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

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

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

// ------------------------------------------------------------------------------------------------
BlenderBMeshConverter::BlenderBMeshConverter(const Mesh *mesh) :
        BMesh(mesh),
        triMesh(nullptr) {
    ai_assert(nullptr != mesh);
}

// ------------------------------------------------------------------------------------------------
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 = nullptr;
}

// ------------------------------------------------------------------------------------------------
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 : nullptr);
        }
    } 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;
    face.flag = 0;
    // 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
