import Foundation
import Testing
@testable import Kanban

/// `BoardRegistry` is app-private state about the user's boards, and its two hardest promises are
/// negative ones: it must match a board that moved (so settings survive a rename), and it must
/// never write a byte into a board folder (so files-first stays absolute). Both are tested here
/// against real directories and a real storage file in temp — a fake filesystem would prove neither,
/// since both are claims about file identity and about what is on disk.
///
/// The third promise is that nothing it does can take the app down: a missing file, a corrupt file,
/// and a bookmark that no longer resolves all have expected, boring outcomes, and each has a test.

// MARK: - Fixtures

/// A temp folder holding the registry's JSON file, kept separate from every board folder so the
/// quarantine test can see exactly what the registry put next to it.
@MainActor
private struct RegistryStorage {
    let folder: URL

    var url: URL { folder.appendingPathComponent("board-registry.json", isDirectory: false) }

    init() throws {
        folder = FileManager.default.temporaryDirectory
            .appendingPathComponent("BoardRegistryTests-\(UUID().uuidString)", isDirectory: true)
        try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
    }

    func tearDown() {
        try? FileManager.default.removeItem(at: folder)
    }

    func entryNames() throws -> [String] {
        try FileManager.default.contentsOfDirectory(atPath: folder.path).sorted()
    }
}

/// A small real board — the registry never reads inside one, but a folder with contents is what
/// makes the files-first test able to notice a single stray byte.
@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: "First"))
    return fixture
}

/// Every path under `root` (the root itself included, hidden entries included) with its
/// modification date — the shape "the registry touched nothing" takes as an assertion.
private func treeSnapshot(of root: URL) throws -> [String: Date] {
    var snapshot: [String: Date] = [:]

    func modified(_ url: URL) throws -> Date {
        try url.resourceValues(forKeys: [.contentModificationDateKey]).contentModificationDate ?? .distantPast
    }

    snapshot["."] = try modified(root)
    let walker = FileManager.default.enumerator(
        at: root,
        includingPropertiesForKeys: [.contentModificationDateKey],
        options: []
    )
    while let url = walker?.nextObject() as? URL {
        let relative = url.path.replacingOccurrences(of: root.path + "/", with: "")
        snapshot[relative] = try modified(url)
    }
    return snapshot
}

private func ids(_ recents: [RecentBoard]) -> [UUID] {
    recents.map(\.record.id)
}

// MARK: - Tests

@MainActor
@Suite("BoardRegistry")
struct BoardRegistryTests {

    // MARK: Matching on open

    @Test("A second open of the same board updates its record; a rename does not fool it")
    func recordOpenMatchesByIdentity() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let registry = BoardRegistry(storageURL: storage.url)

        let id = registry.recordOpen(of: fixture.root, displayName: "Todo Board")
        let created = try #require(registry.record(id: id))
        #expect(!created.bookmark.isEmpty)
        #expect(created.displayName == "Todo Board")
        #expect(created.lastKnownPath == fixture.root.path)
        #expect(created.laneCount == nil, "counts are stamped at close, never guessed at open")
        #expect(created.pushOnCommit == false)
        #expect(created.remoteLocationWarned == false)
        #expect(registry.recents().count == 1)

        try await Task.sleep(for: .milliseconds(5))
        let again = registry.recordOpen(of: fixture.root, displayName: "Renamed In Title")
        #expect(again == id, "the same folder is the same board")
        #expect(registry.recents().count == 1, "a second open updates a record, it does not add one")
        let updated = try #require(registry.record(id: id))
        #expect(updated.displayName == "Renamed In Title")
        #expect(updated.lastOpened > created.lastOpened)

        // The done-when criterion: a Finder rename, then an open through the new path. Only file
        // identity gets this right — every path-keyed answer produces a second record here.
        let renamed = fixture.root
            .deletingLastPathComponent()
            .appendingPathComponent("renamed-\(UUID().uuidString)", isDirectory: true)
        try FileManager.default.moveItem(at: fixture.root, to: renamed)
        defer { try? FileManager.default.removeItem(at: renamed) }

        let afterRename = registry.recordOpen(of: renamed, displayName: "Todo Board")
        #expect(afterRename == id, "a renamed board keeps its record, and so keeps its settings")
        #expect(registry.recents().count == 1)
        #expect(registry.record(id: id)?.lastKnownPath == renamed.path)
    }

    // MARK: Counts

    @Test("Counts are stamped at close and read back without a scan")
    func closeStampsCountsAndRecentsNeverScans() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let fixture = try makeBoard()
        defer { fixture.tearDown() }
        let registry = BoardRegistry(storageURL: storage.url)

        let id = registry.recordOpen(of: fixture.root, displayName: "Todo Board")
        registry.recordClose(id: id, laneCount: 2, cardCount: 7)

