/*
 * Copyright 2015 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;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.collect.ImmutableList;
import org.onlab.osgi.ServiceDirectory;
import org.onlab.packet.IpAddress;
import org.onosproject.cluster.ClusterEvent;
import org.onosproject.cluster.ClusterService;
import org.onosproject.cluster.ControllerNode;
import org.onosproject.cluster.NodeId;
import org.onosproject.core.CoreService;
import org.onosproject.incubator.net.PortStatisticsService;
import org.onosproject.incubator.net.tunnel.OpticalTunnelEndPoint;
import org.onosproject.incubator.net.tunnel.Tunnel;
import org.onosproject.incubator.net.tunnel.TunnelService;
import org.onosproject.mastership.MastershipService;
import org.onosproject.net.Annotated;
import org.onosproject.net.AnnotationKeys;
import org.onosproject.net.Annotations;
import org.onosproject.net.ConnectPoint;
import org.onosproject.net.DefaultEdgeLink;
import org.onosproject.net.Device;
import org.onosproject.net.DeviceId;
import org.onosproject.net.EdgeLink;
import org.onosproject.net.Host;
import org.onosproject.net.HostId;
import org.onosproject.net.HostLocation;
import org.onosproject.net.Link;
import org.onosproject.net.LinkKey;
import org.onosproject.net.NetworkResource;
import org.onosproject.net.PortNumber;
import org.onosproject.net.device.DeviceEvent;
import org.onosproject.net.device.DeviceService;
import org.onosproject.net.flow.FlowEntry;
import org.onosproject.net.flow.FlowRuleService;
import org.onosproject.net.flow.TrafficTreatment;
import org.onosproject.net.flow.instructions.Instruction;
import org.onosproject.net.flow.instructions.Instructions.OutputInstruction;
import org.onosproject.net.host.HostEvent;
import org.onosproject.net.host.HostService;
import org.onosproject.net.intent.FlowRuleIntent;
import org.onosproject.net.intent.Intent;
import org.onosproject.net.intent.IntentService;
import org.onosproject.net.intent.LinkCollectionIntent;
import org.onosproject.net.intent.OpticalConnectivityIntent;
import org.onosproject.net.intent.OpticalPathIntent;
import org.onosproject.net.intent.PathIntent;
import org.onosproject.net.link.LinkEvent;
import org.onosproject.net.link.LinkService;
import org.onosproject.net.provider.ProviderId;
import org.onosproject.net.statistic.Load;
import org.onosproject.net.statistic.StatisticService;
import org.onosproject.net.topology.Topology;
import org.onosproject.net.topology.TopologyService;
import org.onosproject.ui.JsonUtils;
import org.onosproject.ui.UiConnection;
import org.onosproject.ui.UiMessageHandler;
import org.onosproject.ui.topo.ButtonId;
import org.onosproject.ui.topo.PropertyPanel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Strings.isNullOrEmpty;
import static org.onosproject.cluster.ClusterEvent.Type.INSTANCE_ADDED;
import static org.onosproject.cluster.ClusterEvent.Type.INSTANCE_REMOVED;
import static org.onosproject.cluster.ControllerNode.State.ACTIVE;
import static org.onosproject.net.DefaultEdgeLink.createEdgeLink;
import static org.onosproject.net.DeviceId.deviceId;
import static org.onosproject.net.HostId.hostId;
import static org.onosproject.net.LinkKey.linkKey;
import static org.onosproject.net.PortNumber.P0;
import static org.onosproject.net.PortNumber.portNumber;
import static org.onosproject.net.device.DeviceEvent.Type.DEVICE_ADDED;
import static org.onosproject.net.device.DeviceEvent.Type.DEVICE_REMOVED;
import static org.onosproject.net.host.HostEvent.Type.HOST_ADDED;
import static org.onosproject.net.host.HostEvent.Type.HOST_REMOVED;
import static org.onosproject.net.link.LinkEvent.Type.LINK_ADDED;
import static org.onosproject.net.link.LinkEvent.Type.LINK_REMOVED;
import static org.onosproject.ui.impl.TopologyViewMessageHandlerBase.StatsType.FLOW;
import static org.onosproject.ui.impl.TopologyViewMessageHandlerBase.StatsType.PORT;
import static org.onosproject.ui.topo.TopoConstants.CoreButtons;
import static org.onosproject.ui.topo.TopoConstants.Properties;

