#pragma once

#include <list>
#include <map>
#include <memory>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

#include <dune/common/fvector.hh>
#include <dune/common/fmatrix.hh>
#include <dune/grid/common/grid.hh>
#include <amdis/AdaptInfo.hpp>
#include <amdis/CreatorInterface.hpp>
#include <amdis/CreatorMap.hpp>
#include <amdis/DirichletBC.hpp>
//#include <amdis/Estimator.hpp>
#include <amdis/Flag.hpp>
#include <amdis/Initfile.hpp>
#include <amdis/LinearAlgebra.hpp>
#include <amdis/OperatorList.hpp>
#include <amdis/Marker.hpp>
#include <amdis/MeshCreator.hpp>
#include <amdis/PeriodicBC.hpp>
#include <amdis/ProblemStatBase.hpp>
#include <amdis/ProblemStatTraits.hpp>
#include <amdis/StandardProblemIteration.hpp>

#include <amdis/common/TupleUtility.hpp>
#include <amdis/common/TypeTraits.hpp>

#include <amdis/GridFunctions.hpp>
#include <amdis/gridfunctions/DiscreteFunction.hpp>
#include <amdis/gridfunctions/DOFVectorView.hpp>

#include <amdis/FileWriterInterface.hpp>

#include <amdis/typetree/TreeData.hpp>
#include <amdis/typetree/TreePath.hpp>

namespace AMDiS
{
  // forward declaration
  template <class Traits>
  class ProblemInstat;

  template <class Traits>
  class ProblemStat
      : public ProblemStatBase
      , public StandardProblemIterationAdaptor<ProblemStat<Traits>>
  {
    using Self = ProblemStat;

    friend class ProblemInstat<Traits>;

  public: // typedefs and static constants

    using GlobalBasis = typename Traits::GlobalBasis;
    using GridView    = typename GlobalBasis::GridView;
    using Grid        = typename GridView::Grid;
    using Element     = typename GridView::template Codim<0>::Entity;
    using WorldVector = typename Element::Geometry::GlobalCoordinate;
    using WorldMatrix = FieldMatrix<typename WorldVector::field_type, WorldVector::dimension, WorldVector::dimension>;

    /// Dimension of the grid
    static constexpr int dim = Grid::dimension;

    /// Dimension of the world
    static constexpr int dow = Grid::dimensionworld;

    using SystemMatrix = DOFMatrix<GlobalBasis, GlobalBasis, typename Traits::CoefficientType>;
    using SystemVector = DOFVector<GlobalBasis, typename Traits::CoefficientType>;
    using LinearSolverTraits = SolverTraits<typename SystemMatrix::BaseMatrix,
                                            typename SystemVector::BaseVector,
                                            typename SystemVector::BaseVector,
                                            GlobalBasis>;

    using LinearSolverType = LinearSolverInterface<LinearSolverTraits>;
    using CommInfo = typename LinearSolverTraits::Comm;

  public:
    /**
     * \brief Constructor. Takes the name of the problem that is used to
     * access values corresponding to this problem in the parameter file.
     **/
    explicit ProblemStat(std::string const& name)
      : name_(name)
    {}

    /// Constructor taking additionally a reference to a grid that is used
    /// instead of the default created grid, \ref ProblemStat
    ProblemStat(std::string const& name, Grid& grid)
      : ProblemStat(name)
    {
      adoptGrid(Dune::stackobject_to_shared_ptr(grid));
    }

    /// \brief Constructor taking a grid reference and a basis reference.
    /// Stores pointers to both.
    ProblemStat(std::string const& name, Grid& grid, GlobalBasis& globalBasis)
      : ProblemStat(name, grid)
    {
      adoptGlobalBasis(Dune::stackobject_to_shared_ptr(globalBasis));
    }


    /**
     * \brief Initialisation of the problem.
     *
     * Parameters read in initialize() for problem with name 'PROB'
     *   MESH[0]->global refinements:  nr of initial global refinements
     **/
    void initialize(Flag initFlag, Self* adoptProblem = nullptr, Flag adoptFlag = INIT_NOTHING);


