// 
// RedundantNamespaceUsageInspector.cs
//  
// Author:
//       Mike Krüger <mkrueger@xamarin.com>
// 
// Copyright (c) 2012 Xamarin <http://xamarin.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;
using ICSharpCode.NRefactory.PatternMatching;
using System.Collections.Generic;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.Semantics;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	/// <summary>
	/// Finds redundant namespace usages.
	/// </summary>
	public class RedundantNamespaceUsageInspector : IInspector
	{
		string title = "Remove redundant namespace usage";

		public string Title {
			get {
				return title;
			}
			set {
				title = value;
			}
		}

		public IEnumerable<InspectionIssue> Run (BaseRefactoringContext context)
		{
			var visitor = new GatherVisitor (context, this);
			context.RootNode.AcceptVisitor (visitor);
			return visitor.FoundIssues;
		}

		class GatherVisitor : GatherVisitorBase
		{
			readonly RedundantNamespaceUsageInspector inspector;
			
			public GatherVisitor (BaseRefactoringContext ctx, RedundantNamespaceUsageInspector inspector) : base (ctx)
			{
				this.inspector = inspector;
			}

			public override void VisitMemberReferenceExpression(MemberReferenceExpression memberReferenceExpression)
			{
				base.VisitMemberReferenceExpression(memberReferenceExpression);
				
				var result = ctx.Resolve(memberReferenceExpression.Target);
				if (!(result is NamespaceResolveResult)) {
					return;
				}
				var wholeResult = ctx.Resolve(memberReferenceExpression);
				if (!(wholeResult is TypeResolveResult)) {
					return;
				}

				var state = ctx.GetResolverStateBefore(memberReferenceExpression);
				var lookupName = state.LookupSimpleNameOrTypeName(memberReferenceExpression.MemberName, new List<IType> (), SimpleNameLookupMode.Expression);
				
				if (lookupName != null && wholeResult.Type.Equals(lookupName.Type)) {
					AddIssue(memberReferenceExpression.StartLocation, memberReferenceExpression.MemberNameToken.StartLocation, inspector.Title, delegate {
						using (var script = ctx.StartScript ()) {
							script.Replace(memberReferenceExpression, new IdentifierExpression (memberReferenceExpression.MemberName));
						}
					}
					);
				}
			}
		}
	}
}