//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20

// <flat_map>

// class flat_multimap

// iterator erase(iterator position);
// iterator erase(const_iterator position);

#include <compare>
#include <concepts>
#include <deque>
#include <flat_map>
#include <functional>
#include <utility>
#include <vector>

#include "MinSequenceContainer.h"
#include "../helpers.h"
#include "test_macros.h"
#include "min_allocator.h"

template <class KeyContainer, class ValueContainer>
constexpr void test() {
  using Key   = typename KeyContainer::value_type;
  using Value = typename ValueContainer::value_type;
  using M     = std::flat_multimap<Key, Value, std::less<Key>, KeyContainer, ValueContainer>;
  using P     = std::pair<Key, Value>;
  using I     = M::iterator;

  P ar[] = {
      P(1, 1.5),
      P(2, 2.5),
      P(2, 2.6),
      P(3, 3.5),
      P(4, 4.5),
      P(4, 4.5),
      P(4, 4.7),
      P(5, 5.5),
      P(6, 6.5),
      P(7, 7.5),
      P(8, 8.5),
  };
  M m(ar, ar + sizeof(ar) / sizeof(ar[0]));
  assert(m.size() == 11);
  std::same_as<I> decltype(auto) i1 = m.erase(std::next(m.cbegin(), 2));
  assert(m.size() == 10);
  assert(i1 == std::next(m.begin(), 2));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{1, 2, 3, 4, 4, 4, 5, 6, 7, 8}));
  check_possible_values(m.values(),
                        std::vector<std::vector<Value>>{
                            {1.5}, {2.5, 2.6}, {3.5}, {4.5, 4.7}, {4.5, 4.7}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}, {8.5}});

  std::same_as<I> decltype(auto) i2 = m.erase(std::next(m.begin(), 0));
  assert(m.size() == 9);
  assert(i2 == m.begin());
  assert(std::ranges::equal(m.keys(), std::vector<Key>{2, 3, 4, 4, 4, 5, 6, 7, 8}));
  check_possible_values(m.values(),
                        std::vector<std::vector<Value>>{
                            {2.5, 2.6}, {3.5}, {4.5, 4.7}, {4.5, 4.7}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}, {8.5}});

  std::same_as<I> decltype(auto) i3 = m.erase(std::next(m.cbegin(), 8));
  assert(m.size() == 8);
  assert(i3 == m.end());
  assert(std::ranges::equal(m.keys(), std::vector<Key>{2, 3, 4, 4, 4, 5, 6, 7}));
  check_possible_values(
      m.values(),
      std::vector<std::vector<Value>>{{2.5, 2.6}, {3.5}, {4.5, 4.7}, {4.5, 4.7}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}});

  std::same_as<I> decltype(auto) i4 = m.erase(std::next(m.begin(), 1));
  assert(m.size() == 7);
  assert(i4 == std::next(m.begin()));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{2, 4, 4, 4, 5, 6, 7}));
  check_possible_values(
      m.values(), std::vector<std::vector<Value>>{{2.5, 2.6}, {4.5, 4.7}, {4.5, 4.7}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}});

  std::same_as<I> decltype(auto) i5 = m.erase(std::next(m.cbegin(), 2));
  assert(m.size() == 6);
  assert(i5 == std::next(m.begin(), 2));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{2, 4, 4, 5, 6, 7}));
  check_possible_values(
      m.values(), std::vector<std::vector<Value>>{{2.5, 2.6}, {4.5, 4.7}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}});

  std::same_as<I> decltype(auto) i6 = m.erase(std::next(m.begin(), 2));
  assert(m.size() == 5);
  assert(i6 == std::next(m.begin(), 2));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{2, 4, 5, 6, 7}));
  check_possible_values(m.values(), std::vector<std::vector<Value>>{{2.5, 2.6}, {4.5, 4.7}, {5.5}, {6.5}, {7.5}});

  std::same_as<I> decltype(auto) i7 = m.erase(std::next(m.cbegin(), 0));
  assert(m.size() == 4);
  assert(i7 == std::next(m.begin(), 0));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{4, 5, 6, 7}));
  check_possible_values(m.values(), std::vector<std::vector<Value>>{{4.5, 4.7}, {5.5}, {6.5}, {7.5}});

  std::same_as<I> decltype(auto) i8 = m.erase(std::next(m.cbegin(), 2));
  assert(m.size() == 3);
  assert(i8 == std::next(m.begin(), 2));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{4, 5, 7}));
  check_possible_values(m.values(), std::vector<std::vector<Value>>{{4.5, 4.7}, {5.5}, {7.5}});

  std::same_as<I> decltype(auto) i9 = m.erase(std::next(m.cbegin(), 2));
  assert(m.size() == 2);
  assert(i9 == std::next(m.begin(), 2));
  assert(std::ranges::equal(m.keys(), std::vector<Key>{4, 5}));
  check_possible_values(m.values(), std::vector<std::vector<Value>>{{4.5, 4.7}, {5.5}});

  std::same_as<I> decltype(auto) i10 = m.erase(m.cbegin());
  assert(m.size() == 1);
  assert(i10 == m.cbegin());
  assert(std::ranges::equal(m, std::vector<P>{{5, 5.5}}));

  std::same_as<I> decltype(auto) i11 = m.erase(m.begin());
  assert(m.size() == 0);
  assert(i11 == m.begin());
  assert(i11 == m.end());
}

constexpr bool test() {
  test<std::vector<int>, std::vector<double>>();
#ifndef __cpp_lib_constexpr_deque
  if (!TEST_IS_CONSTANT_EVALUATED)
#endif
    test<std::deque<int>, std::vector<double>>();
  test<MinSequenceContainer<int>, MinSequenceContainer<double>>();
  test<std::vector<int, min_allocator<int>>, std::vector<double, min_allocator<double>>>();

  if (!TEST_IS_CONSTANT_EVALUATED) {
    auto erase_function = [](auto& m, auto) { m.erase(m.begin() + 2); };
    test_erase_exception_guarantee(erase_function);
  }
  return true;
}

int main(int, char**) {
  test();
#if TEST_STD_VER >= 26
  static_assert(test());
#endif

  return 0;
}