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// Copyright (C) 2002-2025, Open Design Alliance (the "Alliance"). 
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// with their copyright notices:
//   
//   This application incorporates Open Design Alliance software pursuant to a license 
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//   Open Design Alliance Copyright (C) 2002-2025 by Open Design Alliance. 
//   All rights reserved.
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///////////////////////////////////////////////////////////////////////////////


#ifndef TNW_LIGHT_INTENSITY_UTILS_H_
#define TNW_LIGHT_INTENSITY_UTILS_H_

#include "OdaCommon.h"
#include "NwLightIntensityUnits.h"
#include <type_traits>
#include "NwLightItem.h"

/** \details
  Utils of light intensity conversion.

  <group TNW_Namespaces>
*/
namespace NwLightIntensityUtils
{
  /** \details
    Returns the double result of converting lux light intensity into lumen.

    \param intensityValue [in] Double value of lux intensity to be converted.
    \param illuminanceAt  [in] Distance from the light source to the surface.

    \returns Double value with the conversion result.
  */
  constexpr double luxToLumen(double intensityValue, double illuminanceAt)
  {
    return intensityValue * illuminanceAt * illuminanceAt;
  }

  /** \details
    Returns the double result of converting watt light intensity into lumen.

    \param intensityValue        [in] Double value of watt intensity to be converted.
    \param electricalEfficiency  [in] Double value of electrical efficiency(lm/W) produced by a light source.

    \returns Double value with the conversion result.
  */
  constexpr double wattToLumen(double intensityValue, double electricalEfficiency)
  {
    return intensityValue * electricalEfficiency;
  }

  /** \details
    Returns the double result of converting lumen light intensity into candella for isotropic distribution.

    \param value        [in] Double value of lumen intensity to be converted.

    \returns Double value with the conversion result.
  */
  constexpr double isotropicLumenToCandella(double value)
  {
    return value / (4 * OdaPI);
  }

  /** \details
    Returns the double result of converting lumen light intensity into candella for diffuse distribution.

    \param value        [in] Double value of lumen intensity to be converted.

    \returns Double value with the conversion result.
  */
  constexpr double diffuseLumenToCandella(double value)
  {
    return value / OdaPI;
  }

  /** \details
    Returns the double result of converting lumen light intensity into candella for spot distribution.

    \param value        [in] Double value of lumen intensity to be converted.

    \returns Double value with the conversion result.
  */
  constexpr double spotLumenToCandella(double value, double normalizedSpotFlux)
  {
    return value / normalizedSpotFlux;
  }

  /** \details
    Returns the double result of converting lumen light intensity into candella for ies distribution.

    \param value                      [in] Double value of lumen intensity to be converted.
    \param initialRatedLumens         [in] Double value of initial rated lumens for the lamp or -1 if absolute photometry is used and the intensity values do not depend on different lamp ratings.
    \param maxIntensity               [in] Double value of max flux intensity from .ies file.
    \param candellaMultiplyingFactor  [in] Integer value with multiplying factor for all the candela values in the file. Normally the multiplying factor is 1.

    \returns Double value with the conversion result.
  */
  constexpr double iesLumenToCandella(double value, double initialRatedLumens, double maxIntensity, OdInt32 candellaMultiplyingFactor)
  {
    return (initialRatedLumens > 0.) ? (value * maxIntensity / (candellaMultiplyingFactor * initialRatedLumens)) : value;
  }

  /** \details
    Converts light intensity value to candella.

    \param lightIntensity  [in] light intensity structure value with intensity units and value to be converted.
    \param args            [in]  template parameter pack with possible additional parameters for conversion.

    \remarks
      this method change OdNwLampIntensity::m_value in inner parameter 'lightIntensity' by conversion value.
  */
  template< typename T, T funcLumenToCandella, class ...Args>
  constexpr void convertIntensityToCandella(OdNwLampIntensity& lightIntensity, Args ...args)
  {
    static_assert(std::is_pointer<T>::value, "Wrong type of function pointer to lumen-candella conversion ");
    static_assert(std::is_function<typename std::remove_pointer<T>::type>::value, "Function pointer to lumen-candella conversion is not function type");
    static_assert(std::is_same<T, double(*)(double, Args...)>::value, "Function pointer to lumen-candella conversion has wrong signature");
    switch (lightIntensity.m_units)
    {
    case NwLightIntensityUnits::kCandella:
      break;
    case NwLightIntensityUnits::kLumen:
      lightIntensity.m_value = (*funcLumenToCandella)(lightIntensity.m_value, args...);
      break;
    case NwLightIntensityUnits::kLux:
      lightIntensity.m_value = (*funcLumenToCandella)(luxToLumen(lightIntensity.m_value, lightIntensity.m_illuminanceAt), args...);
      break;
    case NwLightIntensityUnits::kWatt:
      lightIntensity.m_value = (*funcLumenToCandella)(wattToLumen(lightIntensity.m_value, lightIntensity.m_electricalEfficiency), args...);
      break;
    default:
      break;
    }
  }
}

#endif  // TNW_LIGHT_INTENSITY_UTILS_H_