import Foundation
import SwiftUI

@MainActor
class NotificationsViewModel: ObservableObject {
    @Published var notifications: [NotificationItem] = []
    @Published var isLoading: Bool = false
    @Published var badgeCount: Int = 0
    @Published var lastRefreshDate: Date?
    @Published var error: NotificationError?

    private let notificationsService: NotificationsServiceProtocol

    init(notificationsService: NotificationsServiceProtocol = NotificationsService()) {
        self.notificationsService = notificationsService
    }

    func fetchNotifications() async {
        isLoading = true
        error = nil
        defer {
            isLoading = false
            lastRefreshDate = Date()
        }

        do {
            let fetchedNotifications = try await notificationsService.list()
            notifications = fetchedNotifications.sorted { $0.createdAt > $1.createdAt }
            badgeCount = notifications.filter { !$0.isRead }.count
        } catch let error as NotificationError {
            self.error = error
        } catch {
            print("Failed to fetch notifications: \(error)")
        }
    }

    func refresh() async {
        await fetchNotifications()
    }

    func fetchUnreadCount() async {
        do {
            let count = try await notificationsService.getUnreadCount()
            badgeCount = count
        } catch {
            print("Failed to fetch unread count: \(error)")
        }
    }

    func markAsRead(id: String) async {
        guard let index = notifications.firstIndex(where: { $0.id == id }) else { return }

        do {
            try await notificationsService.markAsRead(id: id)
            notifications[index].isRead = true
            badgeCount = max(0, badgeCount - 1)
            objectWillChange.send()
        } catch {
            print("Failed to mark notification as read: \(error)")
        }
    }

    func markAllAsRead() async {
        let unreadIds = notifications.filter { !$0.isRead }.map { $0.id }
        guard !unreadIds.isEmpty else { return }

        do {
            try await notificationsService.markAllAsRead()
            for index in notifications.indices {
                notifications[index].isRead = true
            }
            badgeCount = 0
            objectWillChange.send()
        } catch {
            print("Failed to mark all as read: \(error)")
        }
    }

    var unreadCount: Int {
        notifications.filter { !$0.isRead }.count
    }
}