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

Copyright (c) 2006-2008, ASSIMP Development Team

All rights reserved.

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* Redistributions of source code must retain the above
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  following disclaimer.

* Redistributions in binary form must reproduce the above
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  derived from this software without specific prior
  written permission of the ASSIMP Development Team.

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*/

/** @file Implementation of the "PretransformVertices" post processing step 
*/

#include "AssimpPCH.h"
#include "PretransformVertices.h"


using namespace Assimp;

// some array offsets
#define AI_PTVS_VERTEX 0x0
#define AI_PTVS_FACE 0x1

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
PretransformVertices::PretransformVertices()
{
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
PretransformVertices::~PretransformVertices()
{
	// nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool PretransformVertices::IsActive( unsigned int pFlags) const
{
	return	(pFlags & aiProcess_PreTransformVertices) != 0;
}

// ------------------------------------------------------------------------------------------------
// Count the number of nodes
unsigned int CountNodes( aiNode* pcNode )
{
	unsigned int iRet = 1;
	for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
	{
		iRet += CountNodes(pcNode->mChildren[i]);
	}
	return iRet;
}

// ------------------------------------------------------------------------------------------------
// Get a bitwise combination identifying the vertex format of a mesh
unsigned int GetMeshVFormat(aiMesh* pcMesh)
{
	// the vertex format is stored in aiMesh::mBones for later retrieval.
	// there isn't a good reason to compute it a few hundred times
	// from scratch. The pointer is unused as animations are lost
	// during PretransformVertices.
	if (pcMesh->mBones)
		return (unsigned int)(unsigned long)pcMesh->mBones;

	ai_assert(NULL != pcMesh->mVertices);

	// FIX: the hash may never be 0. Otherwise a comparison against
	// nullptr could be successful
	unsigned int iRet = 1;

	// normals
	if (pcMesh->HasNormals())iRet |= 0x2;
	// tangents and bitangents
	if (pcMesh->HasTangentsAndBitangents())iRet |= 0x4;

	// texture coordinates
	unsigned int p = 0;
	ai_assert(8 >= AI_MAX_NUMBER_OF_TEXTURECOORDS);
	while (pcMesh->HasTextureCoords(p))
	{
		iRet |= (0x100 << p);
		if (3 == pcMesh->mNumUVComponents[p])
			iRet |= (0x10000 << p);

		++p;
	}
	// vertex colors
	p = 0;
	ai_assert(8 >= AI_MAX_NUMBER_OF_COLOR_SETS);
	while (pcMesh->HasVertexColors(p))iRet |= (0x1000000 << p++);

	// store the value for later use
	pcMesh->mBones = (aiBone**)(unsigned long)iRet;
	return iRet;
}

// ------------------------------------------------------------------------------------------------
// Count the number of vertices in the whole scene and a given
// material index
void CountVerticesAndFaces( aiScene* pcScene, aiNode* pcNode, unsigned int iMat,
	unsigned int iVFormat, unsigned int* piFaces, unsigned int* piVertices)
{
	for (unsigned int i = 0; i < pcNode->mNumMeshes;++i)
	{
		aiMesh* pcMesh = pcScene->mMeshes[ pcNode->mMeshes[i] ]; 
		if (iMat == pcMesh->mMaterialIndex && iVFormat == GetMeshVFormat(pcMesh))
		{
			*piVertices += pcMesh->mNumVertices;
			*piFaces += pcMesh->mNumFaces;
		}
	}
	for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
	{
		CountVerticesAndFaces(pcScene,pcNode->mChildren[i],iMat,
			iVFormat,piFaces,piVertices);
	}
}

// ------------------------------------------------------------------------------------------------
// Collect vertex/face data
void CollectData( aiScene* pcScene, aiNode* pcNode, unsigned int iMat,
	unsigned int iVFormat, aiMesh* pcMeshOut, 
	unsigned int aiCurrent[2])
{
	for (unsigned int i = 0; i < pcNode->mNumMeshes;++i)
	{
		aiMesh* pcMesh = pcScene->mMeshes[ pcNode->mMeshes[i] ]; 
		if (iMat == pcMesh->mMaterialIndex && iVFormat == GetMeshVFormat(pcMesh))
		{
			// copy positions, transform them to worldspace
			for (unsigned int n = 0; n < pcMesh->mNumVertices;++n)
			{
				pcMeshOut->mVertices[aiCurrent[AI_PTVS_VERTEX]+n] = 
					pcNode->mTransformation * pcMesh->mVertices[n];
			}
			if (iVFormat & 0x2)
			{
				aiMatrix4x4 mWorldIT = pcNode->mTransformation;
				mWorldIT.Inverse().Transpose();