        // The board grows after the close — an agent filing cards, a colleague's pull. A welcome
        // window that scanned would notice; this one must not, because scanning is what makes
        // welcome slow on a big board and hangs it on an unavailable one.
        try fixture.item(Ident.lane2, Item.rich(order: "2048", title: "Doing"))
        try fixture.item("\(Ident.lane2)/\(Ident.card2)", Item.rich(order: "1024", title: "Second"))
        try fixture.item("\(Ident.lane2)/\(Ident.card3)", Item.rich(order: "2048", title: "Third"))

        let rows = registry.recents()
        #expect(rows.count == 1)
        guard case let .available(record, at: url) = rows[0] else {
            Issue.record("expected the board to be available, got \(rows[0])")
            return
        }
        #expect(record.laneCount == 2, "the stamped count, not the tree's count")
        #expect(record.cardCount == 7)
        #expect(FileIdentity(of: url) == FileIdentity(of: fixture.root))
    }

    // MARK: Orphaning

    @Test("A deleted board is orphaned in recents and can be forgotten")
    func deletedBoardIsOrphaned() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let fixture = try makeBoard()
        let registry = BoardRegistry(storageURL: storage.url)

        let id = registry.recordOpen(of: fixture.root, displayName: "Doomed")
        registry.recordClose(id: id, laneCount: 1, cardCount: 1)
        fixture.tearDown()

        let rows = registry.recents()
        #expect(rows.count == 1)
        guard case let .unavailable(record) = rows[0] else {
            Issue.record("expected an orphan, got \(rows[0])")
            return
        }
        #expect(record.id == id)
        #expect(record.displayName == "Doomed", "an orphan still renders — with Forget, not nothing")
        #expect(record.lastKnownPath == fixture.root.path)

        registry.forget(id: id)
        #expect(registry.recents().isEmpty)
        #expect(registry.record(id: id) == nil)
        #expect(BoardRegistry(storageURL: storage.url).recents().isEmpty, "forgetting persists")
    }

    @Test("A bookmark that cannot resolve at all classifies as unavailable")
    func unresolvableBookmarkIsUnavailable() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }

        // Hand-written rather than produced by the registry: deleting a folder *ought* to make its
        // bookmark stop resolving, but "ought to" is the filesystem's opinion, and this rule needs a
        // case that cannot resolve by construction. It doubles as the only place the on-disk shape
        // is pinned literally — including the fractional-seconds timestamp format.
        let id = UUID()
        let garbage = Data("not a bookmark".utf8).base64EncodedString()
        let json = """
        [
          {
            "bookmark" : "\(garbage)",
            "cardCount" : 9,
            "displayName" : "Archive",
            "id" : "\(id.uuidString)",
            "laneCount" : 4,
            "lastKnownPath" : "/Volumes/Archive/Boards/Archive",
            "lastOpened" : "2026-01-01T09:00:00.000Z",
            "pushOnCommit" : true,
            "remoteLocationWarned" : true
          }
        ]
        """
        try Data(json.utf8).write(to: storage.url)

        let registry = BoardRegistry(storageURL: storage.url)
        let rows = registry.recents()
        #expect(rows.count == 1, "an unreadable bookmark is an orphaned row, not a decoding failure")
        guard case let .unavailable(record) = rows[0] else {
            Issue.record("expected an orphan, got \(rows[0])")
            return
        }
        #expect(record.id == id)
        #expect(record.laneCount == 4, "an orphan still shows the counts it was closed with")
        #expect(record.pushOnCommit)
        #expect(record.remoteLocationWarned)
        #expect(record.lastKnownPath == "/Volumes/Archive/Boards/Archive")

        registry.forget(id: id)
        #expect(registry.recents().isEmpty)
    }

    // MARK: Persistence

    @Test("Every mutation survives a reload of the file, dates included")
    func mutationsPersistAcrossInstances() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let first = try makeBoard()
        defer { first.tearDown() }
        let second = try makeBoard()
        defer { second.tearDown() }

        let registry = BoardRegistry(storageURL: storage.url)
        let firstID = registry.recordOpen(of: first.root, displayName: "First")
        try await Task.sleep(for: .milliseconds(5))
        let secondID = registry.recordOpen(of: second.root, displayName: "Second")
        registry.recordClose(id: firstID, laneCount: 3, cardCount: 11)
        registry.updateWindowFrame(id: firstID, frame: WindowFrame(x: 120, y: 60, width: 1440, height: 900))
        registry.setPushOnCommit(id: firstID, true)
        registry.setRemoteLocationWarned(id: firstID)

        let reloaded = BoardRegistry(storageURL: storage.url)

        // Equality of the whole record, not a field-by-field approximation: `lastOpened` is stamped
        // at the resolution the file records, so the reloaded value is the *same* date rather than
        // one within a second of it.
        #expect(reloaded.record(id: firstID) == registry.record(id: firstID))
        #expect(reloaded.record(id: secondID) == registry.record(id: secondID))

        let restored = try #require(reloaded.record(id: firstID))
        #expect(restored.laneCount == 3)
        #expect(restored.cardCount == 11)
        #expect(restored.windowFrame == WindowFrame(x: 120, y: 60, width: 1440, height: 900))
        #expect(restored.pushOnCommit)
        #expect(restored.remoteLocationWarned)
        #expect(restored.lastOpened == registry.record(id: firstID)?.lastOpened)

