/*
Open Asset Import Library (assimp)
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*/

#ifndef AI_PROCESS_HELPER_H_INCLUDED
#define AI_PROCESS_HELPER_H_INCLUDED

#include <assimp/postprocess.h>
#include <assimp/anim.h>
#include <assimp/mesh.h>
#include <assimp/material.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/scene.h>

#include "SpatialSort.h"
#include "BaseProcess.h"
#include "ParsingUtils.h"

#include <list>

// -------------------------------------------------------------------------------
// Some extensions to std namespace. Mainly std::min and std::max for all
// flat data types in the aiScene. They're used to quickly determine the
// min/max bounds of data arrays.
#ifdef __cplusplus
namespace std {

    // std::min for aiVector3D
    template <typename TReal>
    inline ::aiVector3t<TReal> min (const ::aiVector3t<TReal>& a, const ::aiVector3t<TReal>& b) {
        return ::aiVector3t<TReal> (min(a.x,b.x),min(a.y,b.y),min(a.z,b.z));
    }

    // std::max for aiVector3t<TReal>
    template <typename TReal>
    inline ::aiVector3t<TReal> max (const ::aiVector3t<TReal>& a, const ::aiVector3t<TReal>& b) {
        return ::aiVector3t<TReal> (max(a.x,b.x),max(a.y,b.y),max(a.z,b.z));
    }

    // std::min for aiVector2t<TReal>
    template <typename TReal>
    inline ::aiVector2t<TReal> min (const ::aiVector2t<TReal>& a, const ::aiVector2t<TReal>& b) {
        return ::aiVector2t<TReal> (min(a.x,b.x),min(a.y,b.y));
    }

    // std::max for aiVector2t<TReal>
    template <typename TReal>
    inline ::aiVector2t<TReal> max (const ::aiVector2t<TReal>& a, const ::aiVector2t<TReal>& b) {
        return ::aiVector2t<TReal> (max(a.x,b.x),max(a.y,b.y));
    }

    // std::min for aiColor4D
    template <typename TReal>
    inline ::aiColor4t<TReal> min (const ::aiColor4t<TReal>& a, const ::aiColor4t<TReal>& b)    {
        return ::aiColor4t<TReal> (min(a.r,b.r),min(a.g,b.g),min(a.b,b.b),min(a.a,b.a));
    }

    // std::max for aiColor4D
    template <typename TReal>
    inline ::aiColor4t<TReal> max (const ::aiColor4t<TReal>& a, const ::aiColor4t<TReal>& b)    {
        return ::aiColor4t<TReal> (max(a.r,b.r),max(a.g,b.g),max(a.b,b.b),max(a.a,b.a));
    }


    // std::min for aiQuaterniont<TReal>
    template <typename TReal>
    inline ::aiQuaterniont<TReal> min (const ::aiQuaterniont<TReal>& a, const ::aiQuaterniont<TReal>& b)    {
        return ::aiQuaterniont<TReal> (min(a.w,b.w),min(a.x,b.x),min(a.y,b.y),min(a.z,b.z));
    }

    // std::max for aiQuaterniont<TReal>
    template <typename TReal>
    inline ::aiQuaterniont<TReal> max (const ::aiQuaterniont<TReal>& a, const ::aiQuaterniont<TReal>& b)    {
        return ::aiQuaterniont<TReal> (max(a.w,b.w),max(a.x,b.x),max(a.y,b.y),max(a.z,b.z));
    }


    // std::min for aiVectorKey
    inline ::aiVectorKey min (const ::aiVectorKey& a, const ::aiVectorKey& b)   {
        return ::aiVectorKey (min(a.mTime,b.mTime),min(a.mValue,b.mValue));
    }

    // std::max for aiVectorKey
    inline ::aiVectorKey max (const ::aiVectorKey& a, const ::aiVectorKey& b)   {
        return ::aiVectorKey (max(a.mTime,b.mTime),max(a.mValue,b.mValue));
    }

    // std::min for aiQuatKey
    inline ::aiQuatKey min (const ::aiQuatKey& a, const ::aiQuatKey& b) {
        return ::aiQuatKey (min(a.mTime,b.mTime),min(a.mValue,b.mValue));
    }

    // std::max for aiQuatKey
    inline ::aiQuatKey max (const ::aiQuatKey& a, const ::aiQuatKey& b) {
        return ::aiQuatKey (max(a.mTime,b.mTime),max(a.mValue,b.mValue));
    }

    // std::min for aiVertexWeight
    inline ::aiVertexWeight min (const ::aiVertexWeight& a, const ::aiVertexWeight& b)  {
        return ::aiVertexWeight (min(a.mVertexId,b.mVertexId),min(a.mWeight,b.mWeight));
    }

    // std::max for aiVertexWeight
    inline ::aiVertexWeight max (const ::aiVertexWeight& a, const ::aiVertexWeight& b)  {
        return ::aiVertexWeight (max(a.mVertexId,b.mVertexId),max(a.mWeight,b.mWeight));
    }

