// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;

namespace Microsoft.CodeAnalysis.Shared.Utilities;

internal static partial class ExtensionOrderer
{
    private sealed class Node<TExtension, TMetadata>(Lazy<TExtension, TMetadata> extension)
    {
        public readonly Lazy<TExtension, TMetadata> Extension = extension;
        public readonly HashSet<Node<TExtension, TMetadata>> ExtensionsBeforeMeSet = [];

        public void CheckForCycles()
            => this.CheckForCycles([]);

        private void CheckForCycles(
            HashSet<Node<TExtension, TMetadata>> seenNodes)
        {
            if (!seenNodes.Add(this))
            {
                // Cycle detected in extensions
                throw new ArgumentException(WorkspacesResources.Cycle_detected_in_extensions);
            }

            foreach (var before in this.ExtensionsBeforeMeSet)
            {
                before.CheckForCycles(seenNodes);
            }

            seenNodes.Remove(this);
        }
    }
}