/*
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Open Asset Import Library (assimp)
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*/


#ifndef ASSIMP_BUILD_NO_MD2_IMPORTER

/** @file Implementation of the MD2 importer class */
#include "MD2Loader.h"
#include <assimp/ByteSwapper.h>
#include "MD2NormalTable.h" // shouldn't be included by other units
#include <assimp/DefaultLogger.hpp>
#include <assimp/Importer.hpp>
#include <assimp/IOSystem.hpp>
#include <assimp/scene.h>
#include <assimp/importerdesc.h>
#include <assimp/StringUtils.h>

#include <memory>

using namespace Assimp;
using namespace Assimp::MD2;

// helper macro to determine the size of an array
#if (!defined ARRAYSIZE)
#   define ARRAYSIZE(_array) (int(sizeof(_array) / sizeof(_array[0])))
#endif

static const aiImporterDesc desc = {
    "Quake II Mesh Importer",
    "",
    "",
    "",
    aiImporterFlags_SupportBinaryFlavour,
    0,
    0,
    0,
    0,
    "md2"
};

// ------------------------------------------------------------------------------------------------
// Helper function to lookup a normal in Quake 2's precalculated table
void MD2::LookupNormalIndex(uint8_t iNormalIndex,aiVector3D& vOut)
{
    // make sure the normal index has a valid value
    if (iNormalIndex >= ARRAYSIZE(g_avNormals)) {
        ASSIMP_LOG_WARN("Index overflow in Quake II normal vector list");
        iNormalIndex = ARRAYSIZE(g_avNormals) - 1;
    }
    vOut = *((const aiVector3D*)(&g_avNormals[iNormalIndex]));
}


// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
MD2Importer::MD2Importer()
    : configFrameID(),
    m_pcHeader(),
    mBuffer(),
    fileSize()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
MD2Importer::~MD2Importer() = default;

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool MD2Importer::CanRead( const std::string& pFile, IOSystem* pIOHandler, bool /*checkSig*/) const
{
    static const uint32_t tokens[] = { AI_MD2_MAGIC_NUMBER_LE };
    return CheckMagicToken(pIOHandler,pFile,tokens,AI_COUNT_OF(tokens));
}

// ------------------------------------------------------------------------------------------------
// Get a list of all extensions supported by this loader
const aiImporterDesc* MD2Importer::GetInfo () const
{
    return &desc;
}

// ------------------------------------------------------------------------------------------------
// Setup configuration properties
void MD2Importer::SetupProperties(const Importer* pImp)
{
    // The
    // AI_CONFIG_IMPORT_MD2_KEYFRAME option overrides the
    // AI_CONFIG_IMPORT_GLOBAL_KEYFRAME option.
    configFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_MD2_KEYFRAME,-1);
    if(static_cast<unsigned int>(-1) == configFrameID){
        configFrameID = pImp->GetPropertyInteger(AI_CONFIG_IMPORT_GLOBAL_KEYFRAME,0);
    }
}
// ------------------------------------------------------------------------------------------------
// Validate the file header
void MD2Importer::ValidateHeader( )
{
    // check magic number
    if (m_pcHeader->magic != AI_MD2_MAGIC_NUMBER_BE &&
        m_pcHeader->magic != AI_MD2_MAGIC_NUMBER_LE)
    {
        throw DeadlyImportError("Invalid MD2 magic word: expected IDP2, found ",
                                ai_str_toprintable((char *)&m_pcHeader->magic, 4));
    }

    // check file format version
    if (m_pcHeader->version != 8)
        ASSIMP_LOG_WARN( "Unsupported MD2 file version. Continuing happily ...");

    // check some values whether they are valid
    if (0 == m_pcHeader->numFrames)
        throw DeadlyImportError( "Invalid MD2 file: NUM_FRAMES is 0");

    if (m_pcHeader->offsetEnd > (uint32_t)fileSize)
        throw DeadlyImportError( "Invalid MD2 file: File is too small");

    if (m_pcHeader->numSkins > AI_MAX_ALLOC(MD2::Skin)) {
        throw DeadlyImportError("Invalid MD2 header: Too many skins, would overflow");
    }

    if (m_pcHeader->numVertices > AI_MAX_ALLOC(MD2::Vertex)) {
        throw DeadlyImportError("Invalid MD2 header: Too many vertices, would overflow");
    }

    if (m_pcHeader->numTexCoords > AI_MAX_ALLOC(MD2::TexCoord)) {
        throw DeadlyImportError("Invalid MD2 header: Too many texcoords, would overflow");
    }

    if (m_pcHeader->numTriangles > AI_MAX_ALLOC(MD2::Triangle)) {
        throw DeadlyImportError("Invalid MD2 header: Too many triangles, would overflow");
    }

    if (m_pcHeader->numFrames > AI_MAX_ALLOC(MD2::Frame)) {
        throw DeadlyImportError("Invalid MD2 header: Too many frames, would overflow");
    }

