import ManaCore
import SwiftData
import SwiftUI

// swiftlint:disable file_length
// swiftlint:disable type_body_length

/// Deck-Detail mit Aktionen + Card-Liste. Wird per Tap auf eine Deck-Row
/// aus der DeckListView geöffnet.
///
/// `type_body_length` ist bewusst übersprungen — Detail-View hostet
/// 5 verschiedene Sheets (Edit, CardCreate, CardEdit, Publish, Print),
/// Confirmation-Dialog + Alerts; aufspalten ginge nur über Multi-State-
/// Plumbing zwischen Parent und Children.
struct DeckDetailView: View {
    let deckId: String

    @Environment(AuthClient.self) private var auth
    @Environment(\.modelContext) private var context
    @Environment(\.dismiss) private var dismiss
    @Query private var decks: [CachedDeck]

    @State private var showEditor = false
    @State private var showCardEditor = false
    @State private var showDeleteConfirm = false
    @State private var navigateToStudy = false
    @State private var deleteError: String?
    @State private var editingCard: Card?

    @State private var cards: [Card] = []
    @State private var isLoadingCards = false
    @State private var cardsError: String?

    @State private var isPullingUpdate = false
    @State private var isDuplicating = false
    @State private var pullAlert: AlertMessage?
    @State private var actionError: String?
    @State private var showPublishSheet = false
    @State private var showPrintSheet = false

    init(deckId: String) {
        self.deckId = deckId
        _decks = Query(filter: #Predicate<CachedDeck> { $0.id == deckId })
    }

    var body: some View {
        ZStack {
            CardsTheme.background.ignoresSafeArea()
            if let deck = decks.first {
                content(deck: deck)
            } else {
                ContentUnavailableView("Deck nicht gefunden", systemImage: "questionmark.folder")
                    .foregroundStyle(CardsTheme.mutedForeground)
            }
        }
        .navigationTitle(decks.first?.name ?? "")
        #if os(iOS)
            .navigationBarTitleDisplayMode(.inline)
        #endif
            .sheet(isPresented: $showEditor) {
                NavigationStack {
                    DeckEditorView(
                        mode: .edit(deckId: deckId),
                        existing: decks.first
                    ) { _ in
                        Task { await refreshAfterEdit() }
                    }
                }
            }
            .sheet(isPresented: $showCardEditor) {
                NavigationStack {
                    CardEditorView(mode: .create(deckId: deckId)) { _ in
                        Task {
                            await refreshAfterEdit()
                            await loadCards()
                        }
                    }
                }
            }
            .sheet(item: $editingCard) { card in
                NavigationStack {
                    CardEditorView(mode: .edit(card: card)) { _ in
                        Task {
                            await refreshAfterEdit()
                            await loadCards()
                            editingCard = nil
                        }
                    }
                }
            }
            .sheet(isPresented: $showPublishSheet) {
                if let deck = decks.first {
                    NavigationStack {
                        MarketplacePublishView(privateDeck: deck) { _ in
                            showPublishSheet = false
                        }
                    }
                }
            }
            .sheet(isPresented: $showPrintSheet) {
                NavigationStack {
                    DeckPrintView(deckId: deckId)
                        .toolbar {
                            ToolbarItem(placement: .cancellationAction) {
                                Button("Fertig") { showPrintSheet = false }
                            }
                        }
                }
            }
            .confirmationDialog(
                "Deck löschen?",
                isPresented: $showDeleteConfirm,
                titleVisibility: .visible
            ) {
                Button("Löschen", role: .destructive) {
                    Task { await delete() }
                }
                Button("Abbrechen", role: .cancel) {}
            } message: {
                Text(
                    """
                    Alle Karten und Reviews dieses Decks werden ebenfalls \
                    gelöscht. Diese Aktion kann nicht rückgängig gemacht werden.
                    """
                )
            }
            .navigationDestination(isPresented: $navigateToStudy) {
                if let deck = decks.first {
                    StudySessionView(deckId: deck.id, deckName: deck.name)
                }
            }
            .task(id: deckId) {
                await loadCards()
            }
            .refreshable {
                await loadCards()
            }
            .alert(item: $pullAlert) { alert in
                Alert(title: Text(alert.title), message: Text(alert.message), dismissButton: .default(Text("OK")))
            }
            .alert(
                "Aktion fehlgeschlagen",
                isPresented: Binding(
                    get: { actionError != nil },
                    set: { if !$0 { actionError = nil } }
                ),
                presenting: actionError
            ) { _ in
                Button("OK") { actionError = nil }
            } message: { message in
                Text(message)
            }
    }

