/*
 * Copyright © 2003-2022 Dynare Team
 *
 * This file is part of Dynare.
 *
 * Dynare 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.
 *
 * Dynare 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 Dynare.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef _DATATREE_HH
#define _DATATREE_HH

#include <string>
#include <map>
#include <vector>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <utility>
#include <memory>
#include <filesystem>
#include <string_view>

#include "SymbolTable.hh"
#include "NumericalConstants.hh"
#include "ExternalFunctionsTable.hh"
#include "ExprNode.hh"
#include "SubModel.hh"

using namespace std;

class DataTree
{
public:
  //! A reference to the symbol table
  SymbolTable &symbol_table;
  //! Reference to numerical constants table
  NumericalConstants &num_constants;
  //! A reference to the external functions table
  ExternalFunctionsTable &external_functions_table;
  //! Is it possible to use leads/lags on variable nodes?
  const bool is_dynamic;

private:
  //! num_constant_id -> NumConstNode
  using num_const_node_map_t = map<int, NumConstNode *>;
  num_const_node_map_t num_const_node_map;

  //! (symbol_id, lag) -> VariableNode
  using variable_node_map_t = map<pair<int, int>, VariableNode *>;
  variable_node_map_t variable_node_map;

  //! (arg, op_code, arg_exp_info_set, param1_symb_id, param2_symb_id, adl_param_name, adl_lags) -> UnaryOpNode
  using unary_op_node_map_t = map<tuple<expr_t, UnaryOpcode, int, int, int, string, vector<int>>, UnaryOpNode *>;
  unary_op_node_map_t unary_op_node_map;

  //! ( arg1, arg2, opCode, order of Power Derivative) -> BinaryOpNode
  using binary_op_node_map_t = map<tuple<expr_t, expr_t, BinaryOpcode, int>, BinaryOpNode *>;
  binary_op_node_map_t binary_op_node_map;

  //! ( arg1, arg2, arg3, opCode) -> TrinaryOpNode
  using trinary_op_node_map_t = map<tuple<expr_t, expr_t, expr_t, TrinaryOpcode>, TrinaryOpNode *>;
  trinary_op_node_map_t trinary_op_node_map;

  // (arguments, symb_id) -> ExternalFunctionNode
  using external_function_node_map_t = map<pair<vector<expr_t>, int>, ExternalFunctionNode *>;
  external_function_node_map_t external_function_node_map;

  // (model_name, symb_id, forecast_horizon) -> VarExpectationNode
  using var_expectation_node_map_t = map<string, VarExpectationNode *>;
  var_expectation_node_map_t var_expectation_node_map;

  // model_name -> PacExpectationNode
  using pac_expectation_node_map_t = map<string, PacExpectationNode *>;
  pac_expectation_node_map_t pac_expectation_node_map;

  // model_name -> PacTargetNonstationaryNode
  using pac_target_nonstationary_node_map_t = map<string, PacTargetNonstationaryNode *>;
  pac_target_nonstationary_node_map_t pac_target_nonstationary_node_map;

  // (arguments, deriv_idx, symb_id) -> FirstDerivExternalFunctionNode
  using first_deriv_external_function_node_map_t = map<tuple<vector<expr_t>, int, int>, FirstDerivExternalFunctionNode *>;
  first_deriv_external_function_node_map_t first_deriv_external_function_node_map;

  // (arguments, deriv_idx1, deriv_idx2, symb_id) -> SecondDerivExternalFunctionNode
  using second_deriv_external_function_node_map_t = map<tuple<vector<expr_t>, int, int, int>, SecondDerivExternalFunctionNode *>;
  second_deriv_external_function_node_map_t second_deriv_external_function_node_map;

  // Flag to disable simplifications related to commutativity of addition and multiplication
  static bool no_commutativity;

protected:
  //! Stores local variables value (maps symbol ID to corresponding node)
  map<int, expr_t> local_variables_table;
  //! Stores the order of appearance of local variables in the model block. Needed following change in #563
  vector<int> local_variables_vector;

