/*
Open Asset Import Library (assimp)
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  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
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  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
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*/

/** @file  BlenderBMesh.cpp
 *  @brief Conversion of Blender's new BMesh stuff
 */


#ifndef ASSIMP_BUILD_NO_BLEND_IMPORTER

#include "BlenderDNA.h"
#include "BlenderScene.h"
#include "BlenderBMesh.h"
#include "BlenderTessellator.h"

namespace Assimp
{
    template< > const char* LogFunctions< BlenderBMeshConverter >::Prefix()
    {
        static auto prefix = "BLEND_BMESH: ";
        return prefix;
    }
}

using namespace Assimp;
using namespace Assimp::Blender;
using namespace Assimp::Formatter;

// ------------------------------------------------------------------------------------------------
BlenderBMeshConverter::BlenderBMeshConverter( const Mesh* mesh ):
    BMesh( mesh ),
    triMesh( NULL )
{
}

// ------------------------------------------------------------------------------------------------
BlenderBMeshConverter::~BlenderBMeshConverter( )
{
    DestroyTriMesh( );
}

// ------------------------------------------------------------------------------------------------
bool BlenderBMeshConverter::ContainsBMesh( ) const
{
    // TODO - Should probably do some additional verification here
    return BMesh->totpoly && BMesh->totloop && BMesh->totvert;
}

// ------------------------------------------------------------------------------------------------
const Mesh* BlenderBMeshConverter::TriangulateBMesh( )
{
    AssertValidMesh( );
    AssertValidSizes( );
    PrepareTriMesh( );

    for ( int i = 0; i < BMesh->totpoly; ++i )
    {
        const MPoly& poly = BMesh->mpoly[ i ];
        ConvertPolyToFaces( poly );
    }

    return triMesh;
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::AssertValidMesh( )
{
    if ( !ContainsBMesh( ) )
    {
        ThrowException( "BlenderBMeshConverter requires a BMesh with \"polygons\" - please call BlenderBMeshConverter::ContainsBMesh to check this first" );
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::AssertValidSizes( )
{
    if ( BMesh->totpoly != static_cast<int>( BMesh->mpoly.size( ) ) )
    {
        ThrowException( "BMesh poly array has incorrect size" );
    }
    if ( BMesh->totloop != static_cast<int>( BMesh->mloop.size( ) ) )
    {
        ThrowException( "BMesh loop array has incorrect size" );
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::PrepareTriMesh( )
{
    if ( triMesh )
    {
        DestroyTriMesh( );
    }

    triMesh = new Mesh( *BMesh );
    triMesh->totface = 0;
    triMesh->mface.clear( );
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::DestroyTriMesh( )
{
    delete triMesh;
    triMesh = NULL;
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::ConvertPolyToFaces( const MPoly& poly )
{
    const MLoop* polyLoop = &BMesh->mloop[ poly.loopstart ];

    if ( poly.totloop == 3 || poly.totloop == 4 )
    {
        AddFace( polyLoop[ 0 ].v, polyLoop[ 1 ].v, polyLoop[ 2 ].v, poly.totloop == 4 ? polyLoop[ 3 ].v : 0 );

        // UVs are optional, so only convert when present.
        if ( BMesh->mloopuv.size() )
        {
            if ( (poly.loopstart + poly.totloop ) > static_cast<int>( BMesh->mloopuv.size() ) )
            {
                ThrowException( "BMesh uv loop array has incorrect size" );
            }
            const MLoopUV* loopUV = &BMesh->mloopuv[ poly.loopstart ];
            AddTFace( loopUV[ 0 ].uv, loopUV[ 1 ].uv, loopUV[ 2 ].uv, poly.totloop == 4 ? loopUV[ 3 ].uv : 0 );
        }
    }
    else if ( poly.totloop > 4 )
    {
#if ASSIMP_BLEND_WITH_GLU_TESSELLATE
        BlenderTessellatorGL tessGL( *this );
        tessGL.Tessellate( polyLoop, poly.totloop, triMesh->mvert );
#elif ASSIMP_BLEND_WITH_POLY_2_TRI
        BlenderTessellatorP2T tessP2T( *this );
        tessP2T.Tessellate( polyLoop, poly.totloop, triMesh->mvert );
#endif
    }
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::AddFace( int v1, int v2, int v3, int v4 )
{
    MFace face;
    face.v1 = v1;
    face.v2 = v2;
    face.v3 = v3;
    face.v4 = v4;
    // TODO - Work out how materials work
    face.mat_nr = 0;
    triMesh->mface.push_back( face );
    triMesh->totface = static_cast<int>(triMesh->mface.size( ));
}

// ------------------------------------------------------------------------------------------------
void BlenderBMeshConverter::AddTFace( const float* uv1, const float *uv2, const float *uv3, const float* uv4 )
{
    MTFace mtface;
    memcpy( &mtface.uv[ 0 ], uv1, sizeof(float) * 2 );
    memcpy( &mtface.uv[ 1 ], uv2, sizeof(float) * 2 );
    memcpy( &mtface.uv[ 2 ], uv3, sizeof(float) * 2 );

    if ( uv4 )
    {
        memcpy( &mtface.uv[ 3 ], uv4, sizeof(float) * 2 );
    }

    triMesh->mtface.push_back( mtface );
}

#endif // ASSIMP_BUILD_NO_BLEND_IMPORTER