@Test
void testSignatureHelpOnMethod() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 11);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(1, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveParameter());
}
 

@Test
void testSignatureHelpOnMethodWithMultipleParameters() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0, String param1) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 11);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0, String param1)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(2, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	ParameterInformation param1 = params.get(1);
	Assertions.assertEquals("String param1", param1.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveParameter());
}
 

@Test
void testSignatureHelpOnMethodWithActiveParameter() throws Exception {
	Path filePath = srcRoot.resolve("Completion.groovy");
	String uri = filePath.toUri().toString();
	StringBuilder contents = new StringBuilder();
	contents.append("class SignatureHelp {\n");
	contents.append("  public SignatureHelp() {\n");
	contents.append("    method(123,\n");
	contents.append("  }\n");
	contents.append("  public void method(int param0, String param1) {}\n");
	contents.append("}");
	TextDocumentItem textDocumentItem = new TextDocumentItem(uri, LANGUAGE_GROOVY, 1, contents.toString());
	services.didOpen(new DidOpenTextDocumentParams(textDocumentItem));
	TextDocumentIdentifier textDocument = new TextDocumentIdentifier(uri);
	Position position = new Position(2, 15);
	SignatureHelp signatureHelp = services.signatureHelp(new TextDocumentPositionParams(textDocument, position))
			.get();
	List<SignatureInformation> signatures = signatureHelp.getSignatures();
	Assertions.assertEquals(1, signatures.size());
	SignatureInformation signature = signatures.get(0);
	Assertions.assertEquals("public void method(int param0, String param1)", signature.getLabel());
	List<ParameterInformation> params = signature.getParameters();
	Assertions.assertEquals(2, params.size());
	ParameterInformation param0 = params.get(0);
	Assertions.assertEquals("int param0", param0.getLabel().get());
	ParameterInformation param1 = params.get(1);
	Assertions.assertEquals("String param1", param1.getLabel().get());
	Assertions.assertEquals((int) 0, (int) signatureHelp.getActiveSignature());
	Assertions.assertEquals((int) 1, (int) signatureHelp.getActiveParameter());
}
 

/** @return string for given element */
public String toString(ParameterInformation parmInfo) {
	if (parmInfo == null) {
		return "";
	}
	String str = Strings.join(", ",
			toString8(parmInfo.getLabel()),
			toString7(parmInfo.getDocumentation()));

	return "(" + str + ")";
}
 

public SignatureInformation toSignatureInformation(CompletionProposal methodProposal) {
	SignatureInformation $ = new SignatureInformation();
	StringBuilder desription = descriptionProvider.createMethodProposalDescription(methodProposal);
	$.setLabel(desription.toString());
	$.setDocumentation(this.computeJavaDoc(methodProposal));

	char[] signature = SignatureUtil.fix83600(methodProposal.getSignature());
	char[][] parameterNames = methodProposal.findParameterNames(null);
	char[][] parameterTypes = Signature.getParameterTypes(signature);

	for (int i = 0; i < parameterTypes.length; i++) {
		parameterTypes[i] = Signature.getSimpleName(Signature.toCharArray(SignatureUtil.getLowerBound(parameterTypes[i])));
	}

	if (Flags.isVarargs(methodProposal.getFlags())) {
		int index = parameterTypes.length - 1;
		parameterTypes[index] = convertToVararg(parameterTypes[index]);
	}

	List<ParameterInformation> parameterInfos = new LinkedList<>();
	for (int i = 0; i < parameterTypes.length; i++) {
		StringBuilder builder = new StringBuilder();
		builder.append(parameterTypes[i]);
		builder.append(' ');
		builder.append(parameterNames[i]);

		parameterInfos.add(new ParameterInformation(builder.toString()));
	}

	$.setParameters(parameterInfos);

	return $;
}
 

public CompletableFuture<SignatureHelp> provideSignatureHelp(TextDocumentIdentifier textDocument,
		Position position) {
	if (ast == null) {
		//this shouldn't happen, but let's avoid an exception if something
		//goes terribly wrong.
		return CompletableFuture.completedFuture(new SignatureHelp(Collections.emptyList(), -1, -1));
	}
	URI uri = URI.create(textDocument.getUri());
	ASTNode offsetNode = ast.getNodeAtLineAndColumn(uri, position.getLine(), position.getCharacter());
	if (offsetNode == null) {
		return CompletableFuture.completedFuture(new SignatureHelp(Collections.emptyList(), -1, -1));
	}
	int activeParamIndex = -1;
	MethodCall methodCall = null;
	ASTNode parentNode = ast.getParent(offsetNode);

	if (offsetNode instanceof ArgumentListExpression) {
		methodCall = (MethodCall) parentNode;

		ArgumentListExpression argsList = (ArgumentListExpression) offsetNode;
		List<Expression> expressions = argsList.getExpressions();
		activeParamIndex = getActiveParameter(position, expressions);
	}

	if (methodCall == null) {
		return CompletableFuture.completedFuture(new SignatureHelp(Collections.emptyList(), -1, -1));
	}

	List<MethodNode> methods = GroovyASTUtils.getMethodOverloadsFromCallExpression(methodCall, ast);
	if (methods.isEmpty()) {
		return CompletableFuture.completedFuture(new SignatureHelp(Collections.emptyList(), -1, -1));
	}

	List<SignatureInformation> sigInfos = new ArrayList<>();
	for (MethodNode method : methods) {
		List<ParameterInformation> parameters = new ArrayList<>();
		Parameter[] methodParams = method.getParameters();
		for (int i = 0; i < methodParams.length; i++) {
			Parameter methodParam = methodParams[i];

			ParameterInformation paramInfo = new ParameterInformation();
			paramInfo.setLabel(GroovyNodeToStringUtils.variableToString(methodParam, ast));
			parameters.add(paramInfo);
		}
		SignatureInformation sigInfo = new SignatureInformation();
		sigInfo.setLabel(GroovyNodeToStringUtils.methodToString(method, ast));
		sigInfo.setParameters(parameters);
		sigInfos.add(sigInfo);
	}

	MethodNode bestMethod = GroovyASTUtils.getMethodFromCallExpression(methodCall, ast, activeParamIndex);
	int activeSignature = methods.indexOf(bestMethod);

	return CompletableFuture.completedFuture(new SignatureHelp(sigInfos, activeSignature, activeParamIndex));
}
 

public SignatureInformation(@NonNull final String label, final String documentation, final List<ParameterInformation> parameters) {
  this(label);
  this.setDocumentation(documentation);
  this.parameters = parameters;
}
 

public SignatureInformation(@NonNull final String label, final MarkupContent documentation, final List<ParameterInformation> parameters) {
  this(label);
  this.setDocumentation(documentation);
  this.parameters = parameters;
}
 

/**
 * The parameters of this signature.
 */
@Pure
public List<ParameterInformation> getParameters() {
  return this.parameters;
}
 

/**
 * The parameters of this signature.
 */
public void setParameters(final List<ParameterInformation> parameters) {
  this.parameters = parameters;
}