  //! Internal implementation of ParamUsedWithLeadLag()
  bool ParamUsedWithLeadLagInternal() const;

  /* Writes the contents of “new_contents” to the file “filename”. However, if
     the file already exists and would not be modified by this operation, then do
     nothing. */
  static void writeToFileIfModified(stringstream &new_contents, const filesystem::path &filename);

private:
  constexpr static int constants_precision{16};

  //! The list of nodes
  vector<unique_ptr<ExprNode>> node_list;

  inline expr_t AddUnaryOp(UnaryOpcode op_code, expr_t arg, int arg_exp_info_set = 0, int param1_symb_id = 0, int param2_symb_id = 0, const string &adl_param_name = "", const vector<int> &adl_lags = vector<int>());
  inline expr_t AddBinaryOp(expr_t arg1, BinaryOpcode op_code, expr_t arg2, int powerDerivOrder = 0);
  inline expr_t AddTrinaryOp(expr_t arg1, TrinaryOpcode op_code, expr_t arg2, expr_t arg3);

  //! Initializes the predefined constants, used only from the constructors
  void initConstants();

public:
  DataTree(SymbolTable &symbol_table_arg,
           NumericalConstants &num_constants_arg,
           ExternalFunctionsTable &external_functions_table_arg,
           bool is_static_args = false);

  virtual ~DataTree() = default;

  DataTree(const DataTree &d);
  DataTree &operator=(const DataTree &d);

  //! Some predefined constants
  NumConstNode *Zero, *One, *Two, *Three, *NaN, *Infinity, *Pi;
  expr_t MinusOne, MinusInfinity;

  //! Raised when a local parameter is declared twice
  struct LocalVariableException
  {
    string name;
  };

  class DivisionByZeroException
  {
  };