/**
 * Facility for creating messages bound for the topology viewer.
 */
public abstract class TopologyViewMessageHandlerBase extends UiMessageHandler {

    protected static final Logger log =
            LoggerFactory.getLogger(TopologyViewMessageHandlerBase.class);

    private static final ProviderId PID =
            new ProviderId("core", "org.onosproject.core", true);
    private static final String COMPACT = "%s/%s-%s/%s";

    private static final String SHOW_HIGHLIGHTS = "showHighlights";

    private static final double KILO = 1024;
    private static final double MEGA = 1024 * KILO;
    private static final double GIGA = 1024 * MEGA;

    private static final String GBITS_UNIT = "Gb";
    private static final String MBITS_UNIT = "Mb";
    private static final String KBITS_UNIT = "Kb";
    private static final String BITS_UNIT = "b";
    private static final String GBYTES_UNIT = "GB";
    private static final String MBYTES_UNIT = "MB";
    private static final String KBYTES_UNIT = "KB";
    private static final String BYTES_UNIT = "B";
    //4 Kilo Bytes as threshold
    private static final double BPS_THRESHOLD = 4 * KILO;

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

    protected enum StatsType {
        FLOW, PORT
    }

    private String version;

    // TODO: extract into an external & durable state; good enough for now and demo
    private static Map<String, ObjectNode> metaUi = new ConcurrentHashMap<>();

    /**
     * Returns read-only view of the meta-ui information.
     *
     * @return map of id to meta-ui mementos
     */
    static Map<String, ObjectNode> getMetaUi() {
        return Collections.unmodifiableMap(metaUi);
    }

    @Override
    public void init(UiConnection connection, ServiceDirectory directory) {
        super.init(connection, 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);

        String ver = directory.get(CoreService.class).version().toString();
        version = ver.replace(".SNAPSHOT", "*").replaceFirst("~.*$", "");
    }

    // Returns the specified set of IP addresses as a string.
    private String ip(Set<IpAddress> ipAddresses) {
        Iterator<IpAddress> it = ipAddresses.iterator();
        return it.hasNext() ? it.next().toString() : "unknown";
    }

    // Produces JSON structure from annotations.
    private JsonNode props(Annotations annotations) {
        ObjectNode props = objectNode();
        if (annotations != null) {
            for (String key : annotations.keys()) {
                props.put(key, annotations.value(key));
            }
        }
        return props;
    }

    // Produces an informational log message event bound to the client.
    protected ObjectNode info(long id, String message) {
        return message("info", id, message);
    }

    // Produces a warning log message event bound to the client.
    protected ObjectNode warning(long id, String message) {
        return message("warning", id, message);
    }

    // Produces an error log message event bound to the client.
    protected ObjectNode error(long id, String message) {
        return message("error", id, message);
    }

    // Produces a log message event bound to the client.
    private ObjectNode message(String severity, long id, String message) {
        ObjectNode payload = objectNode()
                .put("severity", severity)
                .put("message", message);

        return JsonUtils.envelope("message", id, payload);
    }

    // Produces a set of all hosts listed in the specified JSON array.
    protected Set<Host> getHosts(ArrayNode array) {
        Set<Host> hosts = new HashSet<>();
        if (array != null) {
            for (JsonNode node : array) {
                try {
                    addHost(hosts, hostId(node.asText()));
                } catch (IllegalArgumentException e) {
                    log.debug("Skipping ID {}", node.asText());
                }
            }
        }
        return hosts;
    }

    // Adds the specified host to the set of hosts.
    private void addHost(Set<Host> hosts, HostId hostId) {
        Host host = hostService.getHost(hostId);
        if (host != null) {
            hosts.add(host);
        }
    }


    // Produces a set of all devices listed in the specified JSON array.
    protected Set<Device> getDevices(ArrayNode array) {
        Set<Device> devices = new HashSet<>();
        if (array != null) {
            for (JsonNode node : array) {
                try {
                    addDevice(devices, deviceId(node.asText()));
                } catch (IllegalArgumentException e) {
                    log.debug("Skipping ID {}", node.asText());
                }
            }
        }
        return devices;
    }

    private void addDevice(Set<Device> devices, DeviceId deviceId) {
        Device device = deviceService.getDevice(deviceId);
        if (device != null) {
            devices.add(device);
        }
    }

    protected void addHover(Set<Host> hosts, Set<Device> devices, String hover) {
        try {
            addHost(hosts, hostId(hover));
        } catch (IllegalArgumentException e) {
            try {
                addDevice(devices, deviceId(hover));
            } catch (IllegalArgumentException ne) {
                log.debug("Skipping ID {}", hover);
            }
        }
    }

