import AppKit
import AVFoundation

class CapturaCaptureSession: AVCaptureSession, AVCaptureFileOutputRecordingDelegate, AVCaptureVideoDataOutputSampleBufferDelegate {

  let videoOutput = AVCaptureVideoDataOutput()
  let movieFileOutput = AVCaptureMovieFileOutput()
  var receivedFrames = false
  
  init(_ screen: NSScreen, box: NSRect) {
    super.init()
    
    let displayId = screen.deviceDescription[NSDeviceDescriptionKey("NSScreenNumber")] as! CGDirectDisplayID
    let screenInput = AVCaptureScreenInput(displayID: displayId)
    screenInput?.cropRect = box.insetBy(dx: 1, dy: 1)
    
    if self.canAddInput(screenInput!) {
      self.addInput(screenInput!)
    }
    
    videoOutput.setSampleBufferDelegate(self, queue: Dispatch.DispatchQueue(label: "sample buffer delegate", attributes: []))
    
    if self.canAddOutput(videoOutput) {
      self.addOutput(videoOutput)
    }
    
    if self.canAddOutput(movieFileOutput) {
      self.addOutput(movieFileOutput)
    }
  }
  
  func startRecording() {
    receivedFrames = false
    self.startRunning()
    
    DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
      if !self.receivedFrames {
        NotificationCenter.default.post(name: .failedToStart, object: nil, userInfo: nil)
      }
    }
  }
  
  func startRecording(to url: URL) {
    self.startRecording()
    movieFileOutput.startRecording(to: url, recordingDelegate: self)
  }
  
  // MARK: - AVCaptureVideoDataOutputSampleBufferDelegate Implementation
  
  func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    receivedFrames = true
    
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
    NotificationCenter.default.post(name: .receivedFrame, object: nil, userInfo: ["frame": imageBuffer])
  }
  
  // MARK: - AVCaptureFileOutputRecordingDelegate Implementation
  
  func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {}
}