/*
---------------------------------------------------------------------------
Open Asset Import Library (assimp)
---------------------------------------------------------------------------

Copyright (c) 2006-2017, assimp team


All rights reserved.

Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the following
conditions are met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
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* Neither the name of the assimp team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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---------------------------------------------------------------------------
*/

/** @file  DXFLoader.cpp
 *  @brief Implementation of the DXF importer class
 */


#ifndef ASSIMP_BUILD_NO_DXF_IMPORTER

#include "DXFLoader.h"
#include "ParsingUtils.h"
#include "ConvertToLHProcess.h"
#include "fast_atof.h"

#include "DXFHelper.h"
#include <assimp/IOSystem.hpp>
#include <assimp/scene.h>
#include <assimp/importerdesc.h>

#include <numeric>

using namespace Assimp;

// AutoCAD Binary DXF<CR><LF><SUB><NULL>
#define AI_DXF_BINARY_IDENT ("AutoCAD Binary DXF\r\n\x1a\0")
#define AI_DXF_BINARY_IDENT_LEN (24)

// default vertex color that all uncolored vertices will receive
#define AI_DXF_DEFAULT_COLOR aiColor4D(0.6f,0.6f,0.6f,0.6f)

// color indices for DXF - 16 are supported, the table is
// taken directly from the DXF spec.
static aiColor4D g_aclrDxfIndexColors[] =
{
    aiColor4D (0.6f, 0.6f, 0.6f, 1.0f),
    aiColor4D (1.0f, 0.0f, 0.0f, 1.0f), // red
    aiColor4D (0.0f, 1.0f, 0.0f, 1.0f), // green
    aiColor4D (0.0f, 0.0f, 1.0f, 1.0f), // blue
    aiColor4D (0.3f, 1.0f, 0.3f, 1.0f), // light green
    aiColor4D (0.3f, 0.3f, 1.0f, 1.0f), // light blue
    aiColor4D (1.0f, 0.3f, 0.3f, 1.0f), // light red
    aiColor4D (1.0f, 0.0f, 1.0f, 1.0f), // pink
    aiColor4D (1.0f, 0.6f, 0.0f, 1.0f), // orange
    aiColor4D (0.6f, 0.3f, 0.0f, 1.0f), // dark orange
    aiColor4D (1.0f, 1.0f, 0.0f, 1.0f), // yellow
    aiColor4D (0.3f, 0.3f, 0.3f, 1.0f), // dark gray
    aiColor4D (0.8f, 0.8f, 0.8f, 1.0f), // light gray
    aiColor4D (0.0f, 00.f, 0.0f, 1.0f), // black
    aiColor4D (1.0f, 1.0f, 1.0f, 1.0f), // white
    aiColor4D (0.6f, 0.0f, 1.0f, 1.0f)  // violet
};
#define AI_DXF_NUM_INDEX_COLORS (sizeof(g_aclrDxfIndexColors)/sizeof(g_aclrDxfIndexColors[0]))
#define AI_DXF_ENTITIES_MAGIC_BLOCK "$ASSIMP_ENTITIES_MAGIC"


static const aiImporterDesc desc = {
    "Drawing Interchange Format (DXF) Importer",
    "",
    "",
    "",
    aiImporterFlags_SupportTextFlavour | aiImporterFlags_LimitedSupport,
    0,
    0,
    0,
    0,
    "dxf"
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
DXFImporter::DXFImporter()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
DXFImporter::~DXFImporter()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the class can handle the format of the given file.
bool DXFImporter::CanRead( const std::string& pFile, IOSystem* /*pIOHandler*/, bool /*checkSig*/) const
{
    return SimpleExtensionCheck(pFile,"dxf");
}

// ------------------------------------------------------------------------------------------------
// Get a list of all supported file extensions
const aiImporterDesc* DXFImporter::GetInfo () const
{
    return &desc;
}

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

    // Check whether we can read the file
    if( file.get() == NULL) {
        throw DeadlyImportError( "Failed to open DXF file " + pFile + "");
    }