    // -1 because Frame already contains one
    unsigned int frameSize = sizeof (MD2::Frame) + (m_pcHeader->numVertices - 1) * sizeof(MD2::Vertex);

    if (m_pcHeader->offsetSkins     + m_pcHeader->numSkins * sizeof (MD2::Skin)         >= fileSize ||
        m_pcHeader->offsetTexCoords + m_pcHeader->numTexCoords * sizeof (MD2::TexCoord) >= fileSize ||
        m_pcHeader->offsetTriangles + m_pcHeader->numTriangles * sizeof (MD2::Triangle) >= fileSize ||
        m_pcHeader->offsetFrames    + m_pcHeader->numFrames * frameSize                 >= fileSize ||
        m_pcHeader->offsetEnd           > fileSize)
    {
        throw DeadlyImportError("Invalid MD2 header: Some offsets are outside the file");
    }

    if (m_pcHeader->numSkins > AI_MD2_MAX_SKINS)
        ASSIMP_LOG_WARN("The model contains more skins than Quake 2 supports");
    if ( m_pcHeader->numFrames > AI_MD2_MAX_FRAMES)
        ASSIMP_LOG_WARN("The model contains more frames than Quake 2 supports");
    if (m_pcHeader->numVertices > AI_MD2_MAX_VERTS)
        ASSIMP_LOG_WARN("The model contains more vertices than Quake 2 supports");

    if (m_pcHeader->numFrames <= configFrameID )
        throw DeadlyImportError("MD2: The requested frame (", configFrameID, ") does not exist in the file");
}

// ------------------------------------------------------------------------------------------------
// Imports the given file into the given scene structure.
void MD2Importer::InternReadFile( const std::string& pFile,
    aiScene* pScene, IOSystem* pIOHandler)
{
    std::unique_ptr<IOStream> file( pIOHandler->Open( pFile));

    // Check whether we can read from the file
    if (file.get() == nullptr) {
        throw DeadlyImportError("Failed to open MD2 file ", pFile, "");
    }

    // check whether the md3 file is large enough to contain
    // at least the file header
    fileSize = (unsigned int)file->FileSize();
    if (fileSize < sizeof(MD2::Header)) {
        throw DeadlyImportError("MD2 File is too small");
    }

    std::vector<uint8_t> mBuffer2(fileSize);
    file->Read(&mBuffer2[0], 1, fileSize);
    mBuffer = &mBuffer2[0];

    m_pcHeader = (BE_NCONST MD2::Header*)mBuffer;

#ifdef AI_BUILD_BIG_ENDIAN

    ByteSwap::Swap4(&m_pcHeader->frameSize);
    ByteSwap::Swap4(&m_pcHeader->magic);
    ByteSwap::Swap4(&m_pcHeader->numFrames);
    ByteSwap::Swap4(&m_pcHeader->numGlCommands);
    ByteSwap::Swap4(&m_pcHeader->numSkins);
    ByteSwap::Swap4(&m_pcHeader->numTexCoords);
    ByteSwap::Swap4(&m_pcHeader->numTriangles);
    ByteSwap::Swap4(&m_pcHeader->numVertices);
    ByteSwap::Swap4(&m_pcHeader->offsetEnd);
    ByteSwap::Swap4(&m_pcHeader->offsetFrames);
    ByteSwap::Swap4(&m_pcHeader->offsetGlCommands);
    ByteSwap::Swap4(&m_pcHeader->offsetSkins);
    ByteSwap::Swap4(&m_pcHeader->offsetTexCoords);
    ByteSwap::Swap4(&m_pcHeader->offsetTriangles);
    ByteSwap::Swap4(&m_pcHeader->skinHeight);
    ByteSwap::Swap4(&m_pcHeader->skinWidth);
    ByteSwap::Swap4(&m_pcHeader->version);

#endif

    ValidateHeader();