    /// Add an operator to \ref A.
    /** @{ */
    /// Operator evaluated on the whole element
    /**
     * Adds an operator to the list of element operators to be assembled in
     * quadrature points inside the element.
     *
     * \param op   A (pre-) local operator, \see LocalOperator, \see GridFunctionOperator
     * \param row  TreePath identifying the sub-basis in the global basis tree
     *             corresponding to the row basis. \see treepath()
     * \param col  TreePath identifying the sub-basis in the global basis tree
     *             corresponding to the column basis. \see treepath()
     *
     * Example:
     * ```
     * auto op = makeOperator(tag::test_trial{}, 1.0/tau);
     * prob.addMatrixOperator(op, _0, _0);
     * ```
     **/
    template <class Operator, class RowTreePath = RootTreePath, class ColTreePath = RootTreePath>
    void addMatrixOperator(Operator const& op, RowTreePath row = {}, ColTreePath col = {})
    {
      systemMatrix_->addOperator(tag::element_operator<Element>{}, op, row, col);
    }

    /// Operator evaluated on the boundary of the domain with boundary index `b`
    /**
     * Adds an operator to the list of boundary operators to be assembled in
     * quadrature points on the boundary intersections.
     *
     * \param b    Boundary indentifier where to assemble this operator. Can be
     *             constructed from an integer. \see BoundaryType
     * \param op   A (pre-) local operator, \see LocalOperator, \see GridFunctionOperator
     * \param row  TreePath identifying the sub-basis in the global basis tree
     *             corresponding to the row basis. \see treepath()
     * \param col  TreePath identifying the sub-basis in the global basis tree
     *             corresponding to the column basis. \see treepath()
     *
     * Example:
     * ```
     * auto op = makeOperator(tag::test_trial{}, alpha);
     * prob.addMatrixOperator(BoundaryType{1}, op, _0, _0);
     * ```
     **/
    template <class Operator, class RowTreePath = RootTreePath, class ColTreePath = RootTreePath>
    void addMatrixOperator(BoundaryType b, Operator const& op, RowTreePath row = {}, ColTreePath col = {})
    {
      using I = typename GridView::Intersection;
      systemMatrix_->addOperator(tag::boundary_operator<I>{boundaryManager_,b}, op, row, col);
    }
    /** @} */


    /// Add an operator to \ref rhs.
    /** @{ */
    /// Operator evaluated on the whole element
    /**
     * Adds an operator to the list of element operators to be assembled in
     * quadrature points inside the element.
     *
     * \param op    A (pre-) local operator, \see LocalOperator, \see GridFunctionOperator
     * \param path  TreePath identifying the sub-basis in the global basis tree
     *              corresponding to the row basis. \see treepath()
     *
     * Example:
     * ```
     * auto op = makeOperator(tag::test{}, probInstat.getOldSolution(0) / tau);
     * prob.addVectorOperator(op, _0);
     * ```
     **/
    template <class Operator, class TreePath = RootTreePath>
    void addVectorOperator(Operator const& op, TreePath path = {})
    {
      rhs_->addOperator(tag::element_operator<Element>{}, op, path);
    }

    /// Operator evaluated on the boundary of the domain with boundary index `b`
    /**
     * Adds an operator to the list of boundary operators to be assembled in
     * quadrature points on the boundary intersections.
     *
     * \param b     Boundary indentifier where to assemble this operator. Can be
     *              constructed from an integer. \see BoundaryType
     * \param op    A (pre-) local operator, \see LocalOperator, \see GridFunctionOperator
     * \param path  TreePath identifying the sub-basis in the global basis tree
     *              corresponding to the row basis. \see treepath()
     *
     * Example:
     * ```
     * auto op = makeOperator(tag::test{}, [g](auto const& x) { return g(x); });
     * prob.addVectorOperator(BoundaryType{1}, op, _0);
     * ```
     **/
    template <class Operator, class TreePath = RootTreePath>
    void addVectorOperator(BoundaryType b, Operator const& op, TreePath path = {})
    {
      using I = typename GridView::Intersection;
      rhs_->addOperator(tag::boundary_operator<I>{boundaryManager_,b}, op, path);
    }
    /** @} */


