import SwiftUI

struct AppLockView: View {
    @Binding var isUnlocked: Bool
    @AppStorage("faceIdEnabled") private var faceIdEnabled = false
    @AppStorage("pinEnabled") private var pinEnabled = false

    @State private var pin = ""
    @State private var errorMessage: String?
    @State private var didAttemptBiometrics = false
    @FocusState private var pinFocused: Bool

    var body: some View {
        ZStack {
            Color(.systemBackground)
                .ignoresSafeArea()

            VStack(spacing: 20) {
                Spacer()

                Image("BrandMark")
                    .resizable()
                    .scaledToFit()
                    .frame(width: 64, height: 64)

                Text("Locked")
                    .font(.title.weight(.bold))

                Text("Unlock Portfolio Journal to view your data.")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, 30)

                if faceIdEnabled {
                    Button {
                        authenticateWithBiometrics()
                    } label: {
                        Label("Unlock with Face ID", systemImage: "faceid")
                            .font(.headline)
                            .frame(maxWidth: .infinity)
                            .padding()
                            .background(Color.appPrimary)
                            .foregroundColor(.white)
                            .cornerRadius(AppConstants.UI.cornerRadius)
                    }
                    .padding(.horizontal, 24)
                }

                if pinEnabled {
                    VStack(spacing: 10) {
                        SecureField("4-digit PIN", text: $pin)
                            .keyboardType(.numberPad)
                            .textContentType(.oneTimeCode)
                            .multilineTextAlignment(.center)
                            .font(.title3.weight(.semibold))
                            .padding()
                            .background(Color.gray.opacity(0.1))
                            .cornerRadius(12)
                            .focused($pinFocused)
                            .onChange(of: pin) { _, newValue in
                                pin = String(newValue.filter(\.isNumber).prefix(4))
                                errorMessage = nil
                                if pin.count == 4 {
                                    validatePin()
                                }
                            }

                        Button("Unlock") {
                            validatePin()
                        }
                        .font(.subheadline.weight(.semibold))
                        .disabled(pin.count < 4)
                    }
                    .padding(.horizontal, 24)
                }

                if let errorMessage {
                    Text(errorMessage)
                        .font(.caption)
                        .foregroundColor(.negativeRed)
                }

                Spacer()
            }
        }
        .onAppear {
            if faceIdEnabled && !didAttemptBiometrics {
                didAttemptBiometrics = true
                authenticateWithBiometrics()
            } else if pinEnabled {
                pinFocused = true
            }
        }
    }

    private func authenticateWithBiometrics() {
        AppLockService.authenticate(reason: "Unlock your portfolio") { success in
            if success {
                isUnlocked = true
            } else if pinEnabled {
                pinFocused = true
            } else {
                errorMessage = "Face ID failed. Please try again."
            }
        }
    }

    private func validatePin() {
        guard let storedPin = KeychainService.readPin() else {
            errorMessage = "PIN not set."
            pin = ""
            return
        }
        if pin == storedPin {
            isUnlocked = true
            pin = ""
            errorMessage = nil
        } else {
            errorMessage = "Incorrect PIN."
            pin = ""
        }
    }
}