/*
 * Hibernate Validator, declare and validate application constraints
 *
 * License: Apache License, Version 2.0
 * See the license.txt file in the root directory or <http://www.apache.org/licenses/LICENSE-2.0>.
 */
package org.hibernate.validator.parameternameprovider;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import javax.validation.ParameterNameProvider;

import com.thoughtworks.paranamer.AdaptiveParanamer;
import com.thoughtworks.paranamer.CachingParanamer;
import com.thoughtworks.paranamer.Paranamer;

import org.hibernate.validator.internal.engine.DefaultParameterNameProvider;

A ParameterNameProvider implementation backed by the ParaNamer
library.
 The Paranamer implementation to use can be passed when creating a ParanamerParameterNameProvider. By default a AdaptiveParanamer will be used which is wrapped into a CachingParanamer. If no parameter names can be obtained from the configured Paranamer, the default parameter name provider will be used as fall back. 

The ParaNamer library must be present on the classpath when using this parameter name provider.
Author:
Gunnar Morling
See Also:
ParaNamer web site/**
 * A {@link ParameterNameProvider} implementation backed by the <a href="http://paranamer.codehaus.org/">ParaNamer</a>
 * library.
 * <p>
 * The {@link Paranamer} implementation to use can be passed when creating a {@code ParanamerParameterNameProvider}. By
 * default a {@link AdaptiveParanamer} will be used which is wrapped into a {@link CachingParanamer}. If no parameter
 * names can be obtained from the configured {@code Paranamer}, the default parameter name provider will be used as
 * fall back.
 * <p>
 * The ParaNamer library must be present on the classpath when using this parameter name provider.
 *
 * @author Gunnar Morling
 * @see <a href="http://paranamer.codehaus.org/">ParaNamer web site</a>
 */
public class ParanamerParameterNameProvider implements ParameterNameProvider {

	private final ParameterNameProvider fallBackProvider;
	private final Paranamer paranamer;

	public ParanamerParameterNameProvider() {
		this( null );
	}

	public ParanamerParameterNameProvider(Paranamer paranamer) {
		this.paranamer = paranamer != null ? paranamer : new CachingParanamer( new AdaptiveParanamer() );
		fallBackProvider = new DefaultParameterNameProvider();
	}

	@Override
	public List<String> getParameterNames(Constructor<?> constructor) {
		String[] parameterNames;

		//there are no guarantees regarding thread-safety
		synchronized ( paranamer ) {
			parameterNames = paranamer.lookupParameterNames( constructor, false );
		}

		//either null or an empty array is returned if no names could be retrieved
		if ( parameterNames != null && parameterNames.length == constructor.getParameterTypes().length ) {
			return Arrays.asList( parameterNames );
		}

		return fallBackProvider.getParameterNames( constructor );
	}

	@Override
	public List<String> getParameterNames(Method method) {
		String[] parameterNames;

		synchronized ( paranamer ) {
			parameterNames = paranamer.lookupParameterNames( method, false );
		}

		if ( parameterNames != null && parameterNames.length == method.getParameterTypes().length ) {
			return Arrays.asList( parameterNames );
		}

		return fallBackProvider.getParameterNames( method );
	}
}