import XCTest
import SwiftUI
@testable import Lendair

// MARK: - Mock Service

final class MockNotificationsService: NotificationsServiceProtocol {
    var notifications: [NotificationItem] = []
    var markedReadIds: [String] = []
    var markAllCalled = false
    var listCallCount = 0
    var listError: Error?

    func list(params: NotificationListParams = NotificationListParams()) async throws -> [NotificationItem] {
        listCallCount += 1
        if let error = listError {
            throw error
        }
        return notifications
    }

    func markAsRead(id: String) async throws {
        markedReadIds.append(id)
    }

    func markAllAsRead() async throws {
        markAllCalled = true
    }
}

// MARK: - Helper: Sample Notifications

extension NotificationItem {
    static func sample(
        id: String = "test-1",
        type: NotificationType = .loanApproved,
        title: String = "Test",
        message: String = "Test message",
        isRead: Bool = false
    ) -> NotificationItem {
        NotificationItem(
            id: id,
            type: type,
            title: title,
            message: message,
            createdAt: Date(),
            isRead: isRead
        )
    }
}

// MARK: - NotificationServiceTests

final class NotificationServiceTests: XCTestCase {
    // MARK: - Fetch Notifications

    @MainActor
    func testFetchNotificationsLoadsData() async {
        let mock = MockNotificationsService()
        mock.notifications = [.sample(id: "1"), .sample(id: "2")]

        let viewModel = NotificationsViewModel(notificationsService: mock)
        await viewModel.fetchNotifications()

        XCTAssertEqual(viewModel.notifications.count, 2)
        XCTAssertFalse(viewModel.isLoading)
        XCTAssertEqual(mock.listCallCount, 1)
    }

    @MainActor
    func testFetchNotificationsSortsByCreatedAtDescending() async {
        let mock = MockNotificationsService()
        let older = NotificationItem.sample(id: "1", createdAt: Date().addingTimeInterval(-3600))
        let newer = NotificationItem.sample(id: "2", createdAt: Date())
        mock.notifications = [newer, older]

        let viewModel = NotificationsViewModel(notificationsService: mock)
        await viewModel.fetchNotifications()

        XCTAssertEqual(viewModel.notifications.first?.id, "2")
        XCTAssertEqual(viewModel.notifications.last?.id, "1")
    }

    @MainActor
    func testFetchNotificationsSetsLoadingState() async {
        let mock = MockNotificationsService()
        let viewModel = NotificationsViewModel(notificationsService: mock)

        await viewModel.fetchNotifications()
        XCTAssertFalse(viewModel.isLoading)
        XCTAssertNotNil(viewModel.lastRefreshDate)
    }

    @MainActor
    func testFetchNotificationsHandlesError() async {
        let mock = MockNotificationsService()
        mock.listError = NotificationError.unauthorized

        let viewModel = NotificationsViewModel(notificationsService: mock)
        await viewModel.fetchNotifications()

        XCTAssertTrue(viewModel.notifications.isEmpty)
        XCTAssertFalse(viewModel.isLoading)
        XCTAssertEqual(viewModel.error, .unauthorized)
    }

    // MARK: - Mark As Read

    @MainActor
    func testMarkAsReadUpdatesLocalState() async {
        let mock = MockNotificationsService()
        let unread = NotificationItem.sample(id: "1", isRead: false)
        mock.notifications = [unread]

        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [unread]

        await viewModel.markAsRead(id: "1")

        XCTAssertTrue(viewModel.notifications.first?.isRead == true)
        XCTAssertEqual(mock.markedReadIds, ["1"])
    }

    @MainActor
    func testMarkAsReadIgnoresUnknownId() async {
        let mock = MockNotificationsService()
        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [.sample(id: "1")]

        await viewModel.markAsRead(id: "999")

        XCTAssertTrue(mock.markedReadIds.isEmpty)
    }

    @MainActor
    func testMarkAsReadReducesUnreadCount() async {
        let mock = MockNotificationsService()
        let read = NotificationItem.sample(id: "1", isRead: true)
        let unread = NotificationItem.sample(id: "2", isRead: false)

        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [read, unread]

        XCTAssertEqual(viewModel.unreadCount, 1)

        await viewModel.markAsRead(id: "2")
        XCTAssertEqual(viewModel.unreadCount, 0)
    }

