import XCTest
import SwiftUI
@testable import Lendair

// MARK: - Mock Challenge Service

final class MockChallengeService: ChallengeServiceProtocol {
    var challenges: [Challenge] = []
    var selectedChallenge: (challenge: Challenge, participants: [ChallengeParticipant])?
    var joinCalledIds: [String] = []
    var leaveCalledIds: [String] = []
    var createCalled = false
    var leaderboard: [LeaderboardEntry] = []
    var listCallCount = 0
    var listError: Error?

    func listChallenges(filter: ChallengeFilter = ChallengeFilter()) async throws -> [Challenge] {
        listCallCount += 1
        if let error = listError { throw error }
        return challenges
    }

    func getChallenge(id: String) async throws -> (challenge: Challenge, participants: [ChallengeParticipant]) {
        if let selected = selectedChallenge { return selected }
        throw ChallengeError.notFound
    }

    func createChallenge(request: CreateChallengeRequest) async throws -> Challenge {
        createCalled = true
        return Challenge(
            id: "new-1",
            title: request.title,
            description: request.description,
            challengeType: request.challengeType,
            status: .active,
            startDate: request.startDate,
            endDate: request.endDate,
            targetMetric: request.targetMetric,
            targetValue: request.targetValue,
            targetUnit: request.targetMetric.unit,
            participantCount: 1,
            rules: request.rules,
            imageUrl: nil,
            createdBy: "current-user",
            createdByName: "Current User",
            clubId: request.clubId,
            participationStatus: .participating,
            userProgress: 0,
            createdAt: Date()
        )
    }

    func updateChallenge(id: String, request: UpdateChallengeRequest) async throws -> Challenge {
        throw ChallengeError.notFound
    }

    func joinChallenge(id: String) async throws {
        joinCalledIds.append(id)
    }

    func leaveChallenge(id: String) async throws {
        leaveCalledIds.append(id)
    }

    func getLeaderboard(challengeId: String) async throws -> [LeaderboardEntry] {
        return leaderboard
    }

    func submitProgress(challengeId: String, progress: ProgressSubmission) async throws -> (progress: Double, percentage: Double) {
        return (progress.value, min((progress.value / 100) * 100, 100))
    }
}

// MARK: - Helper: Sample Challenges

extension Challenge {
    static func sample(
        id: String = "test-1",
        title: String = "Test Challenge",
        challengeType: ChallengeType = .distance,
        status: ChallengeStatus = .active,
        participationStatus: ParticipationStatus = .participating,
        userProgress: Double = 0,
        targetValue: Double = 100,
        startDate: Date = Date().addingTimeInterval(-7 * 24 * 3600),
        endDate: Date = Date().addingTimeInterval(23 * 24 * 3600)
    ) -> Challenge {
        Challenge(
            id: id,
            title: title,
            description: "Test description",
            challengeType: challengeType,
            status: status,
            startDate: startDate,
            endDate: endDate,
            targetMetric: .distance,
            targetValue: targetValue,
            targetUnit: "km",
            participantCount: 10,
            rules: nil,
            imageUrl: nil,
            createdBy: "user-1",
            createdByName: "Test User",
            clubId: nil,
            participationStatus: participationStatus,
            userProgress: userProgress,
            createdAt: Date()
        )
    }
}

// MARK: - ChallengeServiceTests

final class ChallengeServiceTests: XCTestCase {
    // MARK: - Fetch Challenges

    @MainActor
    func testFetchChallengesLoadsData() async {
        let mock = MockChallengeService()
        mock.challenges = [.sample(id: "1"), .sample(id: "2")]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

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

    @MainActor
    func testFetchChallengesHandlesError() async {
        let mock = MockChallengeService()
        mock.listError = ChallengeError.unauthorized

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

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

    // MARK: - Challenge Type Display

    func testChallengeTypeDisplayNames() {
        XCTAssertEqual(ChallengeType.distance.displayName, "Distance")
        XCTAssertEqual(ChallengeType.time.displayName, "Time")
        XCTAssertEqual(ChallengeType.frequency.displayName, "Frequency")
        XCTAssertEqual(ChallengeType.elevation.displayName, "Elevation")
        XCTAssertEqual(ChallengeType.calories.displayName, "Calories")
        XCTAssertEqual(ChallengeType.streak.displayName, "Streak")
    }

    func testChallengeTypeIcons() {
        XCTAssertEqual(ChallengeType.distance.icon, "arrow.right.arrow.left")
        XCTAssertEqual(ChallengeType.time.icon, "stopwatch.fill")
        XCTAssertEqual(ChallengeType.frequency.icon, "repeat")
        XCTAssertEqual(ChallengeType.elevation.icon, "mountain.2.fill")
        XCTAssertEqual(ChallengeType.calories.icon, "flame.fill")
        XCTAssertEqual(ChallengeType.streak.icon, "calendar.badge.clock")
    }

    func testChallengeMetricUnits() {
        XCTAssertEqual(ChallengeMetric.distance.unit, "km")
        XCTAssertEqual(ChallengeMetric.time.unit, "min")
        XCTAssertEqual(ChallengeMetric.frequency.unit, "sessions")
        XCTAssertEqual(ChallengeMetric.elevation.unit, "m")
        XCTAssertEqual(ChallengeMetric.calories.unit, "kcal")
    }

