import Foundation
import LocalAuthentication
import os.log

@MainActor
final class LoginViewModel: ObservableObject {
    @Published var showMoreSheet = false
    @Published var isAuthenticating = false
    @Published var authError: String? = nil

    var onAuthenticated: (() -> Void)?

    private let logger = Logger(subsystem: "com.albert.nasbackup", category: "Login")

    func authenticateWithFaceID() {
        logger.info("Face ID authentication started")
        isAuthenticating = true
        authError = nil
        let context = LAContext()
        var error: NSError?
        guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {
            let reason = error?.localizedDescription ?? "unknown"
            logger.error("Face ID not available: \(reason, privacy: .public)")
            authError = "Face ID not available"
            isAuthenticating = false
            return
        }
        context.evaluatePolicy(
            .deviceOwnerAuthenticationWithBiometrics,
            localizedReason: "Sign in to Kisani"
        ) { [weak self] success, evalError in
            Task { @MainActor in
                self?.isAuthenticating = false
                if success {
                    self?.logger.info("Face ID authentication succeeded — advancing session")
                    self?.onAuthenticated?()
                } else {
                    let reason = evalError?.localizedDescription ?? "Authentication failed"
                    self?.logger.error("Face ID authentication failed: \(reason, privacy: .public)")
                    self?.authError = reason
                }
            }
        }
    }
}