    // check whether this is a binaray DXF file - we can't read binary DXF files :-(
    char buff[AI_DXF_BINARY_IDENT_LEN+1] = {0};
    file->Read(buff,AI_DXF_BINARY_IDENT_LEN,1);

    if (!strncmp(AI_DXF_BINARY_IDENT,buff,AI_DXF_BINARY_IDENT_LEN)) {
        throw DeadlyImportError("DXF: Binary files are not supported at the moment");
    }

    // DXF files can grow very large, so read them via the StreamReader,
    // which will choose a suitable strategy.
    file->Seek(0,aiOrigin_SET);
    StreamReaderLE stream( file );

    DXF::LineReader reader (stream);
    DXF::FileData output;

    // now get all lines of the file and process top-level sections
    bool eof = false;
    while(!reader.End()) {

        // blocks table - these 'build blocks' are later (in ENTITIES)
        // referenced an included via INSERT statements.
        if (reader.Is(2,"BLOCKS")) {
            ParseBlocks(reader,output);
            continue;
        }

        // primary entity table
        if (reader.Is(2,"ENTITIES")) {
            ParseEntities(reader,output);
            continue;
        }

        // skip unneeded sections entirely to avoid any problems with them
        // altogether.
        else if (reader.Is(2,"CLASSES") || reader.Is(2,"TABLES")) {
            SkipSection(reader);
            continue;
        }

        else if (reader.Is(2,"HEADER")) {
            ParseHeader(reader,output);
            continue;
        }

        // comments
        else if (reader.Is(999)) {
            DefaultLogger::get()->info("DXF Comment: " + reader.Value());
        }

        // don't read past the official EOF sign
        else if (reader.Is(0,"EOF")) {
            eof = true;
            break;
        }

        ++reader;
    }
    if (!eof) {
        DefaultLogger::get()->warn("DXF: EOF reached, but did not encounter DXF EOF marker");
    }

    ConvertMeshes(pScene,output);

    // Now rotate the whole scene by 90 degrees around the x axis to convert from AutoCAD's to Assimp's 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) * pScene->mRootNode->mTransformation;
}

// ------------------------------------------------------------------------------------------------
void DXFImporter::ConvertMeshes(aiScene* pScene, DXF::FileData& output)
{
    // the process of resolving all the INSERT statements can grow the
    // polycount excessively, so log the original number.
    // XXX Option to import blocks as separate nodes?
    if (!DefaultLogger::isNullLogger()) {

        unsigned int vcount = 0, icount = 0;
        for (const DXF::Block& bl : output.blocks) {
            for (std::shared_ptr<const DXF::PolyLine> pl : bl.lines) {
                vcount += static_cast<unsigned int>(pl->positions.size());
                icount += static_cast<unsigned int>(pl->counts.size());
            }
        }

        DefaultLogger::get()->debug((Formatter::format("DXF: Unexpanded polycount is "),
            icount,", vertex count is ",vcount
        ));
    }

    if (! output.blocks.size()  ) {
        throw DeadlyImportError("DXF: no data blocks loaded");
    }

    DXF::Block* entities = 0;

    // index blocks by name
    DXF::BlockMap blocks_by_name;
    for (DXF::Block& bl : output.blocks) {
        blocks_by_name[bl.name] = &bl;
        if ( !entities && bl.name == AI_DXF_ENTITIES_MAGIC_BLOCK ) {
            entities = &bl;
        }
    }

    if (!entities) {
        throw DeadlyImportError("DXF: no ENTITIES data block loaded");
    }

    typedef std::map<std::string, unsigned int> LayerMap;

    LayerMap layers;
    std::vector< std::vector< const DXF::PolyLine*> > corr;

    // now expand all block references in the primary ENTITIES block
    // XXX this involves heavy memory copying, consider a faster solution for future versions.
    ExpandBlockReferences(*entities,blocks_by_name);

    unsigned int cur = 0;
    for (std::shared_ptr<const DXF::PolyLine> pl : entities->lines) {
        if (pl->positions.size()) {

            std::map<std::string, unsigned int>::iterator it = layers.find(pl->layer);
            if (it == layers.end()) {
                ++pScene->mNumMeshes;

                layers[pl->layer] = cur++;

                std::vector< const DXF::PolyLine* > pv;
                pv.push_back(&*pl);

