import ManaAuthUI
import ManaCore
import SwiftUI

/// Top-Level-View: TabView mit vier nativen Tabs.
///
/// **η-0 (de-Hybrid 2026-05-22):** `WebShellView` ist raus. Lesen +
/// Erkunden zeigen jetzt Platzhalter-Views; das volle native Read-
/// Surface kommt in η-2 (Heute / Quote-Detail / Author-Detail) bzw.
/// η-4 (Explore + Filter). Universal-Links werden hier vorerst nur
/// geloggt und in den Lesen-Tab gepinnt, bis `NavigationStack`-Routing
/// in η-2 steht. Submit + Konto sind schon nativ.
struct RootView: View {
    @Environment(AuthClient.self) private var auth
    @Environment(ManaAuthGate.self) private var authGate
    @State private var selectedTab: AppTab = .read
    @State private var pendingDeepLink: URL?
    @State private var healthStatus: HealthStatus = .unknown

    var body: some View {
        TabView(selection: $selectedTab) {
            ReadPlaceholderView(pendingDeepLink: pendingDeepLink)
                .tabItem { Label("Lesen", systemImage: "book") }
                .tag(AppTab.read)

            ExplorePlaceholderView()
                .tabItem { Label("Erkunden", systemImage: "sparkle.magnifyingglass") }
                .tag(AppTab.explore)

            SubmitQuoteView()
                .tabItem { Label("Einreichen", systemImage: "square.and.pencil") }
                .tag(AppTab.submit)

            AccountView(healthStatus: healthStatus)
                .tabItem { Label("Konto", systemImage: "person.circle") }
                .tag(AppTab.account)
        }
        .background(ZitareTheme.background.ignoresSafeArea())
        #if os(macOS)
            .toolbarBackground(ZitareTheme.background, for: .windowToolbar)
            .toolbarBackground(.visible, for: .windowToolbar)
        #endif
            .manaBrand(ZitareBrand.manaBrand)
            .manaAuthGate(authGate) {
                NavigationStack {
                    ManaLoginView(
                        auth: auth,
                        onSignUpTapped: {},
                        onForgotTapped: {}
                    )
                    .manaBrand(ZitareBrand.manaBrand)
                }
            }
            .task {
                await probeHealth()
            }
            .onOpenURL { url in
                handle(url: url)
            }
            .onContinueUserActivity(NSUserActivityTypeBrowsingWeb) { activity in
                if let url = activity.webpageURL { handle(url: url) }
            }
    }

    private func probeHealth() async {
        let api = ZitareAPI(auth: auth)
        do {
            let ok = try await api.healthCheck()
            healthStatus = ok ? .ok : .down
            Log.api.info("Healthz: \(ok ? "OK" : "DOWN")")
        } catch {
            healthStatus = .down
            Log.api.warning(
                "Healthz fehlgeschlagen: \(String(describing: error), privacy: .public)"
            )
        }
    }

    /// Deep-Link- + Universal-Link-Routing.
    ///
    /// η-0: Routing-Logik (URL-Normalisierung + Tab-Auswahl) bleibt
    /// erhalten, das eigentliche Ansteuern einer Quote/Author/Source-
    /// Detail-View kommt in η-2 mit `NavigationPath`. Solange parken
    /// wir die URL in `pendingDeepLink`, die Placeholder-View zeigt
    /// sie zur Diagnose an.
    private func handle(url: URL) {
        Log.app.info("Deep-Link empfangen: \(url.absoluteString, privacy: .public)")
        let routed = DeepLinkRouter.route(url, base: AppConfig.webBaseURL)
        pendingDeepLink = routed.url
        selectedTab = routed.isExplore ? .explore : .read
    }
}

enum AppTab: Hashable {
    case read
    case explore
    case submit
    case account
}

enum HealthStatus {
    case unknown
    case ok
    case down
}

/// η-0 Platzhalter — wird in η-2 durch HeuteView + QuoteFeedView ersetzt.
private struct ReadPlaceholderView: View {
    let pendingDeepLink: URL?

    var body: some View {
        VStack(spacing: 16) {
            Image(systemName: "book")
                .font(.system(size: 56))
                .foregroundStyle(ZitareTheme.mutedForeground)
            Text("Lesen")
                .font(.title2)
                .fontWeight(.semibold)
            Text("Native Read-Surface kommt in η-2 (Heute, Quote-Detail, Author-Detail).")
                .font(.callout)
                .foregroundStyle(ZitareTheme.mutedForeground)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 32)
            if let url = pendingDeepLink {
                Text("Deep-Link wartet auf η-2:\n\(url.absoluteString)")
                    .font(.caption.monospaced())
                    .foregroundStyle(ZitareTheme.mutedForeground)
                    .multilineTextAlignment(.center)
                    .padding(.horizontal, 32)
                    .padding(.top, 8)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(ZitareTheme.background)
    }
}

/// η-0 Platzhalter — wird in η-4 durch ExploreView (Facet-Filter) ersetzt.
private struct ExplorePlaceholderView: View {
    var body: some View {
        VStack(spacing: 16) {
            Image(systemName: "sparkle.magnifyingglass")
                .font(.system(size: 56))
                .foregroundStyle(ZitareTheme.mutedForeground)
            Text("Erkunden")
                .font(.title2)
                .fontWeight(.semibold)
            Text("Filter (Sprache, Länge, Thema, Region, Epoche, Rolle) + lokale Suche kommen in η-4 und η-5.")
                .font(.callout)
                .foregroundStyle(ZitareTheme.mutedForeground)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 32)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(ZitareTheme.background)
    }
}