Generate Proxy Class at Build Time

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Genuilder.Extensibility;
using Genuilder;
using Genuilder.Extensibility.NRefactory;
using ICSharpCode.NRefactory.Visitors;

namespace Membership.Genuilder
{
	public class ProxyGeneratorExtension : IExtension
	{
		class ProxiedInterfaceVisitor : AbstractAstVisitor
		{
			private CodeWriter writer;

			public ProxiedInterfaceVisitor(CodeWriter writer)
			{
				this.writer = writer;
			}

			public override object VisitUsing(ICSharpCode.NRefactory.Ast.Using @using, object data)
			{
				writer.WriteUsing(@using.Name);
				return base.VisitUsing(@using, data);
			}

			public override object VisitNamespaceDeclaration(ICSharpCode.NRefactory.Ast.NamespaceDeclaration namespaceDeclaration, object data)
			{
				using(writer.WriteNamespace(namespaceDeclaration.Name))
				{
					return base.VisitNamespaceDeclaration(namespaceDeclaration, data);
				}
			}

			public override object VisitTypeDeclaration(ICSharpCode.NRefactory.Ast.TypeDeclaration typeDeclaration, object data)
			{
				if(typeDeclaration.Type == ICSharpCode.NRefactory.Ast.ClassType.Interface)
				{
					var typeName = "Proxy" + typeDeclaration.Name;
					writer.Write("public class " + typeName + " : " + typeDeclaration.Name);
					writer.NewLine();
					using(writer.WriteBrackets())
					{
						writer.Write("public " + typeDeclaration.Name + " RealObject { get; private set; }");
						writer.NewLine();
						writer.Write("public " + typeName + "(" + typeDeclaration.Name + " realObject)");
						writer.NewLine();
						using(writer.WriteBrackets())
						{
							writer.Write("this.RealObject = realObject;");
						}
						return base.VisitTypeDeclaration(typeDeclaration, data);
					}

				}
				return null;
			}

			public override object VisitMethodDeclaration(ICSharpCode.NRefactory.Ast.MethodDeclaration methodDeclaration, object data)
			{
				writer.Write("public virtual " + ToName(methodDeclaration.TypeReference) + " " + methodDeclaration.Name + "(" + String.Join(", ", methodDeclaration.Parameters.Select(p => p.TypeReference + " " + p.ParameterName)) + ")");
				writer.NewLine();
				using(writer.WriteBrackets())
				{
					bool isVoid = methodDeclaration.TypeReference.Type == "System.Void";
					writer.Write((isVoid ? "" : "return ") + "RealObject." + methodDeclaration.Name + "(" + String.Join(",", methodDeclaration.Parameters.Select(p => p.ParameterName).ToArray()) + ");");
				}
				return null;
			}

			public override object VisitPropertyDeclaration(ICSharpCode.NRefactory.Ast.PropertyDeclaration propertyDeclaration, object data)
			{
				writer.Write("public virtual " + propertyDeclaration.TypeReference + " " + propertyDeclaration.Name);
				writer.NewLine();
				using(writer.WriteBrackets())
				{
					if(propertyDeclaration.HasGetRegion)
					{
						writer.Write("get");
						writer.NewLine();
						using(writer.WriteBrackets())
						{
							writer.Write("return RealObject." + propertyDeclaration.Name + ";");
						}
					}
					if(propertyDeclaration.HasSetRegion)
					{
						writer.Write("set");
						writer.NewLine();
						using(writer.WriteBrackets())
						{
							writer.Write("RealObject." + propertyDeclaration.Name + " = value;");
						}
					}
				}
				return null;
			}

			private string ToName(ICSharpCode.NRefactory.Ast.TypeReference typeReference)
			{
				if(typeReference.Type == "System.Void")
					return "void";
				return typeReference.ToString();
			}
		}
		#region IExtension Members

		public void Execute(ExtensionContext extensionContext)
		{
			var item = extensionContext.GenItems.FirstOrDefault(o => o.Name == "IRoleProvider.cs");
			item.Logger.Error("See you soon :)", 1, 5);
			if(item != null && item.Modified)
			{
				var asyncItem = item.CreateChildItem("Proxy" + item.Name);
				CodeWriter writer = new CodeWriter(asyncItem.Open());
				var itemAst = item.GetExtension<CompilationUnitExtension>();
				itemAst.ParseMethodBodies = false;
				itemAst.CompilationUnit.AcceptVisitor(new ProxiedInterfaceVisitor(writer), null);
				writer.Flush();
			}
		}

		#endregion
	}
}