//============================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//============================================================================
$# This file uses the pyexpander macro processing utility to build the
$# FunctionInterface facilities that use a variable number of arguments.
$# Information, documentation, and downloads for pyexpander can be found at:
$#
$#     http://pyexpander.sourceforge.net/
$#
$# To build the source code, execute the following (after installing
$# pyexpander, of course):
$#
$#     expander.py WorkletInvokeFunctorDetail.h.in > WorkletInvokeFunctorDetail.h
$#
$# Ignore the following comment. It is meant for the generated file.
// **** DO NOT EDIT THIS FILE!!! ****
// This file is automatically generated by WorkletInvokeFunctorDetail.h.in

// Technically speaking, we can implement this functionality with some clever
// use of FunctionInterface rather than using pyexpander to make variadic
// code. However, this code is probably more friendly to compilers. I expect
// it to compiler faster and optimize better.

#ifndef vtk_m_exec_internal_WorkletInvokeFunctorDetail_h
#define vtk_m_exec_internal_WorkletInvokeFunctorDetail_h

#if !defined(vtk_m_exec_internal_TaskSingular_h) && \\
    !defined(vtk_m_exec_internal_TaskTiling_h) &&  \\
    !defined(vtk_m_exec_cuda_internal_TaskStrided_h) && \\
    !defined(VTKM_TEST_HEADER_BUILD)
#error WorkletInvokeFunctorDetail.h must be included from TaskSingular.h, TaskTiling.h, TaskStrided.h
#endif

#include <vtkm/internal/FunctionInterface.h>
#include <vtkm/internal/Invocation.h>

#include <vtkm/exec/arg/Fetch.h>
#include <vtkm/exec/arg/FetchTagExecObject.h>

$# This needs to match the max_parameters in FunctionInterfaceDetailPre.h.in
$py(max_parameters=20)\
#if VTKM_MAX_FUNCTION_PARAMETERS != $(max_parameters)
#error Mismatch of maximum parameters between FunctionInterfaceDatailPre.h.in and WorkletInvokeFunctorDetail.h.in
#endif

$# Python commands used in template expansion.
$py(
def comma_if(flag):
  if flag:
    return ','
  else:
    return '';

def ptype(num, name=''):
  if num == 0:
    return '%sR' % name
  else:
    return '%sP%d' % (name, num)

def pname(num, name=''):
  if num == 0:
    return '%sr' % name
  else:
    return '%sp%d' % (name, num)

def template_params(num_params, start=0, name=''):
  if num_params < start:
    return ''
  result = 'typename %s' % ptype(start, name)
  for param in range(start+1, num_params+1):
    result += ',\n          typename %s' % ptype(param, name)
  return result

def signature(num_params, return_type=ptype(0), name=''):
  result = '%s(' % return_type
  if num_params > 0:
    result += ptype(1, name)
  for param in range(2, num_params+1):
    result += ', %s' % ptype(param, name)
  result += ')'
  return result

def arg_list(num_params, name='', start=1):
  if num_params < start:
    return ''
  result = pname(start, name)
  for param in range(start+1, num_params+1):
    result += ', %s' % pname(param, name)
  return result
)\
$#
$extend(comma_if, ptype, pname, template_params, signature, arg_list)\

namespace vtkm
{
namespace exec
{
namespace internal
{
namespace detail
{

struct DummyDeviceControlSignatureTag
{
  using FetchTag = vtkm::exec::arg::FetchTagExecObject;
};

/// A helper class that takes an \c Invocation object and an index to a
/// parameter in the ExecutionSignature and finds the \c Fetch type valid for
/// that parameter.
template <typename ThreadIndicesType,
          typename Invocation,
          vtkm::IdComponent ExecutionParameterIndex>
struct InvocationToFetch
{
  using ExecutionSignatureTag =
    typename Invocation::ExecutionInterface::template ParameterType<ExecutionParameterIndex>::type;

  // Expected fields from ExecutionSignatureTag. If these do not exist in
  // ExecutionSignatureTag, then something that is not really an execution
  // signature tag was used in an ExecutionSignature.
  static constexpr vtkm::IdComponent ControlParameterIndex = ExecutionSignatureTag::INDEX;
  using AspectTag = typename ExecutionSignatureTag::AspectTag;

  // Find the fetch tag from the control signature tag pointed to by
  // ParameterIndex. Note that ControlParameterIndex of 0 is reserved
  // for getting the device adapter tag.
  using ControlInterface = typename Invocation::ControlInterface;
  using ControlSignatureTag =
    typename std::conditional<
      ControlParameterIndex == 0,
      DummyDeviceControlSignatureTag,
      typename ControlInterface::template ParameterType<ControlParameterIndex>::type>::type;
  using FetchTag = typename ControlSignatureTag::FetchTag;

  using ExecObjectType =
    typename std::conditional<
      ControlParameterIndex == 0,
      typename Invocation::DeviceAdapterTag,
      typename Invocation::ParameterInterface::template ParameterType<ControlParameterIndex>::type>::type;

  using type = vtkm::exec::arg::Fetch<FetchTag, AspectTag, ThreadIndicesType, ExecObjectType>;

  VTKM_EXEC static ExecObjectType GetParameterImpl(const Invocation&, std::true_type)
  {
    return typename Invocation::DeviceAdapterTag();
  }

  VTKM_EXEC static ExecObjectType GetParameterImpl(const Invocation& invocation, std::false_type)
  {
    return vtkm::internal::ParameterGet<ControlParameterIndex>(invocation.Parameters);
  }

