/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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  following disclaimer.

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  copyright notice, this list of conditions and the
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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----------------------------------------------------------------------
*/

#ifndef AI_PROCESS_HELPER_H_INCLUDED
#define AI_PROCESS_HELPER_H_INCLUDED

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

#include "Common/BaseProcess.h"
#include <assimp/ParsingUtils.h>
#include <assimp/SpatialSort.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),static_cast<ai_real>(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), static_cast<ai_real>(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<ai_real>()(min.mWeight, max.mWeight);
    }
};

// -------------------------------------------------------------------------------
/** @brief Find the min/max values of an array of Ts
 *  @param in Input array
 *  @param size Number 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 colors.
 * @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()
using PerVertexWeight = std::pair<unsigned int, float>;
using VertexWeightTable = std::vector<PerVertexWeight>;

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

// -------------------------------------------------------------------------------
// 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 post-process 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 nullptr != shared && 0 != (pFlags & (aiProcess_CalcTangentSpace |
                                                           aiProcess_GenNormals | aiProcess_JoinIdenticalVertices));
    }

    void Execute(aiScene *pScene) {
        typedef std::pair<SpatialSort, ai_real> _Type;
        ASSIMP_LOG_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 nullptr != 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