                corr.push_back(pv);
            }
            else {
                corr[(*it).second].push_back(&*pl);
            }
        }
    }

    if (!pScene->mNumMeshes) {
        throw DeadlyImportError("DXF: this file contains no 3d data");
    }

    pScene->mMeshes = new aiMesh*[ pScene->mNumMeshes ] ();

    for(const LayerMap::value_type& elem : layers){
        aiMesh* const mesh =  pScene->mMeshes[elem.second] = new aiMesh();
        mesh->mName.Set(elem.first);

        unsigned int cvert = 0,cface = 0;
        for(const DXF::PolyLine* pl : corr[elem.second]){
            // sum over all faces since we need to 'verbosify' them.
            cvert += std::accumulate(pl->counts.begin(),pl->counts.end(),0);
            cface += static_cast<unsigned int>(pl->counts.size());
        }

        aiVector3D* verts = mesh->mVertices = new aiVector3D[cvert];
        aiColor4D* colors = mesh->mColors[0] = new aiColor4D[cvert];
        aiFace* faces = mesh->mFaces = new aiFace[cface];

        mesh->mNumVertices = cvert;
        mesh->mNumFaces = cface;

        unsigned int prims = 0;
        unsigned int overall_indices = 0;
        for(const DXF::PolyLine* pl : corr[elem.second]){

            std::vector<unsigned int>::const_iterator it = pl->indices.begin();
            for(unsigned int facenumv : pl->counts) {
                aiFace& face = *faces++;
                face.mIndices = new unsigned int[face.mNumIndices = facenumv];

                for (unsigned int i = 0; i < facenumv; ++i) {
                    face.mIndices[i] = overall_indices++;

                    ai_assert(pl->positions.size() == pl->colors.size());
                    if (*it >= pl->positions.size()) {
                        throw DeadlyImportError("DXF: vertex index out of bounds");
                    }

                    *verts++ = pl->positions[*it];
                    *colors++ = pl->colors[*it++];
                }

                // set primitive flags now, this saves the extra pass in ScenePreprocessor.
                switch(face.mNumIndices) {
                    case 1:
                        prims |= aiPrimitiveType_POINT;
                        break;
                    case 2:
                        prims |= aiPrimitiveType_LINE;
                        break;
                    case 3:
                        prims |= aiPrimitiveType_TRIANGLE;
                        break;
                    default:
                        prims |= aiPrimitiveType_POLYGON;
                        break;
                }
            }
        }

        mesh->mPrimitiveTypes = prims;
        mesh->mMaterialIndex = 0;
    }

    GenerateHierarchy(pScene,output);
    GenerateMaterials(pScene,output);
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::ExpandBlockReferences(DXF::Block& bl,const DXF::BlockMap& blocks_by_name)
{
    for (const DXF::InsertBlock& insert : bl.insertions) {

        // first check if the referenced blocks exists ...
        const DXF::BlockMap::const_iterator it = blocks_by_name.find(insert.name);
        if (it == blocks_by_name.end()) {
            DefaultLogger::get()->error((Formatter::format("DXF: Failed to resolve block reference: "),
                insert.name,"; skipping"
            ));
            continue;
        }

        // XXX this would be the place to implement recursive expansion if needed.
        const DXF::Block& bl_src = *(*it).second;

        for (std::shared_ptr<const DXF::PolyLine> pl_in : bl_src.lines) {
            std::shared_ptr<DXF::PolyLine> pl_out = std::shared_ptr<DXF::PolyLine>(new DXF::PolyLine(*pl_in));

            if (bl_src.base.Length() || insert.scale.x!=1.f || insert.scale.y!=1.f || insert.scale.z!=1.f || insert.angle || insert.pos.Length()) {
                // manual coordinate system transformation
                // XXX order
                aiMatrix4x4 trafo, tmp;
                aiMatrix4x4::Translation(-bl_src.base,trafo);
                trafo *= aiMatrix4x4::Scaling(insert.scale,tmp);
                trafo *= aiMatrix4x4::Translation(insert.pos,tmp);

