﻿// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using ICSharpCode.Decompiler;
using ICSharpCode.NRefactory;
using ICSharpCode.Decompiler.Ast;
using dnlib.DotNet;

namespace ICSharpCode.ILSpy.TreeNodes.Analyzer
{
	/// <summary>
	/// Searches for overrides of the analyzed method.
	/// </summary>
	internal sealed class AnalyzedMethodOverridesTreeNode : AnalyzerSearchTreeNode
	{
		private readonly MethodDef analyzedMethod;

		public AnalyzedMethodOverridesTreeNode(MethodDef analyzedMethod)
		{
			if (analyzedMethod == null)
				throw new ArgumentNullException("analyzedMethod");

			this.analyzedMethod = analyzedMethod;
		}

		protected override void Write(ITextOutput output, Language language)
		{
			output.Write("Overridden By", TextTokenType.Text);
		}

		protected override IEnumerable<AnalyzerTreeNode> FetchChildren(CancellationToken ct)
		{
			var analyzer = new ScopedWhereUsedAnalyzer<AnalyzerTreeNode>(analyzedMethod, FindReferencesInType);
			return analyzer.PerformAnalysis(ct).OrderBy(n => n.ToString(Language));
		}

		private IEnumerable<AnalyzerTreeNode> FindReferencesInType(TypeDef type)
		{
			AnalyzerTreeNode newNode = null;
			try {
				if (!TypesHierarchyHelpers.IsBaseType(analyzedMethod.DeclaringType, type, resolveTypeArguments: false))
					yield break;

				foreach (MethodDef method in type.Methods) {
					if (TypesHierarchyHelpers.IsBaseMethod(analyzedMethod, method)) {
						bool hidesParent = !method.IsVirtual ^ method.IsNewSlot;
						newNode = new AnalyzedMethodTreeNode(method, hidesParent);
					}
				}
			}
			catch (ResolveException) {
				// ignore this type definition. maybe add a notification about such cases.
			}

			if (newNode != null) {
				newNode.Language = this.Language;
				yield return newNode;
			}
		}

		public static bool CanShow(MethodDef method)
		{
			return method.IsVirtual &&
				!method.IsFinal &&
				!method.DeclaringType.IsSealed &&
				!method.DeclaringType.IsInterface;	// interface methods are definitions not implementations - cannot be overridden
		}
	}
}
