// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Runtime.CompilerServices;
 
namespace Aspire.Hosting.Utils;
 
internal static class AsyncEnumerableUtils
{
    /// <summary>
    /// Iterates an <see cref="IAsyncEnumerable{T}"/> until it completes or the token is cancelled,
    /// yielding each item. Cancellation causes the sequence to complete gracefully rather than
    /// throwing, making it safe to use inside iterator methods that have <c>finally</c> blocks.
    /// </summary>
    public static async IAsyncEnumerable<T> ReadUntilCancelledAsync<T>(
        IAsyncEnumerable<T> source,
        [EnumeratorCancellation] CancellationToken cancellationToken)
    {
        var enumerator = source.GetAsyncEnumerator(cancellationToken);
        try
        {
            while (true)
            {
                bool hasNext;
                try
                {
                    hasNext = await enumerator.MoveNextAsync().ConfigureAwait(false);
                }
                catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
                {
                    yield break;
                }
 
                if (!hasNext)
                {
                    yield break;
                }
 
                yield return enumerator.Current;
            }
        }
        finally
        {
            await enumerator.DisposeAsync().ConfigureAwait(false);
        }
    }
}