import SwiftUI
import AVFoundation
import UIKit

struct ContentView: View {
    var body: some View {
        QRScanView()
    }
}




struct QRScanView: UIViewControllerRepresentable {
    func makeUIViewController(context: Context) -> some UIViewController {
        return QRScanViewController()
    }
    
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        
    }
   
}


class QRScanViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    var session: AVCaptureSession!
    var previewLayer: AVCaptureVideoPreviewLayer!

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = UIColor.black
        session = AVCaptureSession()

        guard let device = AVCaptureDevice.default(for: .video) else { return }
        let videoInput: AVCaptureDeviceInput

        do {
            videoInput = try AVCaptureDeviceInput(device: device)
        } catch {
            return
        }

        if (session.canAddInput(videoInput)) {
            session.addInput(videoInput)
        } else {
            failed()
            return
        }

        let metadataOutput = AVCaptureMetadataOutput()

        if (session.canAddOutput(metadataOutput)) {
            session.addOutput(metadataOutput)

            metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            metadataOutput.metadataObjectTypes = [.qr]
        } else {
            failed()
            return
        }

        previewLayer = AVCaptureVideoPreviewLayer(session: session)
        previewLayer.frame = view.layer.bounds
        previewLayer.videoGravity = .resizeAspectFill
        view.layer.addSublayer(previewLayer)

        session.startRunning()
    }

    func failed() {
        let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default))
        present(ac, animated: true)
        session = nil
    }

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

        if (session?.isRunning == false) {
            session.startRunning()
        }
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        if (session?.isRunning == true) {
            session.stopRunning()
        }
    }

    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        session.stopRunning()

        if let metadataObject = metadataObjects.first {
            guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return }
            guard let stringValue = readableObject.stringValue else { return }
            AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
            found(code: stringValue)
        }

        dismiss(animated: true)
    }

    func found(code: String) {
        print(code)
    }

    override var prefersStatusBarHidden: Bool {
        return true
    }

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return .portrait
    }
}