#ifndef GRID_LATTICE_ET_H
#define GRID_LATTICE_ET_H

#include <iostream>
#include <vector>
#include <tuple>
#include <typeinfo>

namespace Grid {

////////////////////////////////////////////
// recursive evaluation of expressions; Could
// switch to generic approach with variadics, a la
// Antonin's Lat Sim but the repack to variadic with popped
// from tuple is hideous; C++14 introduces std::make_index_sequence for this
////////////////////////////////////////////


//leaf eval of lattice ; should enable if protect using traits

template <typename T> using is_lattice      = std::is_base_of<LatticeBase,T >;

template <typename T> using is_lattice_expr = std::is_base_of<LatticeExpressionBase,T >;

template<class sobj>
inline sobj eval(const unsigned int ss, const sobj &arg)
{
  return arg;
}
template<class lobj>
inline const lobj &eval(const unsigned int ss, const Lattice<lobj> &arg)
{
    return arg._odata[ss];
}

// handle nodes in syntax tree
template <typename Op, typename T1>
auto inline eval(const unsigned int ss, const LatticeUnaryExpression<Op,T1 > &expr) // eval one operand
  -> decltype(expr.first.func(eval(ss,std::get<0>(expr.second))))
{
  return expr.first.func(eval(ss,std::get<0>(expr.second)));
}

template <typename Op, typename T1, typename T2>
auto inline eval(const unsigned int ss, const LatticeBinaryExpression<Op,T1,T2> &expr) // eval two operands
  -> decltype(expr.first.func(eval(ss,std::get<0>(expr.second)),eval(ss,std::get<1>(expr.second))))
{
  return expr.first.func(eval(ss,std::get<0>(expr.second)),eval(ss,std::get<1>(expr.second)));
}

template <typename Op, typename T1, typename T2, typename T3>
auto inline eval(const unsigned int ss, const LatticeTrinaryExpression<Op,T1,T2,T3 > &expr) // eval three operands
  -> decltype(expr.first.func(eval(ss,std::get<0>(expr.second)),eval(ss,std::get<1>(expr.second)),eval(ss,std::get<2>(expr.second))))
{
  return expr.first.func(eval(ss,std::get<0>(expr.second)),eval(ss,std::get<1>(expr.second)),eval(ss,std::get<2>(expr.second)) );
}

//////////////////////////////////////////////////////////////////////////
// Obtain the grid from an expression, ensuring conformable. This must follow a tree recursion
//////////////////////////////////////////////////////////////////////////
template<class T1, typename std::enable_if<is_lattice<T1>::value, T1>::type * =nullptr >
inline void GridFromExpression(GridBase * &grid,const T1& lat)   // Lattice leaf
{
  if ( grid ) {
    conformable(grid,lat._grid);
  } 
  grid=lat._grid;
}
template <typename Op, typename T1>
inline void GridFromExpression(GridBase * &grid,const LatticeUnaryExpression<Op,T1 > &expr)
{
  GridFromExpression(grid,std::get<0>(expr.second));// recurse 
}

template <typename Op, typename T1, typename T2>
inline void GridFromExpression(GridBase * &grid,const LatticeBinaryExpression<Op,T1,T2> &expr) 
{
  GridFromExpression(grid,std::get<0>(expr.second));// recurse
  GridFromExpression(grid,std::get<1>(expr.second));
}
template <typename Op, typename T1, typename T2, typename T3>
inline void GridFromExpression( GridBase * &grid,const LatticeTrinaryExpression<Op,T1,T2,T3 > &expr) 
{
  GridFromExpression(grid,std::get<0>(expr.second));// recurse
  GridFromExpression(grid,std::get<1>(expr.second));
  GridFromExpression(grid,std::get<2>(expr.second));
}
template<class T1,typename std::enable_if<!is_lattice<T1>::value, T1>::type * = nullptr >
inline void GridFromExpression(GridBase * &grid,const T1& notlat)   // non-lattice leaf
{
}

////////////////////////////////////////////
// Unary operators and funcs
////////////////////////////////////////////
#define GridUnopClass(name,ret)\
template <class arg> struct name\
{\
  static auto inline func(const arg a)-> decltype(ret) { return ret; } \
};

GridUnopClass(UnarySub,-a);
GridUnopClass(UnaryAdj,adj(a));
GridUnopClass(UnaryConj,conj(a));
GridUnopClass(UnaryTrace,trace(a));
GridUnopClass(UnaryTranspose,transpose(a));

////////////////////////////////////////////
// Binary operators
////////////////////////////////////////////
#define GridBinOpClass(name,combination)\
template <class left,class right>\
struct name\
{\
  static auto inline func(const left &lhs,const right &rhs)-> decltype(combination) const \
    {\
      return combination;\
    }\
}
GridBinOpClass(BinaryAdd,lhs+rhs);
GridBinOpClass(BinarySub,lhs-rhs);
GridBinOpClass(BinaryMul,lhs*rhs);

////////////////////////////////////////////
// Operator syntactical glue
////////////////////////////////////////////
 
