import Foundation

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

    public init() {}

    /// Returns true only when a fresh, eligible Command-only hold begins.
    public mutating func update(commandOnly: Bool, eligible: Bool, at time: TimeInterval) -> Bool {
        guard commandOnly && eligible else { reset(); 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)
    }

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