D-Net

package eu.dnetlib.xml.database.exist; // NOPMD

import java.io.File;

import java.io.FileOutputStream;

import java.io.FileWriter;

import java.io.IOException;

import java.text.SimpleDateFormat;

import java.util.*;

import java.util.Map.Entry;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantReadWriteLock;

import java.util.zip.ZipEntry;

import java.util.zip.ZipOutputStream;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.exist.collections.CollectionConfiguration;

import org.exist.util.DatabaseConfigurationException;

import org.exist.xmldb.DatabaseImpl;

import org.exist.xmldb.DatabaseInstanceManager;

import org.exist.xmldb.EXistResource;

import org.exist.xmldb.XmldbURI;

import org.springframework.beans.factory.annotation.Required;

import org.springframework.context.Lifecycle;

import org.xmldb.api.DatabaseManager;

import org.xmldb.api.base.*;

import org.xmldb.api.base.Collection;

import org.xmldb.api.modules.CollectionManagementService;

import org.xmldb.api.modules.XPathQueryService;

import eu.dnetlib.miscutils.datetime.DateUtils;

import eu.dnetlib.xml.database.Trigger;

import eu.dnetlib.xml.database.XMLDatabase;

/**

 * eXist database wrapper.

 *

 * @author marko

 *

 */

public class ExistDatabase implements XMLDatabase, Lifecycle { // NOPMD by marko

	/**

	 * logger.

	 */

	private static final Log log = LogFactory.getLog(ExistDatabase.class); // NOPMD

	/**

	 * eXist collection configuration special file.

	 */

	public static final String COLLECTION_XCONF = "collection.xconf";

	/**

	 * exist xml resource type code.

	 */

	private static final String XMLRESOURCE = "XMLResource";

	/**

	 * collection name to trigger instance map.

	 *

	 * all triggers declared here will be registered at startup.

	 *

	 */

	private Map<String, Trigger> triggerConf = new HashMap<>();

	private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();

	private final Lock readLock = rwl.readLock();

	private final Lock writeLock = rwl.writeLock();

	/**

	 * eXist database.

	 */

	private Database database;

	/**

	 * eXist collection.

	 */

	private Collection root;

	/**

	 * eXist database manager.

	 */

	private DatabaseInstanceManager manager;

	/**

	 * eXist xpath service.

	 */

	private XPathQueryService queryService;

	/**

	 * eXist collection manager.

	 */

	private CollectionManagementService colman;

	/**

	 * eXist configuration file.

	 */

	private String configFile;

	/**

	 * Directory in which backups are saved.

	 */

	private String backupDir;

	/**

	 * {@inheritDoc}

	 *

	 * @see org.springframework.context.Lifecycle#start()

	 */

	@Override

	public void start() {

		log.info("starting database");

		try {

			if (getDatabase() == null) {

				setDatabase(new DatabaseImpl());

				getDatabase().setProperty("configuration", getConfigFile());

				getDatabase().setProperty("create-database", "true");

			}

			DatabaseManager.registerDatabase(getDatabase());

			setRoot(DatabaseManager.getCollection("xmldb:exist://" + getRootCollection(), "admin", ""));

			setManager((DatabaseInstanceManager) getRoot().getService("DatabaseInstanceManager", "1.0"));

			setQueryService((XPathQueryService) getRoot().getService("XPathQueryService", "1.0"));

			setColman((CollectionManagementService) getRoot().getService("CollectionManagementService", "1.0"));

			for (final Entry<String, Trigger> entry : getTriggerConf().entrySet())

				registerTrigger(entry.getValue(), entry.getKey());

		} catch (final XMLDBException e) {

			throw new IllegalStateException("cannot open eXist database", e);

		}

	}

	/**

	 * helper method.

	 *

	 * @param collection

	 *            collection name

	 * @return an eXist collection

	 * @throws XMLDBException

	 *             happens

	 */

	protected Collection getCollection(final String collection) throws XMLDBException {

		readLock.lock();

		try {

			if (!collection.startsWith("/db"))

				throw new XMLDBException(0, "collection path should begin with /db");

			return database.getCollection("exist://" + collection, "admin", "");

		}finally {

			readLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#create(java.lang.String, java.lang.String, java.lang.String)

	 */

	@Override

	public void create(final String name, final String collection, final String content) throws XMLDBException {

		writeLock.lock();

		try {

			if ("".equals(name))

				throw new XMLDBException(0, "cannot create a xml file with an empty file name");

			Collection col = getCollection(collection);

			if (col == null) {

				// create parent collections

				createCollection(collection, true);

				col = getCollection(collection);

			}

			final Resource res = col.createResource(name, XMLRESOURCE);

			res.setContent(content);

			col.storeResource(res);

			((EXistResource) res).freeResources();

			col.close();

		}finally {

			writeLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#remove(java.lang.String, java.lang.String)

