#ifndef _BGC_UTILITIES_H_
#define _BGC_UTILITIES_H_

#define BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP32 1.0f

#define BGC_EPSYLON_FP32 5E-7f
#define BGC_SQUARE_EPSYLON_FP32 2.5E-13f

#define BGC_ONE_THIRD_FP32 0.333333333f
#define BGC_ONE_SIXTH_FP32 0.166666667f
#define BGC_ONE_NINETH_FP32 0.111111111f

#define BGC_GOLDEN_RATIO_HIGH_FP32 1.618034f
#define BGC_GOLDEN_RATIO_LOW_FP32 0.618034f

#define BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP64 1.0

#define BGC_EPSYLON_FP64 5E-14
#define BGC_SQUARE_EPSYLON_FP64 2.5E-27

#define BGC_ONE_THIRD_FP64 0.333333333333333333
#define BGC_ONE_SIXTH_FP64 0.166666666666666667
#define BGC_ONE_NINETH_FP64 0.111111111111111111

#define BGC_GOLDEN_RATIO_HIGH_FP64 1.61803398874989485
#define BGC_GOLDEN_RATIO_LOW_FP64 0.61803398874989485

inline int bgc_is_zero_fp32(const float square_value)
{
    return (-BGC_EPSYLON_FP32 <= square_value) && (square_value <= BGC_EPSYLON_FP32);
}

inline int bgc_is_zero_fp64(const double square_value)
{
    return (-BGC_EPSYLON_FP64 <= square_value) && (square_value <= BGC_EPSYLON_FP64);
}


inline int bgc_is_unit_fp32(const float square_value)
{
    return (1.0f - BGC_EPSYLON_FP32 <= square_value) && (square_value <= 1.0f + BGC_EPSYLON_FP32);
}

inline int bgc_is_unit_fp64(const double square_value)
{
    return (1.0 - BGC_EPSYLON_FP64 <= square_value) && (square_value <= 1.0 + BGC_EPSYLON_FP64);
}


inline int bgc_is_sqare_value_unit_fp32(const float square_value)
{
    return (1.0f - 2.0f * BGC_EPSYLON_FP32 <= square_value) && (square_value <= 1.0f + 2.0f * BGC_EPSYLON_FP32);
}

inline int bgc_is_sqare_value_unit_fp64(const double square_value)
{
    return (1.0 - 2.0 * BGC_EPSYLON_FP64 <= square_value) && (square_value <= 1.0 + 2.0 * BGC_EPSYLON_FP64);
}

// ================== Are Close ================= //

inline int bgc_are_close_fp32(const float value1, const float value2)
{
    const float difference = value1 - value2;
    const float square_value1 = value1 * value1;
    const float square_value2 = value2 * value2;
    const float square_difference = difference * difference;

    if (square_value1 <= BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP32 || square_value2 <= BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP32) {
        return square_difference <= BGC_SQUARE_EPSYLON_FP32;
    }

    return square_difference <= BGC_SQUARE_EPSYLON_FP32 * square_value1 && square_difference <= BGC_SQUARE_EPSYLON_FP32 * square_value2;
}

inline int bgc_are_close_fp64(const double value1, const double value2)
{
    const double difference = value1 - value2;
    const double square_value1 = value1 * value1;
    const double square_value2 = value2 * value2;
    const double square_difference = difference * difference;

    if (square_value1 <= BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP64 || square_value2 <= BGC_EPSYLON_EFFECTIVENESS_LIMIT_FP64) {
        return square_difference <= BGC_SQUARE_EPSYLON_FP64;
    }

    return square_difference <= BGC_SQUARE_EPSYLON_FP64 * square_value1 && square_difference <= BGC_SQUARE_EPSYLON_FP64 * square_value2;
}

#endif