} // end namespace std
#endif // !! C++

namespace Assimp {

// -------------------------------------------------------------------------------
// Start points for ArrayBounds<T> for all supported Ts
template <typename T>
struct MinMaxChooser;

template <> struct MinMaxChooser<float> {
    void operator ()(float& min,float& max) {
        max = -1e10f;
        min =  1e10f;
}};
template <> struct MinMaxChooser<double> {
    void operator ()(double& min,double& max) {
        max = -1e10;
        min =  1e10;
}};
template <> struct MinMaxChooser<unsigned int> {
    void operator ()(unsigned int& min,unsigned int& max) {
        max = 0;
        min = (1u<<(sizeof(unsigned int)*8-1));
}};

template <typename T> struct MinMaxChooser< aiVector3t<T> > {
    void operator ()(aiVector3t<T>& min,aiVector3t<T>& max) {
        max = aiVector3t<T>(-1e10f,-1e10f,-1e10f);
        min = aiVector3t<T>( 1e10f, 1e10f, 1e10f);
}};
template <typename T> struct MinMaxChooser< aiVector2t<T> > {
    void operator ()(aiVector2t<T>& min,aiVector2t<T>& max) {
        max = aiVector2t<T>(-1e10f,-1e10f);
        min = aiVector2t<T>( 1e10f, 1e10f);
    }};
template <typename T> struct MinMaxChooser< aiColor4t<T> > {
    void operator ()(aiColor4t<T>& min,aiColor4t<T>& max) {
        max = aiColor4t<T>(-1e10f,-1e10f,-1e10f,-1e10f);
        min = aiColor4t<T>( 1e10f, 1e10f, 1e10f, 1e10f);
}};

template <typename T> struct MinMaxChooser< aiQuaterniont<T> > {
    void operator ()(aiQuaterniont<T>& min,aiQuaterniont<T>& max) {
        max = aiQuaterniont<T>(-1e10f,-1e10f,-1e10f,-1e10f);
        min = aiQuaterniont<T>( 1e10f, 1e10f, 1e10f, 1e10f);
}};

template <> struct MinMaxChooser<aiVectorKey> {
    void operator ()(aiVectorKey& min,aiVectorKey& max) {
        MinMaxChooser<double>()(min.mTime,max.mTime);
        MinMaxChooser<aiVector3D>()(min.mValue,max.mValue);
}};
template <> struct MinMaxChooser<aiQuatKey> {
    void operator ()(aiQuatKey& min,aiQuatKey& max) {
        MinMaxChooser<double>()(min.mTime,max.mTime);
        MinMaxChooser<aiQuaternion>()(min.mValue,max.mValue);
}};

template <> struct MinMaxChooser<aiVertexWeight> {
    void operator ()(aiVertexWeight& min,aiVertexWeight& max) {
        MinMaxChooser<unsigned int>()(min.mVertexId,max.mVertexId);
        MinMaxChooser<float>()(min.mWeight,max.mWeight);
}};

// -------------------------------------------------------------------------------
/** @brief Find the min/max values of an array of Ts
 *  @param in Input array
 *  @param size Numebr of elements to process
 *  @param[out] min minimum value
 *  @param[out] max maximum value
 */
template <typename T>
inline void ArrayBounds(const T* in, unsigned int size, T& min, T& max)
{
    MinMaxChooser<T> ()(min,max);
    for (unsigned int i = 0; i < size;++i) {
        min = std::min(in[i],min);
        max = std::max(in[i],max);
    }
}


// -------------------------------------------------------------------------------
/** Little helper function to calculate the quadratic difference
 * of two colours.
 * @param pColor1 First color
 * @param pColor2 second color
 * @return Quadratic color difference */
inline ai_real GetColorDifference( const aiColor4D& pColor1, const aiColor4D& pColor2)
{
    const aiColor4D c (pColor1.r - pColor2.r, pColor1.g - pColor2.g, pColor1.b - pColor2.b, pColor1.a - pColor2.a);
    return c.r*c.r + c.g*c.g + c.b*c.b + c.a*c.a;
}


// -------------------------------------------------------------------------------
/** @brief Extract single strings from a list of identifiers
 *  @param in Input string list.
 *  @param out Receives a list of clean output strings
 *  @sdee #AI_CONFIG_PP_OG_EXCLUDE_LIST */
void ConvertListToStrings(const std::string& in, std::list<std::string>& out);


// -------------------------------------------------------------------------------
/** @brief Compute the AABB of a mesh after applying a given transform
 *  @param mesh Input mesh
 *  @param[out] min Receives minimum transformed vertex
 *  @param[out] max Receives maximum transformed vertex
 *  @param m Transformation matrix to be applied */
void FindAABBTransformed (const aiMesh* mesh, aiVector3D& min, aiVector3D& max, const aiMatrix4x4& m);


