import SwiftUI

struct NotificationsView: View {
    @StateObject private var viewModel: NotificationsViewModel
    @State private var showingRefreshIndicator = false

    init(viewModel: NotificationsViewModel = NotificationsViewModel()) {
        self._viewModel = StateObject(wrappedValue: viewModel)
    }
    
    var body: some View {
        NavigationStack {
            Group {
                if viewModel.notifications.isEmpty && !viewModel.isLoading {
                    emptyStateView
                } else {
                    notificationListView
                }
            }
            .navigationTitle("Notifications")
            .toolbar {
                if !viewModel.notifications.isEmpty {
                    ToolbarItem(placement: .navigationBarTrailing) {
                        if viewModel.unreadCount > 0 {
                            Button {
                                Task {
                                    await viewModel.markAllAsRead()
                                }
                            } label: {
                                Text("Mark All Read")
                                    .font(.caption)
                            }
                            .foregroundColor(.blue)
                        }
                    }
                }
            }
        }
        .onAppear {
            Task {
                await viewModel.fetchNotifications()
            }
        }
    }
    
    @ViewBuilder
    private var notificationListView: some View {
        List {
            ForEach(viewModel.notifications) { notification in
                NotificationRowView(notification: notification)
                    .onTapGesture {
                        Task {
                            if !notification.isRead {
                                await viewModel.markAsRead(id: notification.id)
                            }
                        }
                    }
            }
            .onDelete { offsets in
                Task {
                    for index in offsets {
                        let notification = viewModel.notifications[index]
                        await viewModel.markAsRead(id: notification.id)
                    }
                    viewModel.notifications.remove(atOffsets: offsets)
                }
            }
        }
        .listStyle(.insetGrouped)
        .refreshable {
            await viewModel.refresh()
        }
    }
    
    private var emptyStateView: some View {
        VStack(spacing: 16) {
            Image(systemName: "bell.slash")
                .font(.system(size: 64))
                .foregroundColor(.secondary)
            
            Text("No Notifications")
                .font(.title2)
                .fontWeight(.semibold)
                .foregroundColor(.primary)
            
            Text("You're all caught up!\nWhen you have notifications, they'll appear here.")
                .font(.subheadline)
                .foregroundColor(.secondary)
                .multilineTextAlignment(.center)
                .padding(.horizontal, 32)
        }
       .padding(.vertical, 60)
    }
}

#Preview {
    NotificationsView()
}

#Preview("With Data") {
    let previewView = NotificationsView()
    
    // Inject mock data for preview
    return previewView
}