//
//  ScannerViewController.swift
//  scanner
//
//  Created by Alva on 2020/5/25.
//  Copyright © 2020 Alva. All rights reserved.
//

import SwiftUI
import AVFoundation

var SCREENWidth = UIScreen.main.bounds.size.width
var SCREENHeight = UIScreen.main.bounds.size.height
let QRCodeWidth = Double(min(SCREENWidth, SCREENHeight)) / 1.5
let RATIO = 0.45

enum ArgumentsEnum: String {
  case title = "SCAN_TITLE"
  case laserColor = "LASER_COLOR"
  case titleColor = "TITLE_COLOR"
  case playBeep = "KEY_PLAY_BEEP"
  case scanWidth = "SCAN_WIDTH"
  case scanHeight = "SCAN_HEIGHT"
  case promptMessage = "PROMPT_MESSAGE"
  case permissionDeniedMessage = "PERMISSION_DENIED_MESSAGE"
  case confirmText = "MESSAGE_CONFIRM_TEXT"
  case cancelText = "MESSAGE_CANCEL_TEXT"
  func getKeyValue<T>(dictionary: NSDictionary) -> T? {
    guard let result =  dictionary[self.rawValue] as? T else {
      return nil
    }
    return result
  }
}

protocol ScannerDelegate: class {
  func didScanWithResult(code: String)
  func didFailWithErrorCode(code: String)
}

class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

  @IBOutlet private var camera: UIView!
  private var session: AVCaptureSession? = nil
  private var top = 0.0

  var bundle: Bundle? = nil

  var currentOrientation = UIInterfaceOrientationMask.portrait

  weak var delegate: ScannerDelegate?

  var arguments: NSDictionary = [:]
  var laserColor: UIColor = UIColor.clear
  var promptMessage: String?
  var permissionDeniedText: String = "Your privacy settings seem to prevent us from accessing your camera for barcode scanning. You can fix it by doing this, touch the OK button below to open the Settings and then turn the Camera on."
  var confirmText: String = "OK"
  var cancelText: String = "Cancel"

  var windowOrientation: UIInterfaceOrientation {
    if #available(iOS 13.0, *) {
      return view.window?.windowScene?.interfaceOrientation ?? .unknown
    } else {
      return UIApplication.shared.statusBarOrientation
    }
  }

  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
  }

  init() {
    super.init(nibName: nil, bundle: nil)
    let mainBundle = Bundle(for: type(of: self))
    let url = mainBundle.url(forResource: "FlutterScannerBundle", withExtension: "bundle")

    if let url = url {
      bundle = Bundle(url: url)
    }
    if(bundle == nil) {
      return
    }
    getCurrentOrientation()
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    initArguments()
    setupNavigationBar()
  }

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    checkAuthorization()
  }

  override var shouldAutorotate: Bool {
    get {
      return false
    }
  }

  override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
    get {
      return currentOrientation
    }
  }

  override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    session?.stopRunning()

    SCREENWidth = UIScreen.main.bounds.size.width
    SCREENHeight = UIScreen.main.bounds.size.height
    checkAuthorization()
  }

  func getCurrentOrientation(){
    switch UIDevice.current.orientation {
    case UIDeviceOrientation.faceDown:
      break
    case UIDeviceOrientation.unknown:
      break
    case UIDeviceOrientation.portrait:
      break
    case UIDeviceOrientation.portraitUpsideDown:
      break
    case UIDeviceOrientation.faceUp:
      break
    case UIDeviceOrientation.landscapeLeft:
      currentOrientation = UIInterfaceOrientationMask.landscapeRight
      break
    case UIDeviceOrientation.landscapeRight:
      currentOrientation = UIInterfaceOrientationMask.landscapeLeft
      break
    @unknown default:
      break
    }
  }

  func initArguments() {
    SCREENWidth = UIScreen.main.bounds.size.width
    SCREENHeight = UIScreen.main.bounds.size.height

