/*
Open Asset Import Library (assimp)
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  following disclaimer.

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*/

/** @file A helper class that processes texture transformations */


#include "AssimpPCH.h"
#include "TextureTransform.h"

using namespace Assimp;


// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
TextureTransformStep::TextureTransformStep()
{
	// nothing to do here
}

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

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

// ------------------------------------------------------------------------------------------------
// Setup properties
void TextureTransformStep::SetupProperties(const Importer* pImp)
{
	configFlags = pImp->GetPropertyInteger(AI_CONFIG_PP_TUV_EVALUATE,AI_UVTRAFO_ALL);
}

// ------------------------------------------------------------------------------------------------
void TextureTransformStep::PreProcessUVTransform(STransformVecInfo& info)
{
	/*  This function tries to simplify the input UV transformation.
	 *  That's very important as it allows us to reduce the number 
	 *  of output UV channels. The oder in which the transformations
	 *  are applied is - as always - scaling, rotation, translation.
	 */

	char szTemp[512];
	int rounded = 0;


	/* Optimize the rotation angle. That's slightly difficult as
	 * we have an inprecise floating-point number (when comparing
	 * UV transformations we'll take that into account by using
	 * an epsilon of 5 degrees). If there is a rotation value, we can't
	 * perform any further optimizations.
	 */
	if (info.mRotation)
	{
		float out = info.mRotation;
		if ((rounded = (int)(info.mRotation / (float)AI_MATH_TWO_PI)))
		{
			out -= rounded*(float)AI_MATH_PI;

			sprintf(szTemp,"Texture coordinate rotation %f can be simplified to %f",info.mRotation,out);
			DefaultLogger::get()->info(szTemp);
		}

		// Next step - convert negative rotation angles to positives
		if (out < 0.f)
			out = (float)AI_MATH_TWO_PI * 2 + out;

		info.mRotation = out;
		return;
	}


	/* Optimize UV translation in the U direction. To determine whether
	 * or not we can optimize we need to look at the requested mapping
	 * type (e.g. if mirroring is active there IS a difference between
	 * offset 2 and 3)
	 */
	if ((rounded  = (int)info.mTranslation.x))	{
		float out;
		szTemp[0] = 0;
		if (aiTextureMapMode_Wrap == info.mapU)	{
			// Wrap - simple take the fraction of the field
			out = info.mTranslation.x-(float)rounded;
			sprintf(szTemp,"[w] UV U offset %f can be simplified to %f",info.mTranslation.x,out);
		}
		else if (aiTextureMapMode_Mirror == info.mapU && 1 != rounded)	{
			// Mirror 
			if (rounded % 2)
				rounded--;
			out = info.mTranslation.x-(float)rounded;

			sprintf(szTemp,"[m/d] UV U offset %f can be simplified to %f",info.mTranslation.x,out);
		}
		else if (aiTextureMapMode_Clamp == info.mapU || aiTextureMapMode_Decal == info.mapU)	{
			// Clamp - translations beyond 1,1 are senseless
			sprintf(szTemp,"[c] UV U offset %f can be clamped to 1.0f",info.mTranslation.x);

			out = 1.f;
		}
		if (szTemp[0])		{
			DefaultLogger::get()->info(szTemp);
			info.mTranslation.x = out;
		}
	}

	/* Optimize UV translation in the V direction. To determine whether
	 * or not we can optimize we need to look at the requested mapping
	 * type (e.g. if mirroring is active there IS a difference between
	 * offset 2 and 3)
	 */
	if ((rounded  = (int)info.mTranslation.y))	{
		float out;
		szTemp[0] = 0;
		if (aiTextureMapMode_Wrap == info.mapV)	{
			// Wrap - simple take the fraction of the field
			out = info.mTranslation.y-(float)rounded;
			sprintf(szTemp,"[w] UV V offset %f can be simplified to %f",info.mTranslation.y,out);
		}
		else if (aiTextureMapMode_Mirror == info.mapV  && 1 != rounded)	{
			// Mirror 
			if (rounded % 2)
				rounded--;
			out = info.mTranslation.x-(float)rounded;

			sprintf(szTemp,"[m/d] UV V offset %f can be simplified to %f",info.mTranslation.y,out);
		}
		else if (aiTextureMapMode_Clamp == info.mapV || aiTextureMapMode_Decal == info.mapV)	{
			// Clamp - translations beyond 1,1 are senseless
			sprintf(szTemp,"[c] UV V offset %f canbe clamped to 1.0f",info.mTranslation.y);

			out = 1.f;
		}
		if (szTemp[0])	{
			DefaultLogger::get()->info(szTemp);
			info.mTranslation.y = out;
		}
	}
	return;
}