    private func content(deck: CachedDeck) -> some View {
        ScrollView {
            VStack(alignment: .leading, spacing: 16) {
                header(deck: deck)
                actions(deck: deck)
                if let deleteError {
                    Text(deleteError)
                        .font(.footnote)
                        .foregroundStyle(CardsTheme.error)
                        .padding(.horizontal, 16)
                }
                cardListSection
            }
            .padding(.vertical, 16)
        }
    }

    private func header(deck: CachedDeck) -> some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack {
                Text(deck.name)
                    .font(.title.bold())
                    .foregroundStyle(CardsTheme.foreground)
                if deck.isFromMarketplace {
                    Image(systemName: "globe")
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            }
            if let description = deck.deckDescription, !description.isEmpty {
                Text(description)
                    .foregroundStyle(CardsTheme.mutedForeground)
            }
            HStack(spacing: 16) {
                Label("\(deck.cardCount) Karten", systemImage: "rectangle.stack")
                if deck.dueCount > 0 {
                    Label("\(deck.dueCount) fällig", systemImage: "clock.badge.exclamationmark")
                        .foregroundStyle(CardsTheme.primary)
                }
                if let category = deck.category {
                    Text(category.label)
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            }
            .font(.footnote)
        }
        .padding(.horizontal, 16)
    }

    private func actions(deck: CachedDeck) -> some View {
        VStack(spacing: 12) {
            primaryActions
            secondaryActions(deck: deck)
        }
        .padding(.horizontal, 16)
    }

    @ViewBuilder
    private var primaryActions: some View {
        Button {
            navigateToStudy = true
        } label: {
            Label("Karten lernen", systemImage: "play.fill")
                .frame(maxWidth: .infinity)
                .padding(.vertical, 12)
                .background(CardsTheme.primary, in: RoundedRectangle(cornerRadius: 10))
                .foregroundStyle(CardsTheme.primaryForeground)
        }
        .buttonStyle(.plain)
        .disabled((decks.first?.dueCount ?? 0) == 0)

        Button {
            showCardEditor = true
        } label: {
            Label("Karte hinzufügen", systemImage: "plus.rectangle.on.rectangle")
                .frame(maxWidth: .infinity)
                .padding(.vertical, 12)
                .background(CardsTheme.surface, in: RoundedRectangle(cornerRadius: 10))
                .foregroundStyle(CardsTheme.foreground)
                .overlay(
                    RoundedRectangle(cornerRadius: 10)
                        .stroke(CardsTheme.border, lineWidth: 1)
                )
        }
        .buttonStyle(.plain)
    }

    private func secondaryActions(deck: CachedDeck) -> some View {
        DeckSecondaryActions(
            isForkedFromMarketplace: deck.isFromMarketplace,
            isPullingUpdate: isPullingUpdate,
            isDuplicating: isDuplicating,
            onPullUpdate: { Task { await pullUpdate() } },
            onDuplicate: { Task { await duplicate() } },
            onPublish: { showPublishSheet = true },
            onPrint: { showPrintSheet = true },
            onEdit: { showEditor = true },
            onDelete: { showDeleteConfirm = true }
        )
    }

    private var cardListSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack {
                Text("Karten")
                    .font(.headline)
                    .foregroundStyle(CardsTheme.foreground)
                Spacer()
                if !cards.isEmpty {
                    Text("\(cards.count)")
                        .font(.footnote)
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            }
            .padding(.horizontal, 16)
            .padding(.top, 8)

            if isLoadingCards, cards.isEmpty {
                HStack {
                    Spacer()
                    ProgressView()
                        .tint(CardsTheme.primary)
                    Spacer()
                }
                .padding(.vertical, 24)
            } else if let cardsError {
                Text(cardsError)
                    .font(.caption)
                    .foregroundStyle(CardsTheme.error)
                    .padding(.horizontal, 16)
            } else if cards.isEmpty {
                Text("Noch keine Karten. Tippe auf »Karte hinzufügen«.")
                    .font(.footnote)
                    .foregroundStyle(CardsTheme.mutedForeground)
                    .padding(.horizontal, 16)
                    .padding(.vertical, 12)
            } else {
                LazyVStack(spacing: 8) {
                    ForEach(cards) { card in
                        Button {
                            editingCard = card
                        } label: {
                            CardPreviewRow(card: card)
                                .padding(.horizontal, 16)
                        }
                        .buttonStyle(.plain)
                        .accessibilityHint("Tippen zum Bearbeiten")
                    }
                }
            }
        }
    }

    private func refreshAfterEdit() async {
        let store = DeckListStore(auth: auth, context: context)
        await store.refresh()
    }

    private func pullUpdate() async {
        isPullingUpdate = true
        defer { isPullingUpdate = false }
        let api = CardsAPI(auth: auth)
        do {
            let result = try await api.pullUpdate(deckId: deckId)
            pullAlert = formatPullResult(result)
            await refreshAfterEdit()
            await loadCards()
        } catch let error as AuthError {
            actionError = error.errorDescription ?? "Update fehlgeschlagen"
        } catch {
            actionError = error.localizedDescription
        }
    }

