import Testing
@testable import Kordant
import Combine

// MARK: - Mock Analytics Provider

/// A mock analytics provider that records all method calls for test verification.
@MainActor
final class MockAnalyticsProvider: AnalyticsProvider {
    var configureCallCount = 0
    var lastConfiguredUsesIDFA: Bool?
    var loggedEvents: [AnalyticsEvent] = []
    var loggedScreenViews: [(name: String, className: String)] = []
    var flushCallCount = 0
    var resetCallCount = 0

    func configure(usesIDFA: Bool) {
        configureCallCount += 1
        lastConfiguredUsesIDFA = usesIDFA
    }

    func logEvent(_ event: AnalyticsEvent) {
        loggedEvents.append(event)
    }

    func logScreenView(screenName: String, screenClass: String) {
        loggedScreenViews.append((screenName, screenClass))
    }

    func flush() {
        flushCallCount += 1
    }

    func reset() {
        resetCallCount += 1
        configureCallCount = 0
        lastConfiguredUsesIDFA = nil
        loggedEvents.removeAll()
        loggedScreenViews.removeAll()
        flushCallCount = 0
    }
}

// MARK: - AnalyticsService Tests

struct AnalyticsServiceTests {

    /// Creates an AnalyticsService with an isolated UserDefaults and mock provider.
    @MainActor
    private func makeService() -> (service: AnalyticsService, mock: MockAnalyticsProvider, att: ATTService) {
        let defaults = UserDefaults(suiteName: UUID().uuidString)!
        let att = ATTService(defaults: defaults)
        let service = AnalyticsService()
        let mock = MockAnalyticsProvider()
        return (service, mock, att)
    }

    // MARK: - Initial State

    @Test("AnalyticsService starts inactive")
    @MainActor
    func initialState() {
        let (service, _, _) = makeService()
        #expect(service.isAnalyticsActive == false)
        #expect(service.isFullAnalyticsActive == false)
    }

    // MARK: - Configuration

    @Test("AnalyticsService configure with authorized ATT enables full analytics")
    @MainActor
    func configureWithAuthorizedATT() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized

        service.configure(provider: mock)

        #expect(service.isAnalyticsActive == true)
        #expect(service.isFullAnalyticsActive == true)
        #expect(mock.configureCallCount >= 1)
        #expect(mock.lastConfiguredUsesIDFA == true)
    }

    @Test("AnalyticsService configure with denied ATT enables anonymous analytics")
    @MainActor
    func configureWithDeniedATT() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .denied

        service.configure(provider: mock)

        #expect(service.isAnalyticsActive == true)
        #expect(service.isFullAnalyticsActive == false)
        #expect(mock.configureCallCount >= 1)
        #expect(mock.lastConfiguredUsesIDFA == false)
    }

    @Test("AnalyticsService configure with restricted ATT enables anonymous analytics")
    @MainActor
    func configureWithRestrictedATT() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .restricted

        service.configure(provider: mock)

        #expect(service.isAnalyticsActive == true)
        #expect(service.isFullAnalyticsActive == false)
        #expect(mock.lastConfiguredUsesIDFA == false)
    }

    @Test("AnalyticsService configure with notDetermined ATT enables anonymous analytics")
    @MainActor
    func configureWithNotDeterminedATT() {
        let (service, mock, _) = makeService()

        service.configure(provider: mock)

        #expect(service.isAnalyticsActive == true)
        #expect(service.isFullAnalyticsActive == false)
        #expect(mock.lastConfiguredUsesIDFA == false)
    }

    @Test("AnalyticsService configure without provider uses null provider")
    @MainActor
    func configureWithoutProvider() {
        let (service, _, att) = makeService()
        att.trackingStatus = .authorized

        service.configure(provider: nil)

        // Should not crash; events silently discarded
        service.logEvent(AnalyticsEvent(name: "test"))
        #expect(service.isAnalyticsActive == true)
    }

    @Test("AnalyticsService configure is idempotent")
    @MainActor
    func configureIsIdempotent() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized

        service.configure(provider: mock)
        service.configure(provider: mock) // second call should be no-op

        #expect(mock.configureCallCount == 1) // only configured once
    }

    // MARK: - Logging

    @Test("AnalyticsService logEvent sends event to provider")
    @MainActor
    func logEvent() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        let event = AnalyticsEvent(name: "test_event", parameters: ["key": "value"], screenName: "TestScreen")
        service.logEvent(event)

        #expect(mock.loggedEvents.count == 2) // 1 for configure event + 1 for our event
        let loggedEvent = mock.loggedEvents.last
        #expect(loggedEvent?.name == "test_event")
        #expect(loggedEvent?.parameters["key"] == "value")
    }

    @Test("AnalyticsService logEvent is no-op before configure")
    @MainActor
    func logEventBeforeConfigure() {
        let (service, mock, _) = makeService()

        service.logEvent(AnalyticsEvent(name: "test"))