// ------------------------------------------------------------------------------------------------
void UpdateUVIndex(const std::list<TTUpdateInfo>& l, unsigned int n)
{
	// Don't set if == 0 && wasn't set before
	for (std::list<TTUpdateInfo>::const_iterator it = l.begin();it != l.end(); ++it) {
		const TTUpdateInfo& info = *it;

		if (info.directShortcut)
			*info.directShortcut = n;
		else if (!n)
		{
			info.mat->AddProperty<int>((int*)&n,1,AI_MATKEY_UVWSRC(info.semantic,info.index));
		}
	}
}

// ------------------------------------------------------------------------------------------------
inline const char* MappingModeToChar(aiTextureMapMode map)
{
	if (aiTextureMapMode_Wrap == map)
		return "-w";

	if (aiTextureMapMode_Mirror == map)
		return "-m";
	
	return "-c";
}

// ------------------------------------------------------------------------------------------------
void TextureTransformStep::Execute( aiScene* pScene) 
{
	DefaultLogger::get()->debug("TransformUVCoordsProcess begin");
	

	/*  We build a per-mesh list of texture transformations we'll need
	 *  to apply. To achieve this, we iterate through all materials, 
	 *  find all textures and get their transformations and UV indices. 
	 *  Then we search for all meshes using this material.
	 */
	typedef std::list<STransformVecInfo> MeshTrafoList;
	std::vector<MeshTrafoList> meshLists(pScene->mNumMeshes);

	for (unsigned int i = 0; i < pScene->mNumMaterials;++i)	{

		aiMaterial* mat = pScene->mMaterials[i];
		for (unsigned int a = 0; a < mat->mNumProperties;++a)	{

			aiMaterialProperty* prop = mat->mProperties[a];
			if (!::strcmp( prop->mKey.data, "$tex.file"))	{
				STransformVecInfo info;

				// Setup a shortcut structure to allow for a fast updating
				// of the UV index later
				TTUpdateInfo update;
				update.mat = (aiMaterial*) mat;
				update.semantic = prop->mSemantic;
				update.index = prop->mIndex;

				// Get textured properties and transform
				for (unsigned int a2 = 0; a2 < mat->mNumProperties;++a2)  {
					aiMaterialProperty* prop2 = mat->mProperties[a2];
					if (prop2->mSemantic != prop->mSemantic || prop2->mIndex != prop->mIndex) {
						continue;
					}

					if ( !::strcmp( prop2->mKey.data, "$tex.uvwsrc")) {
						info.uvIndex = *((int*)prop2->mData);

						// Store a direct pointer for later use
						update.directShortcut = (unsigned int*) prop2->mData;
					}

					else if ( !::strcmp( prop2->mKey.data, "$tex.mapmodeu")) {
						info.mapU = *((aiTextureMapMode*)prop2->mData);
					}
					else if ( !::strcmp( prop2->mKey.data, "$tex.mapmodev")) {
						info.mapV = *((aiTextureMapMode*)prop2->mData);
					}
					else if ( !::strcmp( prop2->mKey.data, "$tex.uvtrafo"))  {
						// ValidateDS should check this
						ai_assert(prop2->mDataLength >= 20); 
						::memcpy(&info.mTranslation.x,prop2->mData,sizeof(float)*5);

						// Directly remove this property from the list 
						mat->mNumProperties--;
						for (unsigned int a3 = a2; a3 < mat->mNumProperties;++a3) {
							mat->mProperties[a3] = mat->mProperties[a3+1];
						}

						delete prop2;

						// Warn: could be an underflow, but this does not invoke undefined behaviour
						--a2; 
					}
				}

				// Find out which transformations are to be evaluated
				if (!(configFlags & AI_UVTRAFO_ROTATION)) {
					info.mRotation = 0.f;
				}
				if (!(configFlags & AI_UVTRAFO_SCALING)) {
					info.mScaling = aiVector2D(1.f,1.f);
				}
				if (!(configFlags & AI_UVTRAFO_TRANSLATION)) {
					info.mTranslation = aiVector2D(0.f,0.f);
				}

				// Do some preprocessing
				PreProcessUVTransform(info);
				info.uvIndex = std::min(info.uvIndex,AI_MAX_NUMBER_OF_TEXTURECOORDS -1u);