  inline expr_t AddPossiblyNegativeConstant(double val);
  //! Adds a non-negative numerical constant (possibly Inf or NaN)
  NumConstNode *AddNonNegativeConstant(const string &value);
  //! Adds a variable
  VariableNode *AddVariable(int symb_id, int lag = 0);
  //! Gets a variable
  /*! Same as AddVariable, except that it fails if the variable node has not
    already been created */
  VariableNode *getVariable(int symb_id, int lag = 0) const;
  //! Adds "arg1+arg2" to model tree
  expr_t AddPlus(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1-arg2" to model tree
  expr_t AddMinus(expr_t iArg1, expr_t iArg2);
  //! Adds "-arg" to model tree
  expr_t AddUMinus(expr_t iArg1);
  //! Adds "arg1*arg2" to model tree
  expr_t AddTimes(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1/arg2" to model tree
  expr_t AddDivide(expr_t iArg1, expr_t iArg2) noexcept(false);
  //! Adds "arg1<arg2" to model tree
  expr_t AddLess(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1>arg2" to model tree
  expr_t AddGreater(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1<=arg2" to model tree
  expr_t AddLessEqual(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1>=arg2" to model tree
  expr_t AddGreaterEqual(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1==arg2" to model tree
  expr_t AddEqualEqual(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1!=arg2" to model tree
  expr_t AddDifferent(expr_t iArg1, expr_t iArg2);
  //! Adds "arg1^arg2" to model tree
  expr_t AddPower(expr_t iArg1, expr_t iArg2);
  //! Adds "getPowerDeriv(arg1, arg2, powerDerivOrder)" to model tree
  expr_t AddPowerDeriv(expr_t iArg1, expr_t iArg2, int powerDerivOrder);
  //! Adds "E(arg1)(arg2)" to model tree
  expr_t AddExpectation(int iArg1, expr_t iArg2);
  //! Adds "diff(arg)" to model tree
  expr_t AddDiff(expr_t iArg1);
  //! Adds "adl(arg1, name, lag/lags)" to model tree
  expr_t AddAdl(expr_t iArg1, const string &name, const vector<int> &lags);
  //! Adds "exp(arg)" to model tree
  expr_t AddExp(expr_t iArg1);
  //! Adds "log(arg)" to model tree
  expr_t AddLog(expr_t iArg1);
  //! Adds "log10(arg)" to model tree
  expr_t AddLog10(expr_t iArg1);
  //! Adds "cos(arg)" to model tree
  expr_t AddCos(expr_t iArg1);
  //! Adds "sin(arg)" to model tree
  expr_t AddSin(expr_t iArg1);
  //! Adds "tan(arg)" to model tree
  expr_t AddTan(expr_t iArg1);
  //! Adds "acos(arg)" to model tree
  expr_t AddAcos(expr_t iArg1);
  //! Adds "asin(arg)" to model tree
  expr_t AddAsin(expr_t iArg1);
  //! Adds "atan(arg)" to model tree
  expr_t AddAtan(expr_t iArg1);
  //! Adds "cosh(arg)" to model tree
  expr_t AddCosh(expr_t iArg1);
  //! Adds "sinh(arg)" to model tree
  expr_t AddSinh(expr_t iArg1);
  //! Adds "tanh(arg)" to model tree
  expr_t AddTanh(expr_t iArg1);
  //! Adds "acosh(arg)" to model tree
  expr_t AddAcosh(expr_t iArg1);
  //! Adds "asinh(arg)" to model tree
  expr_t AddAsinh(expr_t iArg1);
  //! Adds "atanh(args)" to model tree
  expr_t AddAtanh(expr_t iArg1);
  //! Adds "sqrt(arg)" to model tree
  expr_t AddSqrt(expr_t iArg1);
  //! Adds "cbrt(arg)" to model tree
  expr_t AddCbrt(expr_t iArg1);
  //! Adds "abs(arg)" to model tree
  expr_t AddAbs(expr_t iArg1);
  //! Adds "sign(arg)" to model tree
  expr_t AddSign(expr_t iArg1);
  //! Adds "erf(arg)" to model tree
  expr_t AddErf(expr_t iArg1);
  //! Adds "erfc(arg)" to model tree
  expr_t AddErfc(expr_t iArg1);
  //! Adds "max(arg1,arg2)" to model tree
  expr_t AddMax(expr_t iArg1, expr_t iArg2);
  //! Adds "min(arg1,arg2)" to model tree
  expr_t AddMin(expr_t iArg1, expr_t iArg2);
  //! Adds "normcdf(arg1,arg2,arg3)" to model tree
  expr_t AddNormcdf(expr_t iArg1, expr_t iArg2, expr_t iArg3);
  //! Adds "normpdf(arg1,arg2,arg3)" to model tree
  expr_t AddNormpdf(expr_t iArg1, expr_t iArg2, expr_t iArg3);
  //! Adds "steadyState(arg)" to model tree
  expr_t AddSteadyState(expr_t iArg1);
  //! Add derivative of steady state w.r.t. parameter to model tree
  expr_t AddSteadyStateParamDeriv(expr_t iArg1, int param_symb_id);
  //! Add 2nd derivative of steady state w.r.t. parameter to model tree
  expr_t AddSteadyStateParam2ndDeriv(expr_t iArg1, int param1_symb_id, int param2_symb_id);
  //! Adds "arg1=arg2" to model tree
  BinaryOpNode *AddEqual(expr_t iArg1, expr_t iArg2);
  //! Adds "var_expectation(model_name)" to model tree
  expr_t AddVarExpectation(const string &model_name);
  //! Adds pac_expectation command to model tree
  expr_t AddPacExpectation(const string &model_name);
  //! Adds a pac_target_nonstationary node to model tree
  expr_t AddPacTargetNonstationary(const string &model_name);
  //! Adds a model local variable with its value
  void AddLocalVariable(int symb_id, expr_t value) noexcept(false);
  //! Adds an external function node
  expr_t AddExternalFunction(int symb_id, const vector<expr_t> &arguments);
  //! Adds an external function node for the first derivative of an external function
  expr_t AddFirstDerivExternalFunction(int top_level_symb_id, const vector<expr_t> &arguments, int input_index);
  //! Adds an external function node for the second derivative of an external function
  expr_t AddSecondDerivExternalFunction(int top_level_symb_id, const vector<expr_t> &arguments, int input_index1, int input_index2);
  //! Checks if a given symbol is used somewhere in the data tree
  bool isSymbolUsed(int symb_id) const;
  //! Checks if a given unary op is used somewhere in the data tree
  bool isUnaryOpUsed(UnaryOpcode opcode) const;
  //! Checks if a given unary op is used somewhere in the data tree on an endogenous variable
  bool isUnaryOpUsedOnType(SymbolType type, UnaryOpcode opcode) const;
  //! Checks if a given binary op is used somewhere in the data tree
  bool isBinaryOpUsed(BinaryOpcode opcode) const;
  //! Checks if a given binary op is used somewhere in the data tree on an endogenous variable
  bool isBinaryOpUsedOnType(SymbolType type, BinaryOpcode opcode) const;
  //! Returns the minimum lag (as a negative number) of the given symbol in the whole data tree (and not only in the equations !!)
  /*! Returns 0 if the symbol is not used */
  int minLagForSymbol(int symb_id) const;
  //! Write getPowerDeriv in C (function body)
  void writePowerDeriv(ostream &output) const;
  //! Write getPowerDeriv in C (prototype)
  void writePowerDerivHeader(ostream &output) const;
  //! Thrown when trying to access an unknown variable by deriv_id
  class UnknownDerivIDException
  {
  };

