/*
 * Copyright (c) 2014 Cisco Systems, Inc. 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
 */
package org.opendaylight.netconf.sal.streams.listeners;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.opendaylight.yang.gen.v1.urn.sal.restconf.event.subscription.rev140708.NotificationOutputTypeGrouping.NotificationOutputType;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.model.api.NotificationDefinition;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@link Notificator} is responsible to create, remove and find
 * {@link ListenerAdapter} listener.
 */
public final class Notificator {

    private static Map<String, ListenerAdapter> dataChangeListener = new ConcurrentHashMap<>();
    private static Map<String, List<NotificationListenerAdapter>> notificationListenersByStreamName =
            new ConcurrentHashMap<>();

    private static final Logger LOG = LoggerFactory.getLogger(Notificator.class);
    private static final Lock LOCK = new ReentrantLock();

    private Notificator() {
    }

    /**
     * Returns list of all stream names.
     */
    public static Set<String> getStreamNames() {
        return dataChangeListener.keySet();
    }

    /**
     * Gets {@link ListenerAdapter} specified by stream name.
     *
     * @param streamName
     *            The name of the stream.
     * @return {@link ListenerAdapter} specified by stream name.
     */
    public static ListenerAdapter getListenerFor(final String streamName) {
        return dataChangeListener.get(streamName);
    }

    /**
     * Checks if the listener specified by {@link YangInstanceIdentifier} path exist.
     *
     * @param streamName    name of the stream
     * @return True if the listener exist, false otherwise.
     */
    public static boolean existListenerFor(final String streamName) {
        return dataChangeListener.containsKey(streamName);
    }

    /**
     * Creates new {@link ListenerAdapter} listener from
     * {@link YangInstanceIdentifier} path and stream name.
     *
     * @param path
     *            Path to data in data repository.
     * @param streamName
     *            The name of the stream.
     * @param outputType
     *             Spcific type of output for notifications - XML or JSON
     * @return New {@link ListenerAdapter} listener from
     *         {@link YangInstanceIdentifier} path and stream name.
     */
    public static ListenerAdapter createListener(final YangInstanceIdentifier path, final String streamName,
            final NotificationOutputType outputType) {
        final ListenerAdapter listener = new ListenerAdapter(path, streamName, outputType);
        try {
            LOCK.lock();
            dataChangeListener.put(streamName, listener);
        } finally {
            LOCK.unlock();
        }
        return listener;
    }

    /**
     * Looks for listener determined by {@link YangInstanceIdentifier} path and removes it.
     * Creates String representation of stream name from URI. Removes slash from URI in start and end position.
     *
     * @param uri
     *            URI for creation stream name.
     * @return String representation of stream name.
     */
    public static String createStreamNameFromUri(final String uri) {
        if (uri == null) {
            return null;
        }
        String result = uri;
        if (result.startsWith("/")) {
            result = result.substring(1);
        }
        if (result.endsWith("/")) {
            result = result.substring(0, result.length() - 1);
        }
        return result;
    }

    /**
     * Removes all listeners.
     */
    @SuppressWarnings("checkstyle:IllegalCatch")
    public static void removeAllListeners() {
        for (final ListenerAdapter listener : dataChangeListener.values()) {
            try {
                listener.close();
            } catch (final Exception e) {
                LOG.error("Failed to close listener", e);
            }
        }
        try {
            LOCK.lock();
            dataChangeListener = new ConcurrentHashMap<>();
        } finally {
            LOCK.unlock();
        }
    }

    /**
     * Delete {@link ListenerAdapter} listener specified in parameter.
     *
     * @param <T>
     *
     * @param listener
     *            ListenerAdapter
     */
    @SuppressWarnings("checkstyle:IllegalCatch")
    private static <T extends BaseListenerInterface> void deleteListener(final T listener) {
        if (listener != null) {
            try {
                listener.close();
            } catch (final Exception e) {
                LOG.error("Failed to close listener", e);
            }
            try {
                LOCK.lock();
                dataChangeListener.remove(listener.getStreamName());
            } finally {
                LOCK.unlock();
            }
        }
    }

    /**
     * Check if the listener specified by qnames of request exist.
     *
     * @param streamName
     *             name of stream
     * @return True if the listener exist, false otherwise.
     */
    public static boolean existNotificationListenerFor(final String streamName) {
        return notificationListenersByStreamName.containsKey(streamName);
    }

    /**
     * Prepare listener for notification ({@link NotificationDefinition}).
     *
     * @param paths
     *             paths of notifications
     * @param streamName
     *             name of stream (generated by paths)
     * @param outputType
     *             type of output for onNotification - XML or JSON
     * @return List of {@link NotificationListenerAdapter} by paths
     */
    public static List<NotificationListenerAdapter> createNotificationListener(final List<SchemaPath> paths,
            final String streamName, final String outputType) {
        final List<NotificationListenerAdapter> listListeners = new ArrayList<>();
        for (final SchemaPath path : paths) {
            final NotificationListenerAdapter listener = new NotificationListenerAdapter(path, streamName, outputType);
            listListeners.add(listener);
        }
        try {
            LOCK.lock();
            notificationListenersByStreamName.put(streamName, listListeners);
        } finally {
            LOCK.unlock();
        }
        return listListeners;
    }

    public static <T extends BaseListenerInterface> void removeListenerIfNoSubscriberExists(final T listener) {
        if (!listener.hasSubscribers()) {
            if (listener instanceof NotificationListenerAdapter) {
                deleteNotificationListener(listener);
            } else {
                deleteListener(listener);
            }
        }
    }

    @SuppressWarnings("checkstyle:IllegalCatch")
    private static <T extends BaseListenerInterface> void deleteNotificationListener(final T listener) {
        if (listener != null) {
            try {
                listener.close();
            } catch (final Exception e) {
                LOG.error("Failed to close listener", e);
            }
            try {
                LOCK.lock();
                notificationListenersByStreamName.remove(listener.getStreamName());
            } finally {
                LOCK.unlock();
            }
        }
    }

    public static List<NotificationListenerAdapter> getNotificationListenerFor(final String streamName) {
        return notificationListenersByStreamName.get(streamName);
    }
}