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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using ICSharpCode.NRefactory.CSharp.Parser;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.TypeSystem.Implementation;
using NUnit.Framework;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
	/// <summary>
	/// Base class with helper functions for resolver unit tests.
	/// </summary>
	public abstract class ResolverTestBase
	{
		protected readonly IUnresolvedAssembly mscorlib = CecilLoaderTests.Mscorlib;
		protected IProjectContent project;
		protected ICompilation compilation;
		
		[SetUp]
		public virtual void SetUp()
		{
			project = new CSharpProjectContent().AddAssemblyReferences(new [] { mscorlib, CecilLoaderTests.SystemCore });
			compilation = project.CreateCompilation();
		}
		
		protected IType ResolveType(Type type)
		{
			IType t = compilation.FindType(type);
			if (t.Kind == TypeKind.Unknown)
				throw new InvalidOperationException("Could not resolve type");
			return t;
		}
		
		protected ConstantResolveResult MakeConstant(object value)
		{
			if (value == null)
				return new ConstantResolveResult(SpecialType.NullType, null);
			IType type = ResolveType(value.GetType());
			if (type.Kind == TypeKind.Enum)
				value = Convert.ChangeType(value, Enum.GetUnderlyingType(value.GetType()));
			return new ConstantResolveResult(type, value);
		}
		
		protected ResolveResult MakeResult(Type type)
		{
			return new ResolveResult(ResolveType(type));
		}
		
		protected static TypeOrNamespaceReference MakeReference(string namespaceName)
		{
			string[] nameParts = namespaceName.Split('.');
			TypeOrNamespaceReference r = new SimpleTypeOrNamespaceReference(nameParts[0], new ITypeReference[0], NameLookupMode.TypeInUsingDeclaration);
			for (int i = 1; i < nameParts.Length; i++) {
				r = new MemberTypeOrNamespaceReference(r, nameParts[i], new ITypeReference[0]);
			}
			return r;
		}
		
		protected void AssertConstant(object expectedValue, ResolveResult rr)
		{
			Assert.IsFalse(rr.IsError, rr.ToString() + " is an error");
			Assert.IsTrue(rr.IsCompileTimeConstant, rr.ToString() + " is not a compile-time constant");
			Type expectedType = expectedValue.GetType();
			Assert.AreEqual(ResolveType(expectedType), rr.Type, "ResolveResult.Type is wrong");
			if (expectedType.IsEnum) {
				Assert.AreEqual(Enum.GetUnderlyingType(expectedType), rr.ConstantValue.GetType(), "ResolveResult.ConstantValue has wrong Type");
				Assert.AreEqual(Convert.ChangeType(expectedValue, Enum.GetUnderlyingType(expectedType)), rr.ConstantValue);
			} else {
				Assert.AreEqual(expectedType, rr.ConstantValue.GetType(), "ResolveResult.ConstantValue has wrong Type");
				Assert.AreEqual(expectedValue, rr.ConstantValue);
			}
		}
		
		protected void AssertType(Type expectedType, ResolveResult rr)
		{
			Assert.IsFalse(rr.IsError, rr.ToString() + " is an error");
			Assert.IsFalse(rr.IsCompileTimeConstant, rr.ToString() + " is a compile-time constant");
			Assert.AreEqual(compilation.FindType(expectedType), rr.Type);
		}
		
		protected void AssertError(Type expectedType, ResolveResult rr)
		{
			Assert.IsTrue(rr.IsError, rr.ToString() + " is not an error, but an error was expected");
			Assert.IsFalse(rr.IsCompileTimeConstant, rr.ToString() + " is a compile-time constant");
			Assert.AreEqual(compilation.FindType(expectedType), rr.Type);
		}
		
		protected void TestOperator(UnaryOperatorType op, ResolveResult input,
		                            Conversion expectedConversion, Type expectedResultType)
		{
			CSharpResolver resolver = new CSharpResolver(compilation);
			var rr = resolver.ResolveUnaryOperator(op, input);
			AssertType(expectedResultType, rr);
			Assert.AreEqual(typeof(OperatorResolveResult), rr.GetType());
			var uorr = (OperatorResolveResult)rr;
			AssertConversion(uorr.Operands[0], input, expectedConversion, "Conversion");
		}
		
		protected void TestOperator(ResolveResult lhs, BinaryOperatorType op, ResolveResult rhs,
		                            Conversion expectedLeftConversion, Conversion expectedRightConversion, Type expectedResultType)
		{
			CSharpResolver resolver = new CSharpResolver(compilation);
			var rr = resolver.ResolveBinaryOperator(op, lhs, rhs);
			AssertType(expectedResultType, rr);
			Assert.AreEqual(typeof(OperatorResolveResult), rr.GetType());
			var borr = (OperatorResolveResult)rr;
			AssertConversion(borr.Operands[0], lhs, expectedLeftConversion, "Left conversion");
			AssertConversion(borr.Operands[1], rhs, expectedRightConversion, "Right conversion");
		}
		
