// Copyright (c) 2017 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _Graphic3d_LightSet_HeaderFile
#define _Graphic3d_LightSet_HeaderFile

#include "Graphic3d_CLight.hxx"

//! Class defining the set of light sources.
class Graphic3d_LightSet : public Standard_Transient
{
  DEFINE_STANDARD_RTTIEXT(Graphic3d_LightSet, Standard_Transient)
public:
  //! Iteration filter flags.
  enum IterationFilter
  {
    IterationFilter_None            = 0x0000, //!< no filter
    IterationFilter_ExcludeAmbient  = 0x0002, //!< exclude ambient  light sources
    IterationFilter_ExcludeDisabled = 0x0004, //!< exclude disabled light sources
    IterationFilter_ExcludeNoShadow = 0x0008, //!< exclude light sources not casting shadow
    IterationFilter_ExcludeDisabledAndAmbient =
      IterationFilter_ExcludeAmbient | IterationFilter_ExcludeDisabled,
    IterationFilter_ActiveShadowCasters =
      IterationFilter_ExcludeDisabledAndAmbient | IterationFilter_ExcludeNoShadow,
  };

  //! Iterator through light sources.
  class Iterator
  {
  public:
    //! Empty constructor.
    Iterator()
        : myFilter(0)
    {
    }

    //! Constructor with initialization.
    Iterator(const Graphic3d_LightSet& theSet, IterationFilter theFilter = IterationFilter_None)
        : myIter(theSet.myLights),
          myFilter(theFilter)
    {
      skipFiltered();
    }

    //! Constructor with initialization.
    Iterator(const occ::handle<Graphic3d_LightSet>& theSet,
             IterationFilter                        theFilter = IterationFilter_None)
        : myFilter(theFilter)
    {
      if (!theSet.IsNull())
      {
        myIter = NCollection_IndexedDataMap<occ::handle<Graphic3d_CLight>, size_t>::Iterator(
          theSet->myLights);
        skipFiltered();
      }
    }

    //! Returns TRUE if iterator points to a valid item.
    bool More() const { return myIter.More(); }

    //! Returns current item.
    const occ::handle<Graphic3d_CLight>& Value() const { return myIter.Key(); }

    //! Moves to the next item.
    void Next()
    {
      myIter.Next();
      skipFiltered();
    }

  protected:
    //! Skip filtered items.
    void skipFiltered()
    {
      if (myFilter == 0)
      {
        return;
      }

      for (; myIter.More(); myIter.Next())
      {
        if ((myFilter & IterationFilter_ExcludeAmbient) != 0
            && myIter.Key()->Type() == Graphic3d_TypeOfLightSource_Ambient)
        {
          continue;
        }
        else if ((myFilter & IterationFilter_ExcludeDisabled) != 0 && !myIter.Key()->IsEnabled())
        {
          continue;
        }
        else if ((myFilter & IterationFilter_ExcludeNoShadow) != 0
                 && !myIter.Key()->ToCastShadows())
        {
          continue;
        }

        break;
      }
    }

  protected:
    NCollection_IndexedDataMap<occ::handle<Graphic3d_CLight>, size_t>::Iterator myIter;
    int                                                                         myFilter;
  };

public:
  //! Empty constructor.
  Standard_EXPORT Graphic3d_LightSet();

  //! Return lower light index.
  int Lower() const { return 1; }

  //! Return upper light index.
  int Upper() const { return myLights.Extent(); }

  //! Return TRUE if lights list is empty.
  bool IsEmpty() const { return myLights.IsEmpty(); }

  //! Return number of light sources.
  int Extent() const { return myLights.Extent(); }

  //! Return the light source for specified index within range [Lower(), Upper()].
  const occ::handle<Graphic3d_CLight>& Value(int theIndex) const
  {
    return myLights.FindKey(theIndex);
  }

  //! Return TRUE if light source is defined in this set.
  bool Contains(const occ::handle<Graphic3d_CLight>& theLight) const
  {
    return myLights.Contains(theLight);
  }

  //! Append new light source.
  Standard_EXPORT bool Add(const occ::handle<Graphic3d_CLight>& theLight);

  //! Remove light source.
  Standard_EXPORT bool Remove(const occ::handle<Graphic3d_CLight>& theLight);

  //! Returns total amount of lights of specified type.
  int NbLightsOfType(Graphic3d_TypeOfLightSource theType) const { return myLightTypes[theType]; }

  //! @name cached state of lights set updated by UpdateRevision()
public:
  //! Update light sources revision.
  Standard_EXPORT size_t UpdateRevision();

  //! Return light sources revision.
  //! @sa UpdateRevision()
  size_t Revision() const { return myRevision; }

  //! Returns total amount of enabled lights EXCLUDING ambient.
  //! @sa UpdateRevision()
  int NbEnabled() const { return myNbEnabled; }

  //! Returns total amount of enabled lights of specified type.
  //! @sa UpdateRevision()
  int NbEnabledLightsOfType(Graphic3d_TypeOfLightSource theType) const
  {
    return myLightTypesEnabled[theType];
  }

  //! Returns total amount of enabled lights castings shadows.
  //! @sa UpdateRevision()
  int NbCastShadows() const { return myNbCastShadows; }

  //! Returns cumulative ambient color, which is computed as sum of all enabled ambient light
  //! sources. Values are NOT clamped (can be greater than 1.0f) and alpha component is fixed
  //! to 1.0f.
  //! @sa UpdateRevision()
  const NCollection_Vec4<float>& AmbientColor() const { return myAmbient; }

  //! Returns a string defining a list of enabled light sources as concatenation of letters 'd'
  //! (Directional), 'p' (Point), 's' (Spot) depending on the type of light source in the list.
  //! Example: "dppp".
  //! @sa UpdateRevision()
  const TCollection_AsciiString& KeyEnabledLong() const { return myKeyEnabledLong; }

  //! Returns a string defining a list of enabled light sources as concatenation of letters 'd'
  //! (Directional), 'p' (Point), 's' (Spot) depending on the type of light source in the list,
  //! specified only once. Example: "dp".
  //! @sa UpdateRevision()
  const TCollection_AsciiString& KeyEnabledShort() const { return myKeyEnabledShort; }

protected:
  NCollection_IndexedDataMap<occ::handle<Graphic3d_CLight>, size_t>
    // clang-format off
                          myLights;                 //!< list of light sources with their cached state (revision)
  NCollection_Vec4<float>          myAmbient;                //!< cached value of cumulative ambient color
  TCollection_AsciiString myKeyEnabledLong;         //!< key identifying the list of enabled light sources by their type
  TCollection_AsciiString myKeyEnabledShort;        //!< key identifying the list of enabled light sources by the number of sources of each type
  int        myLightTypes       [Graphic3d_TypeOfLightSource_NB]; //!< counters per each light source type defined in the list
  int        myLightTypesEnabled[Graphic3d_TypeOfLightSource_NB]; //!< counters per each light source type enabled in the list
  int        myNbEnabled;              //!< number of enabled light sources, excluding ambient
  int        myNbCastShadows;          //!< number of enabled light sources casting shadows
  // clang-format on
  size_t myRevision;      //!< current revision of light source set
  size_t myCacheRevision; //!< revision of cached state
};

#endif // _Graphic3d_LightSet_HeaderFile