import Foundation
import Testing
@testable import Kanban

/// The live board's speech, as decisions — 10-accessibility.md ▸ Live board announcements:
///
/// > Foreign changes announce, app-mediated echoes never do … one polite (non-interrupting) digest
/// > per reload debounce … A vanishing focus is called out specifically … when the lane itself
/// > vanished, recovery walks up then sideways … Bracketed operations announce once, at completion —
/// > never their internal churn. The live-reload-resilience banner is an accessibility element and
/// > is announced when it appears and when it clears.
///
/// Every one of those is a rule about *what to say and where to put focus*, and `BoardAnnouncer`
/// answers both without a window or a screen reader. The `NSAccessibility.post` on the other side of
/// it is two lines with nothing to decide (`AccessibilityAnnouncer`) and is deliberately not tested.

// MARK: - Fixtures

private let lane1 = Ident.lane1
private let lane2 = Ident.lane2
private let lane3 = Ident.lane3
private let card1 = Ident.card1
private let card2 = Ident.card2
private let card3 = Ident.card3

private let lane1ID = ItemID(rawValue: lane1)
private let lane2ID = ItemID(rawValue: lane2)
private let lane3ID = ItemID(rawValue: lane3)
private let card1ID = ItemID(rawValue: card1)
private let card2ID = ItemID(rawValue: card2)
private let card3ID = ItemID(rawValue: card3)

/// Three lanes left to right — Todo (2 cards), Doing (1 card), Done (empty).
private func makeBoard() throws -> WriterFixture {
    let fixture = try WriterFixture()
    try fixture.board()
    try fixture.lane(lane1, order: "1024", title: "Todo")
    try fixture.lane(lane2, order: "2048", title: "Doing")
    try fixture.lane(lane3, order: "3072", title: "Done")
    try fixture.card(card1, in: lane1, order: "1024", title: "Fix login")
    try fixture.card(card2, in: lane1, order: "2048", title: "Second")
    try fixture.card(card3, in: lane2, order: "1024", title: "Third")
    return fixture
}

private func selection(_ ids: Set<ItemID>, in container: ItemContainer = .board) -> ItemReferenceSet {
    ItemReferenceSet(ids: ids, container: container)
}

// MARK: - Focus

@Suite("BoardAnnouncer — a vanishing focus")
struct BoardAnnouncerFocusTests {

    @Test("A focus that survived the reload says nothing and moves nothing")
    func survivingFocus() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try fixture.card(card1, in: lane1, order: "1024", title: "Fix login again")
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: card1ID
        )

        #expect(outcome == .survived)
    }

    @Test("A vanished card names itself and recovers to its lane")
    func vanishedCard() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: card1ID
        )

        #expect(outcome.vanished == .card(title: "Fix login"))
        #expect(outcome.recovery == .lane(lane1ID))
    }

    /// "The announcement then names the *lane*, not the card" — the implied-events discipline
    /// applied to speech, and the reason `VanishedFocus` has two cases rather than a card case with
    /// a lane attached.
    @Test("A card that went with its lane names the lane, and its count")
    func vanishedLaneStealsTheSubject() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url(lane1))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: card1ID
        )

        #expect(outcome.vanished == .lane(title: "Todo", cards: 2))
        #expect(outcome.recovery == .lane(lane2ID), "up, then sideways: the next lane by order")
    }

    @Test("A focused lane that vanished is the lane case outright")
    func focusedLaneVanished() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url(lane2))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([lane2ID]),
            focused: lane2ID
        )

        #expect(outcome.vanished == .lane(title: "Doing", cards: 1))
        #expect(outcome.recovery == .lane(lane3ID))
    }

    @Test("An emptied lane vanishing still names the lane, with no count clause to add")
    func vanishedEmptyLane() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url(lane3))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([lane3ID]),
            focused: lane3ID
        )

        #expect(outcome.vanished == .lane(title: "Done", cards: 0))
    }

    /// The sideways half of the walk: there is no next lane, so the previous one takes the position.
    @Test("The last lane vanishing recovers to the previous one")
    func lastLaneRecoversBackwards() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url(lane3))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([lane3ID]),
            focused: lane3ID
        )

        #expect(outcome.recovery == .lane(lane2ID))
    }

    /// "The board container only when no lanes remain."
    @Test("A board emptied of lanes recovers to the board container")
    func emptiedBoardRecoversToTheContainer() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        for lane in [lane1, lane2, lane3] {
            try FileManager.default.removeItem(at: fixture.url(lane))
        }
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: card1ID
        )

        #expect(outcome.vanished == .lane(title: "Todo", cards: 2))
        #expect(outcome.recovery == .boardContainer)
    }