                // XXX rotation currently ignored - I didn't find an appropriate sample model.
                if (insert.angle != 0.f) {
                    DefaultLogger::get()->warn("DXF: BLOCK rotation not currently implemented");
                }

                for (aiVector3D& v : pl_out->positions) {
                    v *= trafo;
                }
            }

            bl.lines.push_back(pl_out);
        }
    }
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::GenerateMaterials(aiScene* pScene, DXF::FileData& /*output*/)
{
    // generate an almost-white default material. Reason:
    // the default vertex color is GREY, so we are
    // already at Assimp's usual default color.
    // generate a default material
    aiMaterial* pcMat = new aiMaterial();
    aiString s;
    s.Set(AI_DEFAULT_MATERIAL_NAME);
    pcMat->AddProperty(&s, AI_MATKEY_NAME);

    aiColor4D clrDiffuse(0.9f,0.9f,0.9f,1.0f);
    pcMat->AddProperty(&clrDiffuse,1,AI_MATKEY_COLOR_DIFFUSE);

    clrDiffuse = aiColor4D(1.0f,1.0f,1.0f,1.0f);
    pcMat->AddProperty(&clrDiffuse,1,AI_MATKEY_COLOR_SPECULAR);

    clrDiffuse = aiColor4D(0.05f,0.05f,0.05f,1.0f);
    pcMat->AddProperty(&clrDiffuse,1,AI_MATKEY_COLOR_AMBIENT);

    pScene->mNumMaterials = 1;
    pScene->mMaterials = new aiMaterial*[1];
    pScene->mMaterials[0] = pcMat;
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::GenerateHierarchy(aiScene* pScene, DXF::FileData& /*output*/)
{
    // generate the output scene graph, which is just the root node with a single child for each layer.
    pScene->mRootNode = new aiNode();
    pScene->mRootNode->mName.Set("<DXF_ROOT>");

    if (1 == pScene->mNumMeshes)    {
        pScene->mRootNode->mMeshes = new unsigned int[ pScene->mRootNode->mNumMeshes = 1 ];
        pScene->mRootNode->mMeshes[0] = 0;
    }
    else
    {
        pScene->mRootNode->mChildren = new aiNode*[ pScene->mRootNode->mNumChildren = pScene->mNumMeshes ];
        for (unsigned int m = 0; m < pScene->mRootNode->mNumChildren;++m)   {
            aiNode* p = pScene->mRootNode->mChildren[m] = new aiNode();
            p->mName = pScene->mMeshes[m]->mName;

            p->mMeshes = new unsigned int[p->mNumMeshes = 1];
            p->mMeshes[0] = m;
            p->mParent = pScene->mRootNode;
        }
    }
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::SkipSection(DXF::LineReader& reader)
{
    for( ;!reader.End() && !reader.Is(0,"ENDSEC"); reader++);
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::ParseHeader(DXF::LineReader& reader, DXF::FileData& /*output*/)
{
    for( ;!reader.End() && !reader.Is(0,"ENDSEC"); reader++);
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::ParseBlocks(DXF::LineReader& reader, DXF::FileData& output)
{
    while( !reader.End() && !reader.Is(0,"ENDSEC")) {
        if (reader.Is(0,"BLOCK")) {
            ParseBlock(++reader,output);
            continue;
        }
        ++reader;
    }

    DefaultLogger::get()->debug((Formatter::format("DXF: got "),
        output.blocks.size()," entries in BLOCKS"
    ));
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::ParseBlock(DXF::LineReader& reader, DXF::FileData& output)
{
    // push a new block onto the stack.
    output.blocks.push_back( DXF::Block() );
    DXF::Block& block = output.blocks.back();

    while( !reader.End() && !reader.Is(0,"ENDBLK")) {

        switch(reader.GroupCode()) {
            case 2:
                block.name = reader.Value();
                break;

            case 10:
                block.base.x = reader.ValueAsFloat();
                break;
            case 20:
                block.base.y = reader.ValueAsFloat();
                break;
            case 30:
                block.base.z = reader.ValueAsFloat();
                break;
        }

        if (reader.Is(0,"POLYLINE")) {
            ParsePolyLine(++reader,output);
            continue;
        }

