#include <thrust/extrema.h>
#include <thrust/functional.h>
#include <thrust/iterator/retag.h>
#include <thrust/iterator/transform_iterator.h>

#include <cuda/iterator>

#include <unittest/unittest.h>

template <class Vector>
void TestMaxElementSimple()
{
  using T = typename Vector::value_type;

  Vector data{3, 5, 1, 2, 5, 1};

  ASSERT_EQUAL(*thrust::max_element(data.begin(), data.end()), 5);
  ASSERT_EQUAL(thrust::max_element(data.begin(), data.end()) - data.begin(), 1);

  ASSERT_EQUAL(*thrust::max_element(data.begin(), data.end(), ::cuda::std::greater<T>()), 1);
  ASSERT_EQUAL(thrust::max_element(data.begin(), data.end(), ::cuda::std::greater<T>()) - data.begin(), 2);
}
DECLARE_VECTOR_UNITTEST(TestMaxElementSimple);

template <class Vector>
void TestMaxElementWithTransform()
{
  using T = typename Vector::value_type;

  Vector data{3, 5, 1, 2, 5, 1};

  ASSERT_EQUAL(*thrust::max_element(thrust::make_transform_iterator(data.begin(), ::cuda::std::negate<T>()),
                                    thrust::make_transform_iterator(data.end(), ::cuda::std::negate<T>())),
               -1);
  ASSERT_EQUAL(*thrust::max_element(thrust::make_transform_iterator(data.begin(), ::cuda::std::negate<T>()),
                                    thrust::make_transform_iterator(data.end(), ::cuda::std::negate<T>()),
                                    ::cuda::std::greater<T>()),
               -5);
}
DECLARE_VECTOR_UNITTEST(TestMaxElementWithTransform);

template <typename T>
void TestMaxElement(const size_t n)
{
  thrust::host_vector<T> h_data   = unittest::random_samples<T>(n);
  thrust::device_vector<T> d_data = h_data;

  typename thrust::host_vector<T>::iterator h_max   = thrust::max_element(h_data.begin(), h_data.end());
  typename thrust::device_vector<T>::iterator d_max = thrust::max_element(d_data.begin(), d_data.end());

  ASSERT_EQUAL(h_max - h_data.begin(), d_max - d_data.begin());

  typename thrust::host_vector<T>::iterator h_min =
    thrust::max_element(h_data.begin(), h_data.end(), ::cuda::std::greater<T>());
  typename thrust::device_vector<T>::iterator d_min =
    thrust::max_element(d_data.begin(), d_data.end(), ::cuda::std::greater<T>());

  ASSERT_EQUAL(h_min - h_data.begin(), d_min - d_data.begin());
}
DECLARE_VARIABLE_UNITTEST(TestMaxElement);

template <typename ForwardIterator>
ForwardIterator max_element(my_system& system, ForwardIterator first, ForwardIterator)
{
  system.validate_dispatch();
  return first;
}

void TestMaxElementDispatchExplicit()
{
  thrust::device_vector<int> vec(1);

  my_system sys(0);
  thrust::max_element(sys, vec.begin(), vec.end());

  ASSERT_EQUAL(true, sys.is_valid());
}
DECLARE_UNITTEST(TestMaxElementDispatchExplicit);

template <typename ForwardIterator>
ForwardIterator max_element(my_tag, ForwardIterator first, ForwardIterator)
{
  *first = 13;
  return first;
}

void TestMaxElementDispatchImplicit()
{
  thrust::device_vector<int> vec(1);

  thrust::max_element(thrust::retag<my_tag>(vec.begin()), thrust::retag<my_tag>(vec.end()));

  ASSERT_EQUAL(13, vec.front());
}
DECLARE_UNITTEST(TestMaxElementDispatchImplicit);

void TestMaxElementWithBigIndexesHelper(int magnitude)
{
  thrust::counting_iterator<long long> begin(1);
  thrust::counting_iterator<long long> end = begin + (1ll << magnitude);
  ASSERT_EQUAL(::cuda::std::distance(begin, end), 1ll << magnitude);

  ASSERT_EQUAL(*thrust::max_element(thrust::device, begin, end), (1ll << magnitude));
}

void TestMaxElementWithBigIndexes()
{
  TestMaxElementWithBigIndexesHelper(30);
#ifndef THRUST_FORCE_32_BIT_OFFSET_TYPE
  TestMaxElementWithBigIndexesHelper(31);
  TestMaxElementWithBigIndexesHelper(32);
  TestMaxElementWithBigIndexesHelper(33);
#endif
}
DECLARE_UNITTEST(TestMaxElementWithBigIndexes);

void TestMaxElementCudaIterator()
{
  auto pos = thrust::max_element(thrust::device, cuda::counting_iterator{0}, cuda::counting_iterator{0} + 100);
  ASSERT_EQUAL(*pos, 99);
}
DECLARE_UNITTEST(TestMaxElementCudaIterator);