    // there won't be more than one mesh inside the file
    pScene->mNumMaterials = 1;
    pScene->mRootNode = new aiNode();
    pScene->mRootNode->mNumMeshes = 1;
    pScene->mRootNode->mMeshes = new unsigned int[1];
    pScene->mRootNode->mMeshes[0] = 0;
    pScene->mMaterials = new aiMaterial*[1];
    pScene->mMaterials[0] = new aiMaterial();
    pScene->mNumMeshes = 1;
    pScene->mMeshes = new aiMesh*[1];

    aiMesh* pcMesh = pScene->mMeshes[0] = new aiMesh();
    pcMesh->mPrimitiveTypes = aiPrimitiveType_TRIANGLE;

    // navigate to the begin of the current frame data
	BE_NCONST MD2::Frame* pcFrame = (BE_NCONST MD2::Frame*) ((uint8_t*)
		m_pcHeader + m_pcHeader->offsetFrames + (m_pcHeader->frameSize * configFrameID));

    // navigate to the begin of the triangle data
    MD2::Triangle* pcTriangles = (MD2::Triangle*) ((uint8_t*)
        m_pcHeader + m_pcHeader->offsetTriangles);

    // navigate to the begin of the tex coords data
    BE_NCONST MD2::TexCoord* pcTexCoords = (BE_NCONST MD2::TexCoord*) ((uint8_t*)
        m_pcHeader + m_pcHeader->offsetTexCoords);

    // navigate to the begin of the vertex data
    BE_NCONST MD2::Vertex* pcVerts = (BE_NCONST MD2::Vertex*) (pcFrame->vertices);

#ifdef AI_BUILD_BIG_ENDIAN
    for (uint32_t i = 0; i< m_pcHeader->numTriangles; ++i)
    {
        for (unsigned int p = 0; p < 3;++p)
        {
            ByteSwap::Swap2(& pcTriangles[i].textureIndices[p]);
            ByteSwap::Swap2(& pcTriangles[i].vertexIndices[p]);
        }
    }
    for (uint32_t i = 0; i < m_pcHeader->offsetTexCoords;++i)
    {
        ByteSwap::Swap2(& pcTexCoords[i].s);
        ByteSwap::Swap2(& pcTexCoords[i].t);
    }
    ByteSwap::Swap4( & pcFrame->scale[0] );
    ByteSwap::Swap4( & pcFrame->scale[1] );
    ByteSwap::Swap4( & pcFrame->scale[2] );
    ByteSwap::Swap4( & pcFrame->translate[0] );
    ByteSwap::Swap4( & pcFrame->translate[1] );
    ByteSwap::Swap4( & pcFrame->translate[2] );
#endif

    pcMesh->mNumFaces = m_pcHeader->numTriangles;
    pcMesh->mFaces = new aiFace[m_pcHeader->numTriangles];

    // allocate output storage
    pcMesh->mNumVertices = (unsigned int)pcMesh->mNumFaces*3;
    pcMesh->mVertices = new aiVector3D[pcMesh->mNumVertices];
    pcMesh->mNormals = new aiVector3D[pcMesh->mNumVertices];

    // Not sure whether there are MD2 files without texture coordinates
    // NOTE: texture coordinates can be there without a texture,
    // but a texture can't be there without a valid UV channel
    aiMaterial* pcHelper = (aiMaterial*)pScene->mMaterials[0];
    const int iMode = (int)aiShadingMode_Gouraud;
    pcHelper->AddProperty<int>(&iMode, 1, AI_MATKEY_SHADING_MODEL);

    if (m_pcHeader->numTexCoords && m_pcHeader->numSkins)
    {
        // navigate to the first texture associated with the mesh
        const MD2::Skin* pcSkins = (const MD2::Skin*) ((unsigned char*)m_pcHeader +
            m_pcHeader->offsetSkins);

        aiColor3D clr;
        clr.b = clr.g = clr.r = 1.0f;
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_DIFFUSE);
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_SPECULAR);

        clr.b = clr.g = clr.r = 0.05f;
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_AMBIENT);

        if (pcSkins->name[0])
        {
            aiString szString;
            const ai_uint32 iLen = (ai_uint32) ::strlen(pcSkins->name);
            ::memcpy(szString.data,pcSkins->name,iLen);
            szString.data[iLen] = '\0';
            szString.length = iLen;

            pcHelper->AddProperty(&szString,AI_MATKEY_TEXTURE_DIFFUSE(0));
        }
        else{
            ASSIMP_LOG_WARN("Texture file name has zero length. It will be skipped.");
        }
    }
    else    {
        // apply a default material
        aiColor3D clr;
        clr.b = clr.g = clr.r = 0.6f;
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_DIFFUSE);
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_SPECULAR);

        clr.b = clr.g = clr.r = 0.05f;
        pcHelper->AddProperty<aiColor3D>(&clr, 1,AI_MATKEY_COLOR_AMBIENT);

        aiString szName;
        szName.Set(AI_DEFAULT_MATERIAL_NAME);
        pcHelper->AddProperty(&szName,AI_MATKEY_NAME);

        aiString sz;