        #expect(ids(reloaded.recents()) == ids(registry.recents()), "order survives too")
    }

    // MARK: Corruption

    @Test("A corrupt file is quarantined, not deleted, and the registry carries on empty")
    func corruptFileIsQuarantined() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let fixture = try makeBoard()
        defer { fixture.tearDown() }

        let garbage = Data("{ this is not the registry you are looking for".utf8)
        try garbage.write(to: storage.url)

        let registry = BoardRegistry(storageURL: storage.url)
        #expect(registry.recents().isEmpty, "app-private convenience state never takes the app down")

        let quarantined = try storage.entryNames().filter { $0 != storage.url.lastPathComponent }
        #expect(quarantined.count == 1)
        let quarantinedName = try #require(quarantined.first)
        #expect(quarantinedName.contains("corrupt"))
        #expect(quarantinedName.hasSuffix(".json"))
        let preserved = try Data(contentsOf: storage.folder.appendingPathComponent(quarantinedName))
        #expect(preserved == garbage, "renamed aside, never deleted — it may be the only trace of the user's boards")

        // And the registry is usable from here: the next save writes a clean file over the hole the
        // quarantine left.
        let id = registry.recordOpen(of: fixture.root, displayName: "Fresh Start")
        #expect(BoardRegistry(storageURL: storage.url).record(id: id)?.displayName == "Fresh Start")
    }

    // MARK: Files-first

    @Test("Nothing the registry does touches the board folder")
    func theBoardFolderIsNeverTouched() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let fixture = try makeBoard()
        defer { fixture.tearDown() }

        let before = try treeSnapshot(of: fixture.root)

        let registry = BoardRegistry(storageURL: storage.url)
        let id = registry.recordOpen(of: fixture.root, displayName: "Untouched")
        registry.recordClose(id: id, laneCount: 1, cardCount: 1)
        registry.updateWindowFrame(id: id, frame: WindowFrame(x: 0, y: 0, width: 800, height: 600))
        registry.setPushOnCommit(id: id, true)
        registry.setRemoteLocationWarned(id: id)
        _ = registry.recents()
        _ = BoardRegistry(storageURL: storage.url).recents()

        let after = try treeSnapshot(of: fixture.root)
        #expect(after == before, "no sidecar, no frontmatter key, no xattr — nothing app-private goes in the board")
        #expect(!storage.url.path.hasPrefix(fixture.root.path), "and the file itself lives elsewhere entirely")
    }

    // MARK: Ordering

    @Test("Recents is this registry sorted by last-opened, and an open bumps a board to the top")
    func recentsOrderFollowsLastOpened() async throws {
        let storage = try RegistryStorage()
        defer { storage.tearDown() }
        let first = try makeBoard()
        defer { first.tearDown() }
        let second = try makeBoard()
        defer { second.tearDown() }
        let third = try makeBoard()
        defer { third.tearDown() }
        let registry = BoardRegistry(storageURL: storage.url)

        let firstID = registry.recordOpen(of: first.root, displayName: "First")
        try await Task.sleep(for: .milliseconds(5))
        let secondID = registry.recordOpen(of: second.root, displayName: "Second")
        try await Task.sleep(for: .milliseconds(5))
        let thirdID = registry.recordOpen(of: third.root, displayName: "Third")

        #expect(ids(registry.recents()) == [thirdID, secondID, firstID])

        try await Task.sleep(for: .milliseconds(5))
        _ = registry.recordOpen(of: first.root, displayName: "First")
        #expect(ids(registry.recents()) == [firstID, thirdID, secondID])
    }

    // MARK: Bookmarks in a sandboxed host

    @Test("A bookmark is always produced, and resolves back to the same folder")
    func bookmarkCreationAndResolutionRoundTrip() async throws {
        let fixture = try makeBoard()
        defer { fixture.tearDown() }

        // The contract the fallback exists for: *some* bookmark is always available. Which flavor is
        // the sandbox's call, and production's answer is the security-scoped one — every board URL
        // there arrives through NSOpenPanel or a drag and already carries access.
        let bookmark = try #require(BoardRegistry.makeBookmark(for: fixture.root))
        print("BoardRegistryTests: bookmark flavor in this test host = \(bookmark.isSecurityScoped ? "security-scoped" : "plain")")

        let resolution = try #require(BoardRegistry.resolve(bookmark.data))
        let target = try #require(FileIdentity(of: fixture.root))
        let resolved = BoardRegistry.withScopedAccess(to: resolution.url) { FileIdentity(of: $0) }
        #expect(resolved == target, "a bookmark of either flavor names the file, not the path")

        // Resolution's own fallback, forced: whichever flavor this host hands out, `resolve` must
        // also cope with a plain bookmark, because a registry file written by a non-sandboxed debug
        // build (or on a host where the security-scoped attempt failed) is full of them. Nothing
        // else in this suite reaches that branch when the sandbox is cooperating.
        let plain = try #require(try? fixture.root.bookmarkData(options: []))
        let plainResolution = try #require(BoardRegistry.resolve(plain))
        #expect(FileIdentity(of: plainResolution.url) == target)
    }
}