        // XXX is this a valid case?
        if (reader.Is(0,"INSERT")) {
            DefaultLogger::get()->warn("DXF: INSERT within a BLOCK not currently supported; skipping");
            for( ;!reader.End() && !reader.Is(0,"ENDBLK"); ++reader);
            break;
        }

        else if (reader.Is(0,"3DFACE") || reader.Is(0,"LINE") || reader.Is(0,"3DLINE")) {
            //http://sourceforge.net/tracker/index.php?func=detail&aid=2970566&group_id=226462&atid=1067632
            Parse3DFace(++reader, output);
            continue;
        }
        ++reader;
    }
}


// ------------------------------------------------------------------------------------------------
void DXFImporter::ParseEntities(DXF::LineReader& reader, DXF::FileData& output)
{
    // push a new block onto the stack.
    output.blocks.push_back( DXF::Block() );
    DXF::Block& block = output.blocks.back();

    block.name = AI_DXF_ENTITIES_MAGIC_BLOCK;

    while( !reader.End() && !reader.Is(0,"ENDSEC")) {
        if (reader.Is(0,"POLYLINE")) {
            ParsePolyLine(++reader,output);
            continue;
        }

        else if (reader.Is(0,"INSERT")) {
            ParseInsertion(++reader,output);
            continue;
        }

        else if (reader.Is(0,"3DFACE") || reader.Is(0,"LINE") || reader.Is(0,"3DLINE")) {
            //http://sourceforge.net/tracker/index.php?func=detail&aid=2970566&group_id=226462&atid=1067632
            Parse3DFace(++reader, output);
            continue;
        }

        ++reader;
    }

    DefaultLogger::get()->debug((Formatter::format("DXF: got "),
        block.lines.size()," polylines and ", block.insertions.size() ," inserted blocks in ENTITIES"
    ));
}


void DXFImporter::ParseInsertion(DXF::LineReader& reader, DXF::FileData& output)
{
    output.blocks.back().insertions.push_back( DXF::InsertBlock() );
    DXF::InsertBlock& bl = output.blocks.back().insertions.back();

    while( !reader.End() && !reader.Is(0)) {

        switch(reader.GroupCode())
        {
            // name of referenced block
        case 2:
            bl.name = reader.Value();
            break;

            // translation
        case 10:
            bl.pos.x = reader.ValueAsFloat();
            break;
        case 20:
            bl.pos.y = reader.ValueAsFloat();
            break;
        case 30:
            bl.pos.z = reader.ValueAsFloat();
            break;

            // scaling
        case 41:
            bl.scale.x = reader.ValueAsFloat();
            break;
        case 42:
            bl.scale.y = reader.ValueAsFloat();
            break;
        case 43:
            bl.scale.z = reader.ValueAsFloat();
            break;

            // rotation angle
        case 50:
            bl.angle = reader.ValueAsFloat();
            break;
        }
        reader++;
    }
}

#define DXF_POLYLINE_FLAG_CLOSED        0x1
#define DXF_POLYLINE_FLAG_3D_POLYLINE   0x8
#define DXF_POLYLINE_FLAG_3D_POLYMESH   0x10
#define DXF_POLYLINE_FLAG_POLYFACEMESH  0x40

// ------------------------------------------------------------------------------------------------
void DXFImporter::ParsePolyLine(DXF::LineReader& reader, DXF::FileData& output)
{
    output.blocks.back().lines.push_back( std::shared_ptr<DXF::PolyLine>( new DXF::PolyLine() ) );
    DXF::PolyLine& line = *output.blocks.back().lines.back();

    unsigned int iguess = 0, vguess = 0;
    while( !reader.End() && !reader.Is(0,"ENDSEC")) {

        if (reader.Is(0,"VERTEX")) {
            ParsePolyLineVertex(++reader,line);
            if (reader.Is(0,"SEQEND")) {
                break;
            }
            continue;
        }

        switch(reader.GroupCode())
        {
        // flags --- important that we know whether it is a
        // polyface mesh or 'just' a line.
        case 70:
            if (!line.flags)    {
                line.flags = reader.ValueAsSignedInt();
            }
            break;

        // optional number of vertices
        case 71:
            vguess = reader.ValueAsSignedInt();
            line.positions.reserve(vguess);
            break;

        // optional number of faces
        case 72:
            iguess = reader.ValueAsSignedInt();
            line.indices.reserve(iguess);
            break;

