/////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2022 Equinor ASA
//
//  ResInsight is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
//  FITNESS FOR A PARTICULAR PURPOSE.
//
//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
//  for more details.
//
/////////////////////////////////////////////////////////////////////////////////

#include "RiaNumericalTools.h"

#include "cvfMath.h"

#include <algorithm>
#include <cmath>

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::roundToClosestPowerOfTenCeil( double value )
{
    auto exponent = computeTenExponentCeil( value );
    return pow( 10.0, exponent );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::roundToClosestPowerOfTenFloor( double value )
{
    auto exponent = computeTenExponentFloor( value );
    return pow( 10.0, exponent );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::computeTenExponentCeil( double value )
{
    if ( value < 0.0 ) return 0.0;

    double logDecValueMax = log10( value );
    logDecValueMax        = cvf::Math::ceil( logDecValueMax );

    return logDecValueMax;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::computeTenExponentFloor( double value )
{
    if ( value < 0.0 ) return 0.0;

    double logDecValueMin = log10( value );
    logDecValueMin        = cvf::Math::floor( logDecValueMin );

    return logDecValueMin;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::roundToNumSignificantDigitsFloor( double value, double numSignificantDigits )
{
    return roundToNumSignificantDigits( value, numSignificantDigits, RoundToSignificantDigitsMode::FLOOR );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::roundToNumSignificantDigitsCeil( double value, double numSignificantDigits )
{
    return roundToNumSignificantDigits( value, numSignificantDigits, RoundToSignificantDigitsMode::CEIL );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
double RiaNumericalTools::roundToNumSignificantDigits( double value, double numSignificantDigits, RoundToSignificantDigitsMode mode )
{
    double absoluteValue = cvf::Math::abs( value );
    if ( absoluteValue == 0.0 )
    {
        return 0.0;
    }

    double logDecValue = log10( absoluteValue );
    logDecValue        = cvf::Math::ceil( logDecValue );

    double factor = pow( 10.0, numSignificantDigits - logDecValue );

    double tmp         = value * factor;
    double integerPart = 0.0;
    modf( tmp, &integerPart );

    double candidateValue = integerPart / factor;

    if ( mode == RoundToSignificantDigitsMode::CEIL && candidateValue < value )
    {
        integerPart++;
    }
    else if ( mode == RoundToSignificantDigitsMode::FLOOR && value < candidateValue )
    {
        integerPart--;
    }

    double roundedValue = integerPart / factor;

    return roundedValue;
}