  //! Raised when a trend is declared twice
  struct TrendException
  {
    string name;
  };

  // Returns the derivation ID, or throws an exception if the derivation ID does not exist
  virtual int getDerivID(int symb_id, int lag) const noexcept(false);
  // Get the type corresponding to a derivation ID
  virtual SymbolType getTypeByDerivID(int deriv_id) const noexcept(false);
  // Get the lag corresponding to a derivation ID
  virtual int getLagByDerivID(int deriv_id) const noexcept(false);
  // Get the symbol ID corresponding to a derivation ID
  virtual int getSymbIDByDerivID(int deriv_id) const noexcept(false);
  // Get the type-specific ID corresponding to a derivation ID
  virtual int getTypeSpecificIDByDerivID(int deriv_id) const;
  // Get the symbol name corresponding to a derivation ID
  string
  getNameByDerivID(int deriv_id) const
  {
    return symbol_table.getName(getSymbIDByDerivID(deriv_id));
  }

  /* Returns the column of the Jacobian associated to a derivation ID.
     The “sparse” argument selects between the legacy representation and the
     sparse representation. */
  virtual int
  getJacobianCol([[maybe_unused]] int deriv_id, [[maybe_unused]] bool sparse) const
  {
    throw UnknownDerivIDException();
  }

  /* Returns the number of columns of the Jacobian
     The “sparse” argument selects between the legacy representation and the
     sparse representation. */
  virtual int
  getJacobianColsNbr([[maybe_unused]] bool sparse) const
  {
    throw UnknownDerivIDException();
  }

  //! Adds to the set all the deriv IDs corresponding to parameters
  virtual void addAllParamDerivId(set<int> &deriv_id_set);

  //! Returns bool indicating whether DataTree represents a Dynamic Model (returns true in DynamicModel.hh)
  virtual bool
  isDynamic() const
  {
    return false;
  };

  struct UnknownLocalVariableException
  {
    //! Symbol ID
    int id;
  };

  expr_t
  getLocalVariable(int symb_id) const
  {
    auto it = local_variables_table.find(symb_id);
    if (it == local_variables_table.end())
      throw UnknownLocalVariableException(symb_id);

    return it->second;
  }

  static void
  setNoCommutativity()
  {
    no_commutativity = true;
  }

  /* Equivalent of MATLAB/Octave’s strsplit, except that it ignores empty
     substring components (MATLAB/Octave adds them to the output); in
     particular, returns an empty vector given an empty string. */
  static vector<string> strsplit(string_view str, char delim);