        // 8 specifies the layer on which this line is placed on
        case 8:
            line.layer = reader.Value();
            break;
        }

        reader++;
    }

    //if (!(line.flags & DXF_POLYLINE_FLAG_POLYFACEMESH))   {
    //  DefaultLogger::get()->warn((Formatter::format("DXF: polyline not currently supported: "),line.flags));
    //  output.blocks.back().lines.pop_back();
    //  return;
    //}

    if (vguess && line.positions.size() != vguess) {
        DefaultLogger::get()->warn((Formatter::format("DXF: unexpected vertex count in polymesh: "),
            line.positions.size(),", expected ", vguess
        ));
    }

    if (line.flags & DXF_POLYLINE_FLAG_POLYFACEMESH ) {
        if (line.positions.size() < 3 || line.indices.size() < 3)   {
                DefaultLogger::get()->warn("DXF: not enough vertices for polymesh; ignoring");
                output.blocks.back().lines.pop_back();
                return;
        }

        // if these numbers are wrong, parsing might have gone wild.
        // however, the docs state that applications are not required
        // to set the 71 and 72 fields, respectively, to valid values.
        // So just fire a warning.
        if (iguess && line.counts.size() != iguess) {
            DefaultLogger::get()->warn((Formatter::format("DXF: unexpected face count in polymesh: "),
                line.counts.size(),", expected ", iguess
            ));
        }
    }
    else if (!line.indices.size() && !line.counts.size()) {
        // a polyline - so there are no indices yet.
        size_t guess = line.positions.size() + (line.flags & DXF_POLYLINE_FLAG_CLOSED ? 1 : 0);
        line.indices.reserve(guess);

        line.counts.reserve(guess/2);
        for (unsigned int i = 0; i < line.positions.size()/2; ++i) {
            line.indices.push_back(i*2);
            line.indices.push_back(i*2+1);
            line.counts.push_back(2);
        }

        // closed polyline?
        if (line.flags & DXF_POLYLINE_FLAG_CLOSED) {
            line.indices.push_back(static_cast<unsigned int>(line.positions.size()-1));
            line.indices.push_back(0);
            line.counts.push_back(2);
        }
    }
}

#define DXF_VERTEX_FLAG_PART_OF_POLYFACE 0x80
#define DXF_VERTEX_FLAG_HAS_POSITIONS 0x40

// ------------------------------------------------------------------------------------------------
void DXFImporter::ParsePolyLineVertex(DXF::LineReader& reader, DXF::PolyLine& line)
{
    unsigned int cnti = 0, flags = 0;
    unsigned int indices[4];

    aiVector3D out;
    aiColor4D clr = AI_DXF_DEFAULT_COLOR;

    while( !reader.End() ) {

        if (reader.Is(0)) { // SEQEND or another VERTEX
            break;
        }

        switch (reader.GroupCode())
        {
        case 8:
                // layer to which the vertex belongs to - assume that
                // this is always the layer the top-level polyline
                // entity resides on as well.
                if(reader.Value() != line.layer) {
                    DefaultLogger::get()->warn("DXF: expected vertex to be part of a polyface but the 0x128 flag isn't set");
                }
                break;

        case 70:
                flags = reader.ValueAsUnsignedInt();
                break;

        // VERTEX COORDINATES
        case 10: out.x = reader.ValueAsFloat();break;
        case 20: out.y = reader.ValueAsFloat();break;
        case 30: out.z = reader.ValueAsFloat();break;

        // POLYFACE vertex indices
        case 71:
        case 72:
        case 73:
        case 74:
            if (cnti == 4) {
                DefaultLogger::get()->warn("DXF: more than 4 indices per face not supported; ignoring");
                break;
            }
            indices[cnti++] = reader.ValueAsUnsignedInt();
            break;