    // MARK: - Mark All As Read

    @MainActor
    func testMarkAllAsReadUpdatesAllNotifications() async {
        let mock = MockNotificationsService()
        let unread1 = NotificationItem.sample(id: "1", isRead: false)
        let unread2 = NotificationItem.sample(id: "2", isRead: false)
        let read = NotificationItem.sample(id: "3", isRead: true)

        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [unread1, unread2, read]

        await viewModel.markAllAsRead()

        XCTAssertTrue(viewModel.notifications.allSatisfy { $0.isRead })
        XCTAssertTrue(mock.markAllCalled)
        XCTAssertEqual(viewModel.unreadCount, 0)
    }

    @MainActor
    func testMarkAllAsReadNoOpWhenAllRead() async {
        let mock = MockNotificationsService()
        let read1 = NotificationItem.sample(id: "1", isRead: true)
        let read2 = NotificationItem.sample(id: "2", isRead: true)

        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [read1, read2]

        await viewModel.markAllAsRead()

        XCTAssertFalse(mock.markAllCalled)
    }

    // MARK: - Unread Count

    @MainActor
    func testUnreadCountCalculatesCorrectly() async {
        let mock = MockNotificationsService()
        let viewModel = NotificationsViewModel(notificationsService: mock)
        viewModel.notifications = [
            NotificationItem.sample(id: "1", isRead: false),
            NotificationItem.sample(id: "2", isRead: true),
            NotificationItem.sample(id: "3", isRead: false),
        ]

        XCTAssertEqual(viewModel.unreadCount, 2)
    }

    @MainActor
    func testUnreadCountIsEmptyWhenNoNotifications() async {
        let mock = MockNotificationsService()
        let viewModel = NotificationsViewModel(notificationsService: mock)

        XCTAssertEqual(viewModel.unreadCount, 0)
    }

    // MARK: - Refresh

    @MainActor
    func testRefreshReloadsData() async {
        let mock = MockNotificationsService()
        mock.notifications = [.sample(id: "1")]

        let viewModel = NotificationsViewModel(notificationsService: mock)
        await viewModel.refresh()

        XCTAssertEqual(mock.listCallCount, 1)
        XCTAssertEqual(viewModel.notifications.count, 1)
    }
}

// MARK: - NotificationModelTests

final class NotificationModelTests: XCTestCase {
    func testNotificationTypeIcons() {
        XCTAssertEqual(NotificationType.loanApproved.icon, "checkmark.circle.fill")
        XCTAssertEqual(NotificationType.loanRejected.icon, "xmark.circle.fill")
        XCTAssertEqual(NotificationType.paymentReceived.icon, "arrow.down.circle.fill")
        XCTAssertEqual(NotificationType.paymentDue.icon, "exclamationmark.circle.fill")
        XCTAssertEqual(NotificationType.newLender.icon, "person.circle.fill")
        XCTAssertEqual(NotificationType.systemUpdate.icon, "info.circle.fill")
    }

    func testNotificationTypeColors() {
        XCTAssertEqual(NotificationType.loanApproved.color, .green)
        XCTAssertEqual(NotificationType.loanRejected.color, .red)
        XCTAssertEqual(NotificationType.paymentReceived.color, .green)
        XCTAssertEqual(NotificationType.paymentDue.color, .orange)
        XCTAssertEqual(NotificationType.newLender.color, .blue)
        XCTAssertEqual(NotificationType.systemUpdate.color, .gray)
    }

    func testNotificationItemEquality() {
        let a = NotificationItem.sample(id: "1", isRead: false)
        let b = NotificationItem.sample(id: "1", isRead: false)
        let c = NotificationItem.sample(id: "1", isRead: true)

        XCTAssertEqual(a, b)
        XCTAssertNotEqual(a, c)
    }

    func testNotificationTypeRawValue() {
        XCTAssertEqual(NotificationType.loanApproved.rawValue, "LOAN_APPROVED")
        XCTAssertEqual(NotificationType.paymentDue.rawValue, "PAYMENT_DUE")
    }

    func testNotificationListParamsDefaults() {
        let params = NotificationListParams()
        XCTAssertEqual(params.limit, 20)
        XCTAssertEqual(params.offset, 0)
    }

    func testNotificationListParamsCustom() {
        let params = NotificationListParams(limit: 50, offset: 100)
        XCTAssertEqual(params.limit, 50)
        XCTAssertEqual(params.offset, 100)
    }
}