    // Produces a cluster instance message to the client.
    protected ObjectNode instanceMessage(ClusterEvent event, String messageType) {
        ControllerNode node = event.subject();
        int switchCount = mastershipService.getDevicesOf(node.id()).size();
        ObjectNode payload = objectNode()
                .put("id", node.id().toString())
                .put("ip", node.ip().toString())
                .put("online", clusterService.getState(node.id()) == ACTIVE)
                .put("uiAttached", node.equals(clusterService.getLocalNode()))
                .put("switches", switchCount);

        ArrayNode labels = arrayNode();
        labels.add(node.id().toString());
        labels.add(node.ip().toString());

        // Add labels, props and stuff the payload into envelope.
        payload.set("labels", labels);
        addMetaUi(node.id().toString(), payload);

        String type = messageType != null ? messageType :
                ((event.type() == INSTANCE_ADDED) ? "addInstance" :
                        ((event.type() == INSTANCE_REMOVED ? "removeInstance" :
                                "addInstance")));
        return JsonUtils.envelope(type, 0, payload);
    }

    // Produces a device event message to the client.
    protected ObjectNode deviceMessage(DeviceEvent event) {
        Device device = event.subject();
        ObjectNode payload = objectNode()
                .put("id", device.id().toString())
                .put("type", device.type().toString().toLowerCase())
                .put("online", deviceService.isAvailable(device.id()))
                .put("master", master(device.id()));

        // Generate labels: id, chassis id, no-label, optional-name
        String name = device.annotations().value(AnnotationKeys.NAME);
        ArrayNode labels = arrayNode();
        labels.add("");
        labels.add(isNullOrEmpty(name) ? device.id().toString() : name);
        labels.add(device.id().toString());

        // Add labels, props and stuff the payload into envelope.
        payload.set("labels", labels);
        payload.set("props", props(device.annotations()));
        addGeoLocation(device, payload);
        addMetaUi(device.id().toString(), payload);

        String type = (event.type() == DEVICE_ADDED) ? "addDevice" :
                ((event.type() == DEVICE_REMOVED) ? "removeDevice" : "updateDevice");
        return JsonUtils.envelope(type, 0, payload);
    }

    // Produces a link event message to the client.
    protected ObjectNode linkMessage(LinkEvent event) {
        Link link = event.subject();
        ObjectNode payload = objectNode()
                .put("id", compactLinkString(link))
                .put("type", link.type().toString().toLowerCase())
                .put("online", link.state() == Link.State.ACTIVE)
                .put("linkWidth", 1.2)
                .put("src", link.src().deviceId().toString())
                .put("srcPort", link.src().port().toString())
                .put("dst", link.dst().deviceId().toString())
                .put("dstPort", link.dst().port().toString());
        String type = (event.type() == LINK_ADDED) ? "addLink" :
                ((event.type() == LINK_REMOVED) ? "removeLink" : "updateLink");
        return JsonUtils.envelope(type, 0, payload);
    }

    // Produces a host event message to the client.
    protected ObjectNode hostMessage(HostEvent event) {
        Host host = event.subject();
        String hostType = host.annotations().value(AnnotationKeys.TYPE);
        ObjectNode payload = objectNode()
                .put("id", host.id().toString())
                .put("type", isNullOrEmpty(hostType) ? "endstation" : hostType)
                .put("ingress", compactLinkString(edgeLink(host, true)))
                .put("egress", compactLinkString(edgeLink(host, false)));
        payload.set("cp", hostConnect(host.location()));
        payload.set("labels", labels(ip(host.ipAddresses()),
                                     host.mac().toString()));
        payload.set("props", props(host.annotations()));
        addGeoLocation(host, payload);
        addMetaUi(host.id().toString(), payload);

        String type = (event.type() == HOST_ADDED) ? "addHost" :
                ((event.type() == HOST_REMOVED) ? "removeHost" : "updateHost");
        return JsonUtils.envelope(type, 0, payload);
    }

    // Encodes the specified host location into a JSON object.
    private ObjectNode hostConnect(HostLocation location) {
        return objectNode()
                .put("device", location.deviceId().toString())
                .put("port", location.port().toLong());
    }

