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/** @file  CSMLoader.cpp
 *  Implementation of the CSM importer class.
 */
#ifndef ASSIMP_BUILD_NO_CSM_IMPORTER

#include "CSMLoader.h"
#include <assimp/SkeletonMeshBuilder.h>
#include <assimp/ParsingUtils.h>
#include <assimp/fast_atof.h>
#include <assimp/Importer.hpp>
#include <memory>
#include <assimp/IOSystem.hpp>
#include <assimp/anim.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/scene.h>
#include <assimp/importerdesc.h>

using namespace Assimp;

static constexpr aiImporterDesc desc = {
    "CharacterStudio Motion Importer (MoCap)",
    "",
    "",
    "",
    aiImporterFlags_SupportTextFlavour,
    0,
    0,
    0,
    0,
    "csm"
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
CSMImporter::CSMImporter() : noSkeletonMesh() {
    // empty
}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool CSMImporter::CanRead( const std::string& pFile, IOSystem* pIOHandler, bool /*checkSig*/) const {
    static const char* tokens[] = {"$Filename"};
    return SearchFileHeaderForToken(pIOHandler,pFile,tokens,AI_COUNT_OF(tokens));
}

// ------------------------------------------------------------------------------------------------
// Build a string of all file extensions supported
const aiImporterDesc* CSMImporter::GetInfo () const {
    return &desc;
}

// ------------------------------------------------------------------------------------------------
// Setup configuration properties for the loader
void CSMImporter::SetupProperties(const Importer* pImp) {
    noSkeletonMesh = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_NO_SKELETON_MESHES,0) != 0;
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void CSMImporter::InternReadFile( const std::string& pFile,
        aiScene* pScene, IOSystem* pIOHandler) {
    std::unique_ptr<IOStream> file( pIOHandler->Open( pFile, "rb"));

    // Check whether we can read from the file
    if (file == nullptr) {
        throw DeadlyImportError( "Failed to open CSM file ", pFile, ".");
    }

    // allocate storage and copy the contents of the file to a memory buffer
    std::vector<char> mBuffer2;
    TextFileToBuffer(file.get(),mBuffer2);
    const char* buffer = &mBuffer2[0];
    const char *end = &mBuffer2[mBuffer2.size() - 1] + 1;
    std::unique_ptr<aiAnimation> anim(new aiAnimation());
    int first = 0, last = 0x00ffffff;

    // now process the file and look out for '$' sections
    while (true) {
        SkipSpaces(&buffer, end);
        if ('\0' == *buffer) {
            break;
        }

        if ('$'  == *buffer) {
            ++buffer;
            if (TokenMatchI(buffer,"firstframe",10)) {
                SkipSpaces(&buffer, end);
                first = strtol10(buffer,&buffer);
            }
            else if (TokenMatchI(buffer,"lastframe",9)) {
                SkipSpaces(&buffer, end);
                last = strtol10(buffer,&buffer);
            }
            else if (TokenMatchI(buffer,"rate",4))  {
                SkipSpaces(&buffer, end);
                float d = { 0.0f };
                buffer = fast_atoreal_move(buffer,d);
                anim->mTicksPerSecond = d;
            }
            else if (TokenMatchI(buffer,"order",5)) {
                std::vector< aiNodeAnim* > anims_temp;
                anims_temp.reserve(30);
                while (true) {
                    SkipSpaces(&buffer, end);
                    if (IsLineEnd(*buffer) && SkipSpacesAndLineEnd(&buffer, end) && *buffer == '$')
                        break; // next section

                    // Construct a new node animation channel and setup its name
                    anims_temp.push_back(new aiNodeAnim());
                    aiNodeAnim* nda = anims_temp.back();

                    char *ot = nda->mNodeName.data;
                    const char *ot_end = nda->mNodeName.data + AI_MAXLEN;
                    while (!IsSpaceOrNewLine(*buffer) && buffer != end && ot != ot_end) {
                        *ot++ = *buffer++;
                    }

                    *ot = '\0';
                    nda->mNodeName.length = static_cast<ai_uint32>(ot-nda->mNodeName.data);
                }

                anim->mNumChannels = static_cast<unsigned int>(anims_temp.size());
                if (!anim->mNumChannels) {
                    throw DeadlyImportError("CSM: Empty $order section");
                }

                // copy over to the output animation
                anim->mChannels = new aiNodeAnim*[anim->mNumChannels];
                ::memcpy(anim->mChannels,&anims_temp[0],sizeof(aiNodeAnim*)*anim->mNumChannels);
            } else if (TokenMatchI(buffer,"points",6)) {
                if (!anim->mNumChannels) {
                    throw DeadlyImportError("CSM: \'$order\' section is required to appear prior to \'$points\'");
                }

