import XCTest
@testable import FuelBoardShared

/// Shared payload storage must survive an install whose provisioning profile
/// has NO `com.apple.security.application-groups` entitlement (free/personal
/// team and SideStore installs) — the exact situation this test runner is in.
///
/// Regression guard: `appGroupFileURL` used to return nil without a group
/// container, so every save silently failed and every load returned empty. That
/// left `loadStations()` permanently empty (letting the freshness gate skip the
/// fetch for ever, i.e. a blank station list) and re-downloaded the ~2.8 MB
/// dump on every refresh. Storage now falls back to the app's own container.
final class FuelStoreFileCacheTests: XCTestCase {

    func testSharedFileURLExistsWithoutAppGroupContainer() {
        XCTAssertNotNil(
            FuelStore.appGroupFileURL("fuelboard.test.probe.json"),
            "storage must resolve to a writable location even when the App Group container is unprovisioned"
        )
    }

    func testSharedFileRoundTripsWithoutAppGroupContainer() throws {
        let name = "fuelboard.test.roundtrip.json"
        let payload = Data("hello-cache".utf8)

        XCTAssertTrue(
            FuelStore.saveAppGroupFile(payload, name: name),
            "save must succeed without an App Group container"
        )
        XCTAssertEqual(FuelStore.loadAppGroupFile(name), payload)

        if let url = FuelStore.appGroupFileURL(name) {
            try? FileManager.default.removeItem(at: url)
        }
    }

    /// The dump cache is what stops a ~2.8 MB re-download on every refresh, so
    /// it must round-trip too — not just the station list.
    func testDumpCacheRoundTripsWithoutAppGroupContainer() {
        let day = "2026-01-01"
        let data = Data(repeating: 7, count: 4096)

        MirrorFuelProvider.saveDumpCache(day: day, data: data)
        let cache = MirrorFuelProvider.loadDumpCache()

        XCTAssertEqual(cache?.day, day, "cached dump day must survive a round-trip")
        XCTAssertEqual(cache?.data, data, "cached dump payload must survive a round-trip")

        if let url = FuelStore.appGroupFileURL(MirrorFuelProvider.liveDumpCacheFileName) {
            try? FileManager.default.removeItem(at: url)
        }
    }

    /// The road-distance cache is memoized in memory because re-reading it per
    /// station (it lives in the keychain) stalled the main thread past the iOS
    /// launch watchdog. A save must therefore invalidate the memo — a stale
    /// in-memory cache would show wrong distances after a route refresh.
    func testRoadDistanceMemoRefreshesAfterSave() {
        FuelStore.saveRoadDistances(sourceLat: 51.0, sourceLng: -1.0, entries: [:])
        XCTAssertEqual(FuelStore.loadRoadDistances()?.sourceLat, 51.0)

        FuelStore.saveRoadDistances(sourceLat: 52.0, sourceLng: -2.0, entries: [:])

        XCTAssertEqual(
            FuelStore.loadRoadDistances()?.sourceLat, 52.0,
            "load must reflect the newest save, not a stale memoized cache"
        )
    }
}