    // MARK: - Challenge Time States

    func testChallengeIsUpcoming() {
        let future = Challenge.sample(
            id: "1",
            startDate: Date().addingTimeInterval(7 * 24 * 3600),
            endDate: Date().addingTimeInterval(37 * 24 * 3600)
        )
        XCTAssertTrue(future.isUpcoming)
    }

    func testChallengeIsActive() {
        let active = Challenge.sample(id: "1")
        XCTAssertTrue(active.isActive)
    }

    func testChallengeIsCompleted() {
        let past = Challenge.sample(
            id: "1",
            startDate: Date().addingTimeInterval(-30 * 24 * 3600),
            endDate: Date().addingTimeInterval(-7 * 24 * 3600)
        )
        XCTAssertTrue(past.isCompleted)
    }

    // MARK: - Progress Percentage

    func testProgressPercentage() {
        var challenge = Challenge.sample(id: "1", userProgress: 50, targetValue: 100)
        XCTAssertEqual(challenge.progressPercentage, 50)
    }

    func testProgressPercentageOverTarget() {
        var challenge = Challenge.sample(id: "1", userProgress: 120, targetValue: 100)
        XCTAssertEqual(challenge.progressPercentage, 100)
    }

    func testProgressPercentageNoProgress() {
        var challenge = Challenge.sample(id: "1", userProgress: 0, targetValue: 100)
        XCTAssertEqual(challenge.progressPercentage, 0)
    }

    func testProgressPercentageNilProgress() {
        var challenge = Challenge.sample(id: "1", userProgress: nil, targetValue: 100)
        XCTAssertEqual(challenge.progressPercentage, 0)
    }

    // MARK: - Days Remaining

    func testDaysRemaining() {
        let challenge = Challenge.sample(
            id: "1",
            endDate: Date().addingTimeInterval(5 * 24 * 3600)
        )
        XCTAssertGreaterThan(challenge.daysRemaining, 0)
    }

    // MARK: - Computed Filters

    @MainActor
    func testActiveChallengesFiltersCorrectly() async {
        let mock = MockChallengeService()
        mock.challenges = [
            Challenge.sample(id: "1", startDate: Date().addingTimeInterval(-1 * 86400), endDate: Date().addingTimeInterval(7 * 86400)),
            Challenge.sample(id: "2", startDate: Date().addingTimeInterval(7 * 86400), endDate: Date().addingTimeInterval(37 * 86400)),
            Challenge.sample(id: "3", startDate: Date().addingTimeInterval(-10 * 86400), endDate: Date().addingTimeInterval(-1 * 86400)),
        ]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

        XCTAssertEqual(viewModel.activeChallenges.count, 1)
        XCTAssertEqual(viewModel.activeChallenges.first?.id, "1")
    }

    @MainActor
    func testUpcomingChallengesFiltersCorrectly() async {
        let mock = MockChallengeService()
        mock.challenges = [
            Challenge.sample(id: "1", startDate: Date().addingTimeInterval(-1 * 86400), endDate: Date().addingTimeInterval(7 * 86400)),
            Challenge.sample(id: "2", startDate: Date().addingTimeInterval(7 * 86400), endDate: Date().addingTimeInterval(37 * 86400)),
        ]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

        XCTAssertEqual(viewModel.upcomingChallenges.count, 1)
        XCTAssertEqual(viewModel.upcomingChallenges.first?.id, "2")
    }

    @MainActor
    func testCompletedChallengesFiltersCorrectly() async {
        let mock = MockChallengeService()
        mock.challenges = [
            Challenge.sample(id: "1", startDate: Date().addingTimeInterval(-10 * 86400), endDate: Date().addingTimeInterval(-1 * 86400)),
            Challenge.sample(id: "2", startDate: Date().addingTimeInterval(-1 * 86400), endDate: Date().addingTimeInterval(7 * 86400)),
        ]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

        XCTAssertEqual(viewModel.completedChallenges.count, 1)
        XCTAssertEqual(viewModel.completedChallenges.first?.id, "1")
    }

    @MainActor
    func testUserChallengesFiltersParticipating() async {
        let mock = MockChallengeService()
        mock.challenges = [
            Challenge.sample(id: "1", participationStatus: .participating),
            Challenge.sample(id: "2", participationStatus: .notParticipating),
            Challenge.sample(id: "3", participationStatus: .participating),
        ]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchChallenges()

