import Foundation

// MARK: - AccessibilityPhrases

/// **What the board's elements say** — every label and value VoiceOver reads off the board window,
/// composed by pure functions (10-accessibility.md ▸ The board through VoiceOver).
///
/// ### Why the strings live here and not at the modifiers
///
/// 10-accessibility.md states the board's tree as *sentences*: a lane container is
/// "⟨title⟩, lane, N cards", the header button is "New card in ⟨lane⟩", a card's value carries its
/// attachment count and, when it is cut-pending, "cut, pending paste". Those are rules about text —
/// which placeholder an untitled item wears, how a count folds its plural, what order two value
/// fragments join in — and a rule about text is only checkable if there is a function to ask. Split
/// out, the whole spoken vocabulary is pinned by `AccessibilityPhrasesTests` without a window, a
/// screen reader, or a running app; `Motion`, `TrashModel.purgePrompt` and `HistoryPhrase` are the
/// same shape for the same reason.
///
/// It is also the one place the board and the trash column can be made to *agree*: the lane's spoken
/// count and the trash's are one function, the untitled placeholder is one constant, and the
/// attachment phrase the card face used to spell inline is now the same string the flattened card
/// element carries in its value.
enum AccessibilityPhrases {

    // MARK: - Shared vocabulary

    /// The untitled placeholder — **the same word the face draws** (`LaneView.headerTitle`,
    /// `CardFaceView.titleOrEditor`), because 10-accessibility.md asks for "label = title (or the
    /// untitled placeholder)" and a spoken placeholder that differed from the visible one would make
    /// a sighted user and a VoiceOver user describe different boards.
    static let untitled = "Untitled"

    /// An item's spoken name: its title, or the untitled placeholder. Total, so no caller branches.
    static func displayTitle(_ title: String?) -> String {
        guard let title, !title.isEmpty else { return untitled }
        return title
    }

    /// What the pre-snapshot loading surface says (02-architecture.md § Launch and window lifecycle;
    /// `BoardLoadingView`). The surface draws a bare system spinner and no text — "no skeleton lanes,
    /// the motion language animates real data only" — so this is the *only* description a VoiceOver
    /// user gets of a board window that is still walking its tree, and a spinner with nothing to say
    /// would leave that window silent.
    static let boardLoading = "Loading board"

    /// **What the decision surface is called** (01-storage-format.md § Malformed input, settled
    /// 2026-07-31; `BoardDecisionSurface`) — its heading *and* the group label a VoiceOver user hears
    /// on entering it, which are one string here for the banner row's reason exactly: the sentence
    /// heard and the sentence read are one, or they are two descriptions of one thing waiting to
    /// disagree.
    ///
    /// It says the board did not open and stops there. What is wrong is the sections' to say — the
    /// surface exists precisely because there is usually more than one answer to that.
    static let decisionSurfaceLabel = "Lanework couldn't open this board"

    /// The surface's own subtitle: how much is wrong, and what to do about it. The count is the
    /// number of affected *files*, which is what the rows below it are.
    static func decisionSurfaceSummary(defects count: Int) -> String {
        let subject = count == 1 ? "One file needs" : "\(count) files need"
        return "\(subject) a decision before this board can open."
    }

    /// One affected file, as one utterance: **path then reason**, in that order, because the path is
    /// what identifies the row and the reason is what the user is deciding about
    /// (01: "lists the affected files (path + specifics …)").
    ///
    /// The reason is the loader's own sentence, unrewritten — the same specifics the row shows — for
    /// `BannerCenter.causePhrase`'s reason: fail-fast's diagnostics are specific in a way a
    /// re-phrasing would not be, and the alternative to showing one is a shrug.
    static func decisionRowLabel(path: String, reason: String) -> String {
        "\(path): \(reason)"
    }

    /// "3 cards", "1 card" — the app's **one** plural folding for a card count, borrowed from
    /// `TrashModel.phrase` rather than restated so a lane's spoken count and the trash column's
    /// cannot drift apart.
    static func cardCount(_ count: Int) -> String {
        TrashModel.phrase(count)
    }

    // MARK: - Lanes

    /// A lane container's label — "⟨title⟩, lane, N cards" (10-accessibility.md ▸ The board through
    /// VoiceOver).
    ///
    /// **The count is the caller's, and the caller passes the rendered one**: "the count reads the
    /// search filter like the visible badge", so `LaneView` hands the very collection its badge
    /// counts (`renderedCards`) and the two can no more disagree than the badge can disagree with
    /// the masonry.
    static func laneLabel(title: String?, cards count: Int) -> String {
        "\(displayTitle(title)), lane, \(cardCount(count))"
    }

