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/** @file RemoveRedundantMaterials.cpp

 *  @brief Implementation of the "RemoveRedundantMaterials" post processing step

*/

// internal headers

#include "RemoveRedundantMaterials.h"

#include <assimp/ParsingUtils.h>

#include "ProcessHelper.h"

#include "Material/MaterialSystem.h"

#include <assimp/Exceptional.h>

#include <stdio.h>

using namespace Assimp;

// ------------------------------------------------------------------------------------------------

// Constructor to be privately used by Importer

RemoveRedundantMatsProcess::RemoveRedundantMatsProcess() : mConfigFixedMaterials() {}

// ------------------------------------------------------------------------------------------------

// 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

    mConfigFixedMaterials = pImp->GetPropertyString(AI_CONFIG_PP_RRM_EXCLUDE_LIST,"");

}

// ------------------------------------------------------------------------------------------------

// Executes the post processing step on the given imported data.

void RemoveRedundantMatsProcess::Execute( aiScene* pScene) {

    ASSIMP_LOG_DEBUG("RemoveRedundantMatsProcess begin");

    unsigned int redundantRemoved = 0, unreferencedRemoved = 0;

    if (pScene->mNumMaterials == 0) {

        return;

    }

    // 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 (mConfigFixedMaterials.length()) {

        std::list<std::string> strings;

        ConvertListToStrings(mConfigFixedMaterials,strings);

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

            aiMaterial* mat = pScene->mMaterials[i];

            ai_assert(mat != nullptr);

            aiString name;

            mat->Get(AI_MATKEY_NAME,name);

            if (name.length != 0) {

                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;

                    ASSIMP_LOG_VERBOSE_DEBUG( "Found positive match in exclusion list: \'", name.data, "\'");

                }

            }

        }

    }

    // TODO: re-implement this algorithm to work in-place

    unsigned int *aiMappingTable = new unsigned int[pScene->mNumMaterials];

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

        aiMappingTable[ i ] = 0;

    }

    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 = 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];

            pScene->mMaterials[i] = nullptr;

            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];

                pScene->mMaterials[i] = nullptr;

                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 < 1) {

        delete [] aiMappingTable;

        delete [] aiHashes;

        pScene->mNumMaterials = 0;

        return;

    }

    if (iNewNum != pScene->mNumMaterials) {

        ai_assert(iNewNum > 0);

        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 modified materials that had no names

            const unsigned int idx = aiMappingTable[p];

            if (ppcMaterials[idx]) {

                aiString sz;

                if( ppcMaterials[idx]->Get(AI_MATKEY_NAME, sz) != AI_SUCCESS ) {

                    sz.length = ::ai_snprintf(sz.data, AI_MAXLEN,"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];

            ai_assert(nullptr != mesh);

            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) {

        ASSIMP_LOG_DEBUG("RemoveRedundantMatsProcess finished ");

    } else {

        ASSIMP_LOG_INFO("RemoveRedundantMatsProcess finished. Removed ", redundantRemoved, " redundant and ",

            unreferencedRemoved, " unused materials.");

    }

}