        XCTAssertEqual(viewModel.userChallenges.count, 2)
        XCTAssertTrue(viewModel.userChallenges.allSatisfy { $0.participationStatus == .participating })
    }

    // MARK: - Join and Leave

    @MainActor
    func testJoinChallengeUpdatesLocalState() async {
        let mock = MockChallengeService()
        let challenge = Challenge.sample(id: "1", participationStatus: .notParticipating)
        mock.challenges = [challenge]

        let viewModel = ChallengeViewModel(service: mock)
        viewModel.challenges = [challenge]

        await viewModel.joinChallenge(id: "1")

        XCTAssertEqual(viewModel.challenges.first?.participationStatus, .participating)
        XCTAssertEqual(viewModel.challenges.first?.participantCount, 11)
        XCTAssertEqual(mock.joinCalledIds, ["1"])
    }

    @MainActor
    func testLeaveChallengeUpdatesLocalState() async {
        let mock = MockChallengeService()
        let challenge = Challenge.sample(id: "1", participationStatus: .participating)
        mock.challenges = [challenge]

        let viewModel = ChallengeViewModel(service: mock)
        viewModel.challenges = [challenge]

        await viewModel.leaveChallenge(id: "1")

        XCTAssertEqual(viewModel.challenges.first?.participationStatus, .notParticipating)
        XCTAssertEqual(viewModel.challenges.first?.participantCount, 9)
        XCTAssertEqual(mock.leaveCalledIds, ["1"])
    }

    // MARK: - Challenge Equality

    func testChallengeEquality() {
        let a = Challenge.sample(id: "1", participationStatus: .participating)
        let b = Challenge.sample(id: "1", participationStatus: .participating)
        let c = Challenge.sample(id: "1", participationStatus: .notParticipating)

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

    // MARK: - Create Challenge

    @MainActor
    func testCreateChallengeAddsToList() async {
        let mock = MockChallengeService()
        let viewModel = ChallengeViewModel(service: mock)

        let request = CreateChallengeRequest(
            title: "New Challenge",
            description: "A new challenge",
            challengeType: .distance,
            startDate: Date(),
            endDate: Date().addingTimeInterval(30 * 24 * 3600),
            targetMetric: .distance,
            targetValue: 50,
            rules: nil,
            clubId: nil
        )

        let result = await viewModel.createChallenge(request: request)

        XCTAssertNotNil(result)
        XCTAssertEqual(viewModel.challenges.count, 1)
        XCTAssertEqual(viewModel.challenges.first?.title, "New Challenge")
        XCTAssertTrue(mock.createCalled)
    }

    // MARK: - Leaderboard

    @MainActor
    func testFetchLeaderboardLoadsData() async {
        let mock = MockChallengeService()
        mock.leaderboard = [
            LeaderboardEntry(
                id: "1", position: 1, participantId: "user1",
                participantName: "Alice", participantAvatarUrl: nil,
                progress: 100, progressPercentage: 100
            ),
            LeaderboardEntry(
                id: "2", position: 2, participantId: "user2",
                participantName: "Bob", participantAvatarUrl: nil,
                progress: 75, progressPercentage: 75
            ),
        ]

        let viewModel = ChallengeViewModel(service: mock)
        await viewModel.fetchLeaderboard(challengeId: "1")

        XCTAssertEqual(viewModel.leaderboard.count, 2)
        XCTAssertEqual(viewModel.leaderboard.first?.position, 1)
    }

    // MARK: - Submit Progress

    @MainActor
    func testSubmitProgressUpdatesChallenge() async {
        let mock = MockChallengeService()
        let challenge = Challenge.sample(id: "1", userProgress: 0)
        mock.challenges = [challenge]

        let viewModel = ChallengeViewModel(service: mock)
        viewModel.challenges = [challenge]

        let progress = ProgressSubmission(metric: .distance, value: 50, activityDate: Date())
        await viewModel.submitProgress(challengeId: "1", progress: progress)

        XCTAssertEqual(viewModel.challenges.first?.userProgress, 50)
    }

    // MARK: - Challenge Filter Defaults

    func testChallengeFilterDefaults() {
        let filter = ChallengeFilter()
        XCTAssertEqual(filter.limit, 20)
        XCTAssertEqual(filter.offset, 0)
        XCTAssertNil(filter.challengeType)
        XCTAssertNil(filter.status)
    }

    // MARK: - Challenge Status Cases

    func testChallengeStatusCases() {
        XCTAssertEqual(ChallengeStatus.allCases.count, 4)
        XCTAssertEqual(ChallengeStatus.upcoming.rawValue, "upcoming")
        XCTAssertEqual(ChallengeStatus.active.rawValue, "active")
        XCTAssertEqual(ChallengeStatus.completed.rawValue, "completed")
        XCTAssertEqual(ChallengeStatus.cancelled.rawValue, "cancelled")
    }
}