/*
 *  Copyright 2008-2013 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#pragma once

#include <thrust/detail/config.h>
#include <thrust/detail/execution_policy.h>
#include <thrust/detail/type_traits.h>
#include <thrust/iterator/detail/minimum_system.h>
#include <thrust/iterator/detail/device_system_tag.h>
#include <thrust/iterator/detail/any_system_tag.h>

THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace generic
{

template<typename Tag>
  struct select_system1_exists;

template<typename Tag1, typename Tag2>
  struct select_system2_exists;

template<typename Tag1, typename Tag2, typename Tag3>
  struct select_system3_exists;

template<typename Tag1, typename Tag2, typename Tag3, typename Tag4>
  struct select_system4_exists;

template<typename Tag1, typename Tag2, typename Tag3, typename Tag4, typename Tag5>
  struct select_system5_exists;

template<typename Tag1, typename Tag2, typename Tag3, typename Tag4, typename Tag5, typename Tag6>
  struct select_system6_exists;

template<typename System>
__host__ __device__
  typename thrust::detail::disable_if<
    select_system1_exists<System>::value,
    System &
  >::type
    select_system(thrust::execution_policy<System> &system);

template<typename System1, typename System2>
__host__ __device__
  typename thrust::detail::enable_if_defined<
    thrust::detail::minimum_system<System1,System2>
  >::type
    &select_system(thrust::execution_policy<System1> &system1,
                   thrust::execution_policy<System2> &system2);

template<typename System1, typename System2, typename System3>
__host__ __device__
  typename thrust::detail::lazy_disable_if<
    select_system3_exists<System1,System2,System3>::value,
    thrust::detail::minimum_system<System1,System2,System3>
  >::type
    &select_system(thrust::execution_policy<System1> &system1,
                   thrust::execution_policy<System2> &system2,
                   thrust::execution_policy<System3> &system3);

template<typename System1, typename System2, typename System3, typename System4>
__host__ __device__
  typename thrust::detail::lazy_disable_if<
    select_system4_exists<System1,System2,System3,System4>::value,
    thrust::detail::minimum_system<System1,System2,System3,System4>
  >::type
    &select_system(thrust::execution_policy<System1> &system1,
                   thrust::execution_policy<System2> &system2,
                   thrust::execution_policy<System3> &system3,
                   thrust::execution_policy<System4> &system4);

template<typename System1, typename System2, typename System3, typename System4, typename System5>
__host__ __device__
  typename thrust::detail::lazy_disable_if<
    select_system5_exists<System1,System2,System3,System4,System5>::value,
    thrust::detail::minimum_system<System1,System2,System3,System4,System5>
  >::type
    &select_system(thrust::execution_policy<System1> &system1,
                   thrust::execution_policy<System2> &system2,
                   thrust::execution_policy<System3> &system3,
                   thrust::execution_policy<System4> &system4,
                   thrust::execution_policy<System5> &system5);

template<typename System1, typename System2, typename System3, typename System4, typename System5, typename System6>
__host__ __device__
  typename thrust::detail::lazy_disable_if<
    select_system6_exists<System1,System2,System3,System4,System5,System6>::value,
    thrust::detail::minimum_system<System1,System2,System3,System4,System5,System6>
  >::type
    &select_system(thrust::execution_policy<System1> &system1,
                   thrust::execution_policy<System2> &system2,
                   thrust::execution_policy<System3> &system3,
                   thrust::execution_policy<System4> &system4,
                   thrust::execution_policy<System5> &system5,
                   thrust::execution_policy<System6> &system6);

// Map a single any_system_tag to device_system_tag.
inline __host__ __device__
thrust::device_system_tag select_system(thrust::any_system_tag);

} // end generic
} // end detail
} // end system
THRUST_NAMESPACE_END

#include <thrust/system/detail/generic/select_system.inl>