  /*! Takes a MATLAB/Octave package name (possibly with several levels nested using dots),
    and returns the path to the corresponding filesystem directory.
    In practice the package nesting is used for the planner_objective (stored
    inside +objective subdir). */
  static filesystem::path packageDir(string_view package);
};

inline expr_t
DataTree::AddPossiblyNegativeConstant(double v)
{
  /* Treat NaN and Inf separately. In particular, under Windows, converting
     them to a string does not work as expected */
  if (isnan(v))
    return NaN;
  if (isinf(v))
    return (v < 0 ? MinusInfinity : Infinity);

  bool neg = false;
  if (v < 0)
    {
      v = -v;
      neg = true;
    }
  ostringstream ost;
  ost << setprecision(constants_precision) << v;

  expr_t cnode = AddNonNegativeConstant(ost.str());

  if (neg)
    return AddUMinus(cnode);
  else
    return cnode;
}

inline expr_t
DataTree::AddUnaryOp(UnaryOpcode op_code, expr_t arg, int arg_exp_info_set, int param1_symb_id, int param2_symb_id, const string &adl_param_name, const vector<int> &adl_lags)
{
  // If the node already exists in tree, share it
  if (auto it = unary_op_node_map.find({ arg, op_code, arg_exp_info_set, param1_symb_id, param2_symb_id, adl_param_name, adl_lags });
      it != unary_op_node_map.end())
    return it->second;

  // Try to reduce to a constant
  // Case where arg is a constant and op_code == UnaryOpcode::uminus (i.e. we're adding a negative constant) is skipped
  if (auto carg = dynamic_cast<NumConstNode *>(arg);
      op_code != UnaryOpcode::uminus || !carg)
    {
      try
        {
          double argval = arg->eval({});
          double val = UnaryOpNode::eval_opcode(op_code, argval);
          return AddPossiblyNegativeConstant(val);
        }
      catch (ExprNode::EvalException &e)
        {
        }
    }

  auto sp = make_unique<UnaryOpNode>(*this, node_list.size(), op_code, arg, arg_exp_info_set, param1_symb_id, param2_symb_id, adl_param_name, adl_lags);
  auto p = sp.get();
  node_list.push_back(move(sp));
  unary_op_node_map[{ arg, op_code, arg_exp_info_set, param1_symb_id, param2_symb_id, adl_param_name, adl_lags }] = p;
  return p;
}

inline expr_t
DataTree::AddBinaryOp(expr_t arg1, BinaryOpcode op_code, expr_t arg2, int powerDerivOrder)
{
  if (auto it = binary_op_node_map.find({ arg1, arg2, op_code, powerDerivOrder });
      it != binary_op_node_map.end())
    return it->second;

  // Try to reduce to a constant
  try
    {
      double argval1 = arg1->eval({});
      double argval2 = arg2->eval({});
      double val = BinaryOpNode::eval_opcode(argval1, op_code, argval2, powerDerivOrder);
      return AddPossiblyNegativeConstant(val);
    }
  catch (ExprNode::EvalException &e)
    {
    }

  auto sp = make_unique<BinaryOpNode>(*this, node_list.size(), arg1, op_code, arg2, powerDerivOrder);
  auto p = sp.get();
  node_list.push_back(move(sp));
  binary_op_node_map[{ arg1, arg2, op_code, powerDerivOrder }] = p;
  return p;
}

inline expr_t
DataTree::AddTrinaryOp(expr_t arg1, TrinaryOpcode op_code, expr_t arg2, expr_t arg3)
{
  if (auto it = trinary_op_node_map.find({ arg1, arg2, arg3, op_code });
      it != trinary_op_node_map.end())
    return it->second;

  // Try to reduce to a constant
  try
    {
      double argval1 = arg1->eval({});
      double argval2 = arg2->eval({});
      double argval3 = arg3->eval({});
      double val = TrinaryOpNode::eval_opcode(argval1, op_code, argval2, argval3);
      return AddPossiblyNegativeConstant(val);
    }
  catch (ExprNode::EvalException &e)
    {
    }

  auto sp = make_unique<TrinaryOpNode>(*this, node_list.size(), arg1, op_code, arg2, arg3);
  auto p = sp.get();
  node_list.push_back(move(sp));
  trinary_op_node_map[{ arg1, arg2, arg3, op_code }] = p;
  return p;
}

#endif