    /// The lane header's new-card button — "New card in ⟨lane⟩", the one labeled child
    /// 10-accessibility.md gives the header.
    static func newCardLabel(lane title: String?) -> String {
        "New card in \(displayTitle(title))"
    }

    // MARK: - Cards

    /// A card's label: its title, or the untitled placeholder. Named rather than inlined so the
    /// card element and the lane's own title read through one function.
    static func cardLabel(title: String?) -> String {
        displayTitle(title)
    }

    /// "1 attachment", "4 attachments" — the paperclip chip's information, moved into the card
    /// element's value where 10-accessibility.md puts it ("the flattened element carries the
    /// attachment count in its value"). Plural-folded like every other count in the app; the chip
    /// itself used to say "N attachments" unconditionally, which read wrong at one.
    static func attachmentCount(_ count: Int) -> String {
        "\(count) attachment\(count == 1 ? "" : "s")"
    }

    /// The deferred cut's spoken half — "cut items dim in place until paste moves them"
    /// (04-interactions.md ▸ Clipboard), and **state is never colour-alone** (10-accessibility.md):
    /// the dim is the sighted signal, this is the other one.
    static let cutPending = "cut, pending paste"

    /// A card element's value — the attachment count when it has files, the cut-pending phrase when
    /// it is staged for paste, both when both, and **the empty string when neither**.
    ///
    /// Empty rather than `nil` on purpose: the modifier that consumes it is unconditional, because a
    /// `if` around `.accessibilityValue` would put the whole card face inside a `_ConditionalContent`
    /// that flips identity — and therefore rebuilds the face, dropping its measured height and its
    /// marquee registration — the moment an attachment lands or a cut is pasted. An empty AXValue
    /// speaks as nothing, which is exactly what "no value" should sound like.
    static func cardValue(attachments: Int, isCutPending: Bool) -> String {
        var parts: [String] = []
        if attachments > 0 { parts.append(attachmentCount(attachments)) }
        if isCutPending { parts.append(cutPending) }
        return parts.joined(separator: ", ")
    }

    // MARK: - The trash column

    /// The trash container's label — stable, like the header's visible title (03-board-ui.md §
    /// Trash: one word, never "Hide Trash"-style state in the name).
    static let trashLabel = "Trash"

    /// The trash container's value: its counts, filtered exactly as the lane labels' are — "the
    /// shown trash's cards participate in the filter exactly like any other card" (03-board-ui.md §
    /// Trash), so the column passes the collections its badge counts.
    ///
    /// **Both kinds are named when both are there** (lanes rejoined the trash 2026-07-29): the
    /// container's rows are cards *and* opaque lane units, and a value that spoke only the cards
    /// would understate what the VoiceOver cursor is about to walk into. A trash holding no lane rows
    /// — overwhelmingly the common case — reads exactly as it always did.
    ///
    /// It stops at counting, deliberately: the *freight* phrasing ("2 lanes containing 9 more
    /// cards") belongs to the purge confirmations, where the number is what the user is about to
    /// lose (`TrashModel.subject(for:)`).
    static func trashValue(cards: Int, lanes: Int = 0) -> String {
        guard lanes > 0 else { return cardCount(cards) }
        return "\(cardCount(cards)), \(laneCount(lanes))"
    }

    /// A trashed lane row — **one flattened opaque element**, "⟨title⟩, deleted lane, N cards"
    /// (10-accessibility.md ▸ Trash lane, lanes rejoined 2026-07-29).
    ///
    /// "Deleted lane" and not "lane" is the whole of what the label has to carry beyond a live lane
    /// container's: the row is in the trash, it is not a container, and its N is the freight it took
    /// with it rather than a filtered count of children VoiceOver could enter (`TrashedLane`).
    static func trashedLaneLabel(title: String?, cards count: Int) -> String {
        "\(displayTitle(title)), deleted lane, \(cardCount(count))"
    }

