import SwiftUI
import Combine

/// Central store for the "Hide balances" privacy feature.
///
/// When `balancesHidden` is true, every monetary amount in the app renders
/// redacted (a blurred bullet mask) instead of the real value. This lets the
/// user open the app in public or take screenshots without exposing net worth.
///
/// If `requireBiometricToReveal` is enabled, un-hiding balances must first pass
/// Face ID / biometric auth (reusing `AppLockService`). On failure, balances
/// stay hidden.
///
/// State is persisted in `UserDefaults` so it survives relaunches, and mirrored
/// into `@Published` properties so SwiftUI views observing this object update
/// instantly when the user taps the quick toggle.
@MainActor
final class BalancePrivacyManager: ObservableObject {
    static let shared = BalancePrivacyManager()

    private enum Keys {
        static let balancesHidden = "balancesHidden"
        static let requireBiometricToReveal = "requireBiometricToReveal"
    }

    /// When true, all monetary amounts render redacted.
    @Published var balancesHidden: Bool {
        didSet { UserDefaults.standard.set(balancesHidden, forKey: Keys.balancesHidden) }
    }

    /// When true, revealing hidden balances requires biometric auth.
    @Published var requireBiometricToReveal: Bool {
        didSet { UserDefaults.standard.set(requireBiometricToReveal, forKey: Keys.requireBiometricToReveal) }
    }

    init() {
        self.balancesHidden = UserDefaults.standard.bool(forKey: Keys.balancesHidden)
        self.requireBiometricToReveal = UserDefaults.standard.bool(forKey: Keys.requireBiometricToReveal)
    }

    /// Toggle balance visibility. Hiding is always immediate. Revealing, when
    /// `requireBiometricToReveal` is on and biometrics are available, runs a
    /// Face ID prompt first and only reveals on success.
    func toggleHidden() {
        if balancesHidden {
            reveal()
        } else {
            balancesHidden = true
        }
    }

    /// Attempt to reveal balances, honoring the biometric requirement.
    func reveal() {
        guard balancesHidden else { return }
        if requireBiometricToReveal && AppLockService.canUseBiometrics() {
            AppLockService.authenticate(reason: "Reveal your balances") { [weak self] success in
                if success {
                    self?.balancesHidden = false
                }
                // On failure, stay hidden — do nothing.
            }
        } else {
            balancesHidden = false
        }
    }
}