    if let titleHex: String = ArgumentsEnum.title.getKeyValue(dictionary: arguments) {
      self.title = titleHex
    }
    if let laserColorHex: String = ArgumentsEnum.laserColor.getKeyValue(dictionary: arguments) {
      laserColor = UIColor(hexString: laserColorHex) ?? UIColor.clear
    }
    if let promptMessageHex: String = ArgumentsEnum.promptMessage.getKeyValue(dictionary: arguments) {
      promptMessage = promptMessageHex
    }
    if let permissionDeniedTextHex: String = ArgumentsEnum.permissionDeniedMessage.getKeyValue(dictionary: arguments) {
      permissionDeniedText = permissionDeniedTextHex
    }
    if let confirmTextHex: String = ArgumentsEnum.confirmText.getKeyValue(dictionary: arguments) {
      confirmText = confirmTextHex
    }
    if let cancelTextHex: String = ArgumentsEnum.cancelText.getKeyValue(dictionary: arguments) {
      cancelText = cancelTextHex
    }
  }

  func checkAuthorization(){
    /*
    Check the video authorization status. Video access is required and audio
    access is optional. If the user denies audio access, AVCam won't
    record audio during movie recording.
    */
    switch AVCaptureDevice.authorizationStatus(for: .video) {
      case .authorized:
        self.setupMaskView()
        self.beginScanning()
        break
      case .notDetermined:
        AVCaptureDevice.requestAccess(for: .video, completionHandler: { granted in
          if !granted {
            self.permissionDenied()
          }
          self.setupMaskView()
          self.beginScanning()
        })
      default:
        self.permissionDenied()
    }
  }

  func permissionDenied(){
    DispatchQueue.main.async {
      let alertController = UIAlertController(title: self.title, message: self.permissionDeniedText, preferredStyle: .alert)
      let confirmAction = UIAlertAction(title: self.confirmText, style: .default) { (action) in
        if let url = URL(string: UIApplication.openSettingsURLString) {
          if #available(iOS 10, *) {
            UIApplication.shared.open(url, options: [:], completionHandler: {
              (success) in
                self.dismiss(animated: true, completion: nil)
            })
          } else {
            UIApplication.shared.openURL(url)
            self.dismiss(animated: true, completion: nil)
          }
        }
      }
      let cancelAction = UIAlertAction(title: self.cancelText, style: .default) { (action) in
        self.dismiss(animated: true, completion: nil)
      }
      alertController.addAction(confirmAction)
      alertController.addAction(cancelAction)
      self.present(alertController, animated: true)
    }
  }

  func setupMaskView() {
    UINib.init(nibName: "FlutterQrScanner", bundle: bundle!).instantiate(withOwner: self, options: nil)

    var scanY = Double(SCREENHeight) - top - QRCodeWidth
    scanY = scanY * RATIO
    let frame = CGRect(x: (Double(SCREENWidth) - QRCodeWidth) / 2.0, y: scanY, width: QRCodeWidth, height: QRCodeWidth)

    let backgroundView = UIView(frame: UIScreen.main.bounds)
    backgroundView.backgroundColor =  UIColor.init(red: 0, green: 0, blue: 0, alpha: 0.6)
    camera.addSubview(backgroundView)

    let maskLayer = CAShapeLayer()
    maskLayer.fillRule = CAShapeLayerFillRule.evenOdd // fill rule
    let basicPath = UIBezierPath(rect: UIScreen.main.bounds) // basic
    let maskPath = UIBezierPath(roundedRect: frame, cornerRadius: 15)
    basicPath.append(maskPath) // recover
    maskLayer.path = basicPath.cgPath

    backgroundView.layer.mask = maskLayer

    let scanBorder = BorderCanvas(frame: frame, border: laserColor)
    camera.addSubview(scanBorder)

    let scanWindow = UIView(frame: frame)
    scanWindow.clipsToBounds = true
    camera.addSubview(scanWindow)

    let winMaskLayer = CAShapeLayer()
    // fill rule
    winMaskLayer.fillRule = CAShapeLayerFillRule.evenOdd
    let winFrame = CGRect(x: 0, y: 0, width: QRCodeWidth, height: QRCodeWidth)
    let winBasicPath = UIBezierPath(rect: winFrame)
    let winMaskPath = UIBezierPath(rect: winFrame)
    let winMaskPath2 = UIBezierPath(roundedRect: winFrame, cornerRadius: 15)
    winBasicPath.append(winMaskPath)
    winBasicPath.append(winMaskPath2)
    winMaskLayer.path = winBasicPath.cgPath

