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

#include <cuda/iterator>

#include <unittest/unittest.h>

template <class Vector>
void TestMinMaxElementSimple()
{
  Vector data{3, 5, 1, 2, 5, 1};

  ASSERT_EQUAL(*thrust::minmax_element(data.begin(), data.end()).first, 1);
  ASSERT_EQUAL(*thrust::minmax_element(data.begin(), data.end()).second, 5);
  ASSERT_EQUAL(thrust::minmax_element(data.begin(), data.end()).first - data.begin(), 2);
  ASSERT_EQUAL(thrust::minmax_element(data.begin(), data.end()).second - data.begin(), 1);
}
DECLARE_VECTOR_UNITTEST(TestMinMaxElementSimple);

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

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

  ASSERT_EQUAL(*thrust::minmax_element(thrust::make_transform_iterator(data.begin(), ::cuda::std::negate<T>()),
                                       thrust::make_transform_iterator(data.end(), ::cuda::std::negate<T>()))
                  .first,
               -5);
  ASSERT_EQUAL(*thrust::minmax_element(thrust::make_transform_iterator(data.begin(), ::cuda::std::negate<T>()),
                                       thrust::make_transform_iterator(data.end(), ::cuda::std::negate<T>()))
                  .second,
               -1);
}
DECLARE_VECTOR_UNITTEST(TestMinMaxElementWithTransform);

template <typename T>
void TestMinMaxElement(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_min;
  typename thrust::host_vector<T>::iterator h_max;
  typename thrust::device_vector<T>::iterator d_min;
  typename thrust::device_vector<T>::iterator d_max;

  h_min = thrust::minmax_element(h_data.begin(), h_data.end()).first;
  d_min = thrust::minmax_element(d_data.begin(), d_data.end()).first;
  h_max = thrust::minmax_element(h_data.begin(), h_data.end()).second;
  d_max = thrust::minmax_element(d_data.begin(), d_data.end()).second;

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

  h_max = thrust::minmax_element(h_data.begin(), h_data.end(), ::cuda::std::greater<T>()).first;
  d_max = thrust::minmax_element(d_data.begin(), d_data.end(), ::cuda::std::greater<T>()).first;
  h_min = thrust::minmax_element(h_data.begin(), h_data.end(), ::cuda::std::greater<T>()).second;
  d_min = thrust::minmax_element(d_data.begin(), d_data.end(), ::cuda::std::greater<T>()).second;

  ASSERT_EQUAL(h_min - h_data.begin(), d_min - d_data.begin());
  ASSERT_EQUAL(h_max - h_data.begin(), d_max - d_data.begin());
}
DECLARE_VARIABLE_UNITTEST(TestMinMaxElement);

template <typename ForwardIterator>
cuda::std::pair<ForwardIterator, ForwardIterator>
minmax_element(my_system& system, ForwardIterator first, ForwardIterator)
{
  system.validate_dispatch();
  return cuda::std::make_pair(first, first);
}

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

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

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

template <typename ForwardIterator>
cuda::std::pair<ForwardIterator, ForwardIterator> minmax_element(my_tag, ForwardIterator first, ForwardIterator)
{
  *first = 13;
  return cuda::std::make_pair(first, first);
}

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

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

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

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

  cuda::std::pair<Iter, Iter> result = thrust::minmax_element(thrust::device, begin, end);
  ASSERT_EQUAL(*result.first, 1);
  ASSERT_EQUAL(*result.second, (1ll << magnitude));

  result = thrust::minmax_element(thrust::device, begin, end, ::cuda::std::greater<long long>());
  ASSERT_EQUAL(*result.second, 1);
  ASSERT_EQUAL(*result.first, (1ll << magnitude));
}

void TestMinMaxElementWithBigIndexes()
{
  TestMinMaxElementWithBigIndexesHelper(30);
#ifndef THRUST_FORCE_32_BIT_OFFSET_TYPE
  TestMinMaxElementWithBigIndexesHelper(31);
  TestMinMaxElementWithBigIndexesHelper(32);
  TestMinMaxElementWithBigIndexesHelper(33);
#endif
}
DECLARE_UNITTEST(TestMinMaxElementWithBigIndexes);

void TestMinElementCudaIterator()
{
  auto result = thrust::minmax_element(thrust::device, cuda::counting_iterator{0}, cuda::counting_iterator{0} + 100);
  ASSERT_EQUAL(*result.first, 0);
  ASSERT_EQUAL(*result.second, 99);
}
DECLARE_UNITTEST(TestMinElementCudaIterator);