import SwiftUI
import LocalAuthentication

/// OTP Login screen + biometric auth (matches Android LoginActivity)
struct LoginView: View {
    @EnvironmentObject var appState: AppState

    @State private var phone = ""
    @State private var otpCode = ""
    @State private var otpUUID = ""
    @State private var showOTPField = false
    @State private var isLoading = false
    @State private var errorMessage: String?

    var body: some View {
        NavigationStack {
            VStack(spacing: 32) {
                Spacer()

                // Logo
                Image(systemName: "antenna.radiowaves.left.and.right")
                    .font(.system(size: 64))
                    .foregroundStyle(Color.payfritGreen)

                Text("Payfrit Beacon")
                    .font(.title.bold())

                Text("Provision beacons for your business")
                    .font(.subheadline)
                    .foregroundStyle(.secondary)

                // Phone input
                VStack(spacing: 16) {
                    TextField("Phone number", text: $phone)
                        .keyboardType(.phonePad)
                        .textContentType(.telephoneNumber)
                        .padding()
                        .background(.quaternary, in: RoundedRectangle(cornerRadius: 12))
                        .disabled(showOTPField)

                    if showOTPField {
                        TextField("Enter OTP code", text: $otpCode)
                            .keyboardType(.numberPad)
                            .textContentType(.oneTimeCode)
                            .padding()
                            .background(.quaternary, in: RoundedRectangle(cornerRadius: 12))
                    }

                    if let error = errorMessage {
                        Text(error)
                            .font(.caption)
                            .foregroundStyle(Color.errorRed)
                    }

                    Button(action: handleAction) {
                        if isLoading {
                            ProgressView()
                                .tint(.white)
                        } else {
                            Text(showOTPField ? "Verify OTP" : "Send OTP")
                        }
                    }
                    .buttonStyle(.borderedProminent)
                    .controlSize(.large)
                    .disabled(isLoading || (showOTPField ? otpCode.isEmpty : phone.isEmpty))
                }
                .padding(.horizontal, 32)

                Spacer()
                Spacer()
            }
            .navigationBarTitleDisplayMode(.inline)
        }
        .task {
            // Try biometric login on appear
            await tryBiometricLogin()
        }
    }

    private func handleAction() {
        Task {
            if showOTPField {
                await verifyOTP()
            } else {
                await sendOTP()
            }
        }
    }

    private func sendOTP() async {
        isLoading = true
        errorMessage = nil

        do {
            let uuid = try await APIClient.shared.sendOTP(phone: phone)
            otpUUID = uuid
            showOTPField = true
        } catch {
            errorMessage = error.localizedDescription
        }

        isLoading = false
    }

    private func verifyOTP() async {
        isLoading = true
        errorMessage = nil

        do {
            let result = try await APIClient.shared.verifyOTP(uuid: otpUUID, code: otpCode)
            appState.didLogin(token: result.token, userId: result.userId)
        } catch {
            errorMessage = error.localizedDescription
        }

        isLoading = false
    }

    private func tryBiometricLogin() async {
        guard let session = SecureStorage.loadSession() else { return }

        let context = LAContext()
        var authError: NSError?

        guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &authError) else {
            return
        }

        do {
            let success = try await context.evaluatePolicy(
                .deviceOwnerAuthenticationWithBiometrics,
                localizedReason: "Log in to Payfrit Beacon"
            )
            if success {
                appState.didLogin(token: session.token, userId: session.userId)
            }
        } catch {
            // Biometric failed — show manual login
        }
    }
}