import Foundation
import LocalAuthentication

/// Biometric hardware available on this device. Never assume Face ID: iPad and
/// iPhone Duo can ship with Touch ID, Vision Pro with Optic ID.
enum BiometryKind {
    case faceID
    case touchID
    case opticID
    case none

    /// Marketing name shown in UI ("Face ID", "Touch ID", "Optic ID"). Falls back
    /// to a generic label when no biometry is available (e.g. not enrolled).
    var displayName: String {
        switch self {
        case .faceID: return "Face ID"
        case .touchID: return "Touch ID"
        case .opticID: return "Optic ID"
        case .none: return String(localized: "biometric_generic_name")
        }
    }

    /// SF Symbol matching the hardware.
    var systemImage: String {
        switch self {
        case .faceID: return "faceid"
        case .touchID: return "touchid"
        case .opticID: return "opticid"
        case .none: return "lock.shield"
        }
    }
}

enum AppLockService {
    static func canUseBiometrics() -> Bool {
        let context = LAContext()
        var error: NSError?
        return context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error)
    }

    /// The biometry type reported by the system. `biometryType` is only populated
    /// after `canEvaluatePolicy` runs, and stays set even when not enrolled.
    static var biometryKind: BiometryKind {
        let context = LAContext()
        var error: NSError?
        _ = context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error)
        switch context.biometryType {
        case .faceID: return .faceID
        case .touchID: return .touchID
        case .opticID: return .opticID
        case .none: return .none
        @unknown default: return .none
        }
    }

    /// Localized biometry name for user-facing text.
    static var biometryName: String { biometryKind.displayName }

    static func authenticate(reason: String, completion: @escaping (Bool) -> Void) {
        let context = LAContext()
        context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, _ in
            DispatchQueue.main.async {
                completion(success)
            }
        }
    }
}