import AVFoundation

class ViewController: UIViewController, CLLocationManagerDelegate {

  @IBOutlet weak var takePhotoButton: UIButton!

  let captureSession = AVCaptureSession()
  var previewLayer: AVCaptureVideoPreviewLayer ?

    // If we find a device we'll store it here for later use
  var captureDevice: AVCaptureDevice ?

  func focusTo(value: Float) {
    if let device = captureDevice {
        if (device.lockForConfiguration(nil)) {
            device.setFocusModeLockedWithLensPosition(value, completionHandler: {
              (time) - > Void in
            })
            device.unlockForConfiguration()
          }
        }
      }

  @IBAction func takePhotoButtonPressed(sender: UIButton) {
    captureSession.sessionPreset = AVCaptureSessionPresetHigh

    let devices = AVCaptureDevice.devices()

    // Loop through all the capture devices on this phone
    for device in devices {
      // Make sure this particular device supports video
      if (device.hasMediaType(AVMediaTypeVideo)) {
        // Finally check the position and confirm we've got the back camera
        if (device.position == AVCaptureDevicePosition.Back) {
          captureDevice = device as ? AVCaptureDevice
          if captureDevice != nil {
            println("Capture device found")
            beginSession()
          }
        }
      }
    }
  }

  let screenWidth = UIScreen.mainScreen().bounds.size.width
  override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    var anyTouch = touches.anyObject() as UITouch
    var touchPercent = anyTouch.locationInView(self.view).x / screenWidth
    focusTo(Float(touchPercent))
  }

  override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
    var anyTouch = touches.anyObject() as UITouch
    var touchPercent = anyTouch.locationInView(self.view).x / screenWidth
    focusTo(Float(touchPercent))
  }

  func configureDevice() {
    if let device = captureDevice {
      device.lockForConfiguration(nil)
      device.focusMode = .Locked
      device.unlockForConfiguration()
    }

  }

  func beginSession() {

    configureDevice()

    var err: NSError ? = nil
    captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: & err))

    if err != nil {
      println("error: (err?.localizedDescription)")
    }

    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    self.view.layer.addSublayer(previewLayer)
    previewLayer ? .frame = self.view.layer.frame
    captureSession.startRunning()
  }
}