import SwiftUI
import AVFoundation

struct QrScanView: View {
    @Environment(\.dismiss) var dismiss
    var onResult: (String, String) -> Void  // (value, type)

    static let TYPE_MAC = "mac"
    static let TYPE_UUID = "uuid"
    static let TYPE_UNKNOWN = "unknown"

    var body: some View {
        ZStack {
            CameraPreviewView(onQrDetected: { rawValue in
                let parsed = parseQrData(rawValue)
                onResult(parsed.value, parsed.type)
                dismiss()
            })
            .ignoresSafeArea()

            // Scan frame overlay
            VStack {
                Spacer()

                RoundedRectangle(cornerRadius: 12)
                    .stroke(Color.white.opacity(0.7), lineWidth: 2)
                    .frame(width: 250, height: 250)

                Spacer()
            }

            // Toolbar overlay
            VStack {
                HStack {
                    Button(action: { dismiss() }) {
                        Image(systemName: "xmark")
                            .font(.title2)
                            .foregroundColor(.white)
                            .padding()
                    }
                    Spacer()
                    Text("Scan QR Code")
                        .font(.headline)
                        .foregroundColor(.white)
                    Spacer()
                    // Balance spacer
                    Color.clear.frame(width: 44, height: 44)
                }
                .background(Color.black.opacity(0.3))

                Spacer()

                Text("Point camera at beacon sticker QR code")
                    .foregroundColor(.white)
                    .font(.callout)
                    .padding()
                    .background(Color.black.opacity(0.5))
                    .cornerRadius(8)
                    .padding(.bottom, 60)

                Button("Cancel") {
                    dismiss()
                }
                .foregroundColor(.white)
                .padding()
                .padding(.bottom, 20)
            }
        }
        .modifier(DevBanner())
    }

    private func parseQrData(_ raw: String) -> (value: String, type: String) {
        let trimmed = raw.trimmingCharacters(in: .whitespaces).uppercased()

        // MAC address with colons: AA:BB:CC:DD:EE:FF
        if trimmed.range(of: "^[0-9A-F]{2}(:[0-9A-F]{2}){5}$", options: .regularExpression) != nil {
            return (trimmed, QrScanView.TYPE_MAC)
        }
        // MAC address without separators: AABBCCDDEEFF (12 hex chars)
        if trimmed.range(of: "^[0-9A-F]{12}$", options: .regularExpression) != nil {
            return (formatMac(trimmed), QrScanView.TYPE_MAC)
        }
        // MAC address with dashes: AA-BB-CC-DD-EE-FF
        if trimmed.range(of: "^[0-9A-F]{2}(-[0-9A-F]{2}){5}$", options: .regularExpression) != nil {
            return (trimmed.replacingOccurrences(of: "-", with: ":"), QrScanView.TYPE_MAC)
        }
        // UUID with dashes
        if trimmed.range(of: "^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$", options: .regularExpression) != nil {
            return (trimmed, QrScanView.TYPE_UUID)
        }
        // UUID without dashes (32 hex chars)
        if trimmed.range(of: "^[0-9A-F]{32}$", options: .regularExpression) != nil {
            return (formatUuid(trimmed), QrScanView.TYPE_UUID)
        }
        return (trimmed, QrScanView.TYPE_UNKNOWN)
    }

    private func formatMac(_ hex: String) -> String {
        var result: [String] = []
        var idx = hex.startIndex
        for _ in 0..<6 {
            let next = hex.index(idx, offsetBy: 2)
            result.append(String(hex[idx..<next]))
            idx = next
        }
        return result.joined(separator: ":")
    }

    private func formatUuid(_ hex: String) -> String {
        return BeaconBanList.formatUuid(hex)
    }
}

// MARK: - Camera Preview UIKit wrapper

struct CameraPreviewView: UIViewControllerRepresentable {
    var onQrDetected: (String) -> Void

    func makeUIViewController(context: Context) -> QrCameraViewController {
        let vc = QrCameraViewController()
        vc.onQrDetected = onQrDetected
        return vc
    }

    func updateUIViewController(_ uiViewController: QrCameraViewController, context: Context) {}
}

class QrCameraViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    var onQrDetected: ((String) -> Void)?
    private var captureSession: AVCaptureSession?
    private var hasScanned = false

    override func viewDidLoad() {
        super.viewDidLoad()

        let session = AVCaptureSession()
        captureSession = session

        guard let device = AVCaptureDevice.default(for: .video),
              let input = try? AVCaptureDeviceInput(device: device) else {
            return
        }

        if session.canAddInput(input) {
            session.addInput(input)
        }

        let output = AVCaptureMetadataOutput()
        if session.canAddOutput(output) {
            session.addOutput(output)
            output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            output.metadataObjectTypes = [.qr]
        }

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

        DispatchQueue.global(qos: .userInitiated).async {
            session.startRunning()
        }
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        if let layer = view.layer.sublayers?.first as? AVCaptureVideoPreviewLayer {
            layer.frame = view.bounds
        }
    }

    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject],
                        from connection: AVCaptureConnection) {
        guard !hasScanned else { return }

        for object in metadataObjects {
            guard let readableObject = object as? AVMetadataMachineReadableCodeObject,
                  let value = readableObject.stringValue, !value.isEmpty else {
                continue
            }
            hasScanned = true
            captureSession?.stopRunning()
            onQrDetected?(value)
            return
        }
    }

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