/**
 ********************************************************************************
 * Copyright (c) 2019, 2020 Robert Bosch GmbH and others.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Robert Bosch GmbH - initial API and implementation
 ********************************************************************************
 */
package org.eclipse.app4mc.amalthea.converters.common;

import java.io.File;
import java.io.IOException;
import java.util.Dictionary;
import java.util.Hashtable;
import java.util.Map;

import org.eclipse.app4mc.amalthea.converters.common.base.ICache;
import org.eclipse.app4mc.amalthea.converters.common.base.IConverter;
import org.eclipse.app4mc.amalthea.converters.common.base.IPostProcessor;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.SubMonitor;
import org.jdom2.Document;
import org.osgi.service.component.ComponentFactory;
import org.osgi.service.component.ComponentInstance;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(service = MigrationProcessor.class)
public class MigrationProcessor {

	private static final Logger LOGGER = LoggerFactory.getLogger(MigrationProcessor.class);

	private static final String OUTPUT_DIRECTORY_KEY = "APP4MC_MIGRATION_OUTPUT_DIRECTORY";
	private static final String NEWLINE = System.getProperty("line.separator");

	@Reference(target = "(component.factory=" + ServiceConstants.MODEL_MIGRATION_FACTORY + ")")
	ComponentFactory<ModelMigration> factory;

	/**
	 * Execute the migration for the provided {@link MigrationSettings}.
	 *
	 * @param settings The {@link MigrationSettings} containing the settings for the
	 *                 migration.
	 * @param monitor  The progress monitor to give feedback to the caller. Can be
	 *                 <code>null</code>.
	 * @return A {@link MigrationStatusCode} indicating the status of the migration.
	 * @throws MigrationException In case saving the migrated files fails.
	 */
	public int execute(MigrationSettings settings, IProgressMonitor monitor) {
		// needed for session logging
		// setting the system property will enable the MigrationSessionFileAppender
		System.setProperty(OUTPUT_DIRECTORY_KEY, settings.getOutputDirectoryLocation());

		try {
			if (monitor != null) {
				monitor.setTaskName("Collecting information for intermediate migration steps");
			}

			// check if a migration needs to be executed
			Map<String, String> migStepEntries = MigrationHelper.generateMigrationSteps(
					settings.getInputModelVersion(),
					settings.getMigrationModelVersion());

			if (migStepEntries.size() == 0) {
				LOGGER.error("Migration not supported for the selected model versions. \nInput Model version : \"{}\" Output Model Version : \"{}\"",
						settings.getInputModelVersion(),
						settings.getMigrationModelVersion());

				return MigrationStatusCode.UNSUPPORTED_MODEL_VERSIONS;
			}

			SubMonitor subMonitor = monitor != null ? SubMonitor.convert(monitor, migStepEntries.size() + 1) : null;

			Map<File, Document> fileDocumentMapping = settings.getMigModelFilesMap();

			// info log
			StringBuilder builder = new StringBuilder();
			builder.append(NEWLINE);
			builder.append("***************************************************************************************************************************************");
			builder.append(NEWLINE);
			builder.append("\t\t Starting model migration for the following AMALTHEA models: ");
			builder.append(NEWLINE);
			for (final File modelFile : fileDocumentMapping.keySet()) {
				builder.append("\t\t -- ");
				builder.append(modelFile.getAbsolutePath());
				builder.append(NEWLINE);
			}
			builder.append(NEWLINE);
			builder.append("***************************************************************************************************************************************");
			builder.append(NEWLINE);
			LOGGER.info(builder.toString());

			boolean conversionPerformed = false;
			String currentModelVersion = settings.getInputModelVersion();
			while (!currentModelVersion.equals(settings.getMigrationModelVersion())) {

				if (subMonitor != null && subMonitor.isCanceled()) {
					return MigrationStatusCode.CANCEL;
				}

				// define the target filters and create the ModelMigration component instance
				Dictionary<String, Object> properties = new Hashtable<>();
				String inputFilterExp = "(input_model_version=" + currentModelVersion + ")";
				String inputOuputFilterExpression = "(&(input_model_version=" + currentModelVersion + ")(output_model_version=" + migStepEntries.get(currentModelVersion) + "))";
				properties.put(ServiceConstants.INPUT_MODEL_VERSION_PROPERTY, currentModelVersion);
				properties.put(ServiceConstants.OUTPUT_MODEL_VERSION_PROPERTY, migStepEntries.get(currentModelVersion));
				properties.put("caches.target", inputFilterExp);
				properties.put("converter.target", inputOuputFilterExpression);
				properties.put("postProcessor.target", inputOuputFilterExpression);
				ComponentInstance<ModelMigration> newInstance = factory.newInstance(properties);
				ModelMigration modelMigration = newInstance.getInstance();

				String outputModelVersion = modelMigration.getOutputModelVersion();

				// execute migration
				if (subMonitor != null) {
					subMonitor.setTaskName("Migrating AMALTHEA models from : " + currentModelVersion + " to " + outputModelVersion);
				}

				LOGGER.info("=========== START: Migrating AMALTHEA models from : {} to {} ========== ", currentModelVersion, outputModelVersion);

				// build caches
				LOGGER.trace("Start : Building cache for AMALTHEA models present in : {}", currentModelVersion);
				long st = System.currentTimeMillis();

				// build up the cache for the current file set
				for (ICache cache : modelMigration.getCaches()) {
					// clear the cache to avoid any side effects if a previous migration failed with an exception
					cache.clearCacheMap();

					cache.buildCache(fileDocumentMapping);
				}

				long end = System.currentTimeMillis();

				LOGGER.trace("End : Building cache for AMALTHEA models present in : {}", currentModelVersion);
				LOGGER.trace("Total time taken to build cache for {} models: {} milli seconds", currentModelVersion, (end - st));

				// execute conversion
				for (IConverter converter : modelMigration.getConverter()) {
					for (File file : fileDocumentMapping.keySet()) {
						converter.convert(file, fileDocumentMapping, modelMigration.getCaches());
						conversionPerformed = true;
					}
				}

				for (IPostProcessor postProcessor : modelMigration.getPostProcessor()) {
					postProcessor.process(fileDocumentMapping);
				}

				LOGGER.info("=========== END: Migrating AMALTHEA models from : {} to {}  =========== \n\r", currentModelVersion, outputModelVersion);

				if (currentModelVersion.equals(outputModelVersion)) {
					// if the output is already the current model version,
					// we need to update the output model version to ensure
					// that we exit the loop
					outputModelVersion = migStepEntries.get(currentModelVersion);

				}
				currentModelVersion = outputModelVersion;

				// clear the cache to ensure there are not leftovers on the next migration
				for (ICache cache : modelMigration.getCaches()) {
					cache.clearCacheMap();
				}

				if (subMonitor != null) {
					subMonitor.worked(1);
				}
			}

			if (conversionPerformed) {
				if (subMonitor != null) {
					subMonitor.setTaskName("Saving migrated AMALTHEA model files ");
				}

				try {
					MigrationHelper.saveFiles(settings);
				} catch (IOException e) {
					throw new MigrationException("Error on saving migrated files.", e);
				}
			}

			if (subMonitor != null) {
				subMonitor.worked(1);
			}

			return MigrationStatusCode.OK;
		} finally {
			// removing the system property will disable the MigrationSessionFileAppender
			System.clearProperty(OUTPUT_DIRECTORY_KEY);
			LOGGER.info("Migration session finished");
		}
	}

}