import Foundation

/// Monotonic timestamps are supplied by the window; tests never wait on a real clock.
public struct CommandNumberShortcuts: Sendable {
    private var heldSince: TimeInterval?
    private var cancelledUntilRelease = false
    public private(set) var isVisible = false
    public var isHolding: Bool { heldSince != nil }

    public init() {}

    /// Samples an existing hold too, including when results first become eligible.
    public mutating func update(commandOnly: Bool, eligible: Bool, at time: TimeInterval) -> Bool {
        guard commandOnly else { reset(); return false }
        guard eligible && !cancelledUntilRelease else {
            heldSince = nil
            isVisible = false
            return false
        }
        guard heldSince == nil else { return false }
        heldSince = time
        return true
    }

    public mutating func reveal(at time: TimeInterval) -> Bool {
        guard let heldSince, time - heldSince >= 1 else { return false }
        isVisible = true
        return true
    }

    public func index(for key: String) -> Int? {
        guard isVisible, key.utf8.count == 1, let digit = key.utf8.first,
              (49...57).contains(digit) else { return nil }
        return Int(digit - 49)
    }

    /// An action cancels this hold; modifier sampling must not restart it.
    public mutating func cancel() {
        reset()
        cancelledUntilRelease = true
    }

    public mutating func reset() {
        heldSince = nil
        isVisible = false
        cancelledUntilRelease = false
    }
}