/*
 * Copyright 2016-present Open Networking Laboratory
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.onosproject.ui.impl.topo;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.onlab.osgi.ServiceDirectory;
import org.onosproject.cluster.ClusterService;
import org.onosproject.cluster.NodeId;
import org.onosproject.incubator.net.PortStatisticsService;
import org.onosproject.incubator.net.tunnel.TunnelService;
import org.onosproject.mastership.MastershipService;
import org.onosproject.net.device.DeviceService;
import org.onosproject.net.flow.FlowRuleService;
import org.onosproject.net.host.HostService;
import org.onosproject.net.intent.IntentService;
import org.onosproject.net.link.LinkService;
import org.onosproject.net.region.Region;
import org.onosproject.net.statistic.StatisticService;
import org.onosproject.net.topology.TopologyService;
import org.onosproject.ui.model.topo.UiClusterMember;
import org.onosproject.ui.model.topo.UiDevice;
import org.onosproject.ui.model.topo.UiHost;
import org.onosproject.ui.model.topo.UiLink;
import org.onosproject.ui.model.topo.UiNode;
import org.onosproject.ui.model.topo.UiRegion;
import org.onosproject.ui.model.topo.UiTopoLayout;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import static com.google.common.base.Preconditions.checkNotNull;
import static org.onosproject.ui.model.topo.UiNode.LAYER_DEFAULT;

/**
 * Facility for creating JSON messages to send to the topology view in the
 * Web client.
 */
class Topo2Jsonifier {

    private static final String E_DEF_NOT_LAST =
            "UiNode.LAYER_DEFAULT not last in layer list";
    private static final String E_UNKNOWN_UI_NODE =
            "Unknown subclass of UiNode: ";

    private final ObjectMapper mapper = new ObjectMapper();

    private ServiceDirectory directory;
    private ClusterService clusterService;
    private DeviceService deviceService;
    private LinkService linkService;
    private HostService hostService;
    private MastershipService mastershipService;
    private IntentService intentService;
    private FlowRuleService flowService;
    private StatisticService flowStatsService;
    private PortStatisticsService portStatsService;
    private TopologyService topologyService;
    private TunnelService tunnelService;


    /**
     * Creates an instance with a reference to the services directory, so that
     * additional information about network elements may be looked up on
     * on the fly.
     *
     * @param directory service directory
     */
    Topo2Jsonifier(ServiceDirectory directory) {
        this.directory = checkNotNull(directory, "Directory cannot be null");

        clusterService = directory.get(ClusterService.class);
        deviceService = directory.get(DeviceService.class);
        linkService = directory.get(LinkService.class);
        hostService = directory.get(HostService.class);
        mastershipService = directory.get(MastershipService.class);
        intentService = directory.get(IntentService.class);
        flowService = directory.get(FlowRuleService.class);
        flowStatsService = directory.get(StatisticService.class);
        portStatsService = directory.get(PortStatisticsService.class);
        topologyService = directory.get(TopologyService.class);
        tunnelService = directory.get(TunnelService.class);
    }

    // for unit testing
    Topo2Jsonifier() {
    }

    private ObjectNode objectNode() {
        return mapper.createObjectNode();
    }

    private ArrayNode arrayNode() {
        return mapper.createArrayNode();
    }

    private String nullIsEmpty(Object o) {
        return o == null ? "" : o.toString();
    }


    /**
     * Returns a JSON representation of the cluster members (ONOS instances).
     *
     * @param instances the instance model objects
     * @return a JSON representation of the data
     */
    ObjectNode instances(List<UiClusterMember> instances) {
        NodeId local = clusterService.getLocalNode().id();
        ObjectNode payload = objectNode();

        ArrayNode members = arrayNode();
        payload.set("members", members);
        for (UiClusterMember member : instances) {
            members.add(json(member, member.id().equals(local)));
        }

        return payload;
    }

    private ObjectNode json(UiClusterMember member, boolean isUiAttached) {
        return objectNode()
                .put("id", member.id().toString())
                .put("ip", member.ip().toString())
                .put("online", member.isOnline())
                .put("ready", member.isReady())
                .put("uiAttached", isUiAttached)
                .put("switches", member.deviceCount());
    }

    /**
     * Returns a JSON representation of the layout to use for displaying in
     * the topology view.
     *
     * @param layout the layout to transform
     * @return a JSON representation of the data
     */
    ObjectNode layout(UiTopoLayout layout) {
        return objectNode()
                .put("id", layout.id().toString())
                .put("parent", nullIsEmpty(layout.parent()))
                .put("region", nullIsEmpty(layout.regionId()))
                .put("regionName", regionName(layout.region()));
    }

    private String regionName(Region region) {
        return region == null ? "" : region.name();
    }

    /**
     * Returns a JSON representation of the region to display in the topology
     * view.
     *
     * @param region     the region to transform to JSON
     * @param subRegions the subregions within this region
     * @return a JSON representation of the data
     */
    ObjectNode region(UiRegion region, Set<UiRegion> subRegions) {
        ObjectNode payload = objectNode();
        if (region == null) {
            payload.put("note", "no-region");
            return payload;
        }
        payload.put("id", region.idAsString());
        if (subRegions != null) {
            payload.set("subregions", jsonSubRegions(subRegions));
        }