    /// A checkout-shaped reload: every old lane is gone and different ones are there. The container
    /// is reserved for "no lanes remain", so focus lands on the leftmost lane that *is* there.
    @Test("Lanes replaced wholesale recover to the leftmost surviving lane, not to the container")
    func replacedLanesRecoverToTheFirstLane() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        for lane in [lane1, lane2, lane3] {
            try FileManager.default.removeItem(at: fixture.url(lane))
        }
        try fixture.lane(Ident.lane4, order: "1024", title: "Inbox")
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: card1ID
        )

        #expect(outcome.recovery == .lane(ItemID(rawValue: Ident.lane4)))
    }

    /// 02-architecture.md's re-resolution rule stands where it always did: a selection with
    /// survivors is still the user's selection, and a reload may not re-aim it.
    @Test("Surviving selection members veto the recovery")
    func survivorsVetoRecovery() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID, card2ID]),
            focused: card1ID
        )

        #expect(outcome == .survived)
    }

    @Test("A trash selection never announces and never recovers — focus stays out of the trash")
    func trashSelectionIsOutOfScope() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        try fixture.trashCard(card1, order: "1024", title: "Old")
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url(".trash/\(card1)"))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID], in: .trash),
            focused: card1ID
        )

        #expect(outcome == .survived)
    }

    @Test("No cursor, no sentence — a multi-item selection with no head falls through to the digest")
    func noFocusedItem() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let before = try fixture.snapshot()

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        let outcome = BoardAnnouncer.focusOutcome(
            old: before,
            new: try fixture.snapshot(),
            selection: selection([card1ID]),
            focused: nil
        )

        #expect(outcome == .survived)
    }
}

// MARK: - The ladder

@Suite("BoardAnnouncer — one sentence per reload")
struct BoardAnnouncerSpeechTests {

    /// A digest with something in it, so "silent" in the tests below is never silent by accident.
    private func loudDiff() -> BoardDiff {
        var diff = BoardDiff()
        diff.boardChanged = true
        diff.cards.edited = [card1ID, card2ID]
        diff.cards.added = [card3ID]
        return diff
    }

    private func breakage() -> BoardLoadError {
        BoardLoadError(path: "Todo/index.md", reason: .missingOrder)
    }

    // MARK: Origins

    @Test("A foreign reload speaks its digest — the design's own example sentence")
    func foreignReloadSpeaks() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.diff = loudDiff()

        #expect(BoardAnnouncer.speech(for: facts) == "Board changed: 2 cards edited, 1 card added")
    }

    @Test("App-mediated echoes never announce — the user's own action is not news")
    func appMediatedIsSilent() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .appMediated)
        facts.diff = loudDiff()

        #expect(BoardAnnouncer.speech(for: facts) == nil)
    }

    @Test("A reconciling sweep is silent — it claims nothing changed")
    func reconcilingIsSilent() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .reconciling)
        facts.diff = loudDiff()

        #expect(BoardAnnouncer.speech(for: facts) == nil)
    }

    @Test("A foreign reload that changed nothing says nothing")
    func quietForeignReload() {
        let facts = BoardAnnouncer.ReloadFacts(origin: .foreign)

        #expect(BoardAnnouncer.speech(for: facts) == nil)
    }

    // MARK: Specific beats generic

    @Test("The vanishing-focus sentence displaces the digest — one reload, one sentence")
    func vanishingFocusBeatsTheDigest() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.diff = loudDiff()
        facts.vanishedFocus = .card(title: "Fix login")

        #expect(BoardAnnouncer.speech(for: facts) == "Card 'Fix login' was deleted externally")
    }

    // MARK: Brackets

    @Test("A bracketed operation announces its completion, never its churn")
    func bracketAnnouncesCompletion() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .appMediated)
        facts.endsBracketedOperation = true
        facts.completion = "Pulled 3 commits"
        facts.diff = loudDiff()

        #expect(BoardAnnouncer.speech(for: facts) == "Pulled 3 commits")
    }

    /// Every base-edition bracket today. The seam exists; pro-m1 supplies the phrases.
    @Test("A bracket with no phrase to say stays silent rather than falling back to the digest")
    func bracketWithoutAPhrase() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.endsBracketedOperation = true
        facts.diff = loudDiff()
        facts.vanishedFocus = .card(title: "Fix login")

        #expect(BoardAnnouncer.speech(for: facts) == nil)
    }

    // MARK: Standing conditions

    @Test("A raised read-only lock outranks everything else the reload could say")
    func raisedLockWins() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .appMediated)
        facts.endsBracketedOperation = true
        facts.completion = "Pulled 3 commits"
        facts.lockAfter = .bracketedReloadFailed