                // If we know how many frames we'll read, we can preallocate some storage
                unsigned int alloc = 100;
                if (last != 0x00ffffff) {
                    // re-init if the file has last frame data
                    alloc = last-first;
                    alloc += alloc>>2u; // + 25%
                    for (unsigned int i = 0; i < anim->mNumChannels; ++i) {
                        if (anim->mChannels[i]->mPositionKeys != nullptr) delete[] anim->mChannels[i]->mPositionKeys;
                        anim->mChannels[i]->mPositionKeys = new aiVectorKey[alloc];
                    }
                } else {
                    // default init
                    for (unsigned int i = 0; i < anim->mNumChannels; ++i) {
                        if (anim->mChannels[i]->mPositionKeys != nullptr) continue;
                        anim->mChannels[i]->mPositionKeys = new aiVectorKey[alloc];
                    }
                }

                unsigned int filled = 0;

                // Now read all point data.
                while (true) {
                    SkipSpaces(&buffer, end);
                    if (IsLineEnd(*buffer) && (!SkipSpacesAndLineEnd(&buffer, end) || *buffer == '$'))   {
                        break; // next section
                    }

                    // read frame
                    const int frame = ::strtoul10(buffer,&buffer);
                    last  = std::max(frame,last);
                    first = std::min(frame,last);
                    for (unsigned int i = 0; i < anim->mNumChannels;++i)    {

                        aiNodeAnim* s = anim->mChannels[i];
                        if (s->mNumPositionKeys == alloc)   {
                            // need to reallocate?
                            aiVectorKey* old = s->mPositionKeys;
                            s->mPositionKeys = new aiVectorKey[alloc*2];
                            ::memcpy(s->mPositionKeys,old,sizeof(aiVectorKey)*alloc);
                            delete[] old;
                        }

                        // read x,y,z
                        if (!SkipSpacesAndLineEnd(&buffer, end)) {
                            throw DeadlyImportError("CSM: Unexpected EOF occurred reading sample x coord");
                        }

                        if (TokenMatchI(buffer, "DROPOUT", 7))  {
                            // seems this is invalid marker data; at least the doc says it's possible
                            ASSIMP_LOG_WARN("CSM: Encountered invalid marker data (DROPOUT)");
                        } else {
                            aiVectorKey* sub = s->mPositionKeys + s->mNumPositionKeys;
                            sub->mTime = (double)frame;
                            buffer = fast_atoreal_move(buffer, sub->mValue.x);

                            if (!SkipSpacesAndLineEnd(&buffer, end)) {
                                throw DeadlyImportError("CSM: Unexpected EOF occurred reading sample y coord");
                            }
                            buffer = fast_atoreal_move(buffer, sub->mValue.y);

                            if (!SkipSpacesAndLineEnd(&buffer, end)) {
                                throw DeadlyImportError("CSM: Unexpected EOF occurred reading sample z coord");
                            }
                            buffer = fast_atoreal_move(buffer, sub->mValue.z);

                            ++s->mNumPositionKeys;
                        }
                    }

                    // update allocation granularity
                    if (filled == alloc) {
                        alloc *= 2;
                    }

                    ++filled;
                }
                // all channels must be complete in order to continue safely.
                for (unsigned int i = 0; i < anim->mNumChannels;++i)    {
                    if (!anim->mChannels[i]->mNumPositionKeys) {
                        throw DeadlyImportError("CSM: Invalid marker track");
                    }
                }
            }
        } else {
            // advance to the next line
            SkipLine(&buffer, end);
        }
    }

    // Setup a proper animation duration
    anim->mDuration = last - std::min( first, 0 );

    // build a dummy root node with the tiny markers as children
    pScene->mRootNode = new aiNode();
    pScene->mRootNode->mName.Set("$CSM_DummyRoot");

    pScene->mRootNode->mNumChildren = anim->mNumChannels;
    pScene->mRootNode->mChildren = new aiNode* [anim->mNumChannels];

    for (unsigned int i = 0; i < anim->mNumChannels;++i) {
        aiNodeAnim* na = anim->mChannels[i];

        aiNode* nd  = pScene->mRootNode->mChildren[i] = new aiNode();
        nd->mName   = anim->mChannels[i]->mNodeName;
        nd->mParent = pScene->mRootNode;

        if (na->mPositionKeys != nullptr && na->mNumPositionKeys > 0) {
            aiMatrix4x4::Translation(na->mPositionKeys[0].mValue, nd->mTransformation);
        } else {
            // Use identity matrix if no valid position data is available
            nd->mTransformation = aiMatrix4x4();
            DefaultLogger::get()->warn("CSM: No position keys available for node - using identity transformation");
        }
    }

    // Store the one and only animation in the scene
    pScene->mAnimations    = new aiAnimation*[pScene->mNumAnimations=1];
    anim->mName.Set("$CSM_MasterAnim");
    pScene->mAnimations[0] = anim.release();

    // mark the scene as incomplete and run SkeletonMeshBuilder on it
    pScene->mFlags |= AI_SCENE_FLAGS_INCOMPLETE;

    if (!noSkeletonMesh) {
        SkeletonMeshBuilder maker(pScene,pScene->mRootNode,true);
    }
}

#endif // !! ASSIMP_BUILD_NO_CSM_IMPORTER
