/**
 * \file
 * \copyright
 * Copyright (c) 2012-2022, OpenGeoSys Community (http://www.opengeosys.org)
 *            Distributed under a Modified BSD License.
 *              See accompanying file LICENSE.txt or
 *              http://www.opengeosys.org/project/license
 */

#include <tclap/CmdLine.h>

#include <iostream>
#include <memory>
#include <string>
#include <string_view>
#include <vector>

#include "BaseLib/StringTools.h"
#include "GeoLib/Point.h"
#include "InfoLib/GitInfo.h"
#include "MeshLib/IO/VtkIO/VtuInterface.h"
#include "MeshLib/Mesh.h"
#include "MeshLib/MeshGenerators/RasterToMesh.h"

/// Returns the value for the given parameter name (i.e. for "x = 3" it returns
/// "3")
std::string getValue(std::string const& line,
                     std::string const& val_name,
                     bool is_string)
{
    std::string value;
    std::size_t start(line.find(val_name));
    std::size_t end(std::string::npos);
    if (start == end)
    {
        ERR("Value not found.");
        return "";
    }
    value = line.substr(start + 1, std::string::npos);
    if (is_string)
    {
        start = value.find("\"");
        value = value.substr(start + 1, std::string::npos);
        end = value.find("\"");
    }
    else
    {
        start = value.find_first_not_of(" ");
        value = value.substr(start + 1, std::string::npos);
        BaseLib::trim(value);
        end = value.find_first_of(" ");
    }
    value = value.substr(0, end);
    BaseLib::trim(value);
    return value;
}

/// Returns the name/title from the "Zone"-description
std::string getName(std::string const& line)
{
    return getValue(line, "T=", true);
}

std::string_view getZonetype(std::string const& line)
{
    auto start = line.find("ZONETYPE=");
    if (start == std::string::npos)
    {
        OGS_FATAL(
            "A required 'ZONETYPE=' substring is not available in the ZONE "
            "description: '{:s}'.",
            line);
    }
    start += std::size("ZONETYPE=") - 1;

    auto end = line.find(',', start);
    if (end == std::string::npos)
    {
        OGS_FATAL(
            "Expected the 'ZONETYPE=type' to be followed by a comma in the "
            "ZONE description '{:s}'. The zone type starts at position {:d}.",
            line, start);
    }
    if (start == end)
    {
        ERR("ZONETYPE string is empty in ZONE description '{:s}'.", line);
    }
    return std::string_view(&line[start], end - start);
}

/// Returns raster dimensions from the "Zone"-description
std::pair<std::size_t, std::size_t> getDimensions(std::string const& line)
{
    std::pair<std::size_t, std::size_t> dims;
    std::stringstream start(getValue(line, "I=", false));
    start >> dims.first;
    std::stringstream end(getValue(line, "J=", false));
    end >> dims.second;
    return dims;
}

/// Trims a substring containing a variable-name
std::string trimVariable(std::string& var)
{
    std::size_t const start = var.find_first_not_of("\"");
    var = var.substr(start, std::string::npos);
    std::size_t const end = var.find_first_of("\"");
    return var.substr(0, end);
}

/// Returns an vector of variable names from the "Variables"-description
std::vector<std::string> getVariables(std::string const& line)
{
    std::string const var_str("VARIABLES");
    std::size_t start(line.find(var_str));
    std::string all_vars =
        line.substr(start + var_str.length(), std::string::npos);
    start = all_vars.find("=");
    all_vars = all_vars.substr(start + 1, std::string::npos);
    BaseLib::trim(all_vars);

    std::vector<std::string> variables;
    std::size_t end = 0;
    while (end != std::string::npos)
    {
        end = all_vars.find_first_of(" ");
        std::string var = all_vars.substr(0, end);
        variables.push_back(trimVariable(var));
        all_vars = all_vars.substr(end + 1, std::string::npos);
        BaseLib::trim(all_vars);
    }

    return variables;
}

/// Tests if the number of read values equals the number of expected values
bool dataCountError(std::string const& name,
                    std::size_t const& current,
                    std::size_t const& total)
{
    if (current != total)
    {
        ERR("Data rows found do not fit specified dimensions for section "
            "'{:s}'.",
            name);
        return true;
    }
    return false;
}

/// Tests if the number of read values equals the number of expected values and
/// closes the stream
bool dataCountError(std::ofstream& out,
                    std::string const& name,
                    std::size_t const& current,
                    std::size_t const& total)
{
    if (dataCountError(name, current, total))
    {
        out.close();
        return true;
    }
    return false;
}

/// Resets all data structures after a new "Variables"-description is found
void resetDataStructures(std::size_t const& n_scalars,
                         std::vector<std::vector<double>>& scalars,
                         std::size_t& val_count)
{
    scalars.clear();
    scalars.reserve(n_scalars);
    for (std::size_t i = 0; i < n_scalars; ++i)
    {
        scalars.emplace_back(0);
    }
    val_count = 0;
}