    /// What View ▸ Show Trash announces — "toggling visibility is announced"
    /// (10-accessibility.md ▸ Trash lane). A whole container joining or leaving the board is a
    /// layout change with no focus consequence and therefore nothing else to notice it by.
    ///
    /// Phrased as the resulting *state* rather than as the action ("Trash shown", not "Showing
    /// trash"), because the toolbar item and the menu checkmark both mean the same thing and a user
    /// who mis-hit the toggle needs to know where the board ended up.
    static func trashVisibility(shown: Bool) -> String {
        shown ? "Trash shown" : "Trash hidden"
    }

    /// What View ▸ Zoom In / Zoom Out / Actual Size announces — "a zoom change announces its new
    /// level" (10-accessibility.md ▸ Text scaling).
    ///
    /// `trashVisibility`'s rule exactly, and for its reason: the resulting *state* rather than the
    /// action, because three commands and two toolbar buttons all land on one ladder and what a user
    /// needs to hear is which rung they are on — not that something moved. It is also the only signal
    /// there is: nothing gains or loses focus, no element's label or value changes, and the whole
    /// effect is a redraw a VoiceOver user cannot see.
    static func zoomLevel(_ percent: String) -> String {
        "Zoom \(percent)"
    }

    // MARK: - Live board announcements

    /// "3 lanes", "1 lane" — `cardCount`'s twin, and the second half of the digest's plural folding.
    /// Borrowed from `TrashModel.lanePhrase` for `cardCount`'s reason: since lanes rejoined the trash
    /// (2026-07-29) the purge confirmations count lanes too, and one folding means a spoken count and
    /// a confirmed one cannot drift.
    static func laneCount(_ count: Int) -> String {
        TrashModel.lanePhrase(count)
    }

    /// The digest's opening — and, on its own, the whole sentence for a change no bucket counts.
    ///
    /// Named for the sentence rather than overloading `boardChanged(_:)`: a constant and a function
    /// sharing a base name would make `"\(boardChanged)"` an ambiguity a reader has to resolve by
    /// hand, and string interpolation accepts either.
    static let boardChangedSubject = "Board changed"

    /// **One polite digest per reload debounce** — 10-accessibility.md ▸ Live board announcements,
    /// whose own example sentence this reproduces: "Board changed: 2 cards edited, 1 card added".
    ///
    /// Three phrasing rules, all pinned by `AccessibilityPhrasesTests`:
    ///
    /// - **Zero categories are omitted**, never spoken as "0 cards moved". A digest is a summary,
    ///   and a summary that lists what did *not* happen is a list of noise with the news buried in
    ///   it.
    /// - **Counts fold their plural** (`cardCount`, `laneCount`), like every other count in the app.
    /// - **The order is fixed**: cards before lanes, and within each kind edited, added, moved,
    ///   deleted. Cards lead because they are what a board is mostly made of and what 10's example
    ///   leads with; within a kind the order runs from the change that leaves the board's shape
    ///   alone to the one that takes something out of it, so the sentence ends on the fragment most
    ///   likely to need acting on.
    ///
    /// `nil` — silence — when nothing differs at all, which is the ordinary outcome of a reload that
    /// re-read an unchanged tree. A change that no bucket counts (a renamed board, an edited board
    /// description) still says *something*: "Board changed", bare. Announcing nothing there would be
    /// the lie 10's principle names — "silence about a mutating board is a lie to a VoiceOver user".
    static func boardChanged(_ diff: BoardDiff) -> String? {
        var fragments: [String] = []
        appendFragments(of: diff.cards, counting: cardCount, to: &fragments)
        appendFragments(of: diff.lanes, counting: laneCount, to: &fragments)

        guard !fragments.isEmpty else {
            return diff.boardChanged ? boardChangedSubject : nil
        }
        return "\(boardChangedSubject): \(fragments.joined(separator: ", "))"
    }

    /// One kind's fragments, in the fixed category order. `counting` is the kind's plural folding,
    /// passed in so the two kinds are one piece of code rather than two that could drift.
    private static func appendFragments(
        of changes: BoardDiff.Changes,
        counting count: (Int) -> String,
        to fragments: inout [String]
    ) {
        if !changes.edited.isEmpty { fragments.append("\(count(changes.edited.count)) edited") }
        if !changes.added.isEmpty { fragments.append("\(count(changes.added.count)) added") }
        if !changes.moved.isEmpty { fragments.append("\(count(changes.moved.count)) moved") }
        if !changes.deleted.isEmpty { fragments.append("\(count(changes.deleted.count)) deleted") }
    }

