/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0.txt

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

=========================================================================*/

#include "imstkVegaMeshIO.h"
#include "imstkHexahedralMesh.h"
#include "imstkLogger.h"
#include "imstkTetrahedralMesh.h"
#include "imstkVecDataArray.h"

#include <tetMesh.h>
#include <volumetricMeshLoader.h>

namespace imstk
{
std::shared_ptr<VolumetricMesh>
VegaMeshIO::read(const std::string& filePath, MeshFileType meshType)
{
    CHECK(meshType == MeshFileType::VEG) << "@VegaMeshIO::read error: input file type is not veg for input " << filePath;

    // Read Vega Mesh
    std::shared_ptr<vega::VolumetricMesh> vegaMesh = VegaMeshIO::readVegaMesh(filePath);

    // Convert to Volumetric Mesh
    return VegaMeshIO::convertVegaMeshToVolumetricMesh(vegaMesh);
}

bool
VegaMeshIO::write(const std::shared_ptr<imstk::PointSet> imstkMesh, const std::string& filePath, const MeshFileType meshType)
{
    CHECK(meshType == MeshFileType::VEG) << "@VegaMeshIO::write error: file type is not veg for input " << filePath;

    // extract volumetric mesh
    const auto imstkVolMesh = std::dynamic_pointer_cast<imstk::VolumetricMesh>(imstkMesh);

    CHECK(imstkVolMesh != nullptr) << "@VegaMeshIO::write error: imstk::PointSet object supplied is not a imstk::VolumetricMesh type for input" << filePath;

    const std::string geometryType = imstkVolMesh->getTypeName();
    if (geometryType == "TetrahedralMesh" || geometryType == "HexahedralMesh")
    {
        auto vegaMesh = convertVolumetricMeshToVegaMesh(imstkVolMesh);

        CHECK(vegaMesh != nullptr) << "@VegaMeshIO::write error: failed to convert volumetric mesh to vega mesh for input" << filePath;

        const auto fileName     = const_cast<char*>(filePath.c_str());
        const int  write_status = vegaMesh->save(fileName);

        CHECK(write_status == 0) << "@VegaMeshIO::write error: failed (vega fail code " << write_status <<
            ". Check vega::VolumetricMesh::save for documentation)to write .veg file for input" << filePath;

        return true;
    }

    LOG(WARNING) << "Error: Unknown element type (only tetrahedral and hexahedral elements supported) for input " << filePath;
    return false;
}

std::shared_ptr<vega::VolumetricMesh>
VegaMeshIO::readVegaMesh(const std::string& filePath)
{
    auto                                  fileName = const_cast<char*>(filePath.c_str());
    std::shared_ptr<vega::VolumetricMesh> vegaMesh(vega::VolumetricMeshLoader::load(fileName));
    return vegaMesh;
}

std::shared_ptr<imstk::VolumetricMesh>
VegaMeshIO::convertVegaMeshToVolumetricMesh(std::shared_ptr<vega::VolumetricMesh> vegaMesh)
{
    // Copy vertices
    std::shared_ptr<VecDataArray<double, 3>> vertices = std::make_shared<VecDataArray<double, 3>>();
    VegaMeshIO::copyVertices(vegaMesh, *vertices);

    // Copy cells
    auto                                   cellType = vegaMesh->getElementType();
    std::shared_ptr<imstk::VolumetricMesh> mesh;
    if (cellType == vega::VolumetricMesh::TET)
    {
        std::shared_ptr<VecDataArray<int, 4>> cellsPtr = std::make_shared<VecDataArray<int, 4>>();
        VecDataArray<int, 4>&                 cells    = *cellsPtr;
        VegaMeshIO::copyCells<4>(vegaMesh, cells);

        auto tetMesh = std::make_shared<TetrahedralMesh>();
        tetMesh->initialize(vertices, cellsPtr);
        mesh = tetMesh;
    }
    else if (cellType == vega::VolumetricMesh::CUBIC)
    {
        std::shared_ptr<VecDataArray<int, 8>> cellsPtr = std::make_shared<VecDataArray<int, 8>>();
        VecDataArray<int, 8>&                 cells    = *cellsPtr;
        VegaMeshIO::copyCells<8>(vegaMesh, cells);

        auto hexMesh = std::make_shared<HexahedralMesh>();
        hexMesh->initialize(vertices, cellsPtr);
        mesh = hexMesh;
    }
    else
    {
        vegaMesh.reset();
        LOG(WARNING) << "Error: invalid cell type";
        return nullptr;
    }
    return mesh;
}

void
VegaMeshIO::copyVertices(std::shared_ptr<vega::VolumetricMesh> vegaMesh,
                         VecDataArray<double, 3>& vertices)
{
    for (int i = 0; i < vegaMesh->getNumVertices(); ++i)
    {
        auto pos = vegaMesh->getVertex(i);
        vertices.push_back(Vec3d(pos[0], pos[1], pos[2]));
    }
}

template<size_t dim>
void
VegaMeshIO::copyCells(std::shared_ptr<vega::VolumetricMesh> vegaMesh,
                      VecDataArray<int, dim>& cells)
{
    typename VecDataArray<int, dim>::VecType cell;
    for (size_t cellId = 0; cellId < vegaMesh->getNumElements(); ++cellId)
    {
        for (int i = 0; i < vegaMesh->getNumElementVertices(); ++i)
        {
            cell[i] = vegaMesh->getVertexIndex(static_cast<int>(cellId), i);
        }
        cells.push_back(cell);
    }
}

std::shared_ptr<vega::VolumetricMesh>
VegaMeshIO::convertVolumetricMeshToVegaMesh(const std::shared_ptr<imstk::VolumetricMesh> imstkVolMesh)
{
    // as of now, only works for TET elements
    if (imstkVolMesh->getTypeName() == "TetrahedralMesh")
    {
        auto imstkVolTetMesh = std::dynamic_pointer_cast<imstk::TetrahedralMesh>(imstkVolMesh);

        auto                vertexArray = *imstkVolMesh->getVertexPositions();
        std::vector<double> vertices;
        for (const auto& node : vertexArray)
        {
            vertices.emplace_back(node(0));
            vertices.emplace_back(node(1));
            vertices.emplace_back(node(2));
        }

        VecDataArray<int, 4>& tetArray = *imstkVolTetMesh->getTetrahedraIndices();
        std::vector<int>      elements;
        for (const Vec4i& tet : tetArray)
        {
            elements.emplace_back(int(tet[0]));
            elements.emplace_back(int(tet[1]));
            elements.emplace_back(int(tet[2]));
            elements.emplace_back(int(tet[3]));
        }

        // Using default material properties to append to the .veg file
        auto vegaMesh = std::make_shared<vega::TetMesh>(int(imstkVolTetMesh->getNumVertices()),
            &vertices[0],
            int(imstkVolTetMesh->getNumTetrahedra()),
            &elements[0],
            1E7, /* Young's modulus */
            0.4, /* Poisson's ratio */
            1000.0 /* density */);

        CHECK(vegaMesh != nullptr) << "@VegaMeshIO::convertVolumetricMeshToVegaMesh error: Failed to create vega mesh. "
                                   << "Check vega::TetMesh::TetMesh() for clues";

        return vegaMesh;
    }
    else
    {
        LOG(WARNING) << "Error: Geometry type other than tetrahedral mesh not supported";
        return nullptr;
    }
}
} // imstk