        List<String> layerTags = region.layerOrder();
        List<Set<UiNode>> splitDevices = splitByLayer(layerTags, region.devices());
        List<Set<UiNode>> splitHosts = splitByLayer(layerTags, region.hosts());
        Set<UiLink> links = region.links();

        payload.set("devices", jsonGrouped(splitDevices));
        payload.set("hosts", jsonGrouped(splitHosts));
        payload.set("links", jsonLinks(links));
        payload.set("layerOrder", jsonStrings(layerTags));

        return payload;
    }

    private ArrayNode jsonSubRegions(Set<UiRegion> subregions) {
        ArrayNode kids = arrayNode();
        if (subregions != null) {
            subregions.forEach(s -> kids.add(jsonClosedRegion(s)));
        }
        return kids;
    }

    private ArrayNode jsonStrings(List<String> strings) {
        ArrayNode array = arrayNode();
        strings.forEach(array::add);
        return array;
    }

    private ArrayNode jsonLinks(Set<UiLink> links) {
        ArrayNode result = arrayNode();
        links.forEach(lnk -> result.add(json(lnk)));
        return result;
    }

    private ArrayNode jsonGrouped(List<Set<UiNode>> groupedNodes) {
        ArrayNode result = arrayNode();
        groupedNodes.forEach(g -> {
            ArrayNode subset = arrayNode();
            g.forEach(n -> subset.add(json(n)));
            result.add(subset);
        });
        return result;
    }


    private ObjectNode json(UiNode node) {
        if (node instanceof UiRegion) {
            return jsonClosedRegion((UiRegion) node);
        }
        if (node instanceof UiDevice) {
            return json((UiDevice) node);
        }
        if (node instanceof UiHost) {
            return json((UiHost) node);
        }
        throw new IllegalStateException(E_UNKNOWN_UI_NODE + node.getClass());
    }

    private ObjectNode json(UiDevice device) {
        ObjectNode node = objectNode()
                .put("id", device.idAsString())
                .put("type", device.type())
                .put("online", device.isOnline())
                .put("master", nullIsEmpty(device.master()))
                .put("layer", device.layer());

        // TODO: complete device details
//        addLabels(node, device);
//        addProps(node, device);
//        addGeoLocation(node, device);
//        addMetaUi(node, device);

        return node;
    }

    private void addLabels(ObjectNode node, UiDevice device) {

    }

    private ObjectNode json(UiHost host) {
        return objectNode()
                .put("id", host.idAsString())
                .put("layer", host.layer());
        // TODO: complete host details
    }


    private ObjectNode json(UiLink link) {
        return objectNode()
                .put("id", link.idAsString());
        // TODO: complete link details
    }


    private ObjectNode jsonClosedRegion(UiRegion region) {
        return objectNode()
                .put("id", region.idAsString())
                .put("nDevs", region.deviceCount());
        // TODO: complete closed-region details
    }


    /**
     * Returns a JSON array representation of a list of regions. Note that the
     * information about each region is limited to what needs to be used to
     * show the regions as nodes on the view.
     *
     * @param regions the regions
     * @return a JSON representation of the minimal region information
     */
    public ArrayNode closedRegions(Set<UiRegion> regions) {
        ArrayNode array = arrayNode();
        for (UiRegion r : regions) {
            array.add(jsonClosedRegion(r));
        }
        return array;
    }

    /**
     * Returns a JSON array representation of a list of devices.
     *
     * @param devices the devices
     * @return a JSON representation of the devices
     */
    public ArrayNode devices(Set<UiDevice> devices) {
        ArrayNode array = arrayNode();
        for (UiDevice device : devices) {
            array.add(json(device));
        }
        return array;
    }

    /**
     * Returns a JSON array representation of a list of hosts.
     *
     * @param hosts the hosts
     * @return a JSON representation of the hosts
     */
    public ArrayNode hosts(Set<UiHost> hosts) {
        ArrayNode array = arrayNode();
        for (UiHost host : hosts) {
            array.add(json(host));
        }
        return array;
    }

    /**
     * Returns a JSON array representation of a list of links.
     *
     * @param links the links
     * @return a JSON representation of the links
     */
    public ArrayNode links(Set<UiLink> links) {
        ArrayNode array = arrayNode();
        for (UiLink link : links) {
            array.add(json(link));
        }
        return array;
    }

    // package-private for unit testing
    List<Set<UiNode>> splitByLayer(List<String> layerTags,
                                   Set<? extends UiNode> nodes) {
        final int nLayers = layerTags.size();
        if (!layerTags.get(nLayers - 1).equals(LAYER_DEFAULT)) {
            throw new IllegalArgumentException(E_DEF_NOT_LAST);
        }

        List<Set<UiNode>> splitList = new ArrayList<>(layerTags.size());
        Map<String, Set<UiNode>> byLayer = new HashMap<>(layerTags.size());

        for (String tag : layerTags) {
            Set<UiNode> set = new HashSet<>();
            byLayer.put(tag, set);
            splitList.add(set);
        }

        for (UiNode n : nodes) {
            String which = n.layer();
            if (!layerTags.contains(which)) {
                which = LAYER_DEFAULT;
            }
            byLayer.get(which).add(n);
        }

        return splitList;
    }
}