        #expect(
            BoardAnnouncer.speech(for: facts)
                == "Error: This board couldn't be re-read after the last operation — showing the last good view, read-only"
        )
    }

    @Test("The banner's announcement is the banner's own label — one condition, one sentence")
    func announcementMatchesTheRowLabel() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.lockAfter = .vanishedRoot

        #expect(
            BoardAnnouncer.speech(for: facts)
                == AccessibilityPhrases.bannerLabel(tone: .error, headline: BannerCenter.headline(for: .vanishedRoot))
        )
    }

    @Test("A lock that was already standing is not repeated on every reload")
    func standingLockIsNotRepeated() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.lockBefore = .vanishedRoot
        facts.lockAfter = .vanishedRoot
        facts.diff = { var diff = BoardDiff(); diff.boardChanged = true; return diff }()

        #expect(BoardAnnouncer.speech(for: facts) == "Board changed")
    }

    @Test("A lock whose cause changed is news again")
    func changedLockCauseSpeaksAgain() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.lockBefore = .unwritableLocation
        facts.lockAfter = .vanishedRoot

        #expect(
            BoardAnnouncer.speech(for: facts)
                == "Error: This board's folder is gone — showing the last good view, read-only"
        )
    }

    @Test("Reload breakage announces on arrival")
    func raisedBreakage() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.breakageAfter = breakage()

        #expect(
            BoardAnnouncer.speech(for: facts)
                == AccessibilityPhrases.bannerLabel(tone: .error, headline: BannerCenter.headline(for: breakage()))
        )
    }

    @Test("A cleared lock is announced — the banner speaks when it clears, not only when it appears")
    func clearedLock() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.lockBefore = .bracketedReloadFailed
        facts.diff = loudDiff()

        #expect(BoardAnnouncer.speech(for: facts) == "The board is editable again")
    }

    @Test("Cleared breakage is announced, below the lock when both heal at once")
    func clearedBreakage() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .foreign)
        facts.breakageBefore = breakage()

        #expect(BoardAnnouncer.speech(for: facts) == "The board is loading again")

        facts.lockBefore = .bracketedReloadFailed
        #expect(BoardAnnouncer.speech(for: facts) == "The board is editable again")
    }

    /// A completion phrase already implies the board is reading and writing again, so it takes the
    /// one sentence the reload has.
    @Test("A completion phrase outranks the clearance it implies")
    func completionOutranksClearance() {
        var facts = BoardAnnouncer.ReloadFacts(origin: .appMediated)
        facts.endsBracketedOperation = true
        facts.completion = "Switched to branch 'redesign'"
        facts.lockBefore = .bracketedReloadFailed

        #expect(BoardAnnouncer.speech(for: facts) == "Switched to branch 'redesign'")
    }
}

// MARK: - At the reload seam

/// The half that is not a value function: **focus actually moves**. Driven through a real
/// `BoardStore` over a real temp board, like `TransientBoardStateTests`, because the recovery's
/// contract includes running *after* `TransientBoardState.resolve(against:)` on the reload path —
/// a suite that called the pure function directly could pass with that wire cut.
@MainActor
@Suite("BoardAnnouncer — at the reload seam")
struct BoardAnnouncerStoreTests {

    /// What the board said, read off `BoardStore.announce` — a class rather than a captured local so
    /// the escaping outlet and the assertions look at one value.
    @MainActor
    private final class SpokenLog {
        var lines: [String] = []

        /// `nil` is the store deciding to say nothing, and is recorded as nothing — the outlet's own
        /// tolerance, so a test that expects silence expects an empty log rather than `[nil]`.
        func record(_ phrase: String?) {
            if let phrase { lines.append(phrase) }
        }
    }

    private func listen(to store: BoardStore) -> SpokenLog {
        let log = SpokenLog()
        store.announce = { log.record($0) }
        return log
    }

    private func reload(_ store: BoardStore, _ origin: WatchOrigin = .foreign) async {
        store.handleWatcherEvent(.treeChanged(origin))
        await store.awaitQuiescence()
    }

    @Test("A foreign delete of the selected card leaves focus on its lane")
    func recoversToTheLane() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        store.transient.select([card1ID], in: .board)

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        await reload(store)

        #expect(store.transient.selection.ids == [lane1ID])
        #expect(store.transient.lastActiveLaneID == lane1ID, "⌘N after the surprise files where the user was left")
    }

    @Test("A foreign delete of the selected card's lane walks up, then sideways")
    func recoversSideways() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        store.transient.select([card1ID], in: .board)

        try FileManager.default.removeItem(at: fixture.url(lane1))
        await reload(store)

