// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
using System.Diagnostics;
using ILLink.RoslynAnalyzer;
using Microsoft.CodeAnalysis;
 
namespace ILLink.Shared.TypeSystemProxy
{
	internal partial struct ParameterProxy
	{
		public ParameterProxy (IParameterSymbol parameter)
		{
			Method = new ((IMethodSymbol) parameter.ContainingSymbol);
			Index = (ParameterIndex) parameter.Ordinal + (Method.HasImplicitThis () ? 1 : 0);
		}
 
		public partial ReferenceKind GetReferenceKind ()
		{
			if (IsImplicitThis)
				return Method.Method.ContainingType.IsValueType
					? ReferenceKind.Ref
					: ReferenceKind.None;
 
			switch (Method.Method.Parameters[MetadataIndex].RefKind) {
			case RefKind.Ref: return ReferenceKind.Ref;
			case RefKind.In: return ReferenceKind.In;
			case RefKind.Out: return ReferenceKind.Out;
			case RefKind.None: return ReferenceKind.None;
			default:
				Debug.Fail ($"Unexpected RefKind {Method.Method.Parameters[MetadataIndex].RefKind} found on parameter {GetDisplayName ()}");
				return ReferenceKind.None;
			}
		}
 
		/// <summary>
		/// Returns the IParameterSymbol representing the parameter. Returns null for the implicit this paramter.
		/// </summary>
		public IParameterSymbol? ParameterSymbol => IsImplicitThis ? null : Method.Method.Parameters[MetadataIndex];
 
		/// <summary>
		/// Returns the IParameterSymbol.Location[0] for the parameter. Returns null for the implicit this paramter.
		/// </summary>
		public Location? Location => ParameterSymbol?.Locations[0];
 
		public TypeProxy ParameterType
			=> IsImplicitThis
				? new TypeProxy (Method.Method.ContainingType)
				: new TypeProxy (Method.Method.Parameters[MetadataIndex].Type);
 
		public partial string GetDisplayName ()
		{
			if (IsImplicitThis)
				return "this";
			return ParameterSymbol!.GetDisplayName ();
		}
 
		public partial bool IsTypeOf (string typeName) => ParameterType.IsTypeOf (typeName.Substring (0, typeName.LastIndexOf ('.')), typeName.Substring (1 + typeName.LastIndexOf ('.')));
 
		public bool IsTypeOf (WellKnownType type) => ParameterType.IsTypeOf (type);
	}
}