/*
 * Copyright 2011-2014 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.repository.core.support;

import lombok.Getter;

import java.util.List;

import org.springframework.data.repository.Repository;
import org.springframework.data.repository.core.RepositoryMetadata;
import org.springframework.data.util.ClassTypeInformation;
import org.springframework.data.util.TypeInformation;
import org.springframework.util.Assert;

/**
 * Default implementation of {@link RepositoryMetadata}. Will inspect generic types of {@link Repository} to find out
 * about domain and id class.
 * 
 * @author Oliver Gierke
 * @author Thomas Darimont
 */
@Getter
public class DefaultRepositoryMetadata extends AbstractRepositoryMetadata {

	private static final String MUST_BE_A_REPOSITORY = String.format("Given type must be assignable to %s!",
			Repository.class);

	private final Class<?> idType;
	private final Class<?> domainType;

	/**
	 * Creates a new {@link DefaultRepositoryMetadata} for the given repository interface.
	 * 
	 * @param repositoryInterface must not be {@literal null}.
	 */
	public DefaultRepositoryMetadata(Class<?> repositoryInterface) {

		super(repositoryInterface);
		Assert.isTrue(Repository.class.isAssignableFrom(repositoryInterface), MUST_BE_A_REPOSITORY);

		this.idType = resolveIdType(repositoryInterface);
		this.domainType = resolveDomainType(repositoryInterface);
	}

	private static Class<?> resolveIdType(Class<?> repositoryInterface) {

		TypeInformation<?> information = ClassTypeInformation.from(repositoryInterface);
		List<TypeInformation<?>> arguments = information.getSuperTypeInformation(Repository.class).getTypeArguments();

		if (arguments.size() < 2 || arguments.get(1) == null) {
			throw new IllegalArgumentException(String.format("Could not resolve id type of %s!", repositoryInterface));
		}

		return arguments.get(1).getType();
	}

	private static Class<?> resolveDomainType(Class<?> repositoryInterface) {

		TypeInformation<?> information = ClassTypeInformation.from(repositoryInterface);
		List<TypeInformation<?>> arguments = information.getSuperTypeInformation(Repository.class).getTypeArguments();

		if (arguments.isEmpty() || arguments.get(0) == null) {
			throw new IllegalArgumentException(String.format("Could not resolve domain type of %s!", repositoryInterface));
		}

		return arguments.get(0).getType();
	}
}