/// Writes one section/zone into a separate TecPlot file
void writeTecPlotSection(std::ofstream& out,
                         std::string const& file_name,
                         std::size_t& write_count,
                         std::size_t& val_count,
                         std::size_t& val_total)
{
    if (write_count == 0 || val_total != 0)
    {
        std::size_t const delim_pos(file_name.find_last_of("."));
        std::string const base_name(file_name.substr(0, delim_pos + 1));
        std::string const extension(
            file_name.substr(delim_pos, std::string::npos));

        val_count = 0;
        val_total = 0;
        INFO("Writing section #{:i}", write_count);
        out.close();
        out.open(base_name + std::to_string(write_count++) + extension);
    }
}

/// Writes one section/zone into a separate OGS-mesh
int writeDataToMesh(std::string const& file_name,
                    std::size_t& write_count,
                    std::vector<std::string> const& vec_names,
                    std::vector<std::vector<double>> const& scalars,
                    std::pair<std::size_t, std::size_t> const& dims)
{
    double cellsize = 0;
    for (std::size_t i = 0; i < vec_names.size(); ++i)
    {
        if (vec_names[i] == "x" || vec_names[i] == "X")
        {
            cellsize = scalars[i][1] - scalars[i][0];
            break;
        }
    }

    if (cellsize == 0)
    {
        ERR("Cell size not found. Aborting...");
        return -4;
    }

    GeoLib::Point origin(0, 0, 0);
    GeoLib::RasterHeader header{dims.first, dims.second, 1,
                                origin,     cellsize,    -9999};

    std::unique_ptr<MeshLib::Mesh> mesh(
        MeshLib::RasterToMesh::convert(scalars[0].data(),
                                       header,
                                       MeshLib::MeshElemType::QUAD,
                                       MeshLib::UseIntensityAs::DATAVECTOR,
                                       vec_names[0]));
    MeshLib::Properties& properties = mesh->getProperties();
    for (std::size_t i = 1; i < vec_names.size(); ++i)
    {
        auto* const prop = properties.createNewPropertyVector<double>(
            vec_names[i], MeshLib::MeshItemType::Cell, 1);
        if (!prop)
        {
            ERR("Error creating array '{:s}'.", vec_names[i]);
            return -5;
        }
        prop->reserve(scalars[i].size());
        std::copy(scalars[i].cbegin(), scalars[i].cend(),
                  std::back_inserter(*prop));
    }

    std::size_t const delim_pos(file_name.find_last_of("."));
    std::string const base_name(file_name.substr(0, delim_pos + 1));
    std::string const extension(file_name.substr(delim_pos, std::string::npos));

    INFO("Writing section #{:i}", write_count);
    MeshLib::IO::VtuInterface vtu(mesh.get());
    vtu.writeToFile(base_name + std::to_string(write_count++) + extension);
    return 0;
}

/// If a geometry-section is encountered, it is currently ignored
void skipGeometrySection(std::ifstream& in, std::string& line)
{
    while (std::getline(in, line))
    {
        if ((line.find("TITLE") != std::string::npos) ||
            (line.find("VARIABLES") != std::string::npos) ||
            (line.find("ZONE") != std::string::npos))
        {
            return;
        }
    }
}

/// Splits a TecPlot file containing multiple sections/zones into separate files
int splitFile(std::ifstream& in, std::string const& file_name)
{
    std::ofstream out;
    std::string line;
    std::string name;
    std::size_t val_count(0);
    std::size_t val_total(0);
    std::size_t write_count(0);
    while (std::getline(in, line))
    {
        if (line.find("TITLE") != std::string::npos)
        {
            if (dataCountError(out, name, val_count, val_total))
            {
                return -3;
            }
            writeTecPlotSection(out, file_name, write_count, val_count,
                                val_total);
            out << line << "\n";
            continue;
        }
        if (line.find("VARIABLES") != std::string::npos)
        {
            if (dataCountError(out, name, val_count, val_total))
            {
                return -3;
            }
            writeTecPlotSection(out, file_name, write_count, val_count,
                                val_total);
            out << line << "\n";
            continue;
        }
        if (line.find("ZONE") != std::string::npos)
        {
            if (dataCountError(out, name, val_count, val_total))
            {
                return -3;
            }
            writeTecPlotSection(out, file_name, write_count, val_count,
                                val_total);
            out << line << "\n";
            name = getName(line);
            std::pair<std::size_t, std::size_t> dims = getDimensions(line);
            val_total = dims.first * dims.second;
            val_count = 0;
            continue;
        }

        out << line << "\n";
        val_count++;
    }
    if (dataCountError(out, name, val_count, val_total))
    {
        return -3;
    }
    INFO("Writing time step #{:i}", write_count);
    out.close();
    INFO("Finished split.");
    return 0;
}

