/*
 * 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.internal.properties;

import java.lang.invoke.MethodHandles;
import java.util.Optional;
import java.util.Set;

import org.hibernate.validator.internal.util.CollectionHelper;
import org.hibernate.validator.internal.util.Contracts;
import org.hibernate.validator.internal.util.StringHelper;
import org.hibernate.validator.internal.util.logging.Log;
import org.hibernate.validator.internal.util.logging.LoggerFactory;
import org.hibernate.validator.spi.properties.ConstrainableExecutable;
import org.hibernate.validator.spi.properties.GetterPropertySelectionStrategy;

Author:
Marko Bekhta/**
 * @author Marko Bekhta
 */
public class DefaultGetterPropertySelectionStrategy implements GetterPropertySelectionStrategy {

	private static final Log LOG = LoggerFactory.make( MethodHandles.lookup() );

	private static final String GETTER_PREFIX_GET = "get";
	private static final String GETTER_PREFIX_IS = "is";
	private static final String GETTER_PREFIX_HAS = "has";
	private static final String[] GETTER_PREFIXES = {
			GETTER_PREFIX_GET,
			GETTER_PREFIX_IS,
			GETTER_PREFIX_HAS
	};

	@Override
	public Optional<String> getProperty(ConstrainableExecutable executable) {
		Contracts.assertNotNull( executable, "executable cannot be null" );

		if ( !isGetter( executable ) ) {
			return Optional.empty();
		}

		String methodName = executable.getName();

		for ( String prefix : GETTER_PREFIXES ) {
			if ( methodName.startsWith( prefix ) ) {
				return Optional.of( StringHelper.decapitalize( methodName.substring( prefix.length() ) ) );
			}
		}

		throw new AssertionError( "Method " + executable.getName() + " was considered a getter but we couldn't extract a property name." );
	}

	@Override
	public Set<String> getGetterMethodNameCandidates(String propertyName) {
		Contracts.assertNotEmpty( propertyName, "Name of a property must not be empty" );

		Set<String> nameCandidates = CollectionHelper.newHashSet( GETTER_PREFIXES.length );
		for ( String prefix : GETTER_PREFIXES ) {
			nameCandidates.add( prefix + Character.toUpperCase( propertyName.charAt( 0 ) ) + propertyName.substring( 1 ) );
		}
		return nameCandidates;
	}

	
Checks whether the given executable is a valid JavaBean getter method, which
is the case if

its name starts with "get" and it has a return type but no parameter or
its name starts with "is", it has no parameter and is returning boolean or
its name starts with "has", it has no parameter and is returning boolean (HV-specific, not mandated by the JavaBeans spec).

Params:
executable – The executable of interest.
Returns:
true, if the given executable is a JavaBean getter method, false otherwise./**
	 * Checks whether the given executable is a valid JavaBean getter method, which
	 * is the case if
	 * <ul>
	 * <li>its name starts with "get" and it has a return type but no parameter or</li>
	 * <li>its name starts with "is", it has no parameter and is returning
	 * {@code boolean} or</li>
	 * <li>its name starts with "has", it has no parameter and is returning
	 * {@code boolean} (HV-specific, not mandated by the JavaBeans spec).</li>
	 * </ul>
	 *
	 * @param executable The executable of interest.
	 *
	 * @return {@code true}, if the given executable is a JavaBean getter method,
	 * {@code false} otherwise.
	 */
	private static boolean isGetter(ConstrainableExecutable executable) {
		if ( executable.getParameterTypes().length != 0 ) {
			return false;
		}

		String methodName = executable.getName();

		//<PropertyType> get<PropertyName>()
		if ( methodName.startsWith( GETTER_PREFIX_GET ) && executable.getReturnType() != void.class ) {
			return true;
		}
		//boolean is<PropertyName>()
		else if ( methodName.startsWith( GETTER_PREFIX_IS ) && executable.getReturnType() == boolean.class ) {
			return true;
		}
		//boolean has<PropertyName>()
		else if ( methodName.startsWith( GETTER_PREFIX_HAS ) && executable.getReturnType() == boolean.class ) {
			return true;
		}

		return false;
	}
}