import Foundation

// MARK: - HistoryPhrase

/// The menu phrase an undo step carries — "Move 3 Cards", "Rename Lane", "Restyle Board".
///
/// ### Why the vocabulary is 06's and not a new one
///
/// 13-native-undo.md ▸ Rules hands the naming straight over: "The 06 vocabulary supplies menu titles
/// ('Undo Move 3 Cards'), via NSUndoManager's dynamic retitling — the same naming machinery both
/// editions use." So the verbs here are exactly 06-history-undo.md ▸ Commit messages' list — *Add /
/// Delete / Move / Rename / Edit / Restyle / Resize / Reorder over cards, lanes, and the board*, plus
/// the trash pair's **Restore** — and the plural rule is that section's own plural folding ("Delete
/// 12 cards"), which is also 13's coalescing sentence read out loud: "a multi-card move is one step
/// with a plural title".
///
/// The **"Undo "/"Redo " prefix is never here**: the platform composes and localizes it
/// (`BoardUndoManager.undoMenuItemTitle`), and a phrase that spelled it would read "Undo Undo Move
/// Card" in the Edit menu — see `HistoryStep.name`.
///
/// ### Title case, unlike a commit subject
///
/// A commit subject is a sentence ("Move 3 cards to Done"); a menu item is a title, and macOS titles
/// its Edit-menu rows. The words are 06's; the casing is the menu's. Nothing else differs — and the
/// destination clause a commit subject carries has no place in a title that has to stay short enough
/// for a menu row.
///
/// Pure, and its own type rather than a `String` built at each call site, because a phrase composed
/// in eleven places is a vocabulary that drifts in eleven places.
public enum HistoryPhrase {

    // MARK: Verbs

    /// 06-history-undo.md ▸ Commit messages' verb list, restricted to the operations 13 makes
    /// undoable. `Permanently delete`, `Attach`, `Remove` and `Repair` are deliberately absent —
    /// those are exactly the operations that register no step at all (13 ▸ Rules ▸ what is not
    /// undoable, ▸ Out of scope).
    public enum Verb: String, Sendable, CaseIterable {
        /// A create — File ▸ New Lane, the new-card placeholder's commit, a Finder file drop's cards.
        case add = "Add"
        /// A tombstone (⌫, drop-on-trash, the card window's Actions ▸ Delete).
        case delete = "Delete"
        /// Put Back and drag-to-restore.
        case restore = "Restore"
        /// A drop that changes an item's parent.
        case move = "Move"
        /// A drop, a lane drag or ⌥⌘↑/⌥⌘↓ that changes rank among unchanged siblings.
        case reorder = "Reorder"
        case rename = "Rename"
        case restyle = "Restyle"
        case resize = "Resize"
        /// An Edit session's body save — one step at the Edit→Preview flip (13 ▸ Rules).
        case edit = "Edit"
    }

    // MARK: Nouns

    /// What the gesture acted on. `board` is deliberately count-less: there is one board, and
    /// "Rename 1 Board" is not a phrase anyone writes.
    public enum Kind: Sendable, Equatable {
        case card
        case lane
        case board

        var singular: String {
            switch self {
            case .card: "Card"
            case .lane: "Lane"
            case .board: "Board"
            }
        }

        var plural: String {
            switch self {
            case .card: "Cards"
            case .lane: "Lanes"
            case .board: "Board"
            }
        }
    }

    // MARK: Composition

    /// The phrase for one gesture: `"Move Card"`, `"Move 3 Cards"`, `"Restyle Board"`.
    ///
    /// A `count` of one or less folds to the singular — a batch that turned out to name a single item
    /// is one item, and a zero never reaches here because a gesture that wrote nothing registers
    /// nothing.
    public static func name(_ verb: Verb, kind: Kind, count: Int = 1) -> String {
        guard count > 1, kind != .board else { return "\(verb.rawValue) \(kind.singular)" }
        return "\(verb.rawValue) \(count) \(kind.plural)"
    }
}