// -------------------------------------------------------------------------------
/** @brief Helper function to determine the 'real' center of a mesh
 *
 *  That is the center of its axis-aligned bounding box.
 *  @param mesh Input mesh
 *  @param[out] min Minimum vertex of the mesh
 *  @param[out] max maximum vertex of the mesh
 *  @param[out] out Center point */
void FindMeshCenter (aiMesh* mesh, aiVector3D& out, aiVector3D& min, aiVector3D& max);

// -------------------------------------------------------------------------------
/** @brief Helper function to determine the 'real' center of a scene
 *
 *  That is the center of its axis-aligned bounding box.
 *  @param scene Input scene
 *  @param[out] min Minimum vertex of the scene
 *  @param[out] max maximum vertex of the scene
 *  @param[out] out Center point */
void FindSceneCenter (aiScene* scene, aiVector3D& out, aiVector3D& min, aiVector3D& max);


// -------------------------------------------------------------------------------
// Helper function to determine the 'real' center of a mesh after applying a given transform
void FindMeshCenterTransformed (aiMesh* mesh, aiVector3D& out, aiVector3D& min,aiVector3D& max, const aiMatrix4x4& m);


// -------------------------------------------------------------------------------
// Helper function to determine the 'real' center of a mesh
void FindMeshCenter (aiMesh* mesh, aiVector3D& out);


// -------------------------------------------------------------------------------
// Helper function to determine the 'real' center of a mesh after applying a given transform
void FindMeshCenterTransformed (aiMesh* mesh, aiVector3D& out,const aiMatrix4x4& m);


// -------------------------------------------------------------------------------
// Compute a good epsilon value for position comparisons on a mesh
ai_real ComputePositionEpsilon(const aiMesh* pMesh);


// -------------------------------------------------------------------------------
// Compute a good epsilon value for position comparisons on a array of meshes
ai_real ComputePositionEpsilon(const aiMesh* const* pMeshes, size_t num);


// -------------------------------------------------------------------------------
// Compute an unique value for the vertex format of a mesh
unsigned int GetMeshVFormatUnique(const aiMesh* pcMesh);


// defs for ComputeVertexBoneWeightTable()
typedef std::pair <unsigned int,float> PerVertexWeight;
typedef std::vector <PerVertexWeight> VertexWeightTable;

// -------------------------------------------------------------------------------
// Compute a per-vertex bone weight table
VertexWeightTable* ComputeVertexBoneWeightTable(const aiMesh* pMesh);


// -------------------------------------------------------------------------------
// Get a string for a given aiTextureType
const char* TextureTypeToString(aiTextureType in);


// -------------------------------------------------------------------------------
// Get a string for a given aiTextureMapping
const char* MappingTypeToString(aiTextureMapping in);


// flags for MakeSubmesh()
#define AI_SUBMESH_FLAGS_SANS_BONES 0x1

// -------------------------------------------------------------------------------
// Split a mesh given a list of faces to be contained in the sub mesh
aiMesh* MakeSubmesh(const aiMesh *superMesh, const std::vector<unsigned int> &subMeshFaces, unsigned int subFlags);

// -------------------------------------------------------------------------------
// Utility postprocess step to share the spatial sort tree between
// all steps which use it to speedup its computations.
class ComputeSpatialSortProcess : public BaseProcess
{
    bool IsActive( unsigned int pFlags) const
    {
        return NULL != shared && 0 != (pFlags & (aiProcess_CalcTangentSpace |
            aiProcess_GenNormals | aiProcess_JoinIdenticalVertices));
    }

    void Execute( aiScene* pScene)
    {
        typedef std::pair<SpatialSort, ai_real> _Type;
        DefaultLogger::get()->debug("Generate spatially-sorted vertex cache");

        std::vector<_Type>* p = new std::vector<_Type>(pScene->mNumMeshes);
        std::vector<_Type>::iterator it = p->begin();

        for (unsigned int i = 0; i < pScene->mNumMeshes; ++i, ++it) {
            aiMesh* mesh = pScene->mMeshes[i];
            _Type& blubb = *it;
            blubb.first.Fill(mesh->mVertices,mesh->mNumVertices,sizeof(aiVector3D));
            blubb.second = ComputePositionEpsilon(mesh);
        }

        shared->AddProperty(AI_SPP_SPATIAL_SORT,p);
    }
};

// -------------------------------------------------------------------------------
// ... and the same again to cleanup the whole stuff
class DestroySpatialSortProcess : public BaseProcess
{
    bool IsActive( unsigned int pFlags) const
    {
        return NULL != shared && 0 != (pFlags & (aiProcess_CalcTangentSpace |
            aiProcess_GenNormals | aiProcess_JoinIdenticalVertices));
    }

    void Execute( aiScene* /*pScene*/)
    {
        shared->RemoveProperty(AI_SPP_SPATIAL_SORT);
    }
};


} // ! namespace Assimp
#endif // !! AI_PROCESS_HELPER_H_INCLUDED