	 */

	@Override

	public boolean remove(final String name, final String collection) throws XMLDBException {

		writeLock.lock();

		try {

			final Collection col = getCollection(collection);

			final Resource res = col.getResource(name);

			if (res == null)

				return false;

			col.removeResource(res);

			col.close();

			return true;

		} finally {

			writeLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#update(java.lang.String, java.lang.String, java.lang.String)

	 */

	@Override

	public void update(final String name, final String collection, final String content) throws XMLDBException {

		writeLock.lock();

		try{

			final Collection col = getCollection(collection);

			final Resource res = col.getResource(name);

			if (res == null) {

				throw new XMLDBException(0, "resource doesn't exist");

			}

			res.setContent(content);

			col.storeResource(res);

			((EXistResource) res).freeResources();

			col.close();

		} finally {

			writeLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#read(java.lang.String, java.lang.String)

	 */

	@Override

	public String read(final String name, final String collection) throws XMLDBException {

		readLock.lock();

		try {

			Resource res = null;

			final Collection coll = getCollection(collection);

			try {

				if (coll == null)

					return null;

				res = coll.getResource(name);

				if (res != null)

					return (String) res.getContent();

				return null;

			} finally {

				if (res != null)

					((EXistResource) res).freeResources();

				coll.close();

			}

		}finally {

			readLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#xquery(java.lang.String)

	 */

	@Override

	public Iterator<String> xquery(final String query) throws XMLDBException {

		readLock.lock();

		try {

			final ResourceSet result = getQueryService().query(query);

			if (result == null)

				return null;

			final ResourceIterator iterator = result.getIterator();

			return new Iterator<String>() {

				@Override

				public boolean hasNext() {

					try {

						return iterator.hasMoreResources();

					} catch (XMLDBException e) {

						throw new RuntimeException("Error while getting next element", e);

					}

				}

				@Override

				public String next() {

					Resource res = null;

					try {

						res = iterator.nextResource();

						return (String) res.getContent();

					} catch (XMLDBException e) {

						throw new RuntimeException("Error while getting next element", e);

					} finally {

						if (res != null)

							try {

								((EXistResource) res).freeResources();

							} catch (XMLDBException e) {

								log.error("error on free resource");

							}

					}

				}

			};

		} finally {

			readLock.unlock();

		}

	}

	@Override

	public void xupdate(final String query) throws XMLDBException {

		writeLock.lock();

		try{

			getQueryService().query(query);

		} finally {

			writeLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see org.springframework.context.Lifecycle#stop()

	 */

	@Override

	public void stop() {

		// no operation

		try {

			getManager().shutdown();

			DatabaseManager.deregisterDatabase(database);

		} catch (final XMLDBException e) {

			log.fatal("cannot close database", e);

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#collectionExists(java.lang.String)

	 */

	@Override

	public boolean collectionExists(final String collection) throws XMLDBException {

		Collection col = null;

		try{

			col = getCollection(collection);

			return col != null;

		} finally {

			if (col!=null)

				col.close();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#createCollection(java.lang.String)

	 */

	@Override

	public void createCollection(final String collection) throws XMLDBException {

		writeLock.lock();

		try {

			createCollection(collection, false);

		}finally {

			writeLock.unlock();

		}

	}

	private void createCollection(final String collection, final boolean recursive) throws XMLDBException {

		if (recursive) {

			final XmldbURI uri = XmldbURI.create(collection).removeLastSegment();

			if (!collectionExists(uri.toString()))

				createCollection(uri.toString(), true);

		}

		getColman().createCollection(collection);

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#removeCollection(java.lang.String)

	 */

	@Override

	public void removeCollection(final String collection) throws XMLDBException {

		writeLock.lock();

		try {

			getColman().removeCollection(collection);

		}finally {

			writeLock.unlock();

		}

	}

	public String getConfigFile() {

		return configFile;

	}

	public void setConfigFile(final String configFile) {

		this.configFile = configFile;

	}

	@Override

	public String getBackupDir() {

		return backupDir;

	}

	@Required

	public void setBackupDir(final String backupDir) {

		this.backupDir = backupDir;

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see org.springframework.context.Lifecycle#isRunning() useless contract with spring.

	 *

	 */

	@Override

	public boolean isRunning() {

		return false;

	}

	protected Database getDatabase() {

		return database;

	}

	protected void setDatabase(final Database database) {

		this.database = database;

	}

	protected Collection getRoot() {

		return root;

	}

	protected void setRoot(final Collection root) {

		this.root = root;

	}

	protected DatabaseInstanceManager getManager() {

		return manager;

	}

	protected void setManager(final DatabaseInstanceManager manager) {

		this.manager = manager;

	}

	protected XPathQueryService getQueryService() {

		return queryService;

	}

	protected void setQueryService(final XPathQueryService queryService) {

		this.queryService = queryService;

	}

	protected CollectionManagementService getColman() {

		return colman;

	}

	protected void setColman(final CollectionManagementService colman) {

		this.colman = colman;

