import SwiftUI

struct DashboardView: View {
    @Environment(DeviceStore.self) private var store
    @Environment(BluetoothManager.self) private var bluetooth

    @State private var isAddingDevice = false
    @State private var isManagingProfiles = false

    private let columns = [GridItem(.adaptive(minimum: 300), spacing: 16)]

    var body: some View {
        NavigationStack {
            ScrollView {
                if !bluetooth.isBluetoothReady {
                    statusBanner
                }

                if store.activeDevices.isEmpty {
                    emptyState
                } else {
                    LazyVGrid(columns: columns, spacing: 16) {
                        ForEach(store.activeDevices) { device in
                            NavigationLink {
                                DeviceDetailView(device: device)
                            } label: {
                                DeviceCard(
                                    device: device,
                                    snapshot: bluetooth.snapshots[device.id],
                                    linkState: bluetooth.linkStates[device.id] ?? .searching
                                )
                            }
                            .buttonStyle(.plain)
                        }
                    }
                    .padding(.horizontal)
                    .padding(.top, 8)
                }
            }
            .background(Color(.systemGroupedBackground))
            .navigationTitle(store.activeProfile?.name ?? "Camper")
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    profileMenu
                }
                ToolbarItem(placement: .primaryAction) {
                    Button("Gerät hinzufügen", systemImage: "plus") {
                        isAddingDevice = true
                    }
                }
            }
            .sheet(isPresented: $isAddingDevice) {
                AddDeviceView()
            }
            .sheet(isPresented: $isManagingProfiles) {
                ProfilesView()
            }
        }
    }

    /// Umschalter zwischen den Fahrzeugen.
    private var profileMenu: some View {
        Menu {
            Picker("Fahrzeug", selection: Binding(
                get: { store.activeProfileID },
                set: { id in
                    guard let profile = store.profiles.first(where: { $0.id == id }) else { return }
                    store.selectProfile(profile)
                    bluetooth.refreshConfiguration()
                }
            )) {
                ForEach(store.profiles) { profile in
                    Label(profile.name, systemImage: profile.symbol).tag(profile.id)
                }
            }
            Divider()
            Button("Fahrzeuge verwalten…", systemImage: "gearshape") {
                isManagingProfiles = true
            }
        } label: {
            Label(store.activeProfile?.name ?? "Fahrzeug",
                  systemImage: store.activeProfile?.symbol ?? "box.truck")
                .labelStyle(.iconOnly)
        }
    }

    private var statusBanner: some View {
        Label(bluetooth.bluetoothStatusText, systemImage: "exclamationmark.triangle.fill")
            .font(.callout)
            .frame(maxWidth: .infinity, alignment: .leading)
            .padding()
            .background(.orange.opacity(0.15), in: .rect(cornerRadius: 12))
            .padding(.horizontal)
            .padding(.top, 8)
    }

    private var emptyState: some View {
        ContentUnavailableView {
            Label("Noch keine Geräte", systemImage: "antenna.radiowaves.left.and.right")
        } description: {
            Text("Füge \(store.activeProfile.map { "„\($0.name)“" } ?? "diesem Fahrzeug") "
                 + "den Ladebooster, den Solarladeregler und das BMS hinzu.")
        } actions: {
            Button("Gerät suchen") { isAddingDevice = true }
                .buttonStyle(.borderedProminent)
        }
        .padding(.top, 60)
    }
}