namespace Evergreen.Health.Application.Health.Policies;

/// <summary>Demo 起点，可由用户手动修改，不是医学或人体工学判断。</summary>
public static class BmiFirmnessPolicy
{
    public static decimal? Calculate(decimal? heightCm, decimal? weightKg)
    {
        if (heightCm is null or <= 0 || weightKg is null or <= 0) return null;
        try
        {
            var height = heightCm.Value / 100m;
            return Math.Round(weightKg.Value / (height * height), 1);
        }
        catch (ArithmeticException) { return null; }
    }

    public static string? Firmness(decimal? bmi) => bmi switch
    {
        < 18.5m => "很软", < 24m => "稍软", < 28m => "稍硬",
        < 32m => "很硬", >= 32m => "最硬", _ => null
    };
}