
  }

  private async getLocalStream(): Promise<void> {
    this.localStream = await navigator.mediaDevices.getUserMedia({
      video: {
        width: { ideal: 1280, max: 1920 },
        height: { ideal: 720, max: 1080 },
        frameRate: { ideal: 30, max: 60 }
      },
      audio: {
        echoCancellation: true,
        noiseSuppression: true,
        autoGainControl: true
      }
    });

    this.localVideo.srcObject = this.localStream;
  }

  private async createPeerConnection(): Promise<void> {
    this.peerConnection = new RTCPeerConnection(this.rtcConfiguration);

    // Add local stream to peer connection
    if (this.localStream) {
      this.localStream.getTracks().forEach(track => {
        this.peerConnection!.addTrack(track, this.localStream!);
      });
    }

    this.peerConnection.onicecandidate = (event) => {
      if (event.candidate) {
        this.sendMessage({
          type: 'ice-candidate',
          data: event.candidate
        });
      }
    };

    this.peerConnection.onconnectionstatechange = () => {
      console.log('Connection state:', this.peerConnection?.connectionState);
    };
  }

  private async startSFUNegotiation(): Promise<void> {
    // Simulate SFU negotiation process
    // In a real SFU implementation, this would involve:
    // 1. Getting router RTP capabilities
    // 2. Creating WebRTC transport
    // 3. Connecting transport
    // 4. Creating producers for audio/video

    this.sendMessage({ type: 'getRouterRtpCapabilities' });
    
    // Simulate successful setup
    setTimeout(() => {
      this.sendMessage({ type: 'createWebRtcTransport' });
    }, 100);

    setTimeout(() => {
      this.sendMessage({
        type: 'connectWebRtcTransport',
        data: { dtlsParameters: { fingerprints: [], role: 'client' } }
      });
    }, 200);

    setTimeout(() => {
      if (this.localStream) {
        const videoTrack = this.localStream.getVideoTracks()[0];
        const audioTrack = this.localStream.getAudioTracks()[0];
        
        if (videoTrack) {
          this.sendMessage({
            type: 'produce',
            data: {
              kind: 'video',
              rtpParameters: { codecs: [], encodings: [] }
            }
          });
        }
        
        if (audioTrack) {
          this.sendMessage({
            type: 'produce',
            data: {
              kind: 'audio',
              rtpParameters: { codecs: [], encodings: [] }
            }
          });
        }
      }
    }, 300);
  }

  private sendMessage(message: SFUMessage): void {
    if (this.ws && this.ws.readyState === WebSocket.OPEN) {
      this.ws.send(JSON.stringify(message));
    }
  }

  private updateStatus(status: string, className: string): void {
    this.statusElement.textContent = status;
    this.statusElement.className = `status ${className}`;
  }

  private setButtonStates(startEnabled: boolean, stopEnabled: boolean): void {
    this.startButton.disabled = !startEnabled;
    this.stopButton.disabled = !stopEnabled;
  }

  private updateStats(): void {
    this.subscribersCountElement.textContent = '0';
    this.producersCountElement.textContent = this.isStreaming ? '2' : '0';
  }

  private resetStats(): void {
    this.subscribersCountElement.textContent = '0';
    this.producersCountElement.textContent = '0';
  }
}

new SFUPublisher();