import ManaCore
import SwiftUI

/// Vollständiger Login-Screen: Email + Passwort + Primary-Submit
/// + Sekundär-Buttons "Konto erstellen" und "Passwort vergessen".
///
/// Bei `.emailNotVerified` schaltet die View automatisch auf
/// ``ManaEmailVerifyGateView`` um — der User kann von dort die
/// Verify-Mail erneut anfordern.
///
/// Apps binden ein:
/// ```swift
/// ManaLoginView(
///     auth: authClient,
///     onSignUpTapped: { presentingSignUp = true },
///     onForgotTapped: { presentingForgot = true }
/// )
/// .manaBrand(.cardecky)
/// ```
public struct ManaLoginView: View {
    @Environment(\.manaBrand) private var brand
    @State private var model: LoginViewModel
    private let auth: AuthClient
    private let onSignUpTapped: () -> Void
    private let onForgotTapped: () -> Void

    /// - Parameters:
    ///   - auth: gemeinsamer `AuthClient` der App.
    ///   - onSignUpTapped: präsentiert ``ManaSignUpView`` (Sheet,
    ///     Push, Navigation — die App entscheidet).
    ///   - onForgotTapped: präsentiert ``ManaForgotPasswordView``.
    public init(
        auth: AuthClient,
        onSignUpTapped: @escaping () -> Void,
        onForgotTapped: @escaping () -> Void
    ) {
        self.auth = auth
        _model = State(initialValue: LoginViewModel(auth: auth))
        self.onSignUpTapped = onSignUpTapped
        self.onForgotTapped = onForgotTapped
    }

    public var body: some View {
        switch model.status {
        case let .emailNotVerified(email):
            ManaEmailVerifyGateView(
                email: email,
                auth: auth,
                onBackToLogin: { model.resetToIdle() }
            )
        default:
            loginForm
        }
    }

    @ViewBuilder
    private var loginForm: some View {
        ManaAuthScaffold {
            VStack(spacing: 16) {
                ManaTextField("Email", text: $model.email)
                    .manaEmailField()

                ManaSecureField("Passwort", text: $model.password, textContentType: .password)

                ManaPrimaryButton(
                    "Anmelden",
                    isLoading: model.isSigningIn,
                    isEnabled: model.canSubmit
                ) {
                    Task { await model.submit() }
                }

                if case let .error(message) = model.status {
                    Text(message)
                        .font(.footnote)
                        .foregroundStyle(brand.error)
                        .multilineTextAlignment(.center)
                        .padding(.top, 4)
                }
            }
            .padding(.top, 16)

            VStack(spacing: 12) {
                Button("Konto erstellen", action: onSignUpTapped)
                    .font(.subheadline)
                    .foregroundStyle(brand.primary)

                Button("Passwort vergessen?", action: onForgotTapped)
                    .font(.subheadline)
                    .foregroundStyle(brand.mutedForeground)
            }
            .padding(.top, 8)
        }
    }
}