// 
// ReferenceEqualsCalledWithValueTypeIssue.cs
// 
// Author:
//      Mansheng Yang <lightyang0@gmail.com>
// 
// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.com>
// 
// 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 OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System.Collections.Generic;
using System.Linq;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.Refactoring;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	[IssueDescription("Check for reference equality instead",
		Description = "Check for reference equality instead",
		Category = IssueCategories.CodeQualityIssues,
		Severity = Severity.Suggestion,
		AnalysisDisableKeyword = "ReferenceEqualsWithValueType"
	)]
	public class ReferenceEqualsWithValueTypeIssue : GatherVisitorCodeIssueProvider
	{
		protected override IGatherVisitor CreateVisitor(BaseRefactoringContext context)
		{
			return new GatherVisitor(context);
		}

		class GatherVisitor : GatherVisitorBase<ReferenceEqualsWithValueTypeIssue>
		{
			public GatherVisitor(BaseRefactoringContext ctx)
				: base(ctx)
			{
			}

			public override void VisitInvocationExpression(InvocationExpression invocationExpression)
			{
				base.VisitInvocationExpression(invocationExpression);

				// Quickly determine if this invocation is eligible to speed up the inspector
				var nameToken = invocationExpression.Target.GetChildByRole(Roles.Identifier);
				if (nameToken.Name != "ReferenceEquals")
					return;

				var resolveResult = ctx.Resolve(invocationExpression) as InvocationResolveResult;
				if (resolveResult == null ||
				    resolveResult.Member.DeclaringTypeDefinition == null ||
				    resolveResult.Member.DeclaringTypeDefinition.KnownTypeCode != KnownTypeCode.Object ||
				    resolveResult.Member.Name != "ReferenceEquals" ||
				    invocationExpression.Arguments.All(arg => ctx.Resolve(arg).Type.IsReferenceType ?? true))
					return;

				var action1 = new CodeAction(ctx.TranslateString("Replace expression with 'false'"),
					              script => script.Replace(invocationExpression, new PrimitiveExpression(false)), invocationExpression);

				var action2 = new CodeAction(ctx.TranslateString("Use Equals()"),
					              script => script.Replace(invocationExpression.Target,
						              new PrimitiveType("object").Member("Equals")), invocationExpression);

				AddIssue(new CodeIssue(invocationExpression,
					ctx.TranslateString("'Object.ReferenceEquals' is always false because it is called with value type"),
					new [] { action1, action2 }));
			}
		}
	}
}