        #expect(mock.loggedEvents.isEmpty)
    }

    @Test("AnalyticsService logScreenView sends screen view event")
    @MainActor
    func logScreenView() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        service.logScreenView(screenName: "Dashboard", screenClass: "DashboardView")

        #expect(mock.loggedScreenViews.count == 1)
        #expect(mock.loggedScreenViews[0].name == "Dashboard")
        #expect(mock.loggedScreenViews[0].className == "DashboardView")
    }

    @Test("AnalyticsService logAction convenience method")
    @MainActor
    func logAction() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        service.logAction("button_tap", screen: "Settings", parameters: ["button": "save"])

        let actionEvent = mock.loggedEvents.last
        #expect(actionEvent?.name == "user_action")
        #expect(actionEvent?.parameters["action"] == "button_tap")
        #expect(actionEvent?.parameters["screen"] == "Settings")
        #expect(actionEvent?.parameters["button"] == "save")
    }

    @Test("AnalyticsService logError convenience method")
    @MainActor
    func logError() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        let error = NSError(domain: "test", code: 42, userInfo: [NSLocalizedDescriptionKey: "Something failed"])
        service.logError(error, context: "login")

        let errorEvent = mock.loggedEvents.last
        #expect(errorEvent?.name == "error")
        #expect(errorEvent?.parameters["error"] == "Something failed")
        #expect(errorEvent?.parameters["context"] == "login")
    }

    @Test("AnalyticsService logFeatureUsed convenience method")
    @MainActor
    func logFeatureUsed() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        service.logFeatureUsed("voice_print", parameters: ["duration": "30s"])

        let featureEvent = mock.loggedEvents.last
        #expect(featureEvent?.name == "feature_used")
        #expect(featureEvent?.parameters["feature"] == "voice_print")
        #expect(featureEvent?.parameters["duration"] == "30s")
    }

    // MARK: - Reset

    @Test("AnalyticsService reset clears state and calls provider reset")
    @MainActor
    func reset() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)
        service.logEvent(AnalyticsEvent(name: "test"))

        service.reset()

        #expect(service.isAnalyticsActive == false)
        #expect(service.isFullAnalyticsActive == false)
        #expect(mock.resetCallCount == 1)
    }

    @Test("AnalyticsService can be re-configured after reset")
    @MainActor
    func reconfigureAfterReset() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)
        service.reset()

        // Re-configure
        service.configure(provider: mock)
        #expect(service.isAnalyticsActive == true)
        #expect(service.isFullAnalyticsActive == true)
        #expect(mock.configureCallCount == 1) // reset clears call counts, configure sets it again
    }

    // MARK: - Flush

    @Test("AnalyticsService flush delegates to provider")
    @MainActor
    func flush() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .authorized
        service.configure(provider: mock)

        service.flush()

        #expect(mock.flushCallCount == 1)
    }

    // MARK: - ATT Status Change

    @Test("AnalyticsService reconfigures when ATT status changes")
    @MainActor
    func reconfiguresOnATTChange() {
        let (service, mock, att) = makeService()
        att.trackingStatus = .notDetermined
        service.configure(provider: mock)
        #expect(mock.lastConfiguredUsesIDFA == false)

        // Simulate ATT status changing to authorized
        att.trackingStatus = .authorized
        att.refreshStatus()
        // Allow publisher to fire
        let expectation = #expectation()
        Task { @MainActor in
            try? await Task.sleep(nanoseconds: 100_000_000) // 100ms for Combine to deliver
            #expect(mock.lastConfiguredUsesIDFA == true)
            expectation.fulfill()
        }
        await #expectation(expectation, timeout: 1.0)
    }
}

// MARK: - NullAnalyticsProvider Tests

struct NullAnalyticsProviderTests {
    @MainActor
    @Test("NullAnalyticsProvider discards all events without crashing")
    func discardsEventsWithoutCrash() {
        let provider = NullAnalyticsProvider()

        // Should not crash
        provider.configure(usesIDFA: true)
        provider.logEvent(AnalyticsEvent(name: "test"))
        provider.logScreenView(screenName: "Test", screenClass: "TestView")
        provider.flush()
        provider.reset()

        // No state to assert — just verifying no crash
        #expect(true)
    }
}

// MARK: - AnalyticsEvent Tests

struct AnalyticsEventTests {
    @Test("AnalyticsEvent initializes with defaults")
    func defaults() {
        let event = AnalyticsEvent(name: "test")
        #expect(event.name == "test")
        #expect(event.parameters.isEmpty)
        #expect(event.screenName == nil)
    }

    @Test("AnalyticsEvent initializes with all parameters")
    func fullInitialization() {
        let event = AnalyticsEvent(
            name: "screen_view",
            parameters: ["screen": "Dashboard"],
            screenName: "Dashboard"
        )
        #expect(event.name == "screen_view")
        #expect(event.parameters["screen"] == "Dashboard")
        #expect(event.screenName == "Dashboard")
    }
}