import ManaCore
import SwiftData
import SwiftUI

/// β-1 Hauptbildschirm: Liste aller Decks mit Card- und Due-Counts.
/// Web-Vorbild: `cards/apps/web/src/routes/decks/+page.svelte`.
struct DeckListView: View {
    @Environment(AuthClient.self) private var auth
    @Environment(\.modelContext) private var context
    @Query(sort: \CachedDeck.updatedAt, order: .reverse) private var decks: [CachedDeck]

    @State private var store: DeckListStore?
    @State private var showAccount = false
    @State private var showCreate = false
    @State private var pendingShares: [PendingShare] = []

    var body: some View {
        NavigationStack {
            ZStack {
                CardsTheme.background.ignoresSafeArea()
                content
            }
            .navigationTitle("Decks")
            .navigationDestination(for: String.self) { deckId in
                DeckDetailView(deckId: deckId)
            }
            .navigationDestination(for: PendingShareRoute.self) { route in
                PendingShareConsumeView(share: route.share, onDone: {
                    PendingShareStore.remove(id: route.share.id)
                    pendingShares = PendingShareStore.readAll()
                })
            }
            .toolbar { toolbar }
            .refreshable {
                await store?.refresh()
            }
            .sheet(isPresented: $showCreate) {
                NavigationStack {
                    DeckEditorView(mode: .create) { _ in
                        Task { await store?.refresh() }
                    }
                }
            }
            .task {
                if store == nil {
                    store = DeckListStore(auth: auth, context: context)
                }
                await store?.refresh()
                pendingShares = PendingShareStore.readAll()
            }
            .onAppear {
                pendingShares = PendingShareStore.readAll()
            }
            .sheet(isPresented: $showAccount) {
                NavigationStack {
                    AccountView()
                        .toolbar {
                            ToolbarItem(placement: .confirmationAction) {
                                Button("Fertig") { showAccount = false }
                            }
                        }
                }
            }
        }
    }

    @ViewBuilder
    private var content: some View {
        if decks.isEmpty {
            emptyState
        } else {
            List {
                pendingShareSection
                inboxBannerSection
                ownDecksSection
            }
            .listStyle(.plain)
            .scrollContentBackground(.hidden)
        }
    }

    @ViewBuilder
    private var pendingShareSection: some View {
        if !pendingShares.isEmpty {
            Section {
                ForEach(pendingShares) { share in
                    NavigationLink(value: PendingShareRoute(share: share)) {
                        HStack(spacing: 12) {
                            Image(systemName: "square.and.arrow.down")
                                .foregroundStyle(CardsTheme.primary)
                            VStack(alignment: .leading, spacing: 2) {
                                Text("Aus Teilen-Menü")
                                    .font(.subheadline.weight(.semibold))
                                    .foregroundStyle(CardsTheme.foreground)
                                Text(share.text)
                                    .font(.caption)
                                    .foregroundStyle(CardsTheme.mutedForeground)
                                    .lineLimit(2)
                            }
                            Spacer()
                        }
                        .padding()
                        .background(CardsTheme.warning.opacity(0.12), in: RoundedRectangle(cornerRadius: 10))
                    }
                    .buttonStyle(.plain)
                    .listRowBackground(Color.clear)
                    .listRowSeparator(.hidden)
                    .listRowInsets(EdgeInsets(top: 4, leading: 16, bottom: 4, trailing: 16))
                }
            }
        }
    }

    private var emptyState: some View {
        VStack(spacing: 16) {
            if store?.state == .loading {
                ProgressView()
                    .tint(CardsTheme.primary)
                Text("Lade Decks …")
                    .foregroundStyle(CardsTheme.mutedForeground)
            } else if let message = store?.errorMessage {
                ContentUnavailableView {
                    Label("Decks konnten nicht geladen werden", systemImage: "wifi.exclamationmark")
                        .foregroundStyle(CardsTheme.foreground)
                } description: {
                    Text(message)
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            } else {
                ContentUnavailableView {
                    Label("Noch keine Decks", systemImage: "rectangle.stack")
                        .foregroundStyle(CardsTheme.foreground)
                } description: {
                    Text("Erstelle dein erstes Deck auf cardecky.mana.how oder ziehe nach unten zum Aktualisieren.")
                        .foregroundStyle(CardsTheme.mutedForeground)
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    @ViewBuilder
    private var inboxBannerSection: some View {
        if let inbox = decks.first(where: { $0.isFromMarketplace && $0.dueCount > 0 }) {
            Section {
                HStack(spacing: 12) {
                    Image(systemName: "tray.full.fill")
                        .foregroundStyle(CardsTheme.primary)
                    VStack(alignment: .leading, spacing: 2) {
                        Text("Inbox")
                            .font(.subheadline.weight(.semibold))
                            .foregroundStyle(CardsTheme.foreground)
                        Text("\(inbox.dueCount) fällige Karten aus abonnierten Decks")
                            .font(.caption)
                            .foregroundStyle(CardsTheme.mutedForeground)
                    }
                    Spacer()
                }
                .padding()
                .background(CardsTheme.surface, in: RoundedRectangle(cornerRadius: 10))
                .listRowBackground(Color.clear)
                .listRowSeparator(.hidden)
            }
        }
    }

