// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Mehdi Goli    Codeplay Software Ltd.
// Ralph Potter  Codeplay Software Ltd.
// Luke Iwanski  Codeplay Software Ltd.
// Cummins Chris PhD student at The University of Edinburgh.
// Contact: <eigen@codeplay.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

/*****************************************************************
 * TensorSyclRun.h
 *
 * \brief:
 * Schedule_kernel invoke an specialised version of kernel struct. The
 * specialisation is based on the data dimension in sycl buffer
 *
*****************************************************************/

#ifndef UNSUPPORTED_EIGEN_CXX11_SRC_TENSOR_TENSORSYCL_SYCLRUN_HPP
#define UNSUPPORTED_EIGEN_CXX11_SRC_TENSOR_TENSORSYCL_SYCLRUN_HPP

namespace Eigen {
namespace TensorSycl {


  template<typename Expr, typename FunctorExpr, typename TupleType > struct ExecExprFunctorKernel{
    typedef  typename internal::createPlaceHolderExpression<Expr>::Type PlaceHolderExpr;

    typedef typename Expr::Index Index;
    Index range;
    FunctorExpr functors;
    TupleType tuple_of_accessors;
  ExecExprFunctorKernel(Index range_
    ,
    FunctorExpr functors_, TupleType tuple_of_accessors_
                        )
  :range(range_)
  , functors(functors_), tuple_of_accessors(tuple_of_accessors_)
  {}
    void operator()(cl::sycl::nd_item<1> itemID) {
      typedef  typename internal::ConvertToDeviceExpression<Expr>::Type DevExpr;
      auto device_expr =internal::createDeviceExpression<DevExpr, PlaceHolderExpr>(functors, tuple_of_accessors);
      auto device_evaluator = Eigen::TensorEvaluator<decltype(device_expr.expr), Eigen::DefaultDevice>(device_expr.expr, Eigen::DefaultDevice());
      typename DevExpr::Index gId = static_cast<typename DevExpr::Index>(itemID.get_global_linear_id());
      if (gId < range)
        device_evaluator.evalScalar(gId);
    }
  };
/// The run function in tensor sycl convert the expression tree to a buffer
/// based expression tree;
/// creates the expression tree for the device with accessor to buffers;
/// construct the kernel and submit it to the sycl queue.
template <typename Expr, typename Dev>
void run(Expr &expr, Dev &dev) {
  Eigen::TensorEvaluator<Expr, Dev> evaluator(expr, dev);
  const bool needs_assign = evaluator.evalSubExprsIfNeeded(NULL);
  if (needs_assign) {
    auto functors = internal::extractFunctors(evaluator);
    typedef decltype(functors) FunctorExpr;
    dev.sycl_queue().submit([&](cl::sycl::handler &cgh) {
      // create a tuple of accessors from Evaluator
      auto tuple_of_accessors = internal::createTupleOfAccessors<decltype(evaluator)>(cgh, evaluator);
      typedef decltype(tuple_of_accessors) TupleType;
      typename Expr::Index range, GRange, tileSize;
      dev.parallel_for_setup(static_cast<typename Expr::Index>(evaluator.dimensions().TotalSize()), tileSize, range, GRange);

      cgh.parallel_for(cl::sycl::nd_range<1>(cl::sycl::range<1>(GRange), cl::sycl::range<1>(tileSize)),
      ExecExprFunctorKernel<Expr,FunctorExpr,TupleType>(range
        , functors, tuple_of_accessors
      ));
    });
      dev.asynchronousExec();
  }
  evaluator.cleanup();
}
}  // namespace TensorSycl
}  // namespace Eigen

#endif  // UNSUPPORTED_EIGEN_CXX11_SRC_TENSOR_TENSORSYCL_SYCLRUN_HPP