/*
 * Copyright © 2017 AT&T 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.transportpce.inventory.listener;

import java.util.Collection;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.stream.Collectors;
import org.opendaylight.controller.md.sal.binding.api.DataObjectModification.ModificationType;
import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
import org.opendaylight.transportpce.common.StringConstants;
import org.opendaylight.transportpce.inventory.DeviceInventory;
import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.NetconfNode;
import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.NetconfNodeConnectionStatus;
import org.opendaylight.yang.gen.v1.urn.opendaylight.netconf.node.topology.rev150114.NetconfNodeConnectionStatus.ConnectionStatus;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class implements the {@link DataTreeChangeListener} on a {@link Node}. This listener should
 * be registered on a netconf topology node.
 *
 */
public class DeviceListener implements DataTreeChangeListener<Node> {

    private static final Logger LOG = LoggerFactory.getLogger(DeviceListener.class);
    private final DeviceInventory deviceInventory;

    /**
     * Default constructor invoked by blueprint injects {@link DeviceInventory} as a persistence layer.
     *
     * @param deviceInventory reference to the {@link DeviceInventory}
     */
    public DeviceListener(DeviceInventory deviceInventory) {
        this.deviceInventory = deviceInventory;
    }

    @Override
    public void onDataTreeChanged(Collection<DataTreeModification<Node>> changes) {
        List<DataTreeModification<Node>> changesWithoutDefaultNetconfNode = getRealDevicesOnly(changes);
        for (DataTreeModification<Node> device : changesWithoutDefaultNetconfNode) {
            String nodeId = device.getRootNode().getDataAfter().key().getNodeId().getValue();
            NetconfNode netconfNode = device.getRootNode().getDataAfter().augmentation(NetconfNode.class);
            if (isCreate(device) || isUpdate(device)) {
                LOG.info("Node {} was modified", nodeId);
                try {
                    processModifiedSubtree(nodeId, netconfNode);
                } catch (InterruptedException | ExecutionException e) {
                    LOG.error(e.getMessage(), e);
                }
            } else if (isDelete(device)) {
                LOG.info("Node {} was deleted", nodeId);
            }
        }
    }

    /**
     * Handles the {@link ModificationType#SUBTREE_MODIFIED} case. If the changed node has
     * {@link StringConstants.OPENROADM_DEVICE_MODEL_NAME} capabilities it may be persisted.
     *
     * @param nodeId device id
     * @param netconfNode netconf node
     * @throws InterruptedException may be thrown if there is a problem getting the device from
     *         datastore
     * @throws ExecutionException may be thrown if there is a problem getting the device from datastore
     */
    private void processModifiedSubtree(String nodeId, NetconfNode netconfNode)
            throws InterruptedException, ExecutionException {
        NetconfNodeConnectionStatus.ConnectionStatus connectionStatus = netconfNode.getConnectionStatus();
        long count = netconfNode.getAvailableCapabilities().getAvailableCapability().stream()
                .filter(cp -> cp.getCapability().contains(StringConstants.OPENROADM_DEVICE_MODEL_NAME)).count();
        if (count < 1) {
            LOG.info("No {} capable device was found", StringConstants.OPENROADM_DEVICE_MODEL_NAME);
            return;
        }
        if (ConnectionStatus.Connected.equals(connectionStatus)) {
            this.deviceInventory.initializeDevice(nodeId);
        } else if (ConnectionStatus.Connecting.equals(connectionStatus)
                || ConnectionStatus.UnableToConnect.equals(connectionStatus)) {
            LOG.info("The device is in {} state", connectionStatus);
        } else {
            LOG.warn("Invalid connection status {}", connectionStatus);
        }
    }

    /**
     * Filters the {@link StringConstants#DEFAULT_NETCONF_NODEID} nodes from the provided
     * {@link Collection}.
     *
     * @param changes a change
     * @return {@code List<DataTreeModification<Node>>} a list of modifcations
     */
    private static List<DataTreeModification<Node>> getRealDevicesOnly(Collection<DataTreeModification<Node>> changes) {
        return changes.stream()
                .filter(change -> ((change.getRootNode().getDataAfter() != null)
                        && !StringConstants.DEFAULT_NETCONF_NODEID
                                .equalsIgnoreCase(change.getRootNode().getDataAfter().key().getNodeId().getValue())
                        && (change.getRootNode().getDataAfter().augmentation(NetconfNode.class) != null))
                        || ((change.getRootNode().getDataBefore() != null)
                                && !StringConstants.DEFAULT_NETCONF_NODEID.equalsIgnoreCase(
                                        change.getRootNode().getDataBefore().key().getNodeId().getValue())
                                && (change.getRootNode().getDataBefore().augmentation(NetconfNode.class) != null)

                        )).collect(Collectors.toList());
    }

    /**
     * In the filtered collection checks if the change is a new write.
     *
     * @param change the change
     * @return boolean true if the change is a new write
     */
    private static boolean isCreate(DataTreeModification<Node> change) {
        return (change.getRootNode().getDataBefore() == null) && (change.getRootNode().getDataAfter() != null)
                && ModificationType.WRITE.equals(change.getRootNode().getModificationType());
    }

    /**
     * In the filtered collection checks if the modification is update.
     *
     * @param change the change
     * @return boolean true if the modification is update
     */
    private static boolean isUpdate(DataTreeModification<Node> change) {
        return ModificationType.SUBTREE_MODIFIED.equals(change.getRootNode().getModificationType());
    }

    /**
     * In the filtered collection checks if the node was deleted.
     *
     * @param change the change
     * @return boolean true if the node was deleted
     */
    private static boolean isDelete(DataTreeModification<Node> change) {
        return (change.getRootNode().getDataBefore() != null) && (change.getRootNode().getDataAfter() == null)
                && ModificationType.DELETE.equals(change.getRootNode().getModificationType());
    }
}