import { spawn, ChildProcess } from 'child_process';
import { EventEmitter } from 'events';

export class FrigateStreamer extends EventEmitter {
  private ffmpegProcess: ChildProcess | null = null;
  private isStreaming: boolean = false;
  private restartAttempts: number = 0;
  private readonly MAX_RESTART_ATTEMPTS = 5;
  private restartTimeout: NodeJS.Timeout | null = null;

  async start(rtspOutputUrl: string): Promise<void> {
    if (this.isStreaming) {
      console.log('Already streaming to Frigate');
      return;
    }

    try {
      // Get camera devices
      const videoDevices = await this.getVideoDevices();
      if (videoDevices.length === 0) {
        throw new Error('No video devices found');
      }

      const videoDevice = videoDevices[0]; // Use first available camera
      console.log(`Using video device: ${videoDevice}`);

      // Build FFmpeg command
      const ffmpegArgs = this.buildFfmpegArgs(videoDevice, rtspOutputUrl);

      // Start FFmpeg process
      this.ffmpegProcess = spawn('ffmpeg', ffmpegArgs, {
        stdio: ['ignore', 'pipe', 'pipe'],
      });

      this.ffmpegProcess.stdout?.on('data', (data) => {
        console.log(`FFmpeg stdout: ${data}`);
      });

      this.ffmpegProcess.stderr?.on('data', (data) => {
        // FFmpeg logs to stderr by default
        const message = data.toString();
        if (message.includes('error') || message.includes('Error')) {
          console.error(`FFmpeg error: ${message}`);
          this.emit('error', message);
        }
      });

      this.ffmpegProcess.on('close', (code) => {
        console.log(`FFmpeg process exited with code ${code}`);
        this.isStreaming = false;

        if (code !== 0 && this.restartAttempts < this.MAX_RESTART_ATTEMPTS) {
          this.restartAttempts++;
          console.log(`Restarting FFmpeg (attempt ${this.restartAttempts}/${this.MAX_RESTART_ATTEMPTS})`);
          this.restartTimeout = setTimeout(() => {
            this.start(rtspOutputUrl);
          }, 5000);
        } else if (this.restartAttempts >= this.MAX_RESTART_ATTEMPTS) {
          this.emit('maxRestartsReached');
        }
      });

      this.ffmpegProcess.on('error', (error) => {
        console.error('FFmpeg process error:', error);
        this.emit('error', error);
      });

      this.isStreaming = true;
      this.restartAttempts = 0;
      this.emit('started');
      console.log(`Streaming to ${rtspOutputUrl}`);
    } catch (error) {
      console.error('Failed to start Frigate stream:', error);
      throw error;
    }
  }

  private async getVideoDevices(): Promise<string[]> {
    return new Promise((resolve) => {
      if (process.platform === 'linux') {
        // On Linux, check for /dev/video* devices
        const { exec } = require('child_process');
        exec('ls /dev/video* 2>/dev/null', (error: Error | null, stdout: string) => {
          if (error) {
            resolve([]);
          } else {
            const devices = stdout.trim().split('\n').filter(Boolean);
            resolve(devices);
          }
        });
      } else if (process.platform === 'win32') {
        // On Windows, use DirectShow device listing
        // For simplicity, return default device name
        resolve(['video=Integrated Camera']);
      } else if (process.platform === 'darwin') {
        // On macOS, use AVFoundation
        resolve(['0']); // Device index
      } else {
        resolve([]);
      }
    });
  }

  private buildFfmpegArgs(videoDevice: string, rtspOutputUrl: string): string[] {
    const baseArgs: string[] = [];

    if (process.platform === 'linux') {
      baseArgs.push(
        '-f', 'v4l2',
        '-input_format', 'mjpeg',
        '-framerate', '15',
        '-video_size', '640x480',
        '-i', videoDevice
      );
    } else if (process.platform === 'win32') {
      baseArgs.push(
        '-f', 'dshow',
        '-framerate', '15',
        '-video_size', '640x480',
        '-i', videoDevice
      );
    } else if (process.platform === 'darwin') {
      baseArgs.push(
        '-f', 'avfoundation',
        '-framerate', '15',
        '-video_size', '640x480',
        '-i', videoDevice
      );
    }

    // Output settings for RTSP
    baseArgs.push(
      '-c:v', 'libx264',
      '-preset', 'ultrafast',
      '-tune', 'zerolatency',
      '-profile:v', 'baseline',
      '-level', '3.1',
      '-pix_fmt', 'yuv420p',
      '-g', '30', // Keyframe interval
      '-b:v', '1M',
      '-bufsize', '1M',
      '-f', 'rtsp',
      '-rtsp_transport', 'tcp',
      rtspOutputUrl
    );

    return baseArgs;
  }

  async stop(): Promise<void> {
    if (this.restartTimeout) {
      clearTimeout(this.restartTimeout);
      this.restartTimeout = null;
    }

    if (this.ffmpegProcess) {
      this.ffmpegProcess.kill('SIGTERM');

      // Force kill if still running after 5 seconds
      setTimeout(() => {
        if (this.ffmpegProcess && !this.ffmpegProcess.killed) {
          this.ffmpegProcess.kill('SIGKILL');
        }
      }, 5000);

      this.ffmpegProcess = null;
    }

    this.isStreaming = false;
    this.restartAttempts = 0;
    this.emit('stopped');
  }

  isActive(): boolean {
    return this.isStreaming;
  }
}