	}

	@Override

	public String getRootCollection() {

		return "/db";

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#listChildCollections(java.lang.String)

	 */

	@Override

	public List<String> listChildCollections(final String collection) throws XMLDBException {

		readLock.lock();

		try {

			final Collection col = getCollection(collection);

			if (col == null)

				return new ArrayList<>();

			return Arrays.asList(col.listChildCollections());

		} finally {

			readLock.unlock();

		}

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#list(java.lang.String)

	 */

	@Override

	public List<String> list(final String collection) throws XMLDBException {

		readLock.lock();

		try {

			final Collection col = getCollection(collection);

			if(col == null)

				return new ArrayList();

			return Arrays.asList(col.listResources());

		} finally {

			readLock.unlock();

		}

	}

	/**

	 * sets an underlying eXist trigger class for a given collection.

	 *

	 * @param triggerClass

	 *            exist trigger class

	 * @param collection

	 *            collection name

	 * @param events

	 *            list of event names

	 * @param parameters

	 *            parameter map

	 * @throws XMLDBException

	 *             happens

	 */

	void setExistTrigger(final Class<?> triggerClass, final String collection, final List<String> events, final Map<String, String> parameters)

			throws XMLDBException {

		// Arrays.asList(new String[] { "store", "update", "delete" }

		final StringBuilder conf = new StringBuilder();

		conf.append("<exist:collection xmlns:exist=\"http://exist-db.org/collection-config/1.0\"><exist:triggers>");

		final String className = triggerClass.getCanonicalName(); // PMD

		conf.append("<exist:trigger event=\"store,update,remove\" class=\"" + className + "\">");

		if (parameters != null)

			for (final Entry<String, String> entry : parameters.entrySet())

				conf.append("<exist:parameter name=\"" + entry.getKey() + "\" value=\"" + entry.getValue() + "\"/>");

		conf.append("</exist:trigger>");

		conf.append("</exist:triggers></exist:collection>");

		log.info(conf.toString());

		createCollection("/db/system/config" + collection, true);

		create(CollectionConfiguration.DEFAULT_COLLECTION_CONFIG_FILE_URI.toString(), "/db/system/config" + collection, conf.toString());

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#registerTrigger(eu.dnetlib.xml.database.Trigger, java.lang.String)

	 */

	@Override

	public void registerTrigger(final Trigger trigger, final String collection) throws XMLDBException {

		final Map<String, String> params = new HashMap<String, String>();

		params.put("triggerName", trigger.getName());

		ExistTriggerRegistry.defaultInstance().registerTrigger(trigger.getName(), trigger);

		setExistTrigger(DelegatingDiffTrigger.class, collection, Arrays.asList("store", "update", "delete" ), params);

	}

	public Map<String, Trigger> getTriggerConf() {

		return triggerConf;

	}

	public void setTriggerConf(final Map<String, Trigger> triggerConf) {

		this.triggerConf = triggerConf;

	}

	/**

	 * {@inheritDoc}

	 *

	 * @see eu.dnetlib.xml.database.XMLDatabase#backup()

	 */

	@Override

	public String backup() throws XMLDBException, DatabaseConfigurationException {

		log.info("Starting backup...");

		readLock.lock();

		try {

			verifyBackupDir();

			String seq = (new SimpleDateFormat("yyyyMMdd-HHmm")).format(new Date());

			ZipOutputStream zip = new ZipOutputStream(new FileOutputStream(backupDir + "/data-" + seq + ".zip"));

			FileWriter logFile = new FileWriter(backupDir + "/report-" + seq + ".log");

			logFile.write("Backup started at: " + DateUtils.now_ISO8601() + "\n\n");

			backup(getRoot().getName(), zip, logFile);

			logFile.write("\nBackup finished at: " + DateUtils.now_ISO8601() + "\n");

			logFile.flush();

			logFile.close();

			zip.flush();

			zip.close();

			log.info("Backup finished");

			return backupDir;

		} catch (final Exception e) {

			log.error("Backup failed", e);

			throw new XMLDBException(0, "cannot backup", e);

		}

		finally {

			readLock.unlock();

		}

	}

	private void verifyBackupDir() {

		File d = new File(backupDir);

		if (!d.exists()) d.mkdirs();

	}

	private void backup(String coll, ZipOutputStream zip, FileWriter logFile) throws XMLDBException, IOException {

		readLock.lock();

		logFile.write("COLLECTION: " + coll + "\n");

		log.info("Backup of collection " + coll);

		try {

			for (String file : list(coll)) {

				zip.putNextEntry(new ZipEntry(coll + "/" + file + ".xml"));

				Resource resource = getCollection(coll).getResource(file);

				zip.write(resource.getContent().toString().getBytes());

				zip.closeEntry();

			}

			for (String c : listChildCollections(coll)) {

				backup(coll + "/" + c, zip, logFile);

			}

		}finally {

			readLock.unlock();

		}

	}

}