				// TODO: implement Inverse() for aiMatrix3x3
				aiMatrix3x3 m = aiMatrix3x3(mWorldIT);
				
				// copy normals, transform them to worldspace
				for (unsigned int n = 0; n < pcMesh->mNumVertices;++n)
				{
					pcMeshOut->mNormals[aiCurrent[AI_PTVS_VERTEX]+n] = 
						m * pcMesh->mNormals[n];
				}
			}
			if (iVFormat & 0x4)
			{
				// copy tangents
				memcpy(pcMeshOut->mTangents + aiCurrent[AI_PTVS_VERTEX],
					pcMesh->mTangents,
					pcMesh->mNumVertices * sizeof(aiVector3D));
				// copy bitangents
				memcpy(pcMeshOut->mBitangents + aiCurrent[AI_PTVS_VERTEX],
					pcMesh->mBitangents,
					pcMesh->mNumVertices * sizeof(aiVector3D));
			}
			unsigned int p = 0;
			while (iVFormat & (0x100 << p))
			{
				// copy texture coordinates
				memcpy(pcMeshOut->mTextureCoords[p] + aiCurrent[AI_PTVS_VERTEX],
					pcMesh->mTextureCoords[p],
					pcMesh->mNumVertices * sizeof(aiVector3D));
				++p;
			}
			p = 0;
			while (iVFormat & (0x1000000 << p))
			{
				// copy vertex colors
				memcpy(pcMeshOut->mColors[p] + aiCurrent[AI_PTVS_VERTEX],
					pcMesh->mColors[p],
					pcMesh->mNumVertices * sizeof(aiColor4D));
				++p;
			}
			// now we need to copy all faces
			// since we will delete the source mesh afterwards,
			// we don't need to reallocate the array of indices
			for (unsigned int planck = 0;planck<pcMesh->mNumFaces;++planck)
			{
				pcMeshOut->mFaces[aiCurrent[AI_PTVS_FACE]+planck].mNumIndices =
					pcMesh->mFaces[planck].mNumIndices; 

				unsigned int* pi = pcMeshOut->mFaces[aiCurrent[AI_PTVS_FACE]+planck].
					mIndices = pcMesh->mFaces[planck].mIndices; 

				// offset all vrtex indices
				for (unsigned int hahn = 0; hahn < pcMesh->mFaces[planck].mNumIndices;++hahn)
				{
					pi[hahn] += aiCurrent[AI_PTVS_VERTEX];
				}

				// just make sure the array won't be deleted by the
				// aiFace destructor ...
				pcMesh->mFaces[planck].mIndices = NULL;

				// FIX: update the mPrimitiveTypes member of the mesh
				switch (pcMesh->mFaces[planck].mNumIndices)
				{
				case 0x1:
					pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_POINT;
					break;
				case 0x2:
					pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_LINE;
					break;
				case 0x3:
					pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
					break;
				default:
					pcMeshOut->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
					break;
				};
			}
			aiCurrent[AI_PTVS_VERTEX] += pcMesh->mNumVertices;
			aiCurrent[AI_PTVS_FACE]   += pcMesh->mNumFaces;
		}
	}
	for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
	{
		CollectData(pcScene,pcNode->mChildren[i],iMat,
			iVFormat,pcMeshOut,aiCurrent);
	}
}

// ------------------------------------------------------------------------------------------------
// Get a list of all vertex formats that occur for a given material index
// The output list contains duplicate elements
void GetVFormatList( aiScene* pcScene, unsigned int iMat,
	std::list<unsigned int>& aiOut)
{
	for (unsigned int i = 0; i < pcScene->mNumMeshes;++i)
	{
		aiMesh* pcMesh = pcScene->mMeshes[ i ]; 
		if (iMat == pcMesh->mMaterialIndex)
		{
			aiOut.push_back(GetMeshVFormat(pcMesh));
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Compute the absolute transformation matrices of each node
void ComputeAbsoluteTransform( aiNode* pcNode )
{
	if (pcNode->mParent)
	{
		pcNode->mTransformation = pcNode->mParent->mTransformation*pcNode->mTransformation;
	}

	for (unsigned int i = 0;i < pcNode->mNumChildren;++i)
	{
		ComputeAbsoluteTransform(pcNode->mChildren[i]);
	}
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void PretransformVertices::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("PretransformVerticesProcess begin");

	const unsigned int iOldMeshes = pScene->mNumMeshes;
	const unsigned int iOldAnimationChannels = pScene->mNumAnimations;
	const unsigned int iOldNodes = CountNodes(pScene->mRootNode);

