/**
 * Copyright (c) 2012 - 2019 Data In Motion and others.
 * All rights reserved. 
 * 
 * This program and the accompanying materials are made available under the terms of the 
 * Eclipse Public License v1.0 which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Data In Motion - initial API and implementation
 */
package org.gecko.rsa.discovery;

import java.io.Closeable;
import java.io.IOException;
import java.util.Collection;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Logger;

import org.gecko.rsa.core.converter.EndpointDescriptionConverter;
import org.gecko.rsa.model.rsa.Property;
import org.osgi.framework.BundleContext;
import org.osgi.service.remoteserviceadmin.EndpointDescription;
import org.osgi.service.remoteserviceadmin.EndpointEvent;
import org.osgi.service.remoteserviceadmin.RemoteConstants;

/**
 * End-point handler for incoming service descriptions. 
 * This handler is usually called from a protocol specific implementation.
 * 
 * These are coming from events or turned into {@link EndpointEvent}
 * @author Mark Hoffmann
 * @since 06.07.2018
 */
public class ImportingEndpointManager implements Closeable {

	private static final Logger logger = Logger.getLogger(ImportingEndpointManager.class.getName());

	private final EndpointDescriptionConverter converter = new EndpointDescriptionConverter();
	private final Map<String, org.gecko.rsa.model.rsa.EndpointDescription> descriptionMap = new ConcurrentHashMap<String, org.gecko.rsa.model.rsa.EndpointDescription>();
	private final ImportingEndpointEventManager eventManager;
	private ImportingTopologyManagerTracker endpointListenerTracker;

	/**
	 * Creates a new instance.
	 */
	public ImportingEndpointManager(String discoveryId) {
		eventManager = new ImportingEndpointEventManager(this, discoveryId);
	}

	/**
	 * Initializes the manager and starts tracking for topology managers
	 */
	public void start(BundleContext ctx) {
		endpointListenerTracker = new ImportingTopologyManagerTracker(ctx, eventManager);
		endpointListenerTracker.open();
	}

	/* 
	 * (non-Javadoc)
	 * @see java.io.Closeable#close()
	 */
	@Override
	public void close() throws IOException {
		if (endpointListenerTracker != null) {
			endpointListenerTracker.close();
		}
		if (eventManager != null) {
			eventManager.close();
		}
		descriptionMap.clear();
	}

	/**
	 * Returns all end-point descriptions or an empty collection
	 * @return all end-point descriptions
	 */
	public Collection<org.gecko.rsa.model.rsa.EndpointDescription> getAllDescriptions() {
		return descriptionMap.values();
	}

	/**
	 * Returns the key, which is the end-point id
	 * @param endpointDescription the end-point description
	 * @return the end-point id property or null
	 */
	private String getKey(org.gecko.rsa.model.rsa.EndpointDescription endpointDescription) {
		Optional<Property> endpointId = endpointDescription.getProperty().stream().filter(p->p.getName().equals(RemoteConstants.ENDPOINT_ID)).findFirst();
		return endpointId.map(p->p.getValue()).orElse(null);
	}

	/**
	 * Received {@link EndpointDescription} to be imported
	 * @param description the descriptions to be imported
	 */
	public void addImported(org.gecko.rsa.model.rsa.EndpointDescription description) {
		if (eventManager == null) {
			logger.warning("Cannot consume description because no listener is configured");
			return;
		}
		String key = getKey(description);
		if (key == null) {
			throw new IllegalStateException("Detected an endpoint description with no 'service.id'");
		}
		if (descriptionMap.containsKey(key)) {
			logger.info("Detected and new incoming endpoint, that already exists. Ignore it");
			return;
		} 
		try {
			EndpointDescription endpointDescription = converter.doSwitch(description);
			descriptionMap.put(key, description);
			EndpointEvent event = new EndpointEvent(EndpointEvent.ADDED, endpointDescription);
			eventManager.endpointChanged(event, null);
			logger.info("Detected and incoming endpoint and sent 'ADD' event");
		} catch (Exception e) {
			if (e instanceof IllegalStateException) {
				throw e;
			}
			throw new IllegalStateException(e.getMessage());
		}
	}

	/**
	 * Received a modification for an imported description.
	 * If there is no end-point description, it will be created and an add event will be sent. 
	 * Otherwise a modified event will be sent
	 * @param description the descriptions to be imported
	 */
	public void modifyImported(org.gecko.rsa.model.rsa.EndpointDescription description) {
		if (eventManager == null) {
			logger.warning("Cannot consume modify end-point description because no listener is configured");
			return;
		}
		String key = getKey(description);
		EndpointDescription endpointDescription = converter.doSwitch(description);
		org.gecko.rsa.model.rsa.EndpointDescription edModify = descriptionMap.put(key, description);
		int eventType = EndpointEvent.ADDED;
		if (edModify != null) {
			eventType = EndpointEvent.MODIFIED;
		}
		EndpointEvent event = new EndpointEvent(eventType, endpointDescription);
		eventManager.endpointChanged(event, null);
		logger.info(String.format("Detected and incoming endpoint sent '%s' event", (eventType == EndpointEvent.ADDED ? "ADD" : "MODIFY")));
	}

	/**
	 * Remove a imported description and notifies all listeners about this end-point change.
	 * @param description the description to be imported
	 */
	public void removeImported(org.gecko.rsa.model.rsa.EndpointDescription description) {
		if (eventManager == null) {
			logger.warning("Cannot consume remove message with end-point description because no listener is configured");
			return;
		}
		String key = getKey(description);
		org.gecko.rsa.model.rsa.EndpointDescription edRemove = descriptionMap.remove(key);
		if (edRemove != null) {
			EndpointDescription endpointDescription = converter.doSwitch(edRemove);
			EndpointEvent event = new EndpointEvent(EndpointEvent.REMOVED, endpointDescription);
			eventManager.endpointChanged(event, null);
			logger.info("Detected and incoming endpoint sent REMOVE event");
		} else {
			logger.info("No endpoint was found, that could be removed");
		}
	}

}