src/Godosa.Core/Input/MenuCursor.cs


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namespace Godosa.Core.Input;

/// <summary>Which action a gamepad highlights in an open window (hud spec §4): wraps at the
/// ends, stays inside a list that shrinks, −1 when there's nothing to pick.</summary>
public sealed class MenuCursor
{
    public int Index { get; private set; } = -1;

    public void Clamp(int count)
    {
        if (count <= 0) Index = -1;
        else if (Index < 0) Index = 0;
        else if (Index >= count) Index = count - 1;
    }

    public void Move(int delta, int count)
    {
        if (count <= 0) return;
        Index = ((Index + delta) % count + count) % count;
    }
}