    /// Add boundary conditions to the system
    /** @{ */
    /// Dirichlet boundary condition
    /**
     * Enforce Dirichlet boundary values for the solution vector on boundary
     * regions identified by the predicate.
     *
     * \param predicate  Functor `bool(WorldVector)` returning true for all
     *                   DOFs on the boundary that should be assigned a value.
     * \param row        TreePath identifying the sub-basis in the global basis tree
     *                   corresponding to the row basis. \see treepath()
     * \param col        TreePath identifying the sub-basis in the global basis tree
     *                   corresponding to the column basis. \see treepath()
     * \param values     Functor `Range(WorldVector)` or any \ref GridFunction
     *                   that is evaluated in the DOFs identified by the predicate.
     *
     * Example:
     * ```
     * prob.addDirichletBC([](auto const& x) { return x[0] < 1.e-8; }, 0, 0,
     *                     [](auto const& x) { return 0.0; });
     * ```
     **/
    template <class Predicate, class RowTreePath, class ColTreePath, class Values>
    void addDirichletBC(Predicate const& predicate,
                        RowTreePath row, ColTreePath col,
                        Values const& values);

    template <class RowTreePath, class ColTreePath, class Values>
    void addDirichletBC(BoundaryType id,
                        RowTreePath row, ColTreePath col,
                        Values const& values);

    /// Add a periodic boundary conditions to the system, by specifying a face transformation
    /// y = A*x + b of coordinates. We assume, that A is orthonormal.
    void addPeriodicBC(BoundaryType id, WorldMatrix const& A, WorldVector const& b);
    /** @} */


  public:

    /// Implementation of \ref StandardProblemIteration::oneIteration.
    Flag oneIteration(AdaptInfo& adaptInfo, Flag toDo = FULL_ITERATION) override
    {
      return StandardProblemIteration::oneIteration(adaptInfo, toDo);
    }

    /// Implementation of \ref ProblemStatBase::buildAfterCoarse
    void buildAfterAdapt(AdaptInfo& adaptInfo,
                         Flag flag,
                         bool asmMatrix = true,
                         bool asmVector = true) override;

    /// \brief Assemble the linear system by calling \ref buildAfterAdapt with
    /// `asmMatrix` and `asmVector` set to true.
    void assemble(AdaptInfo& adaptInfo)
    {
      buildAfterAdapt(adaptInfo, Flag{0}, true, true);
    }

    /// Implementation of \ref ProblemStatBase::solve
    void solve(AdaptInfo& adaptInfo,
               bool createMatrixData = true,
               bool storeMatrixData = false) override;

    /// Implementation of \ref ProblemStatBase::estimate.
    void estimate(AdaptInfo& adaptInfo) override { /* do nothing. */ }

    /// Implementation of \ref ProblemStatBase::refineMesh.
    Flag adaptGrid(AdaptInfo& adaptInfo) override;

    /// Implementation of \ref ProblemStatBase::markElements.
    Flag markElements(AdaptInfo& adaptInfo) override;

    /// Uniform global grid coarsening by up to n level
    Flag globalCoarsen(int n) override;

    /// Uniform global refinement by n level
    Flag globalRefine(int n) override;

    /// Writes output files.
    void writeFiles(AdaptInfo& adaptInfo, bool force = false);

    /// Backup the grid
    void backup(std::string const& filename) const;

    /// Implements \ref ProblemStatBase::backup
    void backup(AdaptInfo& adaptInfo) override;

    /// Retore the grid
    auto restore(std::string const& filename);

    /// Implements \ref ProblemStatBase::restore
    void restore(Flag initFlag) override;


  public: // get-methods

    /// Implementation of \ref ProblemStatBase::name
    std::string const& name() const override { return name_; }


