//===----------------------------------------------------------------------===//
//
// 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

// <memory>
//
// template<input_iterator I, nothrow-forward-iterator O, nothrow-sentinel-for<O> S>
//   requires constructible_from<iter_value_t<O>, iter_reference_t<I>>
// uninitialized_copy_n_result<I, O> uninitialized_copy_n(I ifirst, iter_difference_t<I> n, O ofirst, S olast); // since C++20

#include <algorithm>
#include <cassert>
#include <iterator>
#include <memory>
#include <ranges>
#include <type_traits>
#include <utility>

#include "../buffer.h"
#include "../counted.h"
#include "test_macros.h"
#include "test_iterators.h"

// TODO(varconst): consolidate the ADL checks into a single file.
// Because this is a variable and not a function, it's guaranteed that ADL won't be used. However,
// implementations are allowed to use a different mechanism to achieve this effect, so this check is
// libc++-specific.
LIBCPP_STATIC_ASSERT(std::is_class_v<decltype(std::ranges::uninitialized_copy_n)>);

static_assert(std::is_invocable_v<decltype(std::ranges::uninitialized_copy_n), int*, size_t, long*, long*>);
struct NotConvertibleFromInt {};
static_assert(!std::is_invocable_v<decltype(std::ranges::uninitialized_copy_n), int*, size_t, NotConvertibleFromInt*,
                                   NotConvertibleFromInt*>);

int main(int, char**) {
  // An empty range -- no default constructors should be invoked.
  {
    Counted in[] = {Counted()};
    Buffer<Counted, 1> out;
    Counted::reset();

    auto result = std::ranges::uninitialized_copy_n(in, 0, out.begin(), out.end());
    assert(Counted::current_objects == 0);
    assert(Counted::total_objects == 0);
    assert(Counted::total_copies == 0);
    assert(result.in == in);
    assert(result.out == out.begin());
  }
  Counted::reset();

  // A range containing several objects.
  {
    constexpr int N = 5;
    Counted in[N] = {Counted(1), Counted(2), Counted(3), Counted(4), Counted(5)};
    Buffer<Counted, N> out;
    Counted::reset();

    auto result = std::ranges::uninitialized_copy_n(in, N, out.begin(), out.end());
    ASSERT_SAME_TYPE(decltype(result), std::ranges::uninitialized_copy_n_result<Counted*, Counted*>);

    assert(Counted::current_objects == N);
    assert(Counted::total_objects == N);
    assert(Counted::total_copies == N);
    assert(Counted::total_moves == 0);
    assert(std::equal(in, in + N, out.begin(), out.end()));
    assert(result.in == in + N);
    assert(result.out == out.end());

    std::destroy(out.begin(), out.end());
  }
  Counted::reset();

  // An exception is thrown while objects are being created -- the existing objects should stay
  // valid. (iterator, sentinel) overload.
#ifndef TEST_HAS_NO_EXCEPTIONS
  {
    constexpr int M = 3;
    constexpr int N = 5;
    Counted in[N] = {Counted(1), Counted(2), Counted(3), Counted(4), Counted(5)};
    Counted out[N] = {Counted(6), Counted(7), Counted(8), Counted(9), Counted(10)};
    Counted::reset();

    Counted::throw_on = M; // When constructing out[3].
    try {
      std::ranges::uninitialized_copy_n(in, N, out, out + N);
      assert(false);
    } catch (...) {
    }
    assert(Counted::current_objects == 0);
    assert(Counted::total_objects == M);
    assert(Counted::total_copies == M);
    assert(Counted::total_moves == 0);

    assert(out[4].value == 10);
  }
  Counted::reset();

#endif // TEST_HAS_NO_EXCEPTIONS

  // Works with const iterators.
  {
    constexpr int N = 5;
    Counted in[N] = {Counted(1), Counted(2), Counted(3), Counted(4), Counted(5)};
    Buffer<Counted, N> out;
    Counted::reset();

    std::ranges::uninitialized_copy_n(in, N, out.cbegin(), out.cend());
    assert(Counted::current_objects == N);
    assert(Counted::total_objects == N);
    assert(std::equal(in, in + N, out.begin(), out.end()));

    std::destroy(out.begin(), out.end());
  }
  Counted::reset();

  // Conversions.
  {
    constexpr int N = 3;
    int in[N] = {1, 2, 3};
    Buffer<double, N> out;

    std::ranges::uninitialized_copy_n(in, N, out.begin(), out.end());
    assert(std::equal(in, in + N, out.begin(), out.end()));
  }

  // Destination range is shorter than the source range.
  {
    constexpr int M = 3;
    constexpr int N = 5;
    Counted in[N] = {Counted(1), Counted(2), Counted(3), Counted(4), Counted(5)};
    Buffer<Counted, M> out;
    Counted::reset();

    auto result = std::ranges::uninitialized_copy_n(in, N, out.begin(), out.end());
    assert(Counted::current_objects == M);
    assert(Counted::total_objects == M);
    assert(Counted::total_copies == M);
    assert(Counted::total_moves == 0);

    assert(std::equal(in, in + M, out.begin(), out.end()));
    assert(result.in == in + M);
    assert(result.out == out.end());
  }

  // Move-only iterators are supported.
  {
    using MoveOnlyIter = cpp20_input_iterator<const int*>;
    static_assert(!std::is_copy_constructible_v<MoveOnlyIter>);

    constexpr int N = 3;
    int buffer[N] = {1, 2, 3};

    MoveOnlyIter in(buffer);
    Buffer<int, N> out;
    std::ranges::uninitialized_copy_n(std::move(in), N, out.begin(), out.end());
  }

  return 0;
}
