7. Conditional UI dan AutoFill Integration

┌───────────────────────────┐
│  Username: ___________    │
│  Password: ___________    │
│                           │
│  [Log in]                 │
└───────────────────────────┘
┌───────────────────────────┐
│ 🔑 example.com Passkey  > │  ← AutoFill bar
├───────────────────────────┤
│ Q W E R T Y U I O P      │
│ ...                       │
└───────────────────────────┘

import AuthenticationServices

class LoginViewController: UIViewController {
    @IBOutlet weak var usernameField: UITextField!
    @IBOutlet weak var passwordField: UITextField!

    private var conditionalController: ASAuthorizationController?
    private var conditionalChallenge: Data = Data()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Aktifkan AutoFill untuk text fields
        usernameField.textContentType = .username
        passwordField.textContentType = .password

        // Fetch challenge dari server dan mulai conditional request
        Task {
            await beginConditionalSignIn()
        }
    }

    private func beginConditionalSignIn() async {
        do {
            // Fetch challenge dari server (non-blocking untuk UI)
            conditionalChallenge = try await server.fetchChallenge()
            
            let provider = ASAuthorizationPlatformPublicKeyCredentialProvider(
                relyingPartyIdentifier: "example.com"
            )
            let request = provider.createCredentialAssertionRequest(
                challenge: conditionalChallenge
            )

            // Tambah password request agar saved passwords juga muncul di AutoFill
            let passwordProvider = ASAuthorizationPasswordProvider()
            let passwordRequest = passwordProvider.createRequest()

            let controller = ASAuthorizationController(authorizationRequests: [
                request,
                passwordRequest
            ])
            controller.delegate = self
            controller.presentationContextProvider = self

            // KUNCI: performAutoFillAssistedRequests, bukan performRequests
            controller.performAutoFillAssistedRequests()
            conditionalController = controller  // Retain
        } catch {
            // Gagal fetch challenge — AutoFill tidak aktif, tapi login manual masih bisa
            print("Conditional sign-in tidak tersedia: \(error)")
        }
    }

    // Saat user tap tombol Login manual (non-AutoFill)
    @IBAction func loginButtonTapped() {
        // Cancel conditional request yang sedang berjalan
        conditionalController = nil

        // Mulai modal sign-in (akan tampilkan sheet)
        Task {
            do {
                let challenge = try await server.fetchChallenge()
                try await performModalSignIn(challenge: challenge)
            } catch {
                showError(error)
            }
        }
    }

    private func performModalSignIn(challenge: Data) async throws {
        let provider = ASAuthorizationPlatformPublicKeyCredentialProvider(
            relyingPartyIdentifier: "example.com"
        )
        let request = provider.createCredentialAssertionRequest(challenge: challenge)

        let controller = ASAuthorizationController(authorizationRequests: [request])
        controller.delegate = self
        controller.presentationContextProvider = self
        controller.performRequests()  // Modal sheet
    }
}