    /// Return a reference to the grid, \ref grid
    std::shared_ptr<Grid>       grid()       { return grid_; }
    std::shared_ptr<Grid const> grid() const { return grid_; }

    /// Return the gridView of the leaf-level
    GridView gridView() const { return globalBasis_->gridView(); }

    /// Return the boundary manager to identify boundary segments
    std::shared_ptr<BoundaryManager<Grid>>       boundaryManager()       { return boundaryManager_; }
    std::shared_ptr<BoundaryManager<Grid> const> boundaryManager() const { return boundaryManager_; }

    /// Return the \ref globalBasis_
    std::shared_ptr<GlobalBasis>       globalBasis()       { return globalBasis_; }
    std::shared_ptr<GlobalBasis const> globalBasis() const { return globalBasis_; }

    /// Return a reference to the linear solver, \ref linearSolver
    std::shared_ptr<LinearSolverType>       solver()       { return linearSolver_; }
    std::shared_ptr<LinearSolverType const> solver() const { return linearSolver_; }

    /// Returns a reference to system-matrix, \ref systemMatrix_
    std::shared_ptr<SystemMatrix>       systemMatrix()       { return systemMatrix_; }
    std::shared_ptr<SystemMatrix const> systemMatrix() const { return systemMatrix_; }

    /// Returns a reference to the solution vector, \ref solution_
    std::shared_ptr<SystemVector>       solutionVector()       { return solution_; }
    std::shared_ptr<SystemVector const> solutionVector() const { return solution_; }

    /// Return a reference to the rhs system-vector, \ref rhs
    std::shared_ptr<SystemVector>       rhsVector()       { return rhs_; }
    std::shared_ptr<SystemVector const> rhsVector() const { return rhs_; }


    /// Return a mutable view to a solution component
    template <class TreePath = RootTreePath>
    auto solution(TreePath path = {})
    {
      assert(bool(solution_) && "You have to call initialize() before.");
      auto&& tp = makeTreePath(path);
      return makeDOFVectorView(*solution_, tp);
    }

    /// Return a const view to a solution component
    template <class TreePath = RootTreePath>
    auto solution(TreePath path = {}) const
    {
      assert(bool(solution_) && "You have to call initialize() before.");
      auto&& tp = makeTreePath(path);
      return makeDiscreteFunction(*solution_, tp);
    }


  public: // set-methods

    /// Set a new linear solver for the problem
    void setSolver(std::shared_ptr<LinearSolverType> solver)
    {
      linearSolver_ = solver;
    }

    /// Wrap the solver reference into a non-destroying shared_ptr, or move it
    /// into a new shared_ptr if it is a temporary.
    template <class S,
      REQUIRES(std::is_base_of<LinearSolverType, remove_cvref_t<S>>::value)>
    void setSolver(S&& solver)
    {
      setSolver(Dune::wrap_or_move(FWD(solver)));
    }


    /// Set the grid. Stores pointer and initializes feSpaces
    /// matrices and vectors, as well as markers and file-writers.
    void setGrid(std::shared_ptr<Grid> const& grid)
    {
      adoptGrid(grid);
      createGlobalBasis();
      createMatricesAndVectors();
      createMarker();
      createFileWriter();
    }

    /// Wrap the grid into a non-destroying shared_ptr
    void setGrid(Grid& grid)
    {
      setGrid(Dune::stackobject_to_shared_ptr(grid));
    }


    /// Store the shared_ptr and the name of the marker in the problem
    /**
     * Note: multiple markers can be added but must have different names
     **/
    void addMarker(std::shared_ptr<Marker<Grid>> marker)
    {
      auto it = marker_.emplace(marker->name(), std::move(marker));
      if (marker_.size() > 1)
        it.first->second->setMaximumMarking(true);
    }

    /// Wrap the reference into a non-destroying shared_ptr or move it into a
    /// new shared_ptr if it is a temporary.
    template <class M,
      REQUIRES(std::is_base_of<Marker<Grid>, remove_cvref_t<M>>::value)>
    void addMarker(M&& marker)
    {
      addMarker(Dune::wrap_or_move(FWD(marker)));
    }