#define GRID_UNOP(name)   name<decltype(eval(0, arg))>
#define GRID_BINOP(name)  name<decltype(eval(0, lhs)), decltype(eval(0, rhs))>
#define GRID_TRINOP(name) name<decltype(eval(0, pred)), decltype(eval(0, lhs)), decltype(eval(0, rhs))>

#define GRID_DEF_UNOP(op, name)\
template <typename T1,\
  typename std::enable_if<is_lattice<T1>::value||is_lattice_expr<T1>::value, T1>::type* = nullptr> inline auto op(const T1 &arg) \
  -> decltype(LatticeUnaryExpression<GRID_UNOP(name),const T1&>(std::make_pair(GRID_UNOP(name)(),std::forward_as_tuple(arg)))) \
{ return LatticeUnaryExpression<GRID_UNOP(name), const T1 &>(std::make_pair(GRID_UNOP(name)(),std::forward_as_tuple(arg))); }

#define GRID_BINOP_LEFT(op, name)\
template <typename T1,typename T2,\
          typename std::enable_if<is_lattice<T1>::value||is_lattice_expr<T1>::value, T1>::type* = nullptr>\
inline auto op(const T1 &lhs,const T2&rhs) \
  -> decltype(LatticeBinaryExpression<GRID_BINOP(name),const T1&,const T2 &>(std::make_pair(GRID_BINOP(name)(),\
											    std::forward_as_tuple(lhs, rhs)))) \
{\
 return LatticeBinaryExpression<GRID_BINOP(name), const T1 &, const T2 &>(std::make_pair(GRID_BINOP(name)(),\
									  std::forward_as_tuple(lhs, rhs))); \
}

#define GRID_BINOP_RIGHT(op, name)\
 template <typename T1,typename T2,\
           typename std::enable_if<!is_lattice<T1>::value && !is_lattice_expr<T1>::value, T1>::type* = nullptr,\
           typename std::enable_if< is_lattice<T2>::value ||  is_lattice_expr<T2>::value, T2>::type* = nullptr> \
inline auto op(const T1 &lhs,const T2&rhs)			\
  -> decltype(LatticeBinaryExpression<GRID_BINOP(name),const T1&,const T2 &>(std::make_pair(GRID_BINOP(name)(),\
											    std::forward_as_tuple(lhs, rhs)))) \
{\
 return LatticeBinaryExpression<GRID_BINOP(name), const T1 &, const T2 &>(std::make_pair(GRID_BINOP(name)(),\
								          std::forward_as_tuple(lhs, rhs))); \
}

#define GRID_DEF_BINOP(op, name)\
 GRID_BINOP_LEFT(op,name);\
 GRID_BINOP_RIGHT(op,name);


#define GRID_DEF_TRINOP(op, name)\
template <typename T1,typename T2,typename T3> inline auto op(const T1 &pred,const T2&lhs,const T3 &rhs) \
  -> decltype(LatticeTrinaryExpression<GRID_TRINOP(name),const T1&,const T2 &,const T3&>(std::make_pair(GRID_TRINOP(name)(),\
										   std::forward_as_tuple(pred,lhs,rhs)))) \
{\
  return LatticeTrinaryExpression<GRID_TRINOP(name), const T1 &, const T2 &,const T3&>(std::make_pair(GRID_TRINOP(name)(), \
										 std::forward_as_tuple(pred,lhs, rhs))); \
}
////////////////////////
//Operator definitions
////////////////////////

GRID_DEF_UNOP(operator -,UnarySub);
GRID_DEF_UNOP(adj,UnaryAdj);
GRID_DEF_UNOP(conj,UnaryConj);
GRID_DEF_UNOP(trace,UnaryTrace);
GRID_DEF_UNOP(transpose,UnaryTranspose);

GRID_DEF_BINOP(operator+,BinaryAdd);
GRID_DEF_BINOP(operator-,BinarySub);
GRID_DEF_BINOP(operator*,BinaryMul);

#undef GRID_UNOP
#undef GRID_BINOP
#undef GRID_TRINOP

#undef GRID_DEF_UNOP
#undef GRID_DEF_BINOP
#undef GRID_DEF_TRINOP

}

#if 0
using namespace Grid;
 	      
 int main(int argc,char **argv){
   
   Lattice<double> v1(16);
   Lattice<double> v2(16);
   Lattice<double> v3(16);

   BinaryAdd<double,double> tmp;
   LatticeBinaryExpression<BinaryAdd<double,double>,Lattice<double> &,Lattice<double> &> 
     expr(std::make_pair(tmp,
	  std::forward_as_tuple(v1,v2)));
   tmp.func(eval(0,v1),eval(0,v2));

   auto var = v1+v2;
   std::cout<<typeid(var).name()<<std::endl;

   v3=v1+v2;
   v3=v1+v2+v1*v2;
 };

void testit(Lattice<double> &v1,Lattice<double> &v2,Lattice<double> &v3)
{
   v3=v1+v2+v1*v2;
}
#endif

#endif