// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;

namespace System.Linq
{
    public static partial class AsyncEnumerable
    {
        /// <summary>Creates a list from an <see cref="IAsyncEnumerable{T}"/>.</summary>
        /// <typeparam name="TSource">The type of the elements of source.</typeparam>
        /// <param name="source">An <see cref="IEnumerable{T}"/> to create a list from.</param>
        /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
        /// <returns>A list that contains the elements from the input sequence.</returns>
        /// <exception cref="ArgumentNullException"><paramref name="source" /> is <see langword="null" />.</exception>
        public static ValueTask<List<TSource>> ToListAsync<TSource>(
            this IAsyncEnumerable<TSource> source,
            CancellationToken cancellationToken = default)
        {
            ArgumentNullException.ThrowIfNull(source);

            return Impl(source.WithCancellation(cancellationToken));

            static async ValueTask<List<TSource>> Impl(
                ConfiguredCancelableAsyncEnumerable<TSource> source)
            {
                List<TSource> list = [];
                await foreach (TSource element in source)
                {
                    list.Add(element);
                }

                return list;
            }
        }
    }
}