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// 
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// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
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// 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
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using System;
using System.Threading;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
	/// <summary>
	/// Helper class that resolves the node at a specified location.
	/// Can be used for implementing tool tips.
	/// </summary>
	public static class ResolveAtLocation
	{
		public static ResolveResult Resolve(ICompilation compilation, CSharpParsedFile parsedFile, CompilationUnit cu, TextLocation location,
		                                    CancellationToken cancellationToken = default(CancellationToken))
		{
			AstNode node = cu.GetNodeAt(location);
			if (node == null)
				return null;
			if (CSharpAstResolver.IsUnresolvableNode(node)) {
				if (node is Identifier) {
					node = node.Parent;
				} else if (node.NodeType == NodeType.Token) {
					if (node.Parent is ConstructorInitializer) {
						node = node.Parent;
					} else {
						return null;
					}
				} else {
					// don't resolve arbitrary nodes - we don't want to show tooltips for everything
					return null;
				}
			}
			if (node == null)
				return null;
			
			if (node.Parent is ObjectCreateExpression && node.Role == ObjectCreateExpression.Roles.Type) {
				node = node.Parent;
			}
			
			InvocationExpression parentInvocation = null;
			if (node is IdentifierExpression || node is MemberReferenceExpression || node is PointerReferenceExpression) {
				// we also need to resolve the invocation
				parentInvocation = node.Parent as InvocationExpression;
			}
			
			CSharpAstResolver resolver = new CSharpAstResolver(compilation, cu, parsedFile);
			ResolveResult rr = resolver.Resolve(node, cancellationToken);
			if (rr is MethodGroupResolveResult && parentInvocation != null)
				return resolver.Resolve(parentInvocation);
			else
				return rr;
		}
	}
}