// 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;
using System.Collections.Generic;
using System.Linq;

namespace Microsoft.Extensions.FileProviders
{
    /// <summary>
    /// Represents a nonexistent directory.
    /// </summary>
    public class NotFoundDirectoryContents : IDirectoryContents
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="NotFoundDirectoryContents"/> class.
        /// </summary>
        public NotFoundDirectoryContents() { }

        /// <summary>
        /// Gets a shared instance of <see cref="NotFoundDirectoryContents"/>.
        /// </summary>
        public static NotFoundDirectoryContents Singleton { get; } = new();

        /// <summary>
        /// Gets a value that's always <see langword="false"/>.
        /// </summary>
        public bool Exists => false;

        /// <summary>Returns an enumerator that iterates through the collection.</summary>
        /// <returns>An enumerator to an empty collection.</returns>
        public IEnumerator<IFileInfo> GetEnumerator() => Enumerable.Empty<IFileInfo>().GetEnumerator();

        /// <inheritdoc />
        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
    }
}