    private var ownDecksSection: some View {
        Section {
            ForEach(decks) { deck in
                NavigationLink(value: deck.id) {
                    DeckRow(deck: deck)
                }
                .buttonStyle(.plain)
                .listRowBackground(Color.clear)
                .listRowSeparator(.hidden)
                .listRowInsets(EdgeInsets(top: 4, leading: 16, bottom: 4, trailing: 16))
            }
        }
    }

    @ToolbarContentBuilder
    private var toolbar: some ToolbarContent {
        ToolbarItem(placement: .topBarLeading) {
            Button {
                showCreate = true
            } label: {
                Image(systemName: "plus.circle")
                    .foregroundStyle(CardsTheme.primary)
            }
            .accessibilityLabel("Deck hinzufügen")
        }
        ToolbarItem(placement: .topBarTrailing) {
            Button {
                showAccount = true
            } label: {
                Image(systemName: accountIcon)
                    .foregroundStyle(CardsTheme.primary)
            }
            .accessibilityLabel("Account")
        }
    }

    private var accountIcon: String {
        if case .signedIn = auth.status { return "person.crop.circle.fill" }
        return "person.crop.circle.badge.exclamationmark"
    }
}

/// Einzelne Deck-Zeile in der Liste.
struct DeckRow: View {
    let deck: CachedDeck

    var body: some View {
        HStack(spacing: 12) {
            // Farbiger Streifen aus deck.color (Hex), default forest-primary
            RoundedRectangle(cornerRadius: 3)
                .fill(deckColor)
                .frame(width: 4)

            VStack(alignment: .leading, spacing: 4) {
                HStack {
                    Text(deck.name)
                        .font(.headline)
                        .foregroundStyle(CardsTheme.foreground)
                    if deck.isFromMarketplace {
                        Image(systemName: "globe")
                            .font(.caption)
                            .foregroundStyle(CardsTheme.mutedForeground)
                    }
                }

                if let category = deck.category {
                    Text(category.label)
                        .font(.caption)
                        .foregroundStyle(CardsTheme.mutedForeground)
                }

                HStack(spacing: 12) {
                    Label("\(deck.cardCount)", systemImage: "rectangle.stack")
                        .font(.caption)
                        .foregroundStyle(CardsTheme.mutedForeground)
                    if deck.dueCount > 0 {
                        Label("\(deck.dueCount) fällig", systemImage: "clock.badge.exclamationmark")
                            .font(.caption.weight(.semibold))
                            .foregroundStyle(CardsTheme.primary)
                    }
                }
            }
            Spacer()
            Image(systemName: "chevron.right")
                .font(.footnote)
                .foregroundStyle(CardsTheme.mutedForeground)
        }
        .padding(.vertical, 12)
        .padding(.horizontal, 12)
        .background(CardsTheme.surface, in: RoundedRectangle(cornerRadius: 10))
    }

    private var deckColor: Color {
        guard let hex = deck.color, let rgb = parseHex(hex) else {
            return CardsTheme.primary
        }
        return Color.manaHexLocal(rgb)
    }

    private func parseHex(_ hex: String) -> UInt32? {
        var trimmed = hex.trimmingCharacters(in: .whitespacesAndNewlines)
        if trimmed.hasPrefix("#") { trimmed = String(trimmed.dropFirst()) }
        return UInt32(trimmed, radix: 16)
    }
}

private extension Color {
    /// Lokales Hex-Helper analog zu `ManaTokens.Color.manaHex`. Hier
    /// dupliziert, weil DeckRow nicht von ManaTokens abhängen muss.
    static func manaHexLocal(_ rgb: UInt32) -> Color {
        let r = Double((rgb >> 16) & 0xFF) / 255.0
        let g = Double((rgb >> 8) & 0xFF) / 255.0
        let b = Double(rgb & 0xFF) / 255.0
        return Color(red: r, green: g, blue: b)
    }
}