import XCTest
@testable import FuelBoardShared

/// The Best Value announcement gate — shown to users who updated into the
/// feature after finishing onboarding, once per announcement version.
///
/// Every fact the rule depends on is injectable, so the whole truth table is
/// checked here instead of driving a simulator through four combinations (which
/// is how a rule like this quietly rots).
final class BestValueAnnouncementTests: XCTestCase {

    /// Nothing set up: the case that should be announced to.
    private var unconfigured: FuelSavingsSettings { FuelSavingsSettings.defaults }

    /// Enabled with the default 45 MPG / £40, which is a valid configuration.
    private var configured: FuelSavingsSettings {
        var settings = FuelSavingsSettings.defaults
        settings.enabled = true
        return settings
    }

    func testAnnouncesToAnExistingUserWhoHasNotSeenIt() {
        XCTAssertTrue(
            FuelStore.shouldAnnounceBestValue(settings: unconfigured,
                                              hasSeen: false,
                                              onboardingDue: false,
                                              isSuppressed: false),
            "an existing user, nothing configured, announcement unseen: show it"
        )
    }

    func testNeverAnnouncesTwice() {
        XCTAssertFalse(FuelStore.shouldAnnounceBestValue(settings: unconfigured,
                                                         hasSeen: true,
                                                         onboardingDue: false))
    }

    func testNeverWhileOnboardingIsDue() {
        // A new install runs the full onboarding, which already contains this
        // page — showing both would be the obvious first bug.
        XCTAssertFalse(FuelStore.shouldAnnounceBestValue(settings: unconfigured,
                                                         hasSeen: false,
                                                         onboardingDue: true))
    }

    func testNeverWhileOnboardingIsOnScreen() {
        XCTAssertFalse(FuelStore.shouldAnnounceBestValue(settings: unconfigured,
                                                         hasSeen: false,
                                                         onboardingDue: false,
                                                         isSuppressed: true))
    }

    func testNeverForSomebodyWhoAlreadyConfiguredIt() {
        XCTAssertFalse(FuelStore.shouldAnnounceBestValue(settings: configured,
                                                         hasSeen: false,
                                                         onboardingDue: false),
                       "never announce a feature the user set up themselves")
    }

    func testStillAnnouncesWhenEnabledButNotActuallyConfigured() {
        // Enabled with an out-of-range MPG is NOT configured, so the
        // announcement still has something useful to offer.
        var settings = FuelSavingsSettings.defaults
        settings.enabled = true
        settings.mpg = 2  // below the validity floor
        XCTAssertTrue(FuelStore.shouldAnnounceBestValue(settings: settings,
                                                        hasSeen: false,
                                                        onboardingDue: false))
    }

    func testMarkingSeenIsWhatStopsTheNextLaunch() {
        // The stored contract the gate reads.
        FuelStore.markBestValueIntroSeen()
        XCTAssertTrue(FuelStore.hasSeenBestValueIntro())
        XCTAssertFalse(FuelStore.shouldAnnounceBestValue(settings: unconfigured,
                                                         onboardingDue: false))
    }

    func testTheStoredValueIsTheAnnouncementVersionNotTheAppVersion() {
        // Keyed on the announcement version so a bugfix release cannot
        // re-announce anything. Bump `currentBestValueIntroVersion` only when
        // Best Value changes in a way worth re-explaining — this assertion is
        // the reminder that doing so re-shows the page to everyone.
        XCTAssertEqual(FuelStore.currentBestValueIntroVersion, 1)
    }
}