	// first compute absolute transformation matrices for all nodes
	ComputeAbsoluteTransform(pScene->mRootNode);

	// delete aiMesh::mBones for all meshes. The bones are
	// removed during this step and we need the pointer as
	// temporary storage
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
	{
		aiMesh* mesh = pScene->mMeshes[i];

		for (unsigned int a = 0; a < mesh->mNumBones;++a)
			delete mesh->mBones[a];

		delete[] mesh->mBones;
		mesh->mBones = NULL;
	}

	// now build a list of output meshes
	std::vector<aiMesh*> apcOutMeshes;
	apcOutMeshes.reserve(pScene->mNumMaterials<<1u);
	std::list<unsigned int> aiVFormats;
	for (unsigned int i = 0; i < pScene->mNumMaterials;++i)
	{
		// get the list of all vertex formats for this material
		aiVFormats.clear();
		GetVFormatList(pScene,i,aiVFormats);
		aiVFormats.sort();
		aiVFormats.unique();
		for (std::list<unsigned int>::const_iterator
			j =  aiVFormats.begin();
			j != aiVFormats.end();++j)
		{
			unsigned int iVertices = 0;
			unsigned int iFaces = 0; 
			CountVerticesAndFaces(pScene,pScene->mRootNode,i,*j,&iFaces,&iVertices);
			if (iFaces && iVertices)
			{
				apcOutMeshes.push_back(new aiMesh());
				aiMesh* pcMesh = apcOutMeshes.back();
				pcMesh->mNumFaces = iFaces;
				pcMesh->mNumVertices = iVertices;
				pcMesh->mFaces = new aiFace[iFaces];
				pcMesh->mVertices = new aiVector3D[iVertices];
				pcMesh->mMaterialIndex = i;
				if ((*j) & 0x2)pcMesh->mNormals = new aiVector3D[iVertices];
				if ((*j) & 0x4)
				{
					pcMesh->mTangents    = new aiVector3D[iVertices];
					pcMesh->mBitangents  = new aiVector3D[iVertices];
				}
				iFaces = 0;
				while ((*j) & (0x100 << iFaces))
				{
					pcMesh->mTextureCoords[iFaces] = new aiVector3D[iVertices];
					if ((*j) & (0x10000 << iFaces))pcMesh->mNumUVComponents[iFaces] = 3;
					else pcMesh->mNumUVComponents[iFaces] = 2;
					iFaces++;
				}
				iFaces = 0;
				while ((*j) & (0x1000000 << iFaces))
					pcMesh->mColors[iFaces++] = new aiColor4D[iVertices];

				// fill the mesh ...
				unsigned int aiTemp[2] = {0,0};
				CollectData(pScene,pScene->mRootNode,i,*j,pcMesh,aiTemp);
			}
		}
	}

	// remove all animations from the scene
	for (unsigned int i = 0; i < pScene->mNumAnimations;++i)
		delete pScene->mAnimations[i];
	delete[] pScene->mAnimations;

	pScene->mAnimations    = NULL;
	pScene->mNumAnimations = 0;

	// now delete all meshes in the scene and build a new mesh list
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
	{
		pScene->mMeshes[i]->mBones = NULL;
		delete pScene->mMeshes[i];

		// invalidate the contents of the old mesh array. We will most
		// likely have less output meshes now, so the last entries of 
		// the mesh array are not overridden. We set them to NULL to 
		// make sure the developer gets notified when his application
		// attempts to access these fields ...
		pScene->mMeshes[i] = NULL;
	}

	// If no meshes are referenced in the node graph it is
	// possible that we get no output meshes. However, this 
	// is OK if we had no input meshes, too
	if (apcOutMeshes.empty())
	{
		if (pScene->mNumMeshes)
		{
			throw new ImportErrorException("No output meshes: all meshes are orphaned "
				"and have no node references");
		}
	}
	else
	{
		// It is impossible that we have more output meshes than 
		// input meshes, so we can easily reuse the old mesh array
		pScene->mNumMeshes = (unsigned int)apcOutMeshes.size();
		for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
			pScene->mMeshes[i] = apcOutMeshes[i];
	}

