import Foundation
import Testing
@testable import Kanban

/// A card window's whole lifecycle is one decision re-taken on every snapshot: does this key still
/// name a card? Four answers, three of which are "no" for different reasons, and the one that is
/// easiest to get wrong — a live card under a tombstoned lane — is invisible in the card's own data.
/// So the decision is a pure function and this is its suite; nothing here needs a window.

// MARK: - Fixtures

/// - lane 1 (live): one live card, one tombstoned card
/// - lane 2 (**tombstoned**): one live card, whose own flag is clear
@MainActor
private func makeBoard() throws -> WriterFixture {
    let fixture = try WriterFixture()
    try fixture.item("", Item.board)

    try fixture.item(Ident.lane1, Item.rich(order: "1024", title: "Todo"))
    try fixture.item("\(Ident.lane1)/\(Ident.card1)", Item.rich(order: "1024", title: "Fix login"))
    try fixture.item(
        "\(Ident.lane1)/\(Ident.card2)",
        "---\nschema: 1\norder: 2048\ntitle: Gone\ndeleted: 2026-01-01T00:00:00Z\n---\nbody\n"
    )

    try fixture.item(
        Ident.lane2,
        "---\nschema: 1\norder: 2048\ntitle: Archive\ndeleted: 2026-01-01T00:00:00Z\n---\nbody\n"
    )
    try fixture.item("\(Ident.lane2)/\(Ident.card3)", Item.rich(order: "1024", title: "Buried alive"))
    return fixture
}

private func title(_ fate: CardWindowFate) -> String? {
    guard case let .shows(card) = fate else { return nil }
    return card.title.value
}

// MARK: - Tests

@MainActor
@Suite("Card window fate")
struct CardWindowFateTests {

    @Test("A live card in a live lane keeps its window")
    func aLiveCardShows() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let snapshot = try BoardLoader.load(boardRoot: fixture.root).model

        let fate = CardWindowHost.cardWindowFate(cardID: Ident.card1, in: snapshot)
        #expect(title(fate) == "Fix login")
    }

    @Test("A tombstoned card dismisses its window")
    func aTombstonedCardDismisses() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let snapshot = try BoardLoader.load(boardRoot: fixture.root).model

        // ⌫ on the board closes the card's open window — "a tombstone counts as deleted"
        // (05-card-window.md). The card is still in the snapshot; the trash renders it.
        #expect(snapshot.lanes[0].cards.contains { $0.id.rawValue == Ident.card2 })
        #expect(CardWindowHost.cardWindowFate(cardID: Ident.card2, in: snapshot) == .dismisses)
    }

    @Test("A live card under a tombstoned lane dismisses too — liveness is ancestor-walked")
    func aLaneTombstoneDismissesItsCards() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let snapshot = try BoardLoader.load(boardRoot: fixture.root).model

        // The card's own flag says nothing is wrong. Its lane's does, and 03-board-ui.md collapses a
        // tombstoned lane to one restorable trash entry — so the card renders nowhere, and a window
        // onto something that renders nowhere is the case this walk exists for.
        let buried = try #require(snapshot.lanes.first { $0.id.rawValue == Ident.lane2 }?.cards.first)
        #expect(!buried.isDeleted)
        #expect(CardWindowHost.cardWindowFate(cardID: Ident.card3, in: snapshot) == .dismisses)
    }

    @Test("A card that is not in this board's snapshot dismisses — the cross-board move")
    func anAbsentCardDismisses() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let snapshot = try BoardLoader.load(boardRoot: fixture.root).model

        // What a cross-board move looks like from the source board: the UUID travels with the card,
        // but the board half of the window's key no longer names it, so the window goes exactly as it
        // would for a delete.
        #expect(CardWindowHost.cardWindowFate(cardID: Ident.card4, in: snapshot) == .dismisses)
    }

    @Test("A case-respelled card id still finds its card")
    func theCardIDIsComparedAsAUUIDValue() throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let snapshot = try BoardLoader.load(boardRoot: fixture.root).model

        // An agent's `uuidgen` prints uppercase (01-storage-format.md § Fractal layout), so a card
        // window keyed on one spelling must still find a folder written in the other. Comparing the
        // strings would dismiss a perfectly live card.
        let fate = CardWindowHost.cardWindowFate(cardID: Ident.card1.uppercased(), in: snapshot)
        #expect(title(fate) == "Fix login")
    }
}