import SwiftUI
import FlixyDesign
import MediaKit

/// Der Knopf, der zur Suche führt. Steht in mehreren Werkzeugleisten.
struct SearchToolbarItem: ToolbarContent {
    var body: some ToolbarContent {
        ToolbarItem(placement: .topBarTrailing) {
            NavigationLink(value: SearchRoute()) {
                Image(systemName: "magnifyingglass")
            }
            .accessibilityLabel(Text("search.title"))
        }
    }
}

struct SearchRoute: Hashable {}

/// Sucht über alle Mediatheken des Servers.
struct SearchView: View {
    @Environment(FlixySession.self) private var session

    @State private var text = ""
    @State private var hubs: [MediaRowGroup] = []
    @State private var isSearching = false
    @State private var recent: [String] = UserDefaults.standard.stringArray(forKey: recentKey) ?? []

    private static let recentKey = "flixy.search.recent"
    private static let recentLimit = 8

    var body: some View {
        Group {
            if text.isEmpty {
                recentSearches
            } else if hubs.isEmpty && !isSearching {
                ContentUnavailableView.search(text: text)
            } else {
                results
            }
        }
        .background(Color.flixyCanvas)
        .navigationTitle(Text("search.title"))
        .navigationBarTitleDisplayMode(.inline)
        .searchable(text: $text, placement: .navigationBarDrawer(displayMode: .always))
        .navigationDestination(for: MediaRoute.self) { MediaDetailView(route: $0) }
        // Jeder Tastendruck löst eine Anfrage aus — aber erst nach einer
        // kurzen Pause. Ohne sie schickt „Blade Runner" zwölf Anfragen los,
        // von denen elf verworfen werden.
        .task(id: text) { await search() }
    }

    private var results: some View {
        ScrollView {
            LazyVStack(alignment: .leading, spacing: FlixySpacing.section) {
                ForEach(hubs) { hub in
                    MediaRow(row: hub)
                }
            }
            .padding(.vertical, FlixySpacing.loose)
        }
    }

    @ViewBuilder
    private var recentSearches: some View {
        if recent.isEmpty {
            ContentUnavailableView {
                Label("search.title", systemImage: "magnifyingglass")
            } description: {
                Text("search.hint")
            }
        } else {
            List {
                Section {
                    ForEach(recent, id: \.self) { entry in
                        Button {
                            text = entry
                        } label: {
                            Label(entry, systemImage: "clock.arrow.circlepath")
                                .foregroundStyle(Color.flixyTextSecondary)
                        }
                    }
                    .onDelete { offsets in
                        recent.remove(atOffsets: offsets)
                        persistRecent()
                    }
                } header: {
                    Text("search.recent")
                }
                .listRowBackground(Color.flixySurface)
            }
            .scrollContentBackground(.hidden)
        }
    }

    private func search() async {
        let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
        guard let backend = session.backend, trimmed.count >= 2 else {
            hubs = []
            return
        }

        do {
            try await Task.sleep(for: .milliseconds(300))
        } catch {
            // Ein neuer Tastendruck hat diese Aufgabe abgebrochen — genau der
            // Zweck der Pause.
            return
        }

        isSearching = true
        defer { isSearching = false }

        do {
            hubs = try await backend.search(trimmed, limit: 30)
            if !hubs.isEmpty { remember(trimmed) }
        } catch is CancellationError {
            return
        } catch {
            hubs = []
        }
    }

    private func remember(_ entry: String) {
        recent.removeAll { $0.caseInsensitiveCompare(entry) == .orderedSame }
        recent.insert(entry, at: 0)
        recent = Array(recent.prefix(Self.recentLimit))
        persistRecent()
    }

    private func persistRecent() {
        UserDefaults.standard.set(recent, forKey: Self.recentKey)
    }
}