import Foundation
import Observation

@Observable
@MainActor
final class AuthSession {
    var token: String?
    var userName: String?
    var isPremium: Bool = false
    var profile: UserProfile?
    var isLoggingIn: Bool = false
    var errorMessage: String?

    private let tokenKey = "by_token"

    init() {
        if let savedToken = KeychainStore.read(tokenKey) {
            token = savedToken
            APIClient.shared.token = savedToken
        }
        NotificationCenter.default.addObserver(
            forName: .apiUnauthorized,
            object: nil,
            queue: .main
        ) { [weak self] _ in
            Task { @MainActor in self?.logout() }
        }
    }

    var isLoggedIn: Bool { token != nil }

    func login(email: String, password: String) async {
        isLoggingIn = true
        errorMessage = nil
        defer { isLoggingIn = false }
        do {
            let response: LoginResponse = try await APIClient.shared.post(
                "/api/auth/login",
                body: LoginRequest(email: email, password: password)
            )
            KeychainStore.save(response.token, for: tokenKey)
            APIClient.shared.token = response.token
            self.token = response.token
            self.userName = response.name
            self.isPremium = response.isPremium
        } catch {
            self.errorMessage = error.localizedDescription
        }
    }

    func logout() {
        KeychainStore.delete(tokenKey)
        APIClient.shared.token = nil
        token = nil
        userName = nil
        isPremium = false
        profile = nil
    }

    /// Fetches the full user profile from /api/auth/me. Called after login and
    /// when MainTabView appears, so admin/founder/role info shows up.
    func loadProfile() async {
        guard token != nil else { return }
        do {
            let me: UserProfile = try await APIClient.shared.get("/api/auth/me")
            self.profile = me
            if let premium = me.isPremium {
                self.isPremium = premium
            }
        } catch {
            // Profil-Refresh ist non-critical; Settings zeigt sonst nur die Basics.
            // Loggen ist trotzdem nützlich, damit Decode-Fehler nicht stillschweigend untergehen.
            print("loadProfile failed: \(error)")
        }
    }
}