				// Find out whether this material is used by more than
				// one mesh. This will make our task much, much more difficult!
				unsigned int cnt = 0;
				for (unsigned int n = 0; n < pScene->mNumMeshes;++n)	{
					if (pScene->mMeshes[n]->mMaterialIndex == i)
						++cnt;
				}

				if (!cnt)
					continue;
				else if (1 != cnt)	{
					// This material is referenced by more than one mesh!
					// So we need to make sure the UV index for the texture
					// is identical for each of it ...
					info.lockedPos = AI_TT_UV_IDX_LOCK_TBD;
				}

				// Get all coresponding meshes
				for (unsigned int n = 0; n < pScene->mNumMeshes;++n)	{
					aiMesh* mesh = pScene->mMeshes[n];
					if (mesh->mMaterialIndex != i || !mesh->mTextureCoords[0])
						continue;

					unsigned int uv = info.uvIndex;
					if (!mesh->mTextureCoords[uv])	{
						// If the requested UV index is not available, take the first one instead.
						uv = 0;
					}
					
					if (mesh->mNumUVComponents[info.uvIndex] >= 3){
						DefaultLogger::get()->warn("UV transformations on 3D mapping channels are not supported");
						continue;
					}

					MeshTrafoList::iterator it;

					// Check whether we have this transform setup already
					for (it = meshLists[n].begin();it != meshLists[n].end(); ++it)	{

						if ((*it) == info && (*it).uvIndex == uv)	{
							(*it).updateList.push_back(update);
							break;
						}
					}

					if (it == meshLists[n].end())	{
						meshLists[n].push_back(info);
						meshLists[n].back().uvIndex = uv;
						meshLists[n].back().updateList.push_back(update);
					}
				}
			}
		}
	}

	char buffer[1024]; // should be sufficiently large
	unsigned int outChannels = 0, inChannels = 0, transformedChannels = 0;

	// Now process all meshes. Important: we don't remove unreferenced UV channels.
	// This is a job for the RemoveUnreferencedData-Step.
	for (unsigned int q = 0; q < pScene->mNumMeshes;++q)	{

		aiMesh* mesh = pScene->mMeshes[q];
		MeshTrafoList& trafo =  meshLists[q];

		inChannels += mesh->GetNumUVChannels();

		if (!mesh->mTextureCoords[0] || trafo.empty() ||  (trafo.size() == 1 && trafo.begin()->IsUntransformed())) {
			outChannels += mesh->GetNumUVChannels();
			continue;
		}

		// Move untransformed UV channels to the first position in the list .... 
		// except if we need a new locked index which should be as small as possible
		bool veto = false, need = false;
		unsigned int cnt = 0;
		unsigned int untransformed = 0;

		MeshTrafoList::iterator it,it2;
		for (it = trafo.begin();it != trafo.end(); ++it,++cnt)	{

			if (!(*it).IsUntransformed()) {
				need = true;
			}

			if ((*it).lockedPos == AI_TT_UV_IDX_LOCK_TBD)	{
				// Lock this index and make sure it won't be changed
				(*it).lockedPos = cnt;
				veto = true;
				continue;
			}

			if (!veto && it != trafo.begin() && (*it).IsUntransformed())	{
				for (it2 = trafo.begin();it2 != it; ++it2) {
					if (!(*it2).IsUntransformed()) 
						break;
				}
				trafo.insert(it2,*it);
				trafo.erase(it);
				break;
			}
		}
		if (!need)
			continue;

		// Find all that are not at their 'locked' position and move them to it. 
		// Conflicts are possible but quite unlikely.
		cnt = 0;
		for (it = trafo.begin();it != trafo.end(); ++it,++cnt) {
			if ((*it).lockedPos != AI_TT_UV_IDX_LOCK_NONE && (*it).lockedPos != cnt) {
				it2 = trafo.begin();unsigned int t = 0;
				while (t != (*it).lockedPos)
					++it2;

				if ((*it2).lockedPos != AI_TT_UV_IDX_LOCK_NONE) {
					DefaultLogger::get()->error("Channel mismatch, can't compute all transformations properly [design bug]");
					continue;
				}

				std::swap(*it2,*it);
				if ((*it).lockedPos == untransformed)
					untransformed = cnt;
			}
		}

		// ... and add dummies for all unreferenced channels
		// at the end of the list
		bool ref[AI_MAX_NUMBER_OF_TEXTURECOORDS];
		for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n)
			ref[n] = (!mesh->mTextureCoords[n] ? true : false);

		for (it = trafo.begin();it != trafo.end(); ++it)
			ref[(*it).uvIndex] = true;

		for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n) {
			if (ref[n])
				continue;
			trafo.push_back(STransformVecInfo());
			trafo.back().uvIndex = n;
		}

