SharpDevelop/ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/ParameterCanBeDemotedIssue/ParameterCanBeDemotedIssue.cs

//
// ParameterCouldBeDeclaredWithBaseTypeIssue.cs
//
// Author:
//       Simon Lindgren <simon.n.lindgren@gmail.com>
//
// Copyright (c) 2012 Simon Lindgren
//
// 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 ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using System.Linq;
using System;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	[IssueDescription("A parameter can be demoted to base class",
	                   Description = "Finds parameters that can be demoted to a base class.",
	                   Category = IssueCategories.Opportunities,
	                   Severity = Severity.Suggestion)]
	public class ParameterCanBeDemotedIssue : ICodeIssueProvider
	{
		#region ICodeIssueProvider implementation
		public IEnumerable<CodeIssue> GetIssues(BaseRefactoringContext context)
		{
			return new GatherVisitor(context, this).GetIssues();
		}
		#endregion

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

			public override void VisitMethodDeclaration(MethodDeclaration methodDeclaration)
			{
				base.VisitMethodDeclaration(methodDeclaration);

				var collector = new InvocationCollector(context);
				methodDeclaration.AcceptVisitor(collector);
				
				foreach (var parameter in methodDeclaration.Parameters) {
					var localResolveResult = context.Resolve(parameter) as LocalResolveResult;
					var variable = localResolveResult.Variable;
					IList<InvocationResolveResult> invocations;
					if (!collector.Invocations.TryGetValue(variable, out invocations))
						continue;
					var currentType = localResolveResult.Type;
					var candidateTypes = localResolveResult.Type.GetAllBaseTypes().ToList();
					var possibleTypes = GetPossibleTypes(candidateTypes, invocations);
					var suggestedTypes = possibleTypes.Where(t => t != currentType);
					if (suggestedTypes.Any())
						AddIssue(parameter, context.TranslateString("Parameter can be demoted to base class"),
						         GetActions(parameter, suggestedTypes));
				}
			}

			IEnumerable<CodeAction> GetActions(ParameterDeclaration parameter, IEnumerable<IType> possibleTypes)
			{
				foreach (var type in possibleTypes) {
					var typeName = type.Name;
					var message = string.Format("{0} '{1}'", context.TranslateString("Demote parameter to "), typeName);
					yield return new CodeAction(message, script => {
						script.Replace(parameter.Type, new SimpleType(typeName));
						Console.WriteLine(message + "\t|\t" + typeName);
					});
				}
			}

			HashSet<IMember> GetNeededMembers(IEnumerable<InvocationResolveResult> invocations)
			{
				var members = new HashSet<IMember>();
				foreach (var invocation in invocations) {
					members.Add(invocation.Member);
				}
				return members;
			}

			static bool HasCommonMemberDeclaration(IEnumerable<IMember> acceptableMembers, IMember member)
			{
				var implementedInterfaceMembers = member.MemberDefinition.ImplementedInterfaceMembers;
				if (implementedInterfaceMembers.Any()) {
					return acceptableMembers.ContainsAny(implementedInterfaceMembers);
				}
				else {
					return acceptableMembers.Contains(member.MemberDefinition);
				}
			}

			bool SatisfiesMemberRequests(IType candidateType, HashSet<IMember> wantedMembers)
			{
				var allMembers = candidateType.GetMembers();
				foreach (var wantedMember in wantedMembers) {
					IEnumerable<IMember> acceptableMembers;
					if (wantedMember.ImplementedInterfaceMembers.Any()) {
						acceptableMembers = wantedMember.ImplementedInterfaceMembers.ToList();
					} else {
						acceptableMembers = new List<IMember>() { wantedMember.MemberDefinition };
					}

					var hasMember = allMembers.Any(m => HasCommonMemberDeclaration(acceptableMembers, m));
					if (!hasMember)
						return false;
				}
				return true;
			}

			IEnumerable<IType> GetPossibleTypes(IEnumerable<IType> types, IEnumerable<InvocationResolveResult> invocations)
			{
				var members = GetNeededMembers(invocations);
				return from type in types
					where SatisfiesMemberRequests(type, members)
					orderby GetInheritanceDepth(type) ascending
					select type;
			}

			int GetInheritanceDepth(IType declaringType)
			{
				var depth = 0;
				foreach (var baseType in declaringType.DirectBaseTypes) {
					var newDepth = GetInheritanceDepth(baseType);
					depth = Math.Max(depth, newDepth);
				}
				return depth;
			}
		}

		class InvocationCollector : DepthFirstAstVisitor
		{
			BaseRefactoringContext context;

			public InvocationCollector(BaseRefactoringContext context)
			{
				this.context = context;
				Invocations = new Dictionary<IVariable, IList<InvocationResolveResult>>();
			}

			public IDictionary<IVariable, IList<InvocationResolveResult>> Invocations { get; private set; }

			public override void VisitInvocationExpression(InvocationExpression invocationExpression)
			{
				base.VisitInvocationExpression(invocationExpression);
				var resolveResult = context.Resolve(invocationExpression);
				var invocationResolveResult = resolveResult as InvocationResolveResult;
				if (invocationResolveResult == null)
					return;
				var parameterResolveResult = invocationResolveResult.TargetResult as LocalResolveResult;
				if (parameterResolveResult == null)
					return;
				var variable = parameterResolveResult.Variable;
				if (!Invocations.ContainsKey(variable))
					Invocations[variable] = new List<InvocationResolveResult>();
				Invocations[variable].Add(invocationResolveResult);
			}
		}
	}
	
	static class IEnumerableExtensions
	{
		public static bool ContainsAny<T>(this IEnumerable<T> collection, IEnumerable<T> items)
		{
			foreach (var item in items) {
				if (collection.Contains(item))
					return true;
			}
			return false;
		}
	}
}