    /// Remove a marker with the given name from the problem
    void removeMarker(std::string name)
    {
      std::size_t num = marker_.erase(name);
      test_warning(num == 1, "A marker with the given name '{}' does not exist.", name);
    }

    /// Remove a marker from the problem
    void removeMarker(Marker<Grid> const& marker)
    {
      removeMarker(marker.name());
    }


  protected: // initialization methods

    void createGlobalBasis();
    void createGrid();
    void createMatricesAndVectors();
    void createSolver();
    void createMarker();
    void createFileWriter();

    void adoptGlobalBasis(std::shared_ptr<GlobalBasis> const& globalBasis)
    {
      globalBasis_ = globalBasis;
      initGlobalBasis();
    }

    void adoptGrid(std::shared_ptr<Grid> const& grid,
                   std::shared_ptr<BoundaryManager<Grid>> const& boundaryManager)
    {
      grid_ = grid;
      boundaryManager_ = boundaryManager;
      Parameters::get(name_ + "->mesh", gridName_);
    }

    void adoptGrid(std::shared_ptr<Grid> const& grid)
    {
      adoptGrid(grid, std::make_shared<BoundaryManager<Grid>>(grid));
    }

  private:

    void createGlobalBasisImpl(std::true_type);
    void createGlobalBasisImpl(std::false_type);

    void initGlobalBasis();

  private:
    /// Name of this problem.
    std::string name_;

    /// Grid of this problem.
    std::shared_ptr<Grid> grid_;

    /// Name of the grid
    std::string gridName_ = "mesh";

    /// Management of boundary conditions
    std::shared_ptr<BoundaryManager<Grid>> boundaryManager_;

    /// FE spaces of this problem.
    std::shared_ptr<GlobalBasis> globalBasis_;

    /// A FileWriter object
    std::list<std::shared_ptr<FileWriterInterface>> filewriter_;

    /// Pointer to the adaptation markers
    std::map<std::string, std::shared_ptr<Marker<Grid>>> marker_;

    /// Pointer to the estimators for this problem
//    std::vector<Estimator*> estimator;

    /// An object of the linearSolver Interface
    std::shared_ptr<LinearSolverType> linearSolver_;

    /// Matrix that is filled during assembling
    std::shared_ptr<SystemMatrix> systemMatrix_;

    /// Vector with the solution components
    std::shared_ptr<SystemVector> solution_;

    /// Vector (load-vector) corresponding to the right-hand side
    /// of the equation, filled during assembling
    std::shared_ptr<SystemVector> rhs_;

    /// A vector with the local element error estimates
    /// for each node in the basis tree, indexed by [to_string(treePath)][element index]
    std::map<std::string, std::vector<double>> estimates_;


  private: // some internal data-structures

    DirichletBCs<GlobalBasis, GlobalBasis> dirichletBCs_;
    PeriodicBCs<GlobalBasis, GlobalBasis> periodicBCs_;
  };


#if DUNE_HAVE_CXX_CLASS_TEMPLATE_ARGUMENT_DEDUCTION
  // Deduction rule
  template <class Grid, class GlobalBasis>
  ProblemStat(std::string const& name, Grid& grid, GlobalBasis& globalBasis)
    -> ProblemStat<DefaultProblemTraits<GlobalBasis>>;
#endif

  // Generator for ProblemStat with given Grid and GlobalBasis
  template <class Grid, class GlobalBasis>
  ProblemStat<DefaultProblemTraits<GlobalBasis>>
  makeProblemStat(std::string const& name, Grid& grid, GlobalBasis& globalBasis)
  {
    return {name, grid, globalBasis};
  }

  // mark templates as explicitly instantiated in cpp file
  extern template class ProblemStat<YaspGridBasis<2,1>>;
  extern template class ProblemStat<YaspGridBasis<2,2>>;

} // end namespace AMDiS

#include "ProblemStat.inc.hpp"