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Open Asset Import Library (assimp)
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*/
/** @file RemoveRedundantMaterials.cpp
 *  @brief Implementation of the "RemoveRedundantMaterials" post processing step 
*/

// internal headers

#include "RemoveRedundantMaterials.h"
#include "ParsingUtils.h"
#include "ProcessHelper.h"
#include "MaterialSystem.h"
#include <stdio.h>

using namespace Assimp;

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

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

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

// ------------------------------------------------------------------------------------------------
// Setup import properties
void RemoveRedundantMatsProcess::SetupProperties(const Importer* pImp)
{
	// Get value of AI_CONFIG_PP_RRM_EXCLUDE_LIST
	configFixedMaterials = pImp->GetPropertyString(AI_CONFIG_PP_RRM_EXCLUDE_LIST,"");
}

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

	unsigned int redundantRemoved = 0, unreferencedRemoved = 0;
	if (pScene->mNumMaterials)
	{
		// Find out which materials are referenced by meshes
		std::vector<bool> abReferenced(pScene->mNumMaterials,false);
		for (unsigned int i = 0;i < pScene->mNumMeshes;++i)
			abReferenced[pScene->mMeshes[i]->mMaterialIndex] = true;

		// If a list of materials to be excluded was given, match the list with 
		// our imported materials and 'salt' all positive matches to ensure that
		// we get unique hashes later.
		if (configFixedMaterials.length()) {

			std::list<std::string> strings;
			ConvertListToStrings(configFixedMaterials,strings);
			
			for (unsigned int i = 0; i < pScene->mNumMaterials;++i) {
				aiMaterial* mat = pScene->mMaterials[i];

				aiString name;
				mat->Get(AI_MATKEY_NAME,name);

				if (name.length) {
					std::list<std::string>::const_iterator it = std::find(strings.begin(), strings.end(), name.data);
					if (it != strings.end()) {
						
						// Our brilliant 'salt': A single material property with ~ as first
						// character to mark it as internal and temporary.
						const int dummy = 1;
						((aiMaterial*)mat)->AddProperty(&dummy,1,"~RRM.UniqueMaterial",0,0);

						// Keep this material even if no mesh references it
						abReferenced[i] = true;
						DefaultLogger::get()->debug(std::string("Found positive match in exclusion list: \'") + name.data + "\'");
					}
				}
			}
		}

		// TODO: reimplement this algorithm to work in-place
		unsigned int* aiMappingTable = new unsigned int[pScene->mNumMaterials];
		unsigned int iNewNum = 0;

		// Iterate through all materials and calculate a hash for them
		// store all hashes in a list and so a quick search whether
		// we do already have a specific hash. This allows us to
		// determine which materials are identical.
		uint32_t* aiHashes;
		aiHashes = new uint32_t[pScene->mNumMaterials];
		for (unsigned int i = 0; i < pScene->mNumMaterials;++i)
		{
			// No mesh is referencing this material, remove it.
			if (!abReferenced[i]) {
				++unreferencedRemoved;
				delete pScene->mMaterials[i];
				continue;
			}

			// Check all previously mapped materials for a matching hash.
			// On a match we can delete this material and just make it ref to the same index.
			uint32_t me = aiHashes[i] = ComputeMaterialHash(pScene->mMaterials[i]);
			for (unsigned int a = 0; a < i;++a)
			{
				if (abReferenced[a] && me == aiHashes[a]) {
					++redundantRemoved;
					me = 0;
					aiMappingTable[i] = aiMappingTable[a];
					delete pScene->mMaterials[i];
					break;
				}
			}
			// This is a new material that is referenced, add to the map.
			if (me)	{
				aiMappingTable[i] = iNewNum++;
			}
		}
		// If the new material count differs from the original,
		// we need to rebuild the material list and remap mesh material indexes.
		if (iNewNum != pScene->mNumMaterials) {
			aiMaterial** ppcMaterials = new aiMaterial*[iNewNum];
			::memset(ppcMaterials,0,sizeof(void*)*iNewNum); 
			for (unsigned int p = 0; p < pScene->mNumMaterials;++p)
			{
				// if the material is not referenced ... remove it
				if (!abReferenced[p]) {
					continue;
				}

				// generate new names for all modified materials
				const unsigned int idx = aiMappingTable[p]; 
				if (ppcMaterials[idx]) 
				{
					aiString sz;
					sz.length = ::sprintf(sz.data,"JoinedMaterial_#%u",p);
					((aiMaterial*)ppcMaterials[idx])->AddProperty(&sz,AI_MATKEY_NAME);
				}
				else
					ppcMaterials[idx] = pScene->mMaterials[p];
			}
			// update all material indices
			for (unsigned int p = 0; p < pScene->mNumMeshes;++p) {
				aiMesh* mesh = pScene->mMeshes[p];
				mesh->mMaterialIndex = aiMappingTable[mesh->mMaterialIndex];
			}
			// delete the old material list
			delete[] pScene->mMaterials;
			pScene->mMaterials = ppcMaterials;
			pScene->mNumMaterials = iNewNum;
		}
		// delete temporary storage
		delete[] aiHashes;
		delete[] aiMappingTable;
	}
	if (redundantRemoved == 0 && unreferencedRemoved == 0)
	{
		DefaultLogger::get()->debug("RemoveRedundantMatsProcess finished ");
	}
	else 
	{
		char szBuffer[128]; // should be sufficiently large
		::sprintf(szBuffer,"RemoveRedundantMatsProcess finished. Removed %u redundant and %u unused materials.",
			redundantRemoved,unreferencedRemoved);
		DefaultLogger::get()->info(szBuffer);
	}
}