    // Encodes the specified list of labels a JSON array.
    private ArrayNode labels(String... labels) {
        ArrayNode json = arrayNode();
        for (String label : labels) {
            json.add(label);
        }
        return json;
    }

    // Returns the name of the master node for the specified device id.
    private String master(DeviceId deviceId) {
        NodeId master = mastershipService.getMasterFor(deviceId);
        return master != null ? master.toString() : "";
    }

    // Generates an edge link from the specified host location.
    private EdgeLink edgeLink(Host host, boolean ingress) {
        return new DefaultEdgeLink(PID, new ConnectPoint(host.id(), portNumber(0)),
                                   host.location(), ingress);
    }

    // Adds meta UI information for the specified object.
    private void addMetaUi(String id, ObjectNode payload) {
        ObjectNode meta = metaUi.get(id);
        if (meta != null) {
            payload.set("metaUi", meta);
        }
    }

    // Adds a geo location JSON to the specified payload object.
    private void addGeoLocation(Annotated annotated, ObjectNode payload) {
        Annotations annotations = annotated.annotations();
        if (annotations == null) {
            return;
        }

        String slat = annotations.value(AnnotationKeys.LATITUDE);
        String slng = annotations.value(AnnotationKeys.LONGITUDE);
        try {
            if (slat != null && slng != null && !slat.isEmpty() && !slng.isEmpty()) {
                double lat = Double.parseDouble(slat);
                double lng = Double.parseDouble(slng);
                ObjectNode loc = objectNode()
                        .put("type", "latlng").put("lat", lat).put("lng", lng);
                payload.set("location", loc);
            }
        } catch (NumberFormatException e) {
            log.warn("Invalid geo data latitude={}; longiture={}", slat, slng);
        }
    }

    // Updates meta UI information for the specified object.
    protected void updateMetaUi(ObjectNode payload) {
        metaUi.put(JsonUtils.string(payload, "id"),
                   JsonUtils.node(payload, "memento"));
    }

    // -----------------------------------------------------------------------
    // Create models of the data to return, that overlays can adjust / augment

    // Returns property panel model for summary response.
    protected PropertyPanel summmaryMessage(long sid) {
        Topology topology = topologyService.currentTopology();

        return new PropertyPanel("ONOS Summary", "node")
            .addProp(Properties.DEVICES, topology.deviceCount())
            .addProp(Properties.LINKS, topology.linkCount())
            .addProp(Properties.HOSTS, hostService.getHostCount())
            .addProp(Properties.TOPOLOGY_SSCS, topology.clusterCount())
            .addSeparator()
            .addProp(Properties.INTENTS, intentService.getIntentCount())
            .addProp(Properties.TUNNELS, tunnelService.tunnelCount())
            .addProp(Properties.FLOWS, flowService.getFlowRuleCount())
            .addProp(Properties.VERSION, version);
    }

    // Returns property panel model for device details response.
    protected PropertyPanel deviceDetails(DeviceId deviceId, long sid) {
        Device device = deviceService.getDevice(deviceId);
        Annotations annot = device.annotations();
        String name = annot.value(AnnotationKeys.NAME);
        int portCount = deviceService.getPorts(deviceId).size();
        int flowCount = getFlowCount(deviceId);
        int tunnelCount = getTunnelCount(deviceId);

        String title = isNullOrEmpty(name) ? deviceId.toString() : name;
        String typeId = device.type().toString().toLowerCase();

        PropertyPanel pp = new PropertyPanel(title, typeId)
            .id(deviceId.toString())

            .addProp(Properties.URI, deviceId.toString())
            .addProp(Properties.VENDOR, device.manufacturer())
            .addProp(Properties.HW_VERSION, device.hwVersion())
            .addProp(Properties.SW_VERSION, device.swVersion())
            .addProp(Properties.SERIAL_NUMBER, device.serialNumber())
            .addProp(Properties.PROTOCOL, annot.value(AnnotationKeys.PROTOCOL))
            .addSeparator()

            .addProp(Properties.LATITUDE, annot.value(AnnotationKeys.LATITUDE))
            .addProp(Properties.LONGITUDE, annot.value(AnnotationKeys.LONGITUDE))
            .addSeparator()

            .addProp(Properties.PORTS, portCount)
            .addProp(Properties.FLOWS, flowCount)
            .addProp(Properties.TUNNELS, tunnelCount)

