// Copyright (C) 2020-2023 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }

#include <algorithm>
#include <string>
#include <utility>
#include <vector>
#include <testsuite_hooks.h>
#include <testsuite_iterators.h>

using __gnu_test::test_container;
using __gnu_test::test_range;
using __gnu_test::input_iterator_wrapper;

namespace ranges = std::ranges;

template<typename T1, typename T2>
constexpr bool
operator==(const ranges::minmax_result<T1>& lhs,
	   const ranges::minmax_result<T2>& rhs)
{
  return (lhs.min == rhs.min
	  && rhs.max == rhs.max);
}


struct X
{
  int i, j;
};

using res_t = ranges::minmax_result<int>;

void
test01()
{
  VERIFY( ranges::minmax(1, 2) == res_t(1,2) );
  VERIFY( ranges::minmax(2, 1) == res_t(1,2) );
  VERIFY( ranges::minmax(1, 2, ranges::greater{}) == res_t(2,1) );
  VERIFY( ranges::minmax(1, 2, ranges::greater{}, std::negate<>{}) == res_t(1,2) );
  VERIFY( ranges::minmax(1, 2, {}, std::negate<>{}) == res_t(2,1) );
  VERIFY( ranges::minmax(X{1,2}, X{1,3}, {}, &X::i).min.j == 2 );
  VERIFY( ranges::minmax(X{1,2}, X{1,3}, {}, &X::i).max.j == 3 );
}

void
test02()
{
  int x[] = {1,2,3,4};
  do
    {
      test_range<int, input_iterator_wrapper> cx(x);
      VERIFY( ranges::minmax(cx) == res_t(1,4) );
      cx.bounds.first = x;
      VERIFY( ranges::minmax(cx, ranges::greater{}) == res_t(4,1) );
      cx.bounds.first = x;
      VERIFY( ranges::minmax(cx, {}, std::negate<>{}) == res_t(4,1));
      cx.bounds.first = x;
      VERIFY( ranges::minmax(cx, ranges::greater{}, std::negate<>{})
	      == res_t(1,4) );
    } while (ranges::next_permutation(x).found);

  constexpr X y[] = {{1,5},{1,2},{1,3}};
  static_assert(ranges::minmax(y, {}, &X::i).min.j == 5);
  static_assert(ranges::minmax(y, {}, &X::i).max.j == 3);
}

void
test03()
{
  VERIFY( ranges::minmax({2,3,1,4}) == res_t(1,4) );
  VERIFY( ranges::minmax({2,3,1,4}, ranges::greater{}) == res_t(4,1) );
  VERIFY( ranges::minmax({2,3,1,4}, {}, std::negate<>{}) == res_t(4,1) );
  VERIFY( ranges::minmax({2,3,1,4}, ranges::greater{}, std::negate<>{})
	  == res_t(1,4) );
}

void
test04()
{
  // Verify we perform at most 3*N/2 applications of the comparison predicate.
  static int counter;
  struct counted_less
  { bool operator()(int a, int b) { ++counter; return a < b; } };

  ranges::minmax({1,2}, counted_less{});
  VERIFY( counter == 1 );

  counter = 0;
  ranges::minmax({1,2,3}, counted_less{});
  VERIFY( counter == 3 );

  counter = 0;
  ranges::minmax({1,2,3,4,5,6,7,8,9,10}, counted_less{});
  VERIFY( counter <= 15 );

  counter = 0;
  ranges::minmax({10,9,8,7,6,5,4,3,2,1}, counted_less{});
  VERIFY( counter <= 15 );
}

void
test05()
{
  // PR libstdc++/100387
  using namespace std::literals::string_literals;
  auto comp = [](const auto& a, const auto& b) {
    return a.size() == b.size() ? a.front() < b.front() : a.size() > b.size();
  };
  auto result = ranges::minmax({"b"s, "a"s}, comp);
  VERIFY( result.min == "a"s && result.max == "b"s );
  result = ranges::minmax({"c"s, "b"s, "a"s}, comp);
  VERIFY( result.min == "a"s && result.max == "c"s );
}

struct A {
  A() = delete;
  A(int i) : i(i) { }
  A(const A&) = default;
  A(A&& other) : A(std::as_const(other)) { ++move_count; }
  A& operator=(const A&) = default;
  A& operator=(A&& other) {
    ++move_count;
    return *this = std::as_const(other);
  };
  friend auto operator<=>(const A&, const A&) = default;
  static inline int move_count = 0;
  int i;
};

void
test06()
{
  // PR libstdc++/104858
  // Verify ranges::minmax doesn't dereference the iterator for the first
  // element in the range twice.
  A a(42);
  ranges::subrange r = {std::move_iterator(&a), std::move_sentinel(&a + 1)};
  auto result = ranges::minmax(r);
  VERIFY( A::move_count == 1 );
  VERIFY( result.min.i == 42 && result.max.i == 42 );
}

int
main()
{
  test01();
  test02();
  test03();
  test04();
  test05();
  test06();
}