namespace AcDream.Core.Items;

/// <summary>
/// Retail item-cooldown projection shared by inventory, equipment, and shortcut
/// UIItems.
///
/// <para>
/// Port of <c>UIElement_UIItem::UpdateCooldownDisplay @ 0x004E1E20</c>.
/// The remaining fraction selects one of ten authored radial overlays.
/// </para>
/// </summary>
public static class ItemCooldownDisplay
{
    /// <summary>
    /// Retail's exact ten-step display formula:
    /// <c>trunc((remaining / itemDuration) * 10 + 1)</c>. Results 1..9 select
    /// the 10%..90% art, while 10 or above selects the 100% art.
    /// </summary>
    public static int GetOverlayStep(double itemDuration, double remaining)
    {
        if (!(itemDuration > 0d) || !(remaining > 0d))
            return 0;

        double step = Math.Truncate((remaining / itemDuration) * 10d + 1d);
        if (!(step >= 1d))
            return 0;
        if (step >= 10d)
            return 10;
        return (int)step;
    }
}