/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2014  Virginia Tech
 *
 *  This program 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.
 *
 *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Justus Calvin
 *  Department of Chemistry, Virginia Tech
 *
 *  tsr_engine.h
 *  Mar 31, 2014
 *
 */

#ifndef TILEDARRAY_EXPRESSIONS_TSR_ENGINE_H__INCLUDED
#define TILEDARRAY_EXPRESSIONS_TSR_ENGINE_H__INCLUDED

#include <TiledArray/expressions/leaf_engine.h>
#include <TiledArray/tile_op/noop.h>
#include <TiledArray/tile_op/unary_wrapper.h>

namespace TiledArray {

// Forward declaration
template <typename, typename>
class DistArray;

namespace expressions {

// Forward declaration
template <typename, bool>
class TsrExpr;
template <typename, typename, bool>
class TsrEngine;

template <typename Tile, typename Policy, typename Result, bool Alias>
struct EngineTrait<TsrEngine<DistArray<Tile, Policy>, Result, Alias> > {
  // Argument typedefs
  typedef DistArray<Tile, Policy> array_type;  ///< The array type

  // Operational typedefs
  // Note: the consumable flag is true for noop to avoid unnecessary copies.
  // This is OK because the result consumable flag is set to false.
  typedef TiledArray::detail::Noop<Result, typename array_type::eval_type,
                                   true>
      op_base_type;  ///< The tile operation
  typedef TiledArray::detail::UnaryWrapper<op_base_type> op_type;
  typedef TiledArray::detail::LazyArrayTile<typename array_type::value_type,
                                            op_type>
      value_type;  ///< Tile type
  typedef typename eval_trait<value_type>::type
      eval_type;  ///< Evaluation tile type
  typedef typename TiledArray::detail::scalar_type<DistArray<Tile,
                                                             Policy> >::type
      scalar_type;        ///< Scalar type of tile
  typedef Policy policy;  ///< Policy type
  typedef TiledArray::detail::DistEval<value_type, policy>
      dist_eval_type;  ///< The distributed evaluator type

  // Meta data typedefs
  typedef typename policy::ordinal_type size_type;   ///< Size type
  typedef typename policy::trange_type trange_type;  ///< Tiled range type
  typedef typename policy::shape_type shape_type;    ///< Shape type
  typedef typename policy::pmap_interface
      pmap_interface;  ///< Process map interface type

  static constexpr bool consumable =
      (!Alias) || eval_trait<typename array_type::value_type>::is_consumable;
  static constexpr unsigned int leaves = 1;
};

/// Tensor expression engine

/// \tparam Array The `DistArray` type
/// \tparam Alias Indicates the array tiles should be computed as a
/// temporary before assignment
/// \tparam Result The result tile type
template <typename Array, typename Result, bool Alias>
class TsrEngine : public LeafEngine<TsrEngine<Array, Result, Alias> > {
 public:
  // Class hierarchy typedefs
  typedef TsrEngine<Array, Result, Alias> TsrEngine_;  ///< This class type
  typedef LeafEngine<TsrEngine_> LeafEngine_;          ///< Leaf base class type
  typedef typename LeafEngine_::ExprEngine_
      ExprEngine_;  ///< Expression engine base class

  // Argument typedefs
  typedef typename EngineTrait<TsrEngine_>::array_type
      array_type;  ///< The left-hand expression type

  // Operational typedefs
  typedef typename EngineTrait<TsrEngine_>::value_type
      value_type;  ///< Tensor value type
  typedef typename EngineTrait<TsrEngine_>::op_base_type
      op_base_type;  ///< Tile base operation type
  typedef typename EngineTrait<TsrEngine_>::op_type
      op_type;  ///< Tile operation type
  typedef typename EngineTrait<TsrEngine_>::policy
      policy;  ///< The result policy type
  typedef typename EngineTrait<TsrEngine_>::dist_eval_type
      dist_eval_type;  ///< This expression's distributed evaluator type

  // Meta data typedefs
  typedef typename EngineTrait<TsrEngine_>::size_type size_type;  ///< Size type
  typedef typename EngineTrait<TsrEngine_>::trange_type
      trange_type;  ///< Tiled range type type
  typedef typename EngineTrait<TsrEngine_>::shape_type
      shape_type;  ///< Tensor shape type
  typedef typename EngineTrait<TsrEngine_>::pmap_interface
      pmap_interface;  ///< Process map interface type

  template <typename A>
  TsrEngine(const TsrExpr<A, Alias>& expr) : LeafEngine_(expr) {}

  /// Non-permuting tile operation factory function

  /// \return The tile operation
  static op_type make_tile_op() { return op_type(op_base_type()); }

  /// Permuting tile operation factory function

  /// \param perm The permutation to be applied to tiles
  /// \return The tile operation
  static op_type make_tile_op(const Permutation& perm) {
    return op_type(op_base_type(), perm);
  }

};  // class TsrEngine

}  // namespace expressions
}  // namespace TiledArray

#endif  // TILEDARRAY_EXPRESSIONS_TSR_ENGINE_H__INCLUDED
