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

using System;
using System.Collections.Generic;
using Microsoft.Extensions.Internal;

namespace Microsoft.AspNetCore.Razor.Language
{
	internal class DirectiveTokenDescriptorComparer : IEqualityComparer<DirectiveTokenDescriptor>
	{
		public static readonly DirectiveTokenDescriptorComparer Default = new DirectiveTokenDescriptorComparer();

		protected DirectiveTokenDescriptorComparer()
		{
		}

		public bool Equals( DirectiveTokenDescriptor descriptorX, DirectiveTokenDescriptor descriptorY )
		{
			if ( descriptorX == descriptorY )
			{
				return true;
			}

			return descriptorX != null &&
				descriptorX.Kind == descriptorY.Kind &&
				descriptorX.Optional == descriptorY.Optional;
		}

		public int GetHashCode( DirectiveTokenDescriptor descriptor )
		{
			if ( descriptor == null )
			{
				throw new ArgumentNullException( nameof( descriptor ) );
			}

			var hashCodeCombiner = HashCodeCombiner.Start();
			hashCodeCombiner.Add( descriptor.Kind );
			hashCodeCombiner.Add( descriptor.Optional ? 1 : 0 );

			return hashCodeCombiner.CombinedHash;
		}
	}
}