        // color
        case 62:
            clr = g_aclrDxfIndexColors[reader.ValueAsUnsignedInt() % AI_DXF_NUM_INDEX_COLORS];
            break;
        };

        reader++;
    }

    if (line.flags & DXF_POLYLINE_FLAG_POLYFACEMESH && !(flags & DXF_VERTEX_FLAG_PART_OF_POLYFACE)) {
        DefaultLogger::get()->warn("DXF: expected vertex to be part of a polyface but the 0x128 flag isn't set");
    }

    if (cnti) {
        line.counts.push_back(cnti);
        for (unsigned int i = 0; i < cnti; ++i) {
            // IMPORTANT NOTE: POLYMESH indices are ONE-BASED
            if (indices[i] == 0) {
                DefaultLogger::get()->warn("DXF: invalid vertex index, indices are one-based.");
                --line.counts.back();
                continue;
            }
            line.indices.push_back(indices[i]-1);
        }
    }
    else {
        line.positions.push_back(out);
        line.colors.push_back(clr);
    }
}

// ------------------------------------------------------------------------------------------------
void DXFImporter::Parse3DFace(DXF::LineReader& reader, DXF::FileData& output)
{
    // (note) this is also used for for parsing line entities, so we
    // must handle the vertex_count == 2 case as well.

    output.blocks.back().lines.push_back( std::shared_ptr<DXF::PolyLine>( new DXF::PolyLine() )  );
    DXF::PolyLine& line = *output.blocks.back().lines.back();

    aiVector3D vip[4];
    aiColor4D  clr = AI_DXF_DEFAULT_COLOR;

    bool b[4] = {false,false,false,false};
    while( !reader.End() ) {

        // next entity with a groupcode == 0 is probably already the next vertex or polymesh entity
        if (reader.GroupCode() == 0) {
            break;
        }
        switch (reader.GroupCode())
        {

        // 8 specifies the layer
        case 8:
            line.layer = reader.Value();
            break;

        // x position of the first corner
        case 10: vip[0].x = reader.ValueAsFloat();
            b[2] = true;
            break;

        // y position of the first corner
        case 20: vip[0].y = reader.ValueAsFloat();
            b[2] = true;
            break;

        // z position of the first corner
        case 30: vip[0].z = reader.ValueAsFloat();
            b[2] = true;
            break;

        // x position of the second corner
        case 11: vip[1].x = reader.ValueAsFloat();
            b[3] = true;
            break;

        // y position of the second corner
        case 21: vip[1].y = reader.ValueAsFloat();
            b[3] = true;
            break;

        // z position of the second corner
        case 31: vip[1].z = reader.ValueAsFloat();
            b[3] = true;
            break;

        // x position of the third corner
        case 12: vip[2].x = reader.ValueAsFloat();
            b[0] = true;
            break;

        // y position of the third corner
        case 22: vip[2].y = reader.ValueAsFloat();
            b[0] = true;
            break;

        // z position of the third corner
        case 32: vip[2].z = reader.ValueAsFloat();
            b[0] = true;
            break;

        // x position of the fourth corner
        case 13: vip[3].x = reader.ValueAsFloat();
            b[1] = true;
            break;

        // y position of the fourth corner
        case 23: vip[3].y = reader.ValueAsFloat();
            b[1] = true;
            break;

        // z position of the fourth corner
        case 33: vip[3].z = reader.ValueAsFloat();
            b[1] = true;
            break;

        // color
        case 62:
            clr = g_aclrDxfIndexColors[reader.ValueAsUnsignedInt() % AI_DXF_NUM_INDEX_COLORS];
            break;
        };

        ++reader;
    }

    // the fourth corner may even be identical to the third,
    // in this case we treat it as if it didn't exist.
    if (vip[3] == vip[2]) {
        b[1] = false;
    }

    // sanity checks to see if we got something meaningful
    if ((b[1] && !b[0]) || !b[2] || !b[3]) {
        DefaultLogger::get()->warn("DXF: unexpected vertex setup in 3DFACE/LINE/FACE entity; ignoring");
        output.blocks.back().lines.pop_back();
        return;
    }

    const unsigned int cnt = (2+(b[0]?1:0)+(b[1]?1:0));
    line.counts.push_back(cnt);

    for (unsigned int i = 0; i < cnt; ++i) {
        line.indices.push_back(static_cast<unsigned int>(line.positions.size()));
        line.positions.push_back(vip[i]);
        line.colors.push_back(clr);
    }
}

#endif // !! ASSIMP_BUILD_NO_DXF_IMPORTER