	// --- we need to keep all cameras and lights 
	for (unsigned int i = 0; i < pScene->mNumCameras;++i)
	{
		aiCamera* cam = pScene->mCameras[i];
		const aiNode* nd = pScene->mRootNode->FindNode(cam->mName);
		ai_assert(NULL != nd);

		// multiply all properties of the camera with the absolute
		// transformation of the corresponding node
		cam->mPosition = nd->mTransformation * cam->mPosition;
		cam->mLookAt   = aiMatrix3x3( nd->mTransformation ) * cam->mLookAt;
		cam->mUp       = aiMatrix3x3( nd->mTransformation ) * cam->mUp;
	}

	for (unsigned int i = 0; i < pScene->mNumLights;++i)
	{
		aiLight* l = pScene->mLights[i];
		const aiNode* nd = pScene->mRootNode->FindNode(l->mName);
		ai_assert(NULL != nd);

		// multiply all properties of the camera with the absolute
		// transformation of the corresponding node
		l->mPosition   = nd->mTransformation * l->mPosition;
		l->mDirection  = aiMatrix3x3( nd->mTransformation ) * l->mDirection;
	}

	// now delete all nodes in the scene and build a new
	// flat node graph with a root node and some level 1 children
	delete pScene->mRootNode;
	pScene->mRootNode = new aiNode();
	pScene->mRootNode->mName.Set("<dummy_root>");

	if (1 == pScene->mNumMeshes && !pScene->mNumLights && !pScene->mNumCameras)
	{
		pScene->mRootNode->mNumMeshes = 1;
		pScene->mRootNode->mMeshes = new unsigned int[1];
		pScene->mRootNode->mMeshes[0] = 0;
	}
	else
	{
		pScene->mRootNode->mNumChildren = pScene->mNumMeshes+pScene->mNumLights+pScene->mNumCameras;
		aiNode** nodes = pScene->mRootNode->mChildren = new aiNode*[pScene->mRootNode->mNumChildren];

		// generate mesh nodes
		for (unsigned int i = 0; i < pScene->mNumMeshes;++i,++nodes)
		{
			aiNode* pcNode = *nodes = new aiNode();
			pcNode->mParent = pScene->mRootNode;
			pcNode->mName.length = ::sprintf(pcNode->mName.data,"mesh_%i",i);

			// setup mesh indices
			pcNode->mNumMeshes = 1;
			pcNode->mMeshes = new unsigned int[1];
			pcNode->mMeshes[0] = i;
		}
		// generate light nodes
		for (unsigned int i = 0; i < pScene->mNumLights;++i,++nodes)
		{
			aiNode* pcNode = *nodes = new aiNode();
			pcNode->mParent = pScene->mRootNode;
			pcNode->mName.length = ::sprintf(pcNode->mName.data,"light_%i",i);
			pScene->mLights[i]->mName = pcNode->mName;
		}
		// generate camera nodes
		for (unsigned int i = 0; i < pScene->mNumCameras;++i,++nodes)
		{
			aiNode* pcNode = *nodes = new aiNode();
			pcNode->mParent = pScene->mRootNode;
			pcNode->mName.length = ::sprintf(pcNode->mName.data,"cam_%i",i);
			pScene->mCameras[i]->mName = pcNode->mName;
		}
	}

	// print statistics
	if (!DefaultLogger::isNullLogger())
	{
		char buffer[4096];

		DefaultLogger::get()->debug("PretransformVerticesProcess finished");

		::sprintf(buffer,"Removed %i nodes and %i animation channels (%i output nodes)",
			iOldNodes,iOldAnimationChannels,CountNodes(pScene->mRootNode));
		DefaultLogger::get()->info(buffer);

		::sprintf(buffer,"Kept %i lights and %i cameras",
			pScene->mNumLights,pScene->mNumCameras);
		DefaultLogger::get()->info(buffer);

		::sprintf(buffer,"Moved %i meshes to WCS (number of output meshes: %i)",
			iOldMeshes,pScene->mNumMeshes);
		DefaultLogger::get()->info(buffer);
	}

	return;
}