// This file is part of Bertini 2.
//
// function_tree/roots/function.hpp 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.
//
// function_tree/roots/function.hpp 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with function_tree/roots/function.hpp.  If not, see
// <http://www.gnu.org/licenses/>.
//
//  Copyright(C) 2015 - 2021 by Bertini2 Development Team
//
//  See <http://www.gnu.org/licenses/> for a copy of the license,
//  as well as COPYING.  Bertini2 is provided with permitted
//  additional terms in the b2/licenses/ directory.

// individual authors of this file include:
//  James Collins
//  West Texas A&M University
//  Spring, Summer 2015
//
// silviana amethyst, university of wisconsin-eau claire
//
//  silviana amethyst
//  UWEC
//  Spring 2018
//
//  Created by Collins, James B. on 4/30/15.
//
//
// function_tree/roots/function.hpp:  Declares the class Function.

/**
\file function_tree/roots/function.hpp

\brief Provides the Function Node type, a NamedSymbol.

*/

#ifndef BERTINI_FUNCTION_NODE_HPP
#define BERTINI_FUNCTION_NODE_HPP

#include "function_tree/symbols/symbol.hpp"

namespace bertini {
namespace node {

class Handle : public virtual NamedSymbol {
  BERTINI_DEFAULT_VISITABLE()

 public:
  /**
   overridden function for piping the tree to an output stream.
   */
  void print(std::ostream& target) const override;

  Handle(std::string const& new_name);

  /**
   Constructor defines entry node at construct time.
   */
  Handle(const std::shared_ptr<Node>& entry,
         std::string const& name = "unnamed_function");

 protected:
  Handle() = default;

 public:
  /**
   Add a child onto the container for this operator
   */
  void SetRoot(std::shared_ptr<Node> const& entry);

  /**
   throws a runtime error if the root node is nullptr
   */
  void EnsureNotEmpty() const;

  /**
   The function which flips the fresh eval bit back to fresh.
   */
  void Reset() const override;

  /**
   Get the pointer to the entry node for this function.
   */
  const std::shared_ptr<Node>& EntryNode() const;

  /**
   Calls Differentiate on the entry node and returns differentiated entry node.
   */
  std::shared_ptr<Node> Differentiate(
      std::shared_ptr<Variable> const& v = nullptr) const override;

  /**
  Compute the degree of a node.  For functions, the degree is the degree of the
  entry node.
  */
  int Degree(std::shared_ptr<Variable> const& v = nullptr) const override;

  int Degree(VariableGroup const& vars) const override;

  /**
   Compute the multidegree with respect to a variable group.  This is for
   homogenization, and testing for homogeneity.
  */
  std::vector<int> MultiDegree(VariableGroup const& vars) const override;

  void Homogenize(VariableGroup const& vars,
                  std::shared_ptr<Variable> const& homvar) override;

  bool IsHomogeneous(
      std::shared_ptr<Variable> const& v = nullptr) const override;

  /**
  Check for homogeneity, with respect to a variable group.
  */
  bool IsHomogeneous(VariableGroup const& vars) const override;

  /**
   Change the precision of this variable-precision tree node.

   \param prec the number of digits to change precision to.
   */
  void precision(unsigned int prec) const override;

 protected:
  /**
   Calls FreshEval on the entry node to the tree.
   */
  dbl FreshEval_d(
      std::shared_ptr<Variable> const& diff_variable) const override;

  /**
   Calls FreshEval in place on the entry node to the tree.
   */
  void FreshEval_d(
      dbl& evaluation_value,
      std::shared_ptr<Variable> const& diff_variable) const override;

  /**
   Calls FreshEval on the entry node to the tree.
   */
  mpfr_complex FreshEval_mp(
      std::shared_ptr<Variable> const& diff_variable) const override;

  /**
   Calls FreshEval in place on the entry node to the tree.
   */
  void FreshEval_mp(
      mpfr_complex& evaluation_value,
      std::shared_ptr<Variable> const& diff_variable) const override;

  std::shared_ptr<Node> entry_node_ = nullptr;

 private:
  friend class boost::serialization::access;

  template <typename Archive>
  void serialize(Archive& ar, const unsigned version) {
    ar& boost::serialization::base_object<NamedSymbol>(*this);
    ar & entry_node_;
  }

};  // class Function

}  // namespace node
}  // namespace bertini

namespace bertini {
namespace node {

/**
\brief Formal entry point into an expression tree.

This class defines a function.  It stores the entry node for a particular
functions tree.
 */
class Function : public virtual Handle,
                 public virtual EnableSharedFromThisVirtual<Function> {
 public:
  BERTINI_DEFAULT_VISITABLE()

  template <typename... Ts>
  static std::shared_ptr<Function> Make(Ts&&... ts) {
    return std::shared_ptr<Function>(new Function(ts...));
  }

  template <typename... Ts>
  static std::shared_ptr<Function> MakeInPlace(Function* ptr, Ts&&... ts) {
    return std::shared_ptr<Function>(new (ptr) Function(ts...));
  }

 private:
  Function(std::string const& new_name);

  /**
   Constructor defines entry node at construct time.
   */
  Function(const std::shared_ptr<Node>& entry,
           std::string const& name = "unnamed_function");

 public:
  virtual ~Function() = default;

 protected:
  Function() = default;

 private:
  friend class boost::serialization::access;
  // template<class Archive> friend void
  // boost::serialization::load_construct_data(Archive & ar, Function * t, const
  // unsigned int file_version); template<class Archive> friend void
  // boost::serialization::save_construct_data(Archive & ar, const Function * t,
  // const unsigned int file_version);

  template <typename Archive>
  void serialize(Archive& ar, const unsigned version) {
    ar& boost::serialization::base_object<Handle>(*this);
  }
};

}  // namespace node
}  // namespace bertini

#endif