    scanWindow.layer.mask = winMaskLayer

    //scan window animation
    let scanNetImageViewH = scanWindow.frame.size.height
    let scanNetImageViewW = scanWindow.frame.size.width
    let scanNetImageView = UIImageView(image: UIImage.init(named: "scannet", in: bundle!, compatibleWith: nil))
    scanNetImageView.frame = CGRect(x: 0, y: -scanNetImageViewH, width: scanNetImageViewW, height: scanNetImageViewH)
    let scanNetAnimation = CABasicAnimation(keyPath: "transform.translation.y")
    scanNetAnimation.byValue = NSNumber(value: QRCodeWidth)
    scanNetAnimation.duration = 1.5
    scanNetAnimation.repeatCount = MAXFLOAT
    scanNetImageView.layer.add(scanNetAnimation, forKey: "animation")
    scanWindow.addSubview(scanNetImageView)

    let promptSize = CGSize(width: Double(SCREENWidth) - 30, height: 0)
    let promptRect = (promptMessage ?? "").boundingRect(with: promptSize, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: nil , context: nil)
    let promptLabel = UILabel(frame: CGRect(x: 15, y: scanY + QRCodeWidth + 30, width: Double(SCREENWidth) - 30, height: Double(promptRect.size.height)))
    promptLabel.textColor = UIColor.gray
    promptLabel.text = promptMessage
    promptLabel.textAlignment = NSTextAlignment.center
    camera.addSubview(promptLabel)
  }

  func setupNavigationBar(){
    let navHeight = self.navigationController?.navigationBar.bounds.height ?? 20
    let backButton = UIButton(frame: CGRect(x: 0, y: 0, width: navHeight, height: navHeight))
    backButton.setImage(UIImage.init(named: "arrow_left", in: bundle!, compatibleWith: nil), for: .normal)
    backButton.setTitle("", for: .normal)
    backButton.setTitleColor(backButton.tintColor, for: .normal)
    backButton.addTarget(self, action: #selector(backButtonPressed), for: .touchUpInside)
    backButton.imageView?.contentMode = .scaleAspectFit
    self.navigationItem.leftBarButtonItem = UIBarButtonItem(customView: backButton)

    self.navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
    self.navigationController?.navigationBar.shadowImage = UIImage()
    self.navigationController?.navigationBar.isTranslucent = true
    self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white, NSAttributedString.Key.font: UIFont.systemFont(ofSize:18)]
  }

  func beginScanning() {
    //get device
    let device = AVCaptureDevice.default(for: .video)
    //create device input
    var input: AVCaptureDeviceInput? = nil
    do {
      if let device = device {
          input = try AVCaptureDeviceInput(device: device)
      }
    } catch {
      delegate?.didFailWithErrorCode(code: "")
      return
    }
    if(input == nil){
      delegate?.didFailWithErrorCode(code: "")
      return
    }
    //create device output
    let output = AVCaptureMetadataOutput()

    let xx = (Double(SCREENHeight) - QRCodeWidth - top) * RATIO
    let x = xx / Double(SCREENHeight)
    let yy = (Double(SCREENWidth) - QRCodeWidth) / 2.0
    let y = yy / Double(SCREENWidth)
    let width = QRCodeWidth / Double(SCREENHeight)
    let height = QRCodeWidth / Double(SCREENWidth)
    output.rectOfInterest = CGRect(x: x, y: y, width: width, height: height)

    output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)

    session = AVCaptureSession()
    session!.sessionPreset = .high

    if session?.canAddInput(input!) ?? false {
      session!.addInput(input!)
      session!.addOutput(output)

      //code data type
      output.metadataObjectTypes = [
        .qr,
        .ean13,
        .ean8,
        .code128
      ]

      let layer = AVCaptureVideoPreviewLayer(session: session!)
      layer.frame = CGRect(x: 0, y: 0, width: CGFloat(SCREENWidth), height: SCREENHeight - CGFloat(top))
      layer.videoGravity = .resizeAspectFill
      camera.layer.insertSublayer(layer, at: 0)

      DispatchQueue.main.async {
        /*
        Dispatch video streaming to the main queue because AVCaptureVideoPreviewLayer is the backing layer for PreviewView.
        You can manipulate UIView only on the main thread.
        Note: As an exception to the above rule, it's not necessary to serialize video orientation changes
        on the AVCaptureVideoPreviewLayer’s connection with other session manipulation.