    /// **A vanishing focus is called out specifically** (10 ▸ Live board announcements) — the
    /// design's own two sentences, "Card 'Fix login' was deleted externally" and "Lane 'Doing' was
    /// deleted externally, with 5 cards".
    ///
    /// The lane form's trailing clause is what makes the substitution honest: when the lane went, it
    /// took cards with it, and naming the lane *without* the count would hide the larger half of
    /// what happened. It is omitted at zero — an empty lane vanishing has no second clause to add,
    /// and "with 0 cards" would be an odd way to say "and nothing else".
    ///
    /// "Externally" and not "by an agent" or "on disk": the sentence is only ever composed for a
    /// vanishing the `EchoLedger` did not vouch for (`BoardStore.vanishingIsForeign`), and which
    /// outside writer did it — an editor, an agent, `git` in a terminal — is exactly what the store
    /// cannot know.
    static func vanishedFocus(_ vanished: BoardAnnouncer.VanishedFocus) -> String {
        switch vanished {
        case let .card(title):
            "Card '\(displayTitle(title))' was deleted externally"
        case let .lane(title, cards):
            cards == 0
                ? "Lane '\(displayTitle(title))' was deleted externally"
                : "Lane '\(displayTitle(title))' was deleted externally, with \(cardCount(cards))"
        }
    }

    // MARK: - The comments pane

    /// The pane's container label — **"Comments, N"** (10-accessibility.md ▸ Comments: "the pane is a
    /// labeled container ('Comments, N')").
    ///
    /// The count is the *thread's*, not the rendered rows' — there is no filter over a thread — and it
    /// is the same number the visible header shows (`CommentsHeader.title(count:)`), which is the same
    /// discipline the lane label keeps with its badge.
    static func commentsContainerLabel(count: Int) -> String {
        "Comments, \(count)"
    }

    /// "3 comments", "1 comment" — the pane's plural folding, beside `cardCount` and `laneCount`.
    static func commentCount(_ count: Int) -> String {
        "\(count) comment\(count == 1 ? "" : "s")"
    }

    /// **One comment as a single flattened element's label** (10 ▸ Comments: "each comment is **one
    /// flattened element** — author, date, edited state, body").
    ///
    /// The author line is the label and the body is the value (`commentValue`), which is the same split
    /// the card element makes: the label is what the element *is*, the value is what it currently
    /// holds. A comment with no author line at all — no name, no date — falls back to the word
    /// "Comment", because an unlabeled element is an audit failure and "unattributed" is the absence of
    /// a name rather than a name to speak (`CommentAuthorLine`).
    static func commentLabel(authorLine: String?) -> String {
        guard let authorLine, !authorLine.isEmpty else { return commentSubject }
        return authorLine
    }

    /// What a comment with nothing to attribute is called. Named rather than inlined because both the
    /// label fallback and the empty pane's hint read it.
    static let commentSubject = "Comment"

    /// A comment element's **value**: its body, with the attachment count appended when it has files.
    ///
    /// The body is spoken as it is rather than summarized: 10 puts "body" in the flattened element, and
    /// a comment is short by nature — the thing a thread is *for* is the text, and paraphrasing it
    /// would be the app deciding what a VoiceOver user may hear of somebody's comment. Empty for a
    /// comment with neither, which speaks as nothing (`cardValue`'s rule).
    static func commentValue(body: String, attachments: Int) -> String {
        var parts: [String] = []
        let text = body.trimmingCharacters(in: .whitespacesAndNewlines)
        if !text.isEmpty { parts.append(text) }
        if attachments > 0 { parts.append(attachmentCount(attachments)) }
        return parts.joined(separator: ", ")
    }

    /// The three custom actions a comment element carries — its context menu's rows, which is what 10
    /// asks for ("with its context-menu rows (Edit / Delete / Reveal in Finder) riding as custom
    /// actions per the cut").
    ///
    /// Constants rather than literals at the modifier because the menu row and the custom action must
    /// be the *same* string: a user who has learned the pointer inventory should hear the same three
    /// words from the rotor.
    static let commentEditAction = "Edit"
    static let commentDeleteAction = "Delete"
    static let commentRevealAction = "Reveal in Finder"

    /// The composer, labeled — "the composer is a labeled text field (⌘↩ posts)" (10 ▸ Comments).
    static let commentComposerLabel = "Add a comment"

    /// The sort control's label. Its *value* is the direction's own word
    /// (`CommentSortDirection.controlLabel`), which is also its help text — one string, three readers.
    static let commentSortLabel = "Sort"

