/*
 * Author: Andrey Pokidov
 * License: Apache-2.0
 * Date: 12 Nov 2024
 */

namespace BGC
{
    public class UtilityFP32
    {
        public const float EPSYLON = 4.76837E-7f;
        public const float SQUARE_EPSYLON = EPSYLON * EPSYLON;
        
        public const float EPSYLON_EFFECTIVENESS_LIMIT = 1.0f;

        public const float ONE_THIRD = 0.333333333f;
        public const float ONE_SIXTH = 0.166666667f;
        public const float ONE_NINETH = 0.111111111f;

        public const float GOLDEN_RATIO_HIGH = 1.618034f;
        public const float GOLDEN_RATIO_LOW = 0.618034f;

        public static bool IsZero(float value)
        {
            return -EPSYLON <= value && value <= EPSYLON;
        }

        public static bool IsUnit(float value)
        {
            return (1.0f - EPSYLON) <= value && value <= (1.0f + EPSYLON);
        }

        public static bool IsSqareUnit(float square)
        {
            return (1.0f - 2.0f * EPSYLON) <= square && square <= (1.0f + 2.0f * EPSYLON);
        }

        public static bool AreClose(float value1, float value2)
        {
            float difference = value1 - value2;
            float squareValue1 = value1 * value1;
            float squareValue2 = value2 * value2;
            float squareDifference = difference * difference;

            if (squareValue1 <= EPSYLON_EFFECTIVENESS_LIMIT || squareValue2 <= EPSYLON_EFFECTIVENESS_LIMIT) {
                return squareDifference <= SQUARE_EPSYLON;
            }

            return squareDifference <= SQUARE_EPSYLON * squareValue1 && squareDifference <= SQUARE_EPSYLON * squareValue2;
        }
    }
}