            .addButton(CoreButtons.SHOW_DEVICE_VIEW)
            .addButton(CoreButtons.SHOW_FLOW_VIEW)
            .addButton(CoreButtons.SHOW_PORT_VIEW)
            .addButton(CoreButtons.SHOW_GROUP_VIEW);

        return pp;
    }

    protected int getFlowCount(DeviceId deviceId) {
        int count = 0;
        for (FlowEntry flowEntry : flowService.getFlowEntries(deviceId)) {
            count++;
        }
        return count;
    }

    protected int getTunnelCount(DeviceId deviceId) {
        int count = 0;
        Collection<Tunnel> tunnels = tunnelService.queryAllTunnels();
        for (Tunnel tunnel : tunnels) {
            OpticalTunnelEndPoint src = (OpticalTunnelEndPoint) tunnel.src();
            OpticalTunnelEndPoint dst = (OpticalTunnelEndPoint) tunnel.dst();
            DeviceId srcDevice = (DeviceId) src.elementId().get();
            DeviceId dstDevice = (DeviceId) dst.elementId().get();
            if (srcDevice.toString().equals(deviceId.toString()) ||
                dstDevice.toString().equals(deviceId.toString())) {
                count++;
            }
        }
        return count;
    }

    // Counts all entries that egress on the given device links.
    protected Map<Link, Integer> getFlowCounts(DeviceId deviceId) {
        List<FlowEntry> entries = new ArrayList<>();
        Set<Link> links = new HashSet<>(linkService.getDeviceEgressLinks(deviceId));
        Set<Host> hosts = hostService.getConnectedHosts(deviceId);
        for (FlowEntry flowEntry : flowService.getFlowEntries(deviceId)) {
            entries.add(flowEntry);
        }

        // Add all edge links to the set
        if (hosts != null) {
            for (Host host : hosts) {
                links.add(new DefaultEdgeLink(host.providerId(),
                                              new ConnectPoint(host.id(), P0),
                                              host.location(), false));
            }
        }

        Map<Link, Integer> counts = new HashMap<>();
        for (Link link : links) {
            counts.put(link, getEgressFlows(link, entries));
        }
        return counts;
    }

    // Counts all entries that egress on the link source port.
    private Integer getEgressFlows(Link link, List<FlowEntry> entries) {
        int count = 0;
        PortNumber out = link.src().port();
        for (FlowEntry entry : entries) {
            TrafficTreatment treatment = entry.treatment();
            for (Instruction instruction : treatment.allInstructions()) {
                if (instruction.type() == Instruction.Type.OUTPUT &&
                        ((OutputInstruction) instruction).port().equals(out)) {
                    count++;
                }
            }
        }
        return count;
    }


    // Returns host details response.
    protected PropertyPanel hostDetails(HostId hostId, long sid) {
        Host host = hostService.getHost(hostId);
        Annotations annot = host.annotations();
        String type = annot.value(AnnotationKeys.TYPE);
        String name = annot.value(AnnotationKeys.NAME);
        String vlan = host.vlan().toString();

        String title = isNullOrEmpty(name) ? hostId.toString() : name;
        String typeId = isNullOrEmpty(type) ? "endstation" : type;

        PropertyPanel pp = new PropertyPanel(title, typeId)
            .id(hostId.toString())
            .addProp(Properties.MAC, host.mac())
            .addProp(Properties.IP, host.ipAddresses(), "[\\[\\]]")
            .addProp(Properties.VLAN, vlan.equals("-1") ? "none" : vlan)
            .addSeparator()
            .addProp(Properties.LATITUDE, annot.value(AnnotationKeys.LATITUDE))
            .addProp(Properties.LONGITUDE, annot.value(AnnotationKeys.LONGITUDE));

        // TODO: add button descriptors
        return pp;
    }


    // TODO: migrate to Traffic overlay
    // Produces JSON message to trigger flow traffic overview visualization
    protected ObjectNode trafficSummaryMessage(StatsType type) {
        ObjectNode payload = objectNode();
        ArrayNode paths = arrayNode();
        payload.set("paths", paths);

        ObjectNode pathNodeN = objectNode();
        ArrayNode linksNodeN = arrayNode();
        ArrayNode labelsN = arrayNode();

        pathNodeN.put("class", "plain").put("traffic", false);
        pathNodeN.set("links", linksNodeN);
        pathNodeN.set("labels", labelsN);
        paths.add(pathNodeN);

        ObjectNode pathNodeT = objectNode();
        ArrayNode linksNodeT = arrayNode();