    /// The paperclip on either authoring surface.
    static let commentAttachFilesLabel = "Attach Files"

    // MARK: - Foreign comment changes

    /// **What a foreign comment change says out loud** — path-shaped, naming the card
    /// (10-accessibility.md ▸ Comments: "Foreign comment arrivals announce path-shaped ('New comment on
    /// '⟨card⟩'') — the window-scoped read never blocks the announcement, which composes from the path
    /// alone").
    ///
    /// ### Precedence, not concatenation
    ///
    /// One polite sentence per reload is the whole ladder's rule (`BoardAnnouncer`), so three
    /// simultaneous kinds of change pick one: **arrivals lead** — they are the news 10 names and the
    /// only kind that adds something to read — then edits, then deletions. A thread that gained one
    /// comment and lost another says the gain; the loss is visible in the pane and has no reader
    /// waiting on it.
    ///
    /// ### The verbs are 06's family, and the plurals are built on them
    ///
    /// 10 names one sentence and 01 names the family the other two come from ("a changed path under
    /// `…/comments/<uuid>/` composes 'Comment on ⟨card title⟩' / 'Edit comment on…' / 'Delete comment
    /// on…'"). The singular forms are those verbs verbatim; the plural forms fold a count in front,
    /// like every other count in the app, rather than repeating the sentence N times.
    static func commentsChanged(_ changes: CommentThreadChanges, onCard title: String?) -> String? {
        let card = displayTitle(title)
        if let phrase = commentFragment(
            count: changes.arrived.count,
            singular: "New comment",
            plural: { "\($0) new comments" },
            onCard: card
        ) {
            return phrase
        }
        if let phrase = commentFragment(
            count: changes.edited.count,
            singular: "Edit comment",
            plural: { "\($0) comments edited" },
            onCard: card
        ) {
            return phrase
        }
        return commentFragment(
            count: changes.deleted.count,
            singular: "Delete comment",
            plural: { "\($0) comments deleted" },
            onCard: card
        )
    }

    /// One bucket's sentence, or `nil` at zero — the shape all three share, written once so the three
    /// cannot drift in punctuation or in where the card's name sits.
    private static func commentFragment(
        count: Int,
        singular: String,
        plural: (Int) -> String,
        onCard card: String
    ) -> String? {
        guard count > 0 else { return nil }
        return "\(count == 1 ? singular : plural(count)) on '\(card)'"
    }

    // MARK: - The banner strip

    /// What VoiceOver says before a banner's headline. "Status" rather than "Info" because that is
    /// the word the platform uses for a non-alarming state announcement.
    ///
    /// Moved here from `BannerStripView` when the strip's rows started being *announced* as well as
    /// read: 10 makes the live-reload-resilience banner "an accessibility element … announced when
    /// it appears and when it clears", and the row's label and its announcement must be the same
    /// sentence or a user would hear the condition described two different ways.
    static func bannerTonePrefix(_ tone: BannerTone) -> String {
        switch tone {
        case .error: "Error"
        case .warning: "Warning"
        case .info: "Status"
        }
    }

    /// A banner row as one spoken element — tone first, because a VoiceOver user must hear *that*
    /// this is an error before hearing what the error is, and colour cannot carry that.
    static func bannerLabel(tone: BannerTone, headline: String) -> String {
        "\(bannerTonePrefix(tone)): \(headline)"
    }

    /// The read-only lock clearing. Stated as the regained capability rather than as the cause's
    /// disappearance ("the volume came back") because the causes are three and the consequence is
    /// one, and the consequence is what the user was waiting on.
    static let readOnlyLockCleared = "The board is editable again"

    /// Reload breakage clearing — the board is reading its files again, which is a smaller claim
    /// than the lock's and is deliberately phrased as one.
    static let reloadBreakageCleared = "The board is loading again"

    /// The unreadable repository clearing (06-history-undo.md ▸ Rules, ruled 2026-07-31: "the banner
    /// clears when a later open or reload finds the repo readable").
    ///
    /// Stated as the regained capability, `readOnlyLockCleared`'s rule: what the user was waiting on
    /// is history advancing again, not libgit2 changing its mind about a folder. It stays the
    /// smaller claim of the two — nothing about editing the board was ever blocked by this
    /// condition, which is precisely what its own row says.
    static let repositoryUnreadableCleared = "History is recording again"
}