    private func formatPullResult(_ result: PullUpdateResponse) -> AlertMessage {
        if result.upToDate {
            return AlertMessage(
                title: "Schon aktuell",
                message: "Es gibt keine neue Marketplace-Version dieses Decks."
            )
        }
        let inserted = result.cardsInserted ?? 0
        let parts = [
            inserted > 0 ? "\(inserted) Karten hinzugefügt" : nil,
            result.changed > 0 ? "\(result.changed) Karten geändert" : nil,
            result.removed > 0 ? "\(result.removed) im Marketplace entfernt (lokal behalten)" : nil
        ].compactMap(\.self)
        let body = parts.isEmpty ? "Update angewendet." : parts.joined(separator: ", ")
        let versionText = result.to.map { "Version \($0.semver)" } ?? "Update angewendet"
        return AlertMessage(title: versionText, message: body)
    }

    private func duplicate() async {
        isDuplicating = true
        defer { isDuplicating = false }
        let api = CardsAPI(auth: auth)
        do {
            _ = try await api.duplicateDeck(id: deckId)
            await refreshAfterEdit()
            dismiss()
        } catch let error as AuthError {
            actionError = error.errorDescription ?? "Duplizieren fehlgeschlagen"
        } catch {
            actionError = error.localizedDescription
        }
    }

    private func loadCards() async {
        isLoadingCards = true
        cardsError = nil
        defer { isLoadingCards = false }
        let api = CardsAPI(auth: auth)
        do {
            cards = try await api.listCards(deckId: deckId)
                .sorted { $0.createdAt > $1.createdAt }
        } catch {
            cardsError = (error as? LocalizedError)?.errorDescription ?? String(describing: error)
        }
    }

    private func delete() async {
        deleteError = nil
        let api = CardsAPI(auth: auth)
        do {
            try await api.deleteDeck(id: deckId)
            if let deck = decks.first {
                context.delete(deck)
                try? context.save()
            }
            dismiss()
        } catch {
            deleteError = (error as? LocalizedError)?.errorDescription ?? String(describing: error)
        }
    }
}

// swiftlint:enable type_body_length

/// Einfacher Alert-Body — Title + Message für `.alert(item:)`-Trigger.
struct AlertMessage: Identifiable {
    let id = UUID()
    let title: String
    let message: String
}

/// Kompakte Card-Row mit Front-Vorschau und Type-Badge.
private struct CardPreviewRow: View {
    let card: Card

    var body: some View {
        HStack(alignment: .top, spacing: 12) {
            Image(systemName: icon(for: card.type))
                .foregroundStyle(CardsTheme.primary)
                .frame(width: 24)
                .padding(.top, 2)
            VStack(alignment: .leading, spacing: 4) {
                Text(preview(card: card))
                    .font(.subheadline)
                    .foregroundStyle(CardsTheme.foreground)
                    .lineLimit(2)
                Text(typeLabel(card.type))
                    .font(.caption2)
                    .foregroundStyle(CardsTheme.mutedForeground)
            }
            Spacer()
        }
        .padding(12)
        .background(CardsTheme.surface, in: RoundedRectangle(cornerRadius: 10))
        .overlay(
            RoundedRectangle(cornerRadius: 10)
                .stroke(CardsTheme.border, lineWidth: 1)
        )
    }

    private func preview(card: Card) -> String {
        switch card.type {
        case .basic, .basicReverse, .typing, .multipleChoice:
            card.fields["front"] ?? "—"
        case .cloze:
            card.fields["text"] ?? "—"
        case .imageOcclusion:
            card.fields["note"]?.isEmpty == false
                ? card.fields["note"]!
                : "Bild-Verdeckung (\(MaskRegions.count(card.fields["mask_regions"] ?? "")) Masken)"
        case .audioFront:
            card.fields["back"] ?? "Audio-Karte"
        }
    }

    private func icon(for type: CardType) -> String {
        switch type {
        case .basic: "rectangle.split.2x1"
        case .basicReverse: "rectangle.2.swap"
        case .cloze: "text.append"
        case .typing: "keyboard"
        case .multipleChoice: "list.bullet"
        case .imageOcclusion: "photo.on.rectangle.angled"
        case .audioFront: "waveform"
        }
    }

    private func typeLabel(_ type: CardType) -> String {
        switch type {
        case .basic: "Einfach"
        case .basicReverse: "Beidseitig"
        case .cloze: "Lückentext"
        case .typing: "Eintippen"
        case .multipleChoice: "Multiple Choice"
        case .imageOcclusion: "Bild-Verdeckung"
        case .audioFront: "Audio"
        }
    }
}