import ManaAuthUI
import ManaCore
import SwiftData
import SwiftUI

struct AccountView: View {
    @Environment(AuthClient.self) private var auth
    @Environment(ManaAuthGate.self) private var authGate
    @Environment(\.modelContext) private var context
    @State private var showChangeEmail = false
    @State private var showChangePassword = false
    @State private var showDeleteAccount = false

    var body: some View {
        ZStack {
            WordeckTheme.background.ignoresSafeArea()
            Group {
                switch auth.status {
                case .signedIn:
                    signedInContent
                case .guest, .signedOut, .error, .unknown:
                    guestContent
                case .signingIn, .twoFactorRequired:
                    ProgressView().tint(WordeckTheme.primary)
                }
            }
        }
        .navigationTitle("Account")
        #if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
        #endif
            .manaBrand(WordeckBrand.manaBrand)
            .sheet(isPresented: $showChangeEmail) {
                ManaChangeEmailView(
                    auth: auth,
                    callbackUniversalLink: URL(string: "https://wordeck.com/auth/email-changed"),
                    onDone: { showChangeEmail = false }
                )
                .manaBrand(WordeckBrand.manaBrand)
            }
            .sheet(isPresented: $showChangePassword) {
                ManaChangePasswordView(
                    auth: auth,
                    onDone: { showChangePassword = false }
                )
                .manaBrand(WordeckBrand.manaBrand)
            }
            .sheet(isPresented: $showDeleteAccount) {
                ManaDeleteAccountView(
                    auth: auth,
                    onDone: {
                        Task { await wipeLocalCache() }
                        showDeleteAccount = false
                    }
                )
                .manaBrand(WordeckBrand.manaBrand)
            }
    }

    private var signedInContent: some View {
        VStack(spacing: 20) {
            Image(systemName: "person.crop.circle.fill")
                .resizable()
                .frame(width: 80, height: 80)
                .foregroundStyle(WordeckTheme.primary)

            if let email = auth.currentEmail {
                Text(email)
                    .font(.headline)
                    .foregroundStyle(WordeckTheme.foreground)
            }

            VStack(spacing: 12) {
                NavigationLink {
                    SettingsView()
                } label: {
                    rowLabel("Einstellungen", systemImage: "gear")
                }
                .buttonStyle(.plain)

                Button { showChangeEmail = true } label: {
                    rowLabel("Email ändern", systemImage: "envelope")
                }
                .buttonStyle(.plain)

                Button { showChangePassword = true } label: {
                    rowLabel("Passwort ändern", systemImage: "key")
                }
                .buttonStyle(.plain)

                ManaTwoFactorAccountRow(auth: auth)
                    .padding(.vertical, 12)
                    .padding(.horizontal, 16)
                    .background(WordeckTheme.surface, in: RoundedRectangle(cornerRadius: 8))
                    .overlay(
                        RoundedRectangle(cornerRadius: 8)
                            .stroke(WordeckTheme.border, lineWidth: 1)
                    )
            }
            .padding(.horizontal, 32)

            Spacer()

            Button(role: .destructive) {
                // Logout behält die Guest-Identity → App bleibt im
                // anonymen Modus nutzbar (lokale Decks, Marketplace
                // browsen). Wer „alles vergessen" will, nutzt
                // „Account löschen".
                //
                // DSGVO: Cache (Karten + Due-Reviews + Decks +
                // pending Grades) wird vor dem signOut gewipet, damit
                // ein anderer User auf demselben Gerät keine Daten
                // des Vorgängers sieht.
                Task {
                    await wipeLocalCache()
                    await auth.signOut(keepGuestMode: true)
                }
            } label: {
                Text("Abmelden")
                    .frame(maxWidth: .infinity)
                    .padding(.vertical, 12)
                    .background(WordeckTheme.error.opacity(0.1), in: RoundedRectangle(cornerRadius: 8))
                    .foregroundStyle(WordeckTheme.error)
            }
            .padding(.horizontal, 32)

            // App-Store-Guideline 5.1.1(v): jede App mit Sign-Up MUSS
            // eine Account-Löschung anbieten.
            Button(role: .destructive) {
                showDeleteAccount = true
            } label: {
                Text("Account löschen…")
                    .font(.footnote)
                    .foregroundStyle(WordeckTheme.mutedForeground)
            }
            .padding(.bottom, 16)
        }
        .padding(.top, 48)
    }

    private var guestContent: some View {
        VStack(spacing: 20) {
            Image(systemName: "person.crop.circle.dashed")
                .resizable()
                .frame(width: 80, height: 80)
                .foregroundStyle(WordeckTheme.mutedForeground)

            VStack(spacing: 8) {
                Text("Du nutzt Wordeck anonym")
                    .font(.headline)
                    .foregroundStyle(WordeckTheme.foreground)
                Text(
                    """
                    Marketplace und lokale Decks funktionieren ohne Konto. \
                    Für KI-Karten, eigene Decks im Cloud-Sync und Marketplace-\
                    Veröffentlichung brauchst du ein Konto.
                    """
                )
                .font(.subheadline)
                .foregroundStyle(WordeckTheme.mutedForeground)
                .multilineTextAlignment(.center)
            }
            .padding(.horizontal, 32)

            VStack(spacing: 12) {
                Button {
                    // Trigger ohne pending-Action — wir wollen einfach
                    // das Sign-In-Sheet öffnen. `require` mit no-op
                    // schaltet die Sheet-Logik des Gates ein.
                    authGate.require(reason: "account-tab") {}
                } label: {
                    Text("Anmelden / Konto erstellen")
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 14)
                        .background(WordeckTheme.primary, in: RoundedRectangle(cornerRadius: 10))
                        .foregroundStyle(.white)
                }
                .buttonStyle(.plain)

                NavigationLink {
                    SettingsView()
                } label: {
                    rowLabel("Einstellungen", systemImage: "gear")
                }
                .buttonStyle(.plain)
            }
            .padding(.horizontal, 32)

            Spacer()
        }
        .padding(.top, 48)
    }

    /// Löscht alle lokal gecachten User-Daten: Decks, Karten, fällige
    /// Reviews und die offline Grade-Queue. Wird vor jedem signOut und
    /// vor Account-Löschung aufgerufen.
    private func wipeLocalCache() async {
        try? context.delete(model: CachedDeck.self)
        try? context.delete(model: CachedCard.self)
        try? context.delete(model: CachedDueReview.self)
        try? context.delete(model: PendingGrade.self)
        try? context.save()
        Log.app.info("Local cache wiped (signOut / delete-account)")
    }

    private func rowLabel(_ title: String, systemImage: String) -> some View {
        Label(title, systemImage: systemImage)
            .frame(maxWidth: .infinity, alignment: .leading)
            .padding(.vertical, 12)
            .padding(.horizontal, 16)
            .background(WordeckTheme.surface, in: RoundedRectangle(cornerRadius: 8))
            .foregroundStyle(WordeckTheme.foreground)
            .overlay(
                RoundedRectangle(cornerRadius: 8)
                    .stroke(WordeckTheme.border, lineWidth: 1)
            )
    }
}

#Preview {
    NavigationStack {
        AccountView()
            .environment(AuthClient(config: AppConfig.manaAppConfig))
    }
}