		protected void AssertConversion(ResolveResult conversionResult, ResolveResult expectedRR, Conversion expectedConversion, string text)
		{
			if (expectedConversion == Conversion.IdentityConversion) {
				Assert.AreSame(expectedRR, conversionResult, "Expected no " + text);
			} else {
				ConversionResolveResult crr = conversionResult as ConversionResolveResult;
				Assert.IsNotNull(crr, "Could not find ConversionResolveResult for " + text);
				Assert.AreEqual(expectedConversion, crr.Conversion, text);
				Assert.AreSame(expectedRR, crr.Input, "Input of " + text);
			}
		}
		
		protected IEnumerable<TextLocation> FindDollarSigns(string code)
		{
			int line = 1;
			int col = 1;
			foreach (char c in code) {
				if (c == '$') {
					yield return new TextLocation(line, col);
				} else if (c == '\n') {
					line++;
					col = 1;
				} else {
					col++;
				}
			}
		}
		
		protected Tuple<CSharpAstResolver, AstNode> PrepareResolver(string code)
		{
			SyntaxTree syntaxTree = new CSharpParser().Parse(code.Replace("$", ""), "code.cs");
			
			TextLocation[] dollars = FindDollarSigns(code).ToArray();
			Assert.AreEqual(2, dollars.Length, "Expected 2 dollar signs marking start+end of desired node");
			
			SetUp();
			
			CSharpUnresolvedFile unresolvedFile = syntaxTree.ToTypeSystem();
			project = project.AddOrUpdateFiles(unresolvedFile);
			compilation = project.CreateCompilation();
			
			CSharpAstResolver resolver = new CSharpAstResolver(compilation, syntaxTree, unresolvedFile);
			return Tuple.Create(resolver, FindNode(syntaxTree, dollars[0], dollars[1]));
		}
		
		protected ResolveResult Resolve(string code)
		{
			var prep = PrepareResolver(code);
			Debug.WriteLine(new string('=', 70));
			Debug.WriteLine("Starting new resolver for " + prep.Item2);
			
			ResolveResult rr = prep.Item1.Resolve(prep.Item2);
			Assert.IsNotNull(rr, "ResolveResult is null - did something go wrong while navigating to the target node?");
			Debug.WriteLine("ResolveResult is " + rr);
			return rr;
		}
		
		protected Conversion GetConversion(string code)
		{
			var prep = PrepareResolver(code);
			return prep.Item1.GetConversion((Expression)prep.Item2);
		}
		
		protected IType GetExpectedType(string code)
		{
			var prep = PrepareResolver(code);
			return prep.Item1.GetExpectedType((Expression)prep.Item2);
		}
		
		protected T Resolve<T>(string code) where T : ResolveResult
		{
			ResolveResult rr = Resolve(code);
			Assert.IsNotNull(rr);
			if (typeof(T) == typeof(LambdaResolveResult)) {
				Assert.IsTrue(rr is LambdaResolveResult, "Resolve should be " + typeof(T).Name + ", but was " + rr.GetType().Name);
			} else {
				Assert.IsTrue(rr.GetType() == typeof(T), "Resolve should be " + typeof(T).Name + ", but was " + rr.GetType().Name);
			}
			return (T)rr;
		}
		
		protected AstNode FindNode(SyntaxTree syntaxTree, TextLocation start, TextLocation end)
		{
			FindNodeVisitor fnv = new FindNodeVisitor(start, end);
			syntaxTree.AcceptVisitor(fnv);
			Assert.IsNotNull(fnv.ResultNode, "Did not find DOM node at the specified location");
			return fnv.ResultNode;
		}
		
		sealed class FindNodeVisitor : DepthFirstAstVisitor
		{
			readonly TextLocation start;
			readonly TextLocation end;
			public AstNode ResultNode;
			
			public FindNodeVisitor(TextLocation start, TextLocation end)
			{
				this.start = start;
				this.end = end;
			}
			
			protected override void VisitChildren(AstNode node)
			{
				if (node.StartLocation == start && node.EndLocation == end) {
					if (ResultNode != null)
						throw new InvalidOperationException("found multiple nodes with same start+end");
					ResultNode = node;
					return;
				}
				base.VisitChildren(node);
			}
		}
		
		protected ResolveResult ResolveAtLocation(string code)
		{
			SyntaxTree syntaxTree = SyntaxTree.Parse(code.Replace("$", ""), "test.cs");
			
			TextLocation[] dollars = FindDollarSigns(code).ToArray();
			Assert.AreEqual(1, dollars.Length, "Expected 1 dollar signs marking the location");
			
			SetUp();
			
			CSharpUnresolvedFile unresolvedFile = syntaxTree.ToTypeSystem();
			project = project.AddOrUpdateFiles(unresolvedFile);
			compilation = project.CreateCompilation();
			
			ResolveResult rr = Resolver.ResolveAtLocation.Resolve(compilation, unresolvedFile, syntaxTree, dollars[0]);
			return rr;
		}
		
		protected T ResolveAtLocation<T>(string code) where T : ResolveResult
		{
			ResolveResult rr = ResolveAtLocation(code);
			Assert.IsNotNull(rr);
			Assert.IsTrue(rr.GetType() == typeof(T), "Resolve should be " + typeof(T).Name + ", but was " + rr.GetType().Name);
			return (T)rr;
		}
	}
}