        #expect(store.transient.selection.ids == [lane2ID])
    }

    /// The app's own delete already chose its successor (04-interactions.md ▸ The map); a recovery
    /// firing on the echo would override it. 02-architecture.md's silent-vanish rule is what an
    /// app-mediated reload still gets.
    @Test("An app-mediated echo leaves the emptied selection exactly as the set rule left it")
    func appMediatedDoesNotRecover() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        store.transient.select([card1ID], in: .board)

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        await reload(store, .appMediated)

        #expect(store.transient.selection.isEmpty)
    }

    @Test("A reload that leaves the selection standing never re-aims it")
    func survivorsAreLeftAlone() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        store.transient.select([card1ID, card2ID], in: .board)

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        await reload(store)

        #expect(store.transient.selection.ids == [card2ID])
    }

    // MARK: What actually gets said

    @Test("A foreign reload speaks its digest exactly once")
    func foreignReloadSpeaksOnce() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        try fixture.card(card1, in: lane1, order: "1024", title: "Renamed")
        try fixture.card(card2, in: lane1, order: "2048", title: "Also renamed")
        await reload(store)

        #expect(log.lines == ["Board changed: 2 cards edited"])
    }

    @Test("An app-mediated echo says nothing at all")
    func appMediatedEchoIsSilent() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        try fixture.card(card1, in: lane1, order: "1024", title: "Renamed")
        await reload(store, .appMediated)

        #expect(log.lines.isEmpty)
    }

    @Test("A reload that changed nothing says nothing")
    func quietReloadIsSilent() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        await reload(store)

        #expect(log.lines.isEmpty)
    }

    @Test("The vanishing-focus sentence is the one the reload spends its sentence on")
    func vanishingFocusIsWhatIsHeard() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        store.transient.select([card1ID], in: .board)
        let log = listen(to: store)

        try FileManager.default.removeItem(at: fixture.url("\(lane1)/\(card1)"))
        await reload(store)

        #expect(log.lines == ["Card 'Fix login' was deleted externally"])
    }

    /// The seam pro-m1 fills. No base-edition operation passes a phrase today, so this is the one
    /// place the completion path is exercised end to end — including that the phrase is *consumed*
    /// rather than left armed for whatever reload comes next.
    @Test("A bracketed operation announces at completion, once, and never again")
    func bracketSpeaksOnceAtCompletion() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        try store.performWholesale(announcing: "Pulled 3 commits") {
            try fixture.card(card1, in: lane1, order: "1024", title: "From the remote")
        }
        await reload(store, .appMediated)
        #expect(log.lines == ["Pulled 3 commits"], "the operation's result, not the churn inside it")

        log.lines.removeAll()
        try fixture.card(card2, in: lane1, order: "2048", title: "An agent's edit")
        await reload(store)
        #expect(log.lines == ["Board changed: 1 card edited"], "the phrase was consumed, not carried forward")
    }

    @Test("A bracket with no phrase to say stays quiet — every base-edition bracket today")
    func silentBracket() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        try store.performWholesale {
            try fixture.card(card1, in: lane1, order: "1024", title: "Rewritten")
        }
        await reload(store, .appMediated)

        #expect(log.lines.isEmpty)
    }

    /// "Including the read-only lock after a failed bracketed reload" — the banner appears, and the
    /// announcement is the row's own sentence.
    @Test("A failed bracketed reload announces the lock instead of the operation")
    func failedBracketAnnouncesTheLock() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)
        let log = listen(to: store)

        try store.performWholesale(announcing: "Pulled 3 commits") {
            // A lane with no `order` fails the whole load (01-storage-format.md § Malformed input).
            try fixture.item(lane1, "---\nschema: 1\ntitle: Todo\n---\n\n")
        }
        await reload(store, .appMediated)

        #expect(store.readOnlyLock == .bracketedReloadFailed)
        #expect(
            log.lines == [
                "Error: This board couldn't be re-read after the last operation — showing the last good view, read-only"
            ]
        )
    }

    @Test("The lock's clearance is announced too")
    func clearedLockIsAnnounced() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let store = try BoardStore(rootURL: fixture.root)

        try store.performWholesale {
            try fixture.item(lane1, "---\nschema: 1\ntitle: Todo\n---\n\n")
        }
        await reload(store, .appMediated)
        #expect(store.readOnlyLock == .bracketedReloadFailed)

        let log = listen(to: store)
        try fixture.lane(lane1, order: "1024", title: "Todo")
        await reload(store)

        #expect(store.readOnlyLock == nil)
        #expect(log.lines == ["The board is editable again"], "the healing outranks the digest of what healed it")
    }
}