#pragma once

#include <array>
#include <iosfwd>
#include <map>

#include <dune/vtk/filewriter.hh>
#include <dune/vtk/function.hh>
#include <dune/vtk/types.hh>
#include <dune/vtk/datacollectors/continuousdatacollector.hh>

#include <dune/vtk/vtkwriterinterface.hh>

namespace Dune
{
  /// File-Writer for VTK .vtu files
  /**
   * Requirement:
   * - DataCollector must be a model of \ref DataCollector
   **/
  template <class GridView, class DataCollector = Vtk::ContinuousDataCollector<GridView>>
  class VtkUnstructuredGridWriter
      : public VtkWriterInterface<GridView, DataCollector>
  {
    template <class> friend class VtkTimeseriesWriter;

    static constexpr int dimension = GridView::dimension;

    using Super = VtkWriterInterface<GridView, DataCollector>;
    using pos_type = typename Super::pos_type;

  public:
    /// forwarding constructor to \ref VtkWriterInterface
    using Super::Super;

  private:
    /// Write a serial VTK file in Unstructured format
    virtual void writeSerialFile (std::ofstream& out) const override;

    /// Write a parallel VTK file `pfilename.pvtu` in Unstructured format,
    /// with `size` the number of pieces and serial files given by `pfilename_p[i].vtu`
    /// for [i] in [0,...,size).
    virtual void writeParallelFile (std::ofstream& out, std::string const& pfilename, int size) const override;

    /// Write a series of timesteps in one file
    /**
     * \param filename      The name of the output file
     * \param filenameMesh  The name of a file where the mesh is stored. Must exist.
     * \param timesteps     A vector of pairs (timestep, filename) where the filename indicates
     *                      a file where the data of the timestep is stored.
     * \param blocks        A list of block sizes of the binary data stored in the files.
     *                      Order: (points, cells, pointdata[0], celldata[0], pointdata[1], celldata[1],...)
     **/
    void writeTimeseriesSerialFile (std::ofstream& out,
                                    std::string const& filenameMesh,
                                    std::vector<std::pair<double, std::string>> const& timesteps,
                                    std::vector<std::uint64_t> const& blocks) const;

    /// Write parallel VTK file for series of timesteps
    void writeTimeseriesParallelFile (std::ofstream& out,
                                      std::string const& pfilename, int size,
                                      std::vector<std::pair<double, std::string>> const& timesteps) const;

    virtual std::string fileExtension () const override
    {
      return "vtu";
    }

    virtual void writeGridAppended (std::ofstream& out, std::vector<std::uint64_t>& blocks) const override;

    // Write the element connectivity to the output stream `out`. In case
    // of binary format, stores the streampos of XML attributes "offset" in the
    // vector `offsets`.
    void writeCells (std::ofstream& out,
                     std::vector<pos_type>& offsets,
                     std::optional<std::size_t> timestep = {}) const;

    void writePointIds (std::ofstream& out,
                        std::vector<pos_type>& offsets,
                        std::optional<std::size_t> timestep = {}) const;

  private:
    using Super::dataCollector_;
    using Super::format_;
    using Super::datatype_;
    using Super::headertype_;

    // attached data
    using Super::pointData_;
    using Super::cellData_;
  };

  // deduction guides
  template <class GridView,
    class = std::void_t<typename GridView::IndexSet>>
  VtkUnstructuredGridWriter(GridView const&, Vtk::FormatTypes = Vtk::BINARY, Vtk::DataTypes = Vtk::FLOAT32)
    -> VtkUnstructuredGridWriter<GridView, Vtk::ContinuousDataCollector<GridView>>;

  template <class DataCollector,
    class = std::void_t<typename DataCollector::GridView>>
  VtkUnstructuredGridWriter(DataCollector&, Vtk::FormatTypes = Vtk::BINARY, Vtk::DataTypes = Vtk::FLOAT32)
    -> VtkUnstructuredGridWriter<typename DataCollector::GridView, DataCollector>;

  template <class DataCollector,
    class = std::void_t<typename DataCollector::GridView>>
  VtkUnstructuredGridWriter(std::shared_ptr<DataCollector>, Vtk::FormatTypes = Vtk::BINARY, Vtk::DataTypes = Vtk::FLOAT32)
    -> VtkUnstructuredGridWriter<typename DataCollector::GridView, DataCollector>;

} // end namespace Dune

#include "vtkunstructuredgridwriter.impl.hh"