		// Then check whether this list breaks the channel limit.
		// The unimportant ones are at the end of the list, so
		// it shouldn't be too worse if we remove them.
		unsigned int size = (unsigned int)trafo.size();
		if (size > AI_MAX_NUMBER_OF_TEXTURECOORDS) {

			if (!DefaultLogger::isNullLogger()) {
				::sprintf(buffer,"%u UV channels required but just %u available", 
					static_cast<unsigned int>(trafo.size()),AI_MAX_NUMBER_OF_TEXTURECOORDS);

				DefaultLogger::get()->error(buffer);
			}
			size = AI_MAX_NUMBER_OF_TEXTURECOORDS;
		}


		aiVector3D* old[AI_MAX_NUMBER_OF_TEXTURECOORDS];
		for (unsigned int n = 0; n < AI_MAX_NUMBER_OF_TEXTURECOORDS;++n)
			old[n] = mesh->mTextureCoords[n];

		// Now continue and generate the output channels. Channels
		// that we're not going to need later can be overridden.
		it = trafo.begin();
		for (unsigned int n = 0; n < trafo.size();++n,++it)	{

			if (n >= size)	{
				// Try to use an untransformed channel for all channels we threw over board
				UpdateUVIndex((*it).updateList,untransformed);
				continue;
			}

			outChannels++;

			// Write to the log
			if (!DefaultLogger::isNullLogger())	{
				sprintf(buffer,"Mesh %u, channel %u: t(%.3f,%.3f), s(%.3f,%.3f), r(%.3f), %s%s",
					q,n,
					(*it).mTranslation.x,
					(*it).mTranslation.y,
					(*it).mScaling.x,
					(*it).mScaling.y,
					AI_RAD_TO_DEG( (*it).mRotation),
					MappingModeToChar ((*it).mapU),
					MappingModeToChar ((*it).mapV));

				DefaultLogger::get()->info(buffer);
			}

			// Check whether we need a new buffer here
			if (mesh->mTextureCoords[n])	{

				it2 = it;++it2;
				for (unsigned int m = n+1; m < size;++m, ++it2)	{

					if ((*it2).uvIndex == n){
						it2 = trafo.begin();
						break;
					}
				}
				if (it2 == trafo.begin()){
					mesh->mTextureCoords[n] = new aiVector3D[mesh->mNumVertices];
				} 
			}
			else mesh->mTextureCoords[n] = new aiVector3D[mesh->mNumVertices];

			aiVector3D* src = old[(*it).uvIndex];
			aiVector3D* dest, *end;
			dest = mesh->mTextureCoords[n];

			ai_assert(NULL != src);

			// Copy the data to the destination array
			if (dest != src)
				::memcpy(dest,src,sizeof(aiVector3D)*mesh->mNumVertices);

			end = dest + mesh->mNumVertices;

			// Build a transformation matrix and transform all UV coords with it
			if (!(*it).IsUntransformed()) {
				const aiVector2D& trl = (*it).mTranslation;
				const aiVector2D& scl = (*it).mScaling;

				// fixme: simplify ..
				++transformedChannels;
				aiMatrix3x3 matrix;

				aiMatrix3x3 m2,m3,m4,m5;

				m4.a1 = scl.x;
				m4.b2 = scl.y;
				
				m2.a3 = m2.b3 = 0.5f;
				m3.a3 = m3.b3 = -0.5f;

				if ((*it).mRotation > AI_TT_ROTATION_EPSILON )
					aiMatrix3x3::RotationZ((*it).mRotation,matrix);

				m5.a3 += trl.x; m5.b3 += trl.y;
				matrix = m2 * m4 * matrix * m3 * m5;
				
				for (src = dest; src != end; ++src)	{ /* manual homogenious divide */
					src->z = 1.f;
					*src = matrix * *src;
					src->x /= src->z;
					src->y /= src->z;
					src->z = 0.f;
				}
			}

			// Update all UV indices
			UpdateUVIndex((*it).updateList,n);
		}
	}

	// Print some detailled statistics into the log
	if (!DefaultLogger::isNullLogger())	{

		if (transformedChannels)	{
			::sprintf(buffer,"TransformUVCoordsProcess end: %u output channels (in: %u, modified: %u)",
				outChannels,inChannels,transformedChannels);

			DefaultLogger::get()->info(buffer);
		}
		else DefaultLogger::get()->debug("TransformUVCoordsProcess finished");
	}
}