import SwiftUI

// Root home container — 5-tab bottom bar matching Android bottom_nav_menu.xml
struct HomeView: View {
    @State private var vm = HomeViewModel()
    @State private var selectedTab = 0

    var body: some View {
        TabView(selection: $selectedTab) {
            DashboardView()
                .tabItem { Label("Dashboard", systemImage: "house.fill") }
                .tag(0)

            AccountsView()
                .tabItem { Label("Accounts", systemImage: "building.columns.fill") }
                .tag(1)

            ContactsView()
                .tabItem { Label("Contacts", systemImage: "person.2.fill") }
                .tag(2)

            TransferView()
                .tabItem { Label("Transfer", systemImage: "arrow.up.right") }
                .tag(3)

            placeholderTab("More", icon: "ellipsis")
                .tabItem { Label("More", systemImage: "ellipsis") }
                .tag(4)
        }
        .environment(vm)
        .task { await vm.refreshIfNeeded() }
        // When a contact's "Send" button is tapped, jump to the Transfer tab
        .onChange(of: vm.pendingTransferContact) { _, contact in
            if contact != nil { selectedTab = 3 }
        }
        // When a QR code is scanned from Dashboard, jump to the Transfer tab
        .onChange(of: vm.pendingTransferQRData) { _, qrData in
            if qrData != nil { selectedTab = 3 }
        }
        // When a BML gateway QR is scanned from Dashboard, jump to the Transfer tab
        .onChange(of: vm.pendingBmlQrUrl) { _, url in
            if url != nil { selectedTab = 3 }
        }
    }

    @ViewBuilder
    private func placeholderTab(_ title: String, icon: String) -> some View {
        NavigationStack {
            VStack(spacing: 16) {
                Image(systemName: icon)
                    .font(.system(size: 44))
                    .foregroundStyle(.secondary)
                Text(title)
                    .font(.title2.bold())
                    .foregroundStyle(.secondary)
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .background(Color(.systemBackground))
            .navigationTitle(title)
        }
    }
}

#Preview {
    HomeView()
        .environment(AppViewModel())
}