/// Converts a TecPlot file into one or more OGS-meshes (one mesh per
/// section/zone)
int convertFile(std::ifstream& in, std::string const& file_name)
{
    std::string line;
    std::string name;
    std::pair<std::size_t, std::size_t> dims(0, 0);
    std::vector<std::string> var_names;
    std::vector<std::vector<double>> scalars;
    std::size_t val_count(0);
    std::size_t val_total(0);
    std::size_t write_count(0);
    while (std::getline(in, line))
    {
        if (line.find("GEOMETRY") != std::string::npos)
        {
            skipGeometrySection(in, line);
        }

        if (line.empty())
        {
            continue;
        }
        if (line.find("TITLE") != std::string::npos)
        {
            if (dataCountError(name, val_count, val_total))
            {
                return -3;
            }
            if (val_count != 0)
            {
                writeDataToMesh(file_name, write_count, var_names, scalars,
                                dims);
                resetDataStructures(var_names.size(), scalars, val_count);
            }
            continue;
        }
        if (line.find("VARIABLES") != std::string::npos)
        {
            if (val_count != 0)
            {
                if (dataCountError(name, val_count, val_total))
                {
                    return -3;
                }
                writeDataToMesh(file_name, write_count, var_names, scalars,
                                dims);
            }
            var_names.clear();
            var_names = getVariables(line);
            resetDataStructures(var_names.size(), scalars, val_count);
            continue;
        }
        if (line.find("ZONE") != std::string::npos)
        {
            if (val_count != 0)
            {
                if (dataCountError(name, val_count, val_total))
                {
                    return -3;
                }
                writeDataToMesh(file_name, write_count, var_names, scalars,
                                dims);
                resetDataStructures(var_names.size(), scalars, val_count);
            }
            name = getName(line);
            if (auto const zonetype = getZonetype(line); zonetype != "ORDERED")
            {
                ERR("Given zonetype '{:s}' is not supported. Only 'ORDERED' "
                    "zonetype data can be converted.",
                    zonetype);
                return -4;
            }
            dims = getDimensions(line);
            val_total = dims.first * dims.second;
            val_count = 0;
            continue;
        }

        double x;
        std::stringstream iss(line);
        std::size_t i(0);
        std::size_t const n_scalars(scalars.size());
        while (iss >> x)
        {
            if (i > n_scalars - 1)
            {
                ERR("Too much data for existing scalar arrays");
                return -3;
            }
            scalars[i++].push_back(x);
        }
        if (i < n_scalars)
        {
            ERR("Not enough data for existing scalar arrays");
            return -3;
        }
        val_count++;
    }
    if (dataCountError(name, val_count, val_total))
    {
        return -3;
    }
    writeDataToMesh(file_name, write_count, var_names, scalars, dims);
    INFO("Finished conversion.");
    return 0;
}

/**
 * Small collection of scripts to handle TecPlot files.
 *
 * Return codes:
 *      0 : no errors
 *     -1 : missing arguments
 *     -2 : file I/O error
 *     -3 : index error
 *     -4 : error interpreting data
 *     -5 : error creating data structures
 */
int main(int argc, char* argv[])
{
    TCLAP::CmdLine cmd(
        "TecPlot Parser\n\n"
        "OpenGeoSys-6 software, version " +
            GitInfoLib::GitInfo::ogs_version +
            ".\n"
            "Copyright (c) 2012-2022, OpenGeoSys Community "
            "(http://www.opengeosys.org)",
        ' ', GitInfoLib::GitInfo::ogs_version);
    TCLAP::SwitchArg split_arg("s", "split",
                               "split time steps into separate files");
    cmd.add(split_arg);
    TCLAP::SwitchArg convert_arg("c", "convert",
                                 "convert TecPlot data into OGS meshes");
    cmd.add(convert_arg);
    TCLAP::ValueArg<std::string> output_arg(
        "o", "output-file", "output mesh file", false, "", "string");
    cmd.add(output_arg);
    TCLAP::ValueArg<std::string> input_arg(
        "i", "input-file", "TecPlot input file", true, "", "string");
    cmd.add(input_arg);
    cmd.parse(argc, argv);

    if (!input_arg.isSet())
    {
        ERR("No input file given. Please specify TecPlot (*.plt) file");
        return -1;
    }

    if (convert_arg.getValue() && !output_arg.isSet())
    {
        ERR("No output file given. Please specify OGS mesh (*.vtu) file");
        return -1;
    }

    std::ifstream in(input_arg.getValue().c_str());
    if (!in.is_open())
    {
        ERR("Could not open file {:s}.", input_arg.getValue());
        return -2;
    }

    if (!convert_arg.isSet() && !split_arg.isSet())
    {
        INFO("Nothing to do. Use -s to split or -c to convert.");
        return 0;
    }

    std::string const filename =
        (output_arg.isSet()) ? output_arg.getValue() : input_arg.getValue();
    int return_val(0);
    if (split_arg.getValue())
    {
        return_val = splitFile(in, filename);
    }
    else if (convert_arg.getValue())
    {
        return_val = convertFile(in, filename);
    }

    in.close();
    return return_val;
}