import ManaCore
import SwiftUI

/// Sign-Up-Screen: Email + Name (optional) + Passwort. Bei Erfolg
/// und `requireEmailVerification: true` (Default) zeigt der View
/// den Hinweis-Screen mit Resend-Mail-Button — sobald die Mail
/// geklickt wurde, schließt die App den Sheet/Push manuell oder
/// reagiert auf den nächsten `signIn`-Versuch.
///
/// Apps binden ein:
/// ```swift
/// ManaSignUpView(
///     auth: authClient,
///     sourceAppUrl: URL(string: "https://cardecky.mana.how/auth/verify"),
///     onDone: { dismissSignUpSheet() }
/// )
/// ```
public struct ManaSignUpView: View {
    @Environment(\.manaBrand) private var brand
    @State private var model: SignUpViewModel
    private let auth: AuthClient
    private let onDone: () -> Void

    /// - Parameters:
    ///   - auth: gemeinsamer `AuthClient` der App.
    ///   - sourceAppUrl: Universal-Link der App für den Verify-Klick-
    ///     Redirect (z.B. `https://cardecky.mana.how/auth/verify`).
    ///   - onDone: Callback wenn der User "Fertig" auf dem Hinweis-
    ///     Screen drückt oder direkt eingeloggt ist. Apps schließen
    ///     hier das Sheet.
    public init(
        auth: AuthClient,
        sourceAppUrl: URL? = nil,
        onDone: @escaping () -> Void
    ) {
        self.auth = auth
        _model = State(initialValue: SignUpViewModel(auth: auth, sourceAppUrl: sourceAppUrl))
        self.onDone = onDone
    }

    public var body: some View {
        switch model.status {
        case let .awaitingVerification(email):
            awaitingVerificationView(email: email)
        case .signedIn:
            // Server hat direkt Tokens geliefert — UI muss nichts mehr
            // tun, App soll den Sheet schließen.
            ManaAuthScaffold(showsHeader: false) {
                ProgressView()
                    .onAppear { onDone() }
            }
        default:
            signUpForm
        }
    }

    @ViewBuilder
    private var signUpForm: some View {
        ManaAuthScaffold {
            VStack(spacing: 16) {
                Text("Konto erstellen")
                    .font(.title2)
                    .fontWeight(.semibold)
                    .foregroundStyle(brand.foreground)
                    .frame(maxWidth: .infinity, alignment: .leading)

                ManaTextField("Email", text: $model.email)
                    .manaEmailField()

                ManaTextField("Name (optional)", text: $model.name)
                    .textContentType(.name)

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

                if let hint = model.passwordHint {
                    Text(hint)
                        .font(.footnote)
                        .foregroundStyle(brand.mutedForeground)
                        .frame(maxWidth: .infinity, alignment: .leading)
                }

                ManaPrimaryButton(
                    "Registrieren",
                    isLoading: model.isRegistering,
                    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)

            Button("Abbrechen", action: onDone)
                .font(.subheadline)
                .foregroundStyle(brand.mutedForeground)
                .padding(.top, 12)
        }
    }

    @ViewBuilder
    private func awaitingVerificationView(email: String) -> some View {
        ManaAuthScaffold {
            VStack(spacing: 16) {
                Image(systemName: "checkmark.circle.fill")
                    .font(.system(size: 56, weight: .light))
                    .foregroundStyle(brand.success)

                Text("Fast geschafft!")
                    .font(.title2)
                    .fontWeight(.semibold)
                    .foregroundStyle(brand.foreground)

                Text(
                    "Wir haben eine Bestätigungs-Mail an **\(email)** geschickt. "
                        + "Klicke den Link in der Mail, dann kannst du dich anmelden."
                )
                .font(.subheadline)
                .foregroundStyle(brand.mutedForeground)
                .multilineTextAlignment(.center)

                ManaPrimaryButton("Fertig") {
                    onDone()
                }
                .padding(.top, 16)
            }
        }
    }
}