org.eclipse.mdm.apicopy/src/main/java/org/eclipse/mdm/apicopy/boundary/ExportService.java

/********************************************************************************
 * Copyright (c) 2015-2018 Contributors to the Eclipse Foundation
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 ********************************************************************************/
package org.eclipse.mdm.apicopy.boundary;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import javax.ejb.Stateless;
import javax.inject.Inject;
import javax.management.ServiceNotFoundException;

import org.eclipse.mdm.api.base.ConnectionException;
import org.eclipse.mdm.api.base.model.Channel;
import org.eclipse.mdm.api.base.model.ChannelGroup;
import org.eclipse.mdm.api.base.model.Entity;
import org.eclipse.mdm.api.base.model.Measurement;
import org.eclipse.mdm.api.base.model.Test;
import org.eclipse.mdm.api.base.model.TestStep;
import org.eclipse.mdm.api.base.query.DataAccessException;
import org.eclipse.mdm.api.dflt.ApplicationContext;
import org.eclipse.mdm.api.dflt.ApplicationContextFactory;
import org.eclipse.mdm.api.dflt.EntityManager;
import org.eclipse.mdm.api.dflt.model.Pool;
import org.eclipse.mdm.api.dflt.model.Project;
import org.eclipse.mdm.apicopy.ApiCopyException;
import org.eclipse.mdm.apicopy.AtfxExportTask;
import org.eclipse.mdm.connector.boundary.ConnectorService;
import org.eclipse.mdm.shoppingbasket.entity.MDMItem;
import org.eclipse.mdm.shoppingbasket.entity.ShoppingBasket;

import com.google.common.collect.BiMap;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableMap;

/**
 * Service for importing an ATFX file into a MDM datasource.
 *
 */
@Stateless
public class ExportService {

	// TODO make temp path configurable
	private static final Path TMP = Paths.get(System.getProperty("java.io.tmpdir"));

	@Inject
	private ConnectorService connectorService;

	private final String atfxContextFactoryClassname = "org.eclipse.mdm.api.atfxadapter.ATFXContextFactory";

	/**
	 * Default public constructor
	 */
	public ExportService() {
	}

	/**
	 * Imports an ATFX file into the provided datasource.
	 *
	 * @param atfxFileSupplier returns a {@link Path} to an ATFX file. Accompanying binary
	 * files are expected to be on the same folder.
	 * @return
	 */
	public Path exportAtfx(ShoppingBasket basket) {

		try {
			Path tmpDir = Files.createTempDirectory(TMP, "atfxexport");
			Path atfxFile = tmpDir.resolve("export.atfx");
			writeToFile(atfxFile, AtfxExportTask.class.getResourceAsStream("/emptyAtfx.xml"));

			Map<String, String> params = ImmutableMap.of("atfxfile", atfxFile.toFile().getAbsolutePath(), "freetext.active", "false");
			ApplicationContext contextDst = connectContext(atfxContextFactoryClassname, params);

			Map<String, List<MDMItem>> map = basket.getItems().stream()
				.map(i -> i.getRestURI().getPath())
				.map(p -> split(p))
				.collect(Collectors.groupingBy(p -> p.getSource()));
			if (map.size() != 1) {
				throw new ApiCopyException("Currently only exports from exactly one application context are allowed!");
			}
			String srcContextName = map.keySet().iterator().next();
			
			ApplicationContext contextSrc = connectorService.getContextByName(srcContextName);
			List<? extends Entity> entities = loadEntities(contextSrc, basket);


			new AtfxExportTask(contextSrc, contextDst).copy(entities);
			//			apiCopyService.newApiCopyTask(contextSrc, contextDst).copy(entities);

			return tmpDir;
		} catch (ServiceNotFoundException e) {
			throw new ApiCopyException("Could not retrive all required services from ATFX application context!", e);
		} catch (ConnectionException e) {
			throw new ApiCopyException("Could not create ATFX application context!", e);
		} catch (IOException e) {
			throw new ApiCopyException("Cold not create temporary directory!", e);
		}
	}


	private List<? extends Entity> loadEntities(ApplicationContext contextSrc, ShoppingBasket basket) throws ServiceNotFoundException, DataAccessException {
		EntityManager em = contextSrc.getEntityManager()
				.orElseThrow(() -> new ServiceNotFoundException("EntityManager not found!"));

		return basket.getItems().stream()
				.map(i -> i.getRestURI().getPath())
				.map(p -> split(p))
				.map(i -> em.load(typeToClass(i.getType()), i.getId()))
				.collect(Collectors.toList());
	}

	private Class<? extends Entity> typeToClass(String s) {
		return ENTITY2FRAGMENT_URI.inverse().get(s);
	}

	private static final BiMap<Class<? extends Entity>, String> ENTITY2FRAGMENT_URI = ImmutableBiMap
			.<Class<? extends Entity>, String>builder()
			.put(Project.class, "projects")
			.put(Pool.class, "pools")
			.put(Test.class, "tests")
			.put(TestStep.class, "teststeps")
			.put(Measurement.class, "measurements")
			.put(ChannelGroup.class, "channelgroups")
			.put(Channel.class, "channels")
			.build();

	private MDMItem split(String path) {

		String[] splitted = path.split("/");
		MDMItem item = new MDMItem();
		item.setId(splitted[splitted.length - 1]);
		item.setType(splitted[splitted.length - 2]);
		item.setSource(splitted[splitted.length - 3]);
		return item;
	}

	/**
	 * Connects to a {@link ApplicationContext}.
	 * @param contextFactoryClassname classname of the {@link ApplicationContextFactory}
	 * @param parameters connection parameters
	 * @return connected {@link ApplicationContext}
	 * @throws ConnectionException
	 */
	private ApplicationContext connectContext(String contextFactoryClassname, Map<String, String> parameters) throws ConnectionException {
		try {

			Class<? extends ApplicationContextFactory> contextFactoryClass = Thread.currentThread()
					.getContextClassLoader().loadClass(contextFactoryClassname)
					.asSubclass(ApplicationContextFactory.class);

			ApplicationContextFactory contextFactory = contextFactoryClass.newInstance();
			return contextFactory.connect(parameters);
		} catch (Exception e) {
			throw new ConnectionException("failed to initialize entity manager using factory '" + contextFactoryClassname + "'", e);
		}
	}

	private static void writeToFile(Path resolve, InputStream entityAs) throws IOException {
		try (OutputStream out = new FileOutputStream(resolve.toFile())) {
			int read = 0;
			byte[] bytes = new byte[1024];

			while ((read = entityAs.read(bytes)) != -1) {
				out.write(bytes, 0, read);
			}
		}
	}
}