// 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 System.Linq;
using Microsoft.Extensions.Internal;

namespace Microsoft.AspNetCore.Razor.Language
{
	internal class BoundAttributeParameterDescriptorComparer : IEqualityComparer<BoundAttributeParameterDescriptor>
	{
		/// <summary>
		/// A default instance of the <see cref="BoundAttributeParameterDescriptorComparer"/>.
		/// </summary>
		public static readonly BoundAttributeParameterDescriptorComparer Default = new BoundAttributeParameterDescriptorComparer();

		private BoundAttributeParameterDescriptorComparer()
		{
		}

		public virtual bool Equals( BoundAttributeParameterDescriptor descriptorX, BoundAttributeParameterDescriptor descriptorY )
		{
			if ( object.ReferenceEquals( descriptorX, descriptorY ) )
			{
				return true;
			}

			if ( descriptorX == null ^ descriptorY == null )
			{
				return false;
			}

			return
				string.Equals( descriptorX.Kind, descriptorY.Kind, StringComparison.Ordinal ) &&
				descriptorX.IsEnum == descriptorY.IsEnum &&
				string.Equals( descriptorX.Name, descriptorY.Name, StringComparison.Ordinal ) &&
				string.Equals( descriptorX.TypeName, descriptorY.TypeName, StringComparison.Ordinal ) &&
				string.Equals( descriptorX.Documentation, descriptorY.Documentation, StringComparison.Ordinal ) &&
				string.Equals( descriptorX.DisplayName, descriptorY.DisplayName, StringComparison.Ordinal ) &&
				Enumerable.SequenceEqual(
					descriptorX.Metadata.OrderBy( propertyX => propertyX.Key, StringComparer.Ordinal ),
					descriptorY.Metadata.OrderBy( propertyY => propertyY.Key, StringComparer.Ordinal ) );
		}

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

			var hash = HashCodeCombiner.Start();
			hash.Add( descriptor.Kind, StringComparer.Ordinal );
			hash.Add( descriptor.Name, StringComparer.Ordinal );
			hash.Add( descriptor.TypeName, StringComparer.Ordinal );
			hash.Add( descriptor.Metadata?.Count );

			return hash.CombinedHash;
		}
	}
}
