namespace BlurHash;

/// <summary>
/// Utility methods for mathematical calculations
/// </summary>
public static class MathUtils
{
    /// <summary>
    /// Calculates <c>Math.Pow(base, exponent)</c> but retains the sign of <c>base</c> in the result.
    /// </summary>
    /// <param name="base">The base of the power. The sign of this value will be the sign of the result</param>
    /// <param name="exponent">The exponent of the power</param>
    public static double SignPow(double @base, double exponent) => Math.Sign(@base) * Math.Pow(Math.Abs(@base), exponent);

    /// <summary>
    /// Converts an sRGB input value (0 to 255) into a linear double value
    /// </summary>
    public static double SRgbToLinear(int value)
    {
        double v = value / 255.0;
        if (v <= 0.04045)
            return v / 12.92;
        else
            return Math.Pow((v + 0.055) / 1.055, 2.4);
    }

    /// <summary>
    /// Converts a linear double value into an sRGB input value (0 to 255)
    /// </summary>
    public static int LinearTosRgb(double value)
    {
        double v = Math.Max(0.0, Math.Min(1.0, value));
        if (v <= 0.0031308)
            return (int)(v * 12.92 * 255 + 0.5);
        else
            return (int)((1.055 * Math.Pow(v, 1 / 2.4) - 0.055) * 255 + 0.5);
    }
}