  VTKM_EXEC static ExecObjectType GetParameter(const Invocation& invocation)
  {
    return GetParameterImpl(invocation, std::integral_constant<bool, ControlParameterIndex == 0>());
  }
};

// clang-format off

$for(num_params in range(1, max_parameters+1))\
template <typename WorkletType,
          typename ParameterInterface,
          typename ControlInterface,
          vtkm::IdComponent InputDomainIndex,
          typename OutputToInputMapType,
          typename VisitArrayType,
          typename ThreadToOutputMapType,
          typename DeviceAdapterTag,
          typename ThreadIndicesType,
          $template_params(num_params)>
VTKM_EXEC void DoWorkletInvokeFunctor(
  const WorkletType& worklet,
  const vtkm::internal::Invocation<ParameterInterface,
                                   ControlInterface,
                                   vtkm::internal::FunctionInterface<$signature(num_params)>,
                                   InputDomainIndex,
                                   OutputToInputMapType,
                                   VisitArrayType,
                                   ThreadToOutputMapType,
                                   DeviceAdapterTag>& invocation,
  const ThreadIndicesType& threadIndices)
{
  using Invocation =  vtkm::internal::Invocation<ParameterInterface,
                                                 ControlInterface,
                                                 vtkm::internal::FunctionInterface<$signature(num_params)>,
                                                 InputDomainIndex,
                                                 OutputToInputMapType,
                                                 VisitArrayType,
                                                 ThreadToOutputMapType,
                                                 DeviceAdapterTag>;
$for(param_index in range(1, num_params+1))\

  using FetchInfo$(param_index) = InvocationToFetch<ThreadIndicesType, Invocation, $(param_index)>;
  using FetchType$(param_index) = typename FetchInfo$(param_index)::type;
  FetchType$(param_index) fetch$(param_index);
  auto $pname(param_index) =
    fetch$(param_index).Load(threadIndices, FetchInfo$(param_index)::GetParameter(invocation));
$endfor\

  using FetchInfo0 = InvocationToFetch<ThreadIndicesType, Invocation, 0>;
  using ReturnFetchType = typename FetchInfo0::type;
  ReturnFetchType returnFetch;
  // If you got a compile error on the following line, it probably means that
  // the operator() of a worklet does not match the definition expected. One
  // common problem is that the operator() method must be declared const. Check
  // to make sure the "const" keyword is after parameters. Another common
  // problem is that the type of one or more parameters is incompatible with
  // the actual type that VTK-m creates in the execution environment. Make sure
  // that the types of the worklet operator() parameters match those in the
  // ExecutionSignature. The compiler error might help you narrow down which
  // parameter is wrong and the types that did not match.
  auto $pname(0) = worklet($arg_list(num_params));

$for(param_index in range(1, num_params+1))\
  fetch$(param_index).Store(threadIndices, FetchInfo$(param_index)::GetParameter(invocation), $pname(param_index));
$endfor\

  returnFetch.Store(threadIndices, FetchInfo0::GetParameter(invocation), $pname(0));
}

template <typename WorkletType,
          typename ParameterInterface,
          typename ControlInterface,
          vtkm::IdComponent InputDomainIndex,
          typename OutputToInputMapType,
          typename VisitArrayType,
          typename ThreadToOutputMapType,
          typename DeviceAdapterTag,
          typename ThreadIndicesType,
          $template_params(num_params, start=1)>
VTKM_EXEC void DoWorkletInvokeFunctor(
  const WorkletType& worklet,
  const vtkm::internal::Invocation<ParameterInterface,
                                   ControlInterface,
                                   vtkm::internal::FunctionInterface<$signature(num_params, return_type='void')>,
                                   InputDomainIndex,
                                   OutputToInputMapType,
                                   VisitArrayType,
                                   ThreadToOutputMapType,
                                   DeviceAdapterTag>& invocation,
  const ThreadIndicesType& threadIndices)
{
  using Invocation =
    vtkm::internal::Invocation<ParameterInterface,
                               ControlInterface,
                               vtkm::internal::FunctionInterface<$signature(num_params, return_type='void')>,
                               InputDomainIndex,
                               OutputToInputMapType,
                               VisitArrayType,
                               ThreadToOutputMapType,
                               DeviceAdapterTag>;
$for(param_index in range(1, num_params+1))\

  using FetchInfo$(param_index) = InvocationToFetch<ThreadIndicesType, Invocation, $(param_index)>;
  using FetchType$(param_index) = typename FetchInfo$(param_index)::type;
  FetchType$(param_index) fetch$(param_index);
  auto $pname(param_index) =
    fetch$(param_index).Load(threadIndices, FetchInfo$(param_index)::GetParameter(invocation));
$endfor\

  // If you got a compile error on the following line, it probably means that
  // the operator() of a worklet does not match the definition expected. One
  // common problem is that the operator() method must be declared const. Check
  // to make sure the "const" keyword is after parameters. Another common
  // problem is that the type of one or more parameters is incompatible with
  // the actual type that VTK-m creates in the execution environment. Make sure
  // that the types of the worklet operator() parameters match those in the
  // ExecutionSignature. The compiler error might help you narrow down which
  // parameter is wrong and the types that did not match.
  worklet($arg_list(num_params));

$for(param_index in range(1, num_params+1))\
  fetch$(param_index).Store(threadIndices, FetchInfo$(param_index)::GetParameter(invocation), $pname(param_index));
$endfor\
}

$endfor\
// clang-format on
}
}
}
} // namespace vtkm::exec::internal::detail

#endif //vtk_m_exec_internal_WorkletInvokeFunctorDetail_h
