/*
 * Copyright 2002-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.convert.support;

import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterFactory;
import org.springframework.util.Assert;

/**
 * Converts from a String to a java.lang.Enum by calling {@link Enum#valueOf(Class, String)}.
 *
 * @author Keith Donald
 * @since 3.0
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
final class StringToEnumConverterFactory implements ConverterFactory<String, Enum> {

	public <T extends Enum> Converter<String, T> getConverter(Class<T> targetType) {
		Class<?> enumType = targetType;
		while(enumType != null && !enumType.isEnum()) {
			enumType = enumType.getSuperclass();
		}
		Assert.notNull(enumType, "The target type " + targetType.getName()
				+ " does not refer to an enum");
		return new StringToEnum(enumType);
	}

	private class StringToEnum<T extends Enum> implements Converter<String, T> {

		private final Class<T> enumType;

		public StringToEnum(Class<T> enumType) {
			this.enumType = enumType;
		}

		public T convert(String source) {
			if (source.length() == 0) {
				// It's an empty enum identifier: reset the enum value to null.
				return null;
			}
			return (T) Enum.valueOf(this.enumType, source.trim());
		}
	}

}
