import SwiftUI

struct RootView: View {
    @Bindable var model: AppModel

    var body: some View {
        ZStack {
            Group {
                switch model.launchState {
                case .checking, .needsDatabase, .validating, .invalid:
                    FirstLaunchView(model: model)
                case .ready, .readOnly:
                    AppShellView(model: model)
                case .failed:
                    FirstLaunchView(model: model)
                }
            }

            if let message = model.successMessage {
                VStack {
                    Spacer()
                    SuccessToast(message: message)
                        .padding(.bottom, 42)
                }
                .transition(.move(edge: .bottom).combined(with: .opacity))
                .allowsHitTesting(false)
            }
        }
        .tint(AppUI.accent)
        .animation(.snappy(duration: 0.25), value: model.successMessage)
        .sheet(item: $model.editor) { presentation in
            PromptEditorSheet(model: model, presentation: presentation)
        }
        .alert(
            "Prompt löschen?",
            isPresented: Binding(
                get: { model.promptPendingDeletion != nil },
                set: { if !$0 { model.promptPendingDeletion = nil } }
            ),
            presenting: model.promptPendingDeletion
        ) { _ in
            Button("Abbrechen", role: .cancel) {
                model.promptPendingDeletion = nil
            }
            Button("Endgültig löschen", role: .destructive) {
                Task { await model.confirmDelete() }
            }
        } message: { prompt in
            Text("„\(prompt.title)“ wird aus der lokalen Datenbank entfernt. Das kann nicht rückgängig gemacht werden.")
        }
    }
}

private struct AppShellView: View {
    @Bindable var model: AppModel

    var body: some View {
        VStack(spacing: 0) {
            if let error = model.errorPresentation {
                ErrorBanner(
                    error: error,
                    dismiss: model.dismissError,
                    copyDiagnostic: model.copyErrorDiagnostic
                )
            }

            NavigationSplitView {
                SidebarView(model: model)
                    .navigationSplitViewColumnWidth(min: 185, ideal: 215, max: 250)
            } content: {
                switch model.destination {
                case .all, .favorites, .mostUsed, .byDay, .byTopic:
                    LibraryView(model: model)
                case .importCenter:
                    ImportCenterView(model: model)
                case .statistics:
                    StatisticsView(model: model)
                }
            } detail: {
                switch model.destination {
                case .all, .favorites, .mostUsed, .byDay, .byTopic:
                    PromptDetailView(model: model)
                case .importCenter:
                    ImportPreviewDetailView(model: model)
                case .statistics:
                    StatisticsDetailView(model: model)
                }
            }
            .navigationSplitViewStyle(.balanced)

            HStack {
                LocalStatusLabel(databaseName: model.databaseDisplayName)
                Spacer()
                if model.isReadOnly {
                    StatusChip(title: "Nur Lesen", systemImage: "lock.fill", tint: .red)
                }
                Text(model.footerStatus)
                    .font(.caption)
                    .foregroundStyle(.tertiary)
            }
            .padding(.horizontal, 12)
            .frame(height: 28)
            .background(.bar)
            .overlay(alignment: .top) { Divider() }
        }
    }
}

private struct SidebarView: View {
    @Bindable var model: AppModel

    var body: some View {
        List(selection: Binding<SidebarDestination?>(
            get: { model.destination },
            set: { destination in
                if let destination { model.destination = destination }
            }
        )) {
            Section("Bibliothek") {
                sidebarItem(.all, title: "Alle Prompts", icon: "tray.full")
                sidebarItem(.favorites, title: "Favoriten", icon: "star")
                sidebarItem(.mostUsed, title: "Meistgenutzt", icon: "arrow.up.forward.circle")
                sidebarItem(.byDay, title: "Nach Tagen", icon: "calendar")
                sidebarItem(.byTopic, title: "Nach Topics", icon: "tag")
            }

            Section("Werkzeuge") {
                sidebarItem(.importCenter, title: "Import", icon: "square.and.arrow.down")
                sidebarItem(.statistics, title: "Statistik", icon: "chart.bar.xaxis")
            }
        }
        .listStyle(.sidebar)
        .navigationTitle("PromptGarage")
        .safeAreaInset(edge: .bottom) {
            VStack(alignment: .leading, spacing: 8) {
                Divider()
                HStack(spacing: 9) {
                    Image(systemName: "externaldrive.fill")
                        .foregroundStyle(AppUI.accent)
                    VStack(alignment: .leading, spacing: 1) {
                        Text("Diese Garage")
                            .font(.caption.weight(.semibold))
                        Text(model.databaseDisplayName ?? "Lokale Datenbank")
                            .font(.caption2)
                            .foregroundStyle(.secondary)
                            .lineLimit(1)
                    }
                }
                .padding(.horizontal, 10)
                .padding(.bottom, 8)
            }
            .background(.bar)
        }
    }

    private func sidebarItem(
        _ destination: SidebarDestination,
        title: String,
        icon: String
    ) -> some View {
        Label(title, systemImage: icon)
            .tag(destination)
    }
}