/*
 * Copyright 2011-2020 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
 *
 *      https://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.jpa.support;

import java.io.IOException;
import java.net.URI;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.Entity;
import javax.persistence.MappedSuperclass;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.core.env.Environment;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternUtils;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.lang.Nullable;
import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
import org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

PersistenceUnitPostProcessor that will scan for classes annotated with Entity or MappedSuperclass and add them to the PersistenceUnit post processed. Beyond that JPA XML mapping files can be scanned as well by configuring a file name pattern. 
Author:
Oliver Gierke, Thomas Darimont, Mark Paluch, David Madden/**
 * {@link PersistenceUnitPostProcessor} that will scan for classes annotated with {@link Entity} or
 * {@link MappedSuperclass} and add them to the {@link javax.persistence.PersistenceUnit} post processed. Beyond that
 * JPA XML mapping files can be scanned as well by configuring a file name pattern.
 *
 * @author Oliver Gierke
 * @author Thomas Darimont
 * @author Mark Paluch
 * @author David Madden
 */
public class ClasspathScanningPersistenceUnitPostProcessor
		implements PersistenceUnitPostProcessor, ResourceLoaderAware, EnvironmentAware {

	private static final Logger LOG = LoggerFactory.getLogger(ClasspathScanningPersistenceUnitPostProcessor.class);

	private final String basePackage;

	private ResourcePatternResolver mappingFileResolver = new PathMatchingResourcePatternResolver();
	private Environment environment = new StandardEnvironment();
	private ResourceLoader resourceLoader = new DefaultResourceLoader();
	private @Nullable String mappingFileNamePattern;

	
Creates a new ClasspathScanningPersistenceUnitPostProcessor using the given base package as scan base. 
Params:
basePackage – must not be null or empty./**
	 * Creates a new {@link ClasspathScanningPersistenceUnitPostProcessor} using the given base package as scan base.
	 *
	 * @param basePackage must not be {@literal null} or empty.
	 */
	public ClasspathScanningPersistenceUnitPostProcessor(String basePackage) {

		Assert.hasText(basePackage, "Base package must not be null or empty!");

		this.basePackage = basePackage;
	}

	
Configures the file name pattern JPA entity mapping files shall scanned from the classpath. Lookup will use the
configured base package as root.
Params:
mappingFilePattern – must not be null or empty./**
	 * Configures the file name pattern JPA entity mapping files shall scanned from the classpath. Lookup will use the
	 * configured base package as root.
	 *
	 * @param mappingFilePattern must not be {@literal null} or empty.
	 */
	public void setMappingFileNamePattern(String mappingFilePattern) {

		Assert.hasText(mappingFilePattern, "Mapping file pattern must not be null or empty!");

		this.mappingFileNamePattern = mappingFilePattern;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.context.ResourceLoaderAware#setResourceLoader(org.springframework.core.io.ResourceLoader)
	 */
	@Override
	public void setResourceLoader(ResourceLoader resourceLoader) {

		Assert.notNull(resourceLoader, "ResourceLoader must not be null!");

		this.mappingFileResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
		this.resourceLoader = resourceLoader;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.context.EnvironmentAware#setEnvironment(org.springframework.core.env.Environment)
	 */
	@Override
	public void setEnvironment(Environment environment) {

		Assert.notNull(environment, "Environment must not be null!");

		this.environment = environment;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor#postProcessPersistenceUnitInfo(org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo)
	 */
	@Override
	public void postProcessPersistenceUnitInfo(MutablePersistenceUnitInfo pui) {

		ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(false);

		provider.setEnvironment(environment);
		provider.setResourceLoader(resourceLoader);
		provider.addIncludeFilter(new AnnotationTypeFilter(Entity.class));
		provider.addIncludeFilter(new AnnotationTypeFilter(MappedSuperclass.class));

		for (BeanDefinition definition : provider.findCandidateComponents(basePackage)) {

			LOG.debug("Registering classpath-scanned entity {} in persistence unit info!", definition.getBeanClassName());

			if (definition.getBeanClassName() != null) {
				pui.addManagedClassName(definition.getBeanClassName());
			}
		}

		for (String location : scanForMappingFileLocations()) {

			LOG.debug("Registering classpath-scanned entity mapping file {} in persistence unit info!", location);

			pui.addMappingFileName(location);
		}
	}

	
Scans the configured base package for files matching the configured mapping file name pattern. Will simply return an empty Set in case no ResourceLoader or mapping file name pattern was configured. Resulting paths are resource-loadable from the application classpath according to the JPA spec. 
See Also:
PersistenceUnitInfo.getMappingFileNames()
Returns:
/**
	 * Scans the configured base package for files matching the configured mapping file name pattern. Will simply return
	 * an empty {@link Set} in case no {@link ResourceLoader} or mapping file name pattern was configured. Resulting paths
	 * are resource-loadable from the application classpath according to the JPA spec.
	 *
	 * @see javax.persistence.spi.PersistenceUnitInfo#getMappingFileNames()
	 * @return
	 */
	private Set<String> scanForMappingFileLocations() {

		if (!StringUtils.hasText(mappingFileNamePattern)) {
			return Collections.emptySet();
		}

		/*
		 * Note that we cannot use File.pathSeparator here since resourcePath uses a forward slash path ('/') separator
		 * being an URI, while basePackagePathComponent has system dependent separator (on windows it's the backslash separator).
		 *
		 * See DATAJPA-407.
		 */
		char slash = '/';
		String basePackagePathComponent = basePackage.replace('.', slash);
		String path = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX + basePackagePathComponent + slash
				+ mappingFileNamePattern;
		Resource[] scannedResources;

		try {
			scannedResources = mappingFileResolver.getResources(path);
		} catch (IOException e) {
			throw new IllegalStateException(String.format("Cannot load mapping files from path %s!", path), e);
		}

		Set<String> mappingFileUris = new HashSet<>();

		for (Resource resource : scannedResources) {

			try {

				String resourcePath = getResourcePath(resource.getURI());
				String resourcePathInClasspath = resourcePath.substring(resourcePath.indexOf(basePackagePathComponent));
				mappingFileUris.add(resourcePathInClasspath);

			} catch (IOException e) {
				throw new IllegalStateException(String.format("Couldn't get URI for %s!", resource.toString()), e);
			}
		}

		return mappingFileUris;
	}

	
Returns the path from the given URI. In case the given URI is opaque, e.g. beginning with jar:file, the path is extracted from URI by leaving out the protocol prefix, see DATAJPA-519. 
Params:
uri – 
Returns:
/**
	 * Returns the path from the given {@link URI}. In case the given {@link URI} is opaque, e.g. beginning with jar:file,
	 * the path is extracted from URI by leaving out the protocol prefix, see DATAJPA-519.
	 *
	 * @param uri
	 * @return
	 */
	private static String getResourcePath(URI uri) throws IOException {

		if (uri.isOpaque()) {
			// e.g. jar:file:/foo/lib/somelib.jar!/com/acme/orm.xml
			String rawPath = uri.toString();

			if (rawPath != null) {

				int exclamationMarkIndex = rawPath.lastIndexOf('!');

				if (exclamationMarkIndex > -1) {

					// /com/acme/orm.xml
					return rawPath.substring(exclamationMarkIndex + 1);
				}
			}
		}

		return uri.getPath();
	}
}