import Foundation
import Observation

@Observable
final class AppViewModel {

    enum Route: Equatable {
        case onboarding
        case login
        case lock
        case home
    }

    private(set) var route: Route

    init() {
        route = AppViewModel.initialRoute()
    }

    // MARK: - Route transitions (called by child views)

    func completeOnboarding() {
        UserDefaults.standard.set(true, forKey: "onboarding_done")
        route = .login
    }

    func loginSucceeded() {
        route = AppViewModel.requiresLock() ? .lock : .home
    }

    func unlock() {
        route = .home
    }

    func lock() {
        route = .lock
    }

    func logout() {
        route = .login
    }

    // MARK: - Private

    private static func initialRoute() -> Route {
        guard UserDefaults.standard.bool(forKey: "onboarding_done") else {
            return .onboarding
        }
        guard CredentialStore.shared.hasAnyCredentials() else {
            return .login
        }
        return requiresLock() ? .lock : .home
    }

    private static func requiresLock() -> Bool {
        let method = UserDefaults.standard.string(forKey: "security_method") ?? ""
        return !method.isEmpty && method != "none"
    }
}