/////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2025-     Equinor ASA
//
//  ResInsight is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
//  FITNESS FOR A PARTICULAR PURPOSE.
//
//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
//  for more details.
//
/////////////////////////////////////////////////////////////////////////////////

#include "RifVtkSurfaceImporter.h"

#include "RigTriangleMeshData.h"

#include <filesystem>
#include <memory>
#include <sstream>
#include <string>
#include <vector>

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::unique_ptr<RigTriangleMeshData> RifVtkSurfaceImporter::importFromFile( const std::filesystem::path& filepath )
{
    pugi::xml_document     doc;
    pugi::xml_parse_result result = doc.load_file( filepath.string().c_str() );
    if ( !result ) return nullptr;

    return importFromXmlDoc( doc );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::unique_ptr<RigTriangleMeshData> RifVtkSurfaceImporter::importFromXmlDoc( const pugi::xml_document& doc )
{
    auto root = doc.child( "VTKFile" );
    if ( !root ) return nullptr;

    auto grid = root.child( "UnstructuredGrid" );
    if ( !grid ) return nullptr;

    auto piece = grid.child( "Piece" );
    if ( !piece ) return nullptr;

    // Read points
    std::vector<cvf::Vec3d> vertices = readPoints( piece );
    if ( vertices.empty() ) return nullptr;

    // Read connectivity
    std::vector<unsigned> connectivity = readConnectivity( piece );
    if ( connectivity.empty() ) return nullptr;

    // Avoid shared nodes
    std::vector<cvf::Vec3d> nonSharedVertices;
    std::vector<unsigned>   nonSharedConnectivity;

    const auto numTriangles = connectivity.size() / 3;
    for ( size_t triangleIdx = 0; triangleIdx < numTriangles; triangleIdx++ )
    {
        nonSharedVertices.push_back( vertices[connectivity[3 * triangleIdx + 0]] );
        nonSharedVertices.push_back( vertices[connectivity[3 * triangleIdx + 1]] );
        nonSharedVertices.push_back( vertices[connectivity[3 * triangleIdx + 2]] );

        nonSharedConnectivity.push_back( static_cast<unsigned int>( 3 * triangleIdx + 0 ) );
        nonSharedConnectivity.push_back( static_cast<unsigned int>( 3 * triangleIdx + 1 ) );
        nonSharedConnectivity.push_back( static_cast<unsigned int>( 3 * triangleIdx + 2 ) );
    }

    // Set geometry data
    auto triangleMeshData = std::make_unique<RigTriangleMeshData>();
    triangleMeshData->setGeometryData( nonSharedVertices, nonSharedConnectivity );

    // Read properties
    const std::map<std::string, std::vector<float>> properties = readProperties( piece );
    for ( const auto& [name, values] : properties )
    {
        // These values are per element, so we need to duplicate them for each node
        if ( values.size() * 3 == nonSharedVertices.size() )
        {
            std::vector<float> valuesForEachNode;
            for ( auto value : values )
            {
                valuesForEachNode.push_back( value );
                valuesForEachNode.push_back( value );
                valuesForEachNode.push_back( value );
            }

            triangleMeshData->addPropertyData( QString::fromStdString( name ), valuesForEachNode );
        }
    }

    return triangleMeshData;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::vector<cvf::Vec3d> RifVtkSurfaceImporter::readPoints( const pugi::xml_node& piece )
{
    auto points = piece.child( "Points" );
    if ( !points ) return {};

    auto coords = points.child( "DataArray" );
    if ( !coords || std::string( coords.attribute( "Name" ).value() ) != "Coordinates" ) return {};

    std::vector<cvf::Vec3d> vertices;
    std::istringstream      iss( coords.text().get() );

    double x, y, z;
    while ( iss >> x >> y >> z )
    {
        vertices.emplace_back( x, y, -z );
    }

    return vertices;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::vector<unsigned> RifVtkSurfaceImporter::readConnectivity( const pugi::xml_node& piece )
{
    auto cells = piece.child( "Cells" );
    if ( !cells ) return {};

    std::vector<unsigned> connectivity;
    auto                  connectivityArray = cells.child( "DataArray" );

    while ( connectivityArray )
    {
        if ( std::string( connectivityArray.attribute( "Name" ).value() ) == "connectivity" )
        {
            std::string        connectivityText = connectivityArray.text().get();
            std::istringstream iss( connectivityText );

            unsigned index;
            while ( iss >> index )
            {
                connectivity.push_back( index );
            }
            break;
        }
        connectivityArray = connectivityArray.next_sibling( "DataArray" );
    }

    return connectivity;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::map<std::string, std::vector<float>> RifVtkSurfaceImporter::readProperties( const pugi::xml_node& piece )
{
    auto cellData = piece.child( "CellData" );
    if ( !cellData ) return {};

    std::map<std::string, std::vector<float>> properties;

    for ( const auto& dataArray : cellData.children( "DataArray" ) )
    {
        const char* name = dataArray.attribute( "Name" ).value();
        if ( name && *name )
        {
            std::vector<float> values;
            std::istringstream iss( dataArray.text().get() );

            float value;
            while ( iss >> value )
            {
                values.push_back( value );
            }

            if ( !values.empty() )
            {
                properties[name] = std::move( values );
            }
        }
    }

    return properties;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
std::vector<RifVtkSurfaceImporter::PvdDataset> RifVtkSurfaceImporter::parsePvdDatasets( const std::filesystem::path& filepath )
{
    pugi::xml_document     doc;
    pugi::xml_parse_result result = doc.load_file( filepath.string().c_str() );
    if ( !result ) return {};

    auto root = doc.child( "VTKFile" );
    if ( !root ) return {};

    auto collection = root.child( "Collection" );
    if ( !collection ) return {};

    std::filesystem::path baseDir = filepath.parent_path();

    std::vector<PvdDataset> datasets;

    for ( const auto& datasetElem : collection.children( "DataSet" ) )
    {
        const char* file        = datasetElem.attribute( "file" ).value();
        const char* timestepStr = datasetElem.attribute( "timestep" ).value();

        if ( file && timestepStr )
        {
            double                timestep = std::stod( timestepStr );
            std::filesystem::path fullPath = std::filesystem::absolute( baseDir / file );

            datasets.push_back( { timestep, fullPath } );
        }
    }

    return datasets;
}