        // TODO: Try to guess the name of the texture file from the model file name

        sz.Set("$texture_dummy.bmp");
        pcHelper->AddProperty(&sz,AI_MATKEY_TEXTURE_DIFFUSE(0));
    }


    // now read all triangles of the first frame, apply scaling and translation
    unsigned int iCurrent = 0;

    float fDivisorU = 1.0f,fDivisorV = 1.0f;
    if (m_pcHeader->numTexCoords)   {
        // allocate storage for texture coordinates, too
        pcMesh->mTextureCoords[0] = new aiVector3D[pcMesh->mNumVertices];
        pcMesh->mNumUVComponents[0] = 2;

        // check whether the skin width or height are zero (this would
        // cause a division through zero)
        if (!m_pcHeader->skinWidth) {
            ASSIMP_LOG_ERROR("MD2: No valid skin width given");
        }
        else fDivisorU = (float)m_pcHeader->skinWidth;
        if (!m_pcHeader->skinHeight){
            ASSIMP_LOG_ERROR("MD2: No valid skin height given");
        }
        else fDivisorV = (float)m_pcHeader->skinHeight;
    }

    for (unsigned int i = 0; i < (unsigned int)m_pcHeader->numTriangles;++i)    {
        // Allocate the face
        pScene->mMeshes[0]->mFaces[i].mIndices = new unsigned int[3];
        pScene->mMeshes[0]->mFaces[i].mNumIndices = 3;

        // copy texture coordinates
        // check whether they are different from the previous value at this index.
        // In this case, create a full separate set of vertices/normals/texcoords
        for (unsigned int c = 0; c < 3;++c,++iCurrent)  {

            // validate vertex indices
            unsigned int iIndex = (unsigned int)pcTriangles[i].vertexIndices[c];
            if (iIndex >= m_pcHeader->numVertices)  {
                ASSIMP_LOG_ERROR("MD2: Vertex index is outside the allowed range");
                iIndex = m_pcHeader->numVertices-1;
            }

            // read x,y, and z component of the vertex
            aiVector3D& vec = pcMesh->mVertices[iCurrent];

            vec.x = (float)pcVerts[iIndex].vertex[0] * pcFrame->scale[0];
            vec.x += pcFrame->translate[0];

            vec.y = (float)pcVerts[iIndex].vertex[1] * pcFrame->scale[1];
            vec.y += pcFrame->translate[1];

            vec.z = (float)pcVerts[iIndex].vertex[2] * pcFrame->scale[2];
            vec.z += pcFrame->translate[2];

            // read the normal vector from the precalculated normal table
            aiVector3D& vNormal = pcMesh->mNormals[iCurrent];
            LookupNormalIndex(pcVerts[iIndex].lightNormalIndex,vNormal);

            if (m_pcHeader->numTexCoords)   {
                // validate texture coordinates
                iIndex = pcTriangles[i].textureIndices[c];
                if (iIndex >= m_pcHeader->numTexCoords) {
                    ASSIMP_LOG_ERROR("MD2: UV index is outside the allowed range");
                    iIndex = m_pcHeader->numTexCoords-1;
                }

                aiVector3D& pcOut = pcMesh->mTextureCoords[0][iCurrent];

                // the texture coordinates are absolute values but we
                // need relative values between 0 and 1
                pcOut.x = pcTexCoords[iIndex].s / fDivisorU;
                pcOut.y = 1.f-pcTexCoords[iIndex].t / fDivisorV;
            }
            pScene->mMeshes[0]->mFaces[i].mIndices[c] = iCurrent;
        }
        // flip the face order
        std::swap( pScene->mMeshes[0]->mFaces[i].mIndices[0], pScene->mMeshes[0]->mFaces[i].mIndices[2] );
    }
    // Now rotate the whole scene 90 degrees around the x axis to convert to internal coordinate system
    pScene->mRootNode->mTransformation = aiMatrix4x4(
            1.f, 0.f, 0.f, 0.f,
            0.f, 0.f, 1.f, 0.f,
            0.f, -1.f, 0.f, 0.f,
            0.f, 0.f, 0.f, 1.f);
}

#endif // !! ASSIMP_BUILD_NO_MD2_IMPORTER
