IdInterfaceValidator.java

/*
 * Copyright 2017 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.data.cassandra.repository.support;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.springframework.data.cassandra.repository.MapId;
import org.springframework.data.mapping.model.MappingException;

/**
 * @author Matthew T. Adams
 * @author Mark Paluch
 */
public class IdInterfaceValidator {

	/**
	 * Validates the form of the given id interface candidate type. If the interface violates the following restrictions,
	 * then an {@link IdInterfaceExceptions} is thrown containing all of the violations encountered, which can be obtained
	 * from {@link IdInterfaceExceptions#getExceptions()} or, as a convenience,
	 * {@link IdInterfaceExceptions#getMessages()}.
	 * <p/>
	 * Id interfaces are intended to have methods representing setters and getters. Getter methods take the form
	 * <ul>
	 * <li>{@code PropertyType getPropertyName()} or</li>
	 * <li>{@code PropertyType propertyName()}.</li>
	 * </ul>
	 * Setter methods take the form
	 * <ul>
	 * <li>{@code void|IdType setPropertyName(PropertyType)},</li>
	 * <li>{@code void|IdType withPropertyName(PropertyType)}, or</li>
	 * <li>{@code void|IdType propertyName(PropertyType)};</li>
	 * </ul>
	 * setter methods may also declare that they return their id interface type to support method chaining.
	 * <p/>
	 * Id interfaces
	 * <ul>
	 * <li>must be an {@code interface}, not a <code>class</code>,</li>
	 * <li>may extend {@link MapId} or any other interface,</li>
	 * <li>must have setter methods that only take a single argument,</li>
	 * <li>must have setter methods that only return {@code void} or the id interface's type,</li>
	 * <li>must not define any getter methods with the literal name "get", and</li>
	 * <li>must not define any setter methods with the literal names "set" or "with".</li>
	 * </ul>
	 *
	 * @param id The candidate interface type
	 * @throws IdInterfaceExceptions
	 * @see IdInterfaceExceptions#getExceptions()
	 * @see {@link IdInterfaceException}
	 */
	public static void validate(Class<?> id) {

		List<MappingException> exceptions = new ArrayList<>();

		if (!id.isInterface()) {
			exceptions.add(new IdInterfaceException(id, null, "Id type must be an interface"));
		}

		for (Method m : id.getDeclaredMethods()) {

			Class<?>[] args = m.getParameterTypes();
			String name = m.getName();
			Class<?> returnType = m.getReturnType();

			switch (args.length) {
				case 0: // then getter

					if (name.startsWith("get") && name.length() == 3) {
						exceptions
								.add(new IdInterfaceException(id, m, "Getter method must have a property name following 'get' prefix"));
					}

					if (Void.TYPE.isAssignableFrom(returnType) || Void.class.isAssignableFrom(returnType)) {
						exceptions.add(new IdInterfaceException(id, m, "Getter method must return a value"));
					}

					break;
				case 1: // then setter

					if (name.startsWith("set") && name.length() == 3) {
						exceptions
								.add(new IdInterfaceException(id, m, "Setter method must have a property name following 'set' prefix"));
					}

					if (name.startsWith("with") && name.length() == 4) {
						exceptions.add(
								new IdInterfaceException(id, m, "Setter method must have a property name following 'with' prefix"));
					}

					if (!Void.TYPE.isAssignableFrom(returnType) && !Void.class.equals(returnType) && !id.equals(returnType)) {
						exceptions.add(new IdInterfaceException(id, m,
								"Setter method not returning void may only return the same type as their id interface"));
					}
					break;
				default:
					exceptions.add(new IdInterfaceException(id, m,
							"Id interface methods may only take zero parameters for a getter or one parameter for a setter; found "
									+ args.length));
			}
		}

		if (!exceptions.isEmpty()) {
			throw new IdInterfaceExceptions(id, exceptions);
		}
	}
}