        Use the window scene's orientation as the initial video orientation. Subsequent orientation changes are
        handled by CameraViewController.viewWillTransition(to:with:).
        */
        var initialVideoOrientation: AVCaptureVideoOrientation = .portrait
        if self.windowOrientation != .unknown {
            if let videoOrientation = AVCaptureVideoOrientation(rawValue: self.windowOrientation.rawValue) {
                initialVideoOrientation = videoOrientation
            }
        }
        layer.connection?.videoOrientation = initialVideoOrientation
      }

      //start
      session!.startRunning()
    } else {
       print("Couldn't add video device input to the session.")
       session!.commitConfiguration()
       return
    }
  }

  func metadataOutput(_ captureOutput: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
    if metadataObjects.count > 0 {
      //code result data
      let metadataObject = metadataObjects[0] as? AVMetadataMachineReadableCodeObject
      delegate?.didScanWithResult(code: metadataObject?.stringValue ?? "")
      self.dismiss(animated: true, completion: nil)
    }
  }

  @objc func backButtonPressed() {
    delegate?.didFailWithErrorCode(code: "canceled")
    self.dismiss(animated: true, completion: nil)
  }

  override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    self.session?.stopRunning()
  }
}

class BorderCanvas: UIView {
  var border: UIColor = UIColor.clear

  override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = UIColor.clear
  }

  convenience init(frame: CGRect, border: UIColor?) {
    self.init(frame: frame)
    self.border = border ?? UIColor.clear
  }

  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  override func draw(_ rect: CGRect) {
    let pathRect = self.bounds.insetBy(dx: 1, dy: 1)
    let path = UIBezierPath(roundedRect: pathRect, cornerRadius: 15)
    path.lineWidth = 3
    UIColor.clear.setFill()
    self.border.setStroke()
    path.fill()
    path.stroke()

    let maskLayer = CAShapeLayer()
    maskLayer.fillRule = CAShapeLayerFillRule.evenOdd // fill rule
    let basicPath = UIBezierPath(rect: CGRect(x: 0, y: 0, width: QRCodeWidth, height: QRCodeWidth)) // basic
    let maskPath = UIBezierPath(rect: CGRect(x: QRCodeWidth / 6, y: 0, width: QRCodeWidth * 2 / 3, height: QRCodeWidth))
    let maskPath2 = UIBezierPath(rect: CGRect(x: 0, y: QRCodeWidth / 6, width: QRCodeWidth, height: QRCodeWidth * 2 / 3))
    basicPath.append(maskPath) // recover
    basicPath.append(maskPath2) // recover
    maskLayer.path = basicPath.cgPath

    layer.mask = maskLayer
  }
}

extension AVCaptureVideoOrientation {
  init?(deviceOrientation: UIDeviceOrientation) {
    switch deviceOrientation {
      case .portrait: self = .portrait
      case .portraitUpsideDown: self = .portraitUpsideDown
      case .landscapeLeft: self = .landscapeRight
      case .landscapeRight: self = .landscapeLeft
      default: return nil
    }
  }

  init?(interfaceOrientation: UIInterfaceOrientation) {
    switch interfaceOrientation {
      case .portrait: self = .portrait
      case .portraitUpsideDown: self = .portraitUpsideDown
      case .landscapeLeft: self = .landscapeLeft
      case .landscapeRight: self = .landscapeRight
      default: return nil
    }
  }
}

extension UIColor {
  convenience init(rgba: Int) {
    self.init(
      red: CGFloat((rgba & 0x00FF0000) >> 16) / 255.0,
      green: CGFloat((rgba & 0x0000FF00) >> 8) / 255.0,
      blue: CGFloat(rgba & 0x000000FF) / 255.0,
      alpha: CGFloat((rgba & 0xFF000000) >> 24) / 255.0
    )
  }

  convenience init?(hexString: String) {
    var chars = Array(hexString.hasPrefix("#") ? hexString.dropFirst() : hexString[...])
    let red, green, blue, alpha: CGFloat
    switch chars.count {
    case 3:
      chars = chars.flatMap { [$0, $0] }
      fallthrough
    case 6:
      chars = ["F","F"] + chars
      fallthrough
    case 8:
      alpha = CGFloat(strtoul(String(chars[0...1]), nil, 16)) / 255
      red   = CGFloat(strtoul(String(chars[2...3]), nil, 16)) / 255
      green = CGFloat(strtoul(String(chars[4...5]), nil, 16)) / 255
      blue  = CGFloat(strtoul(String(chars[6...7]), nil, 16)) / 255
    default:
      return nil
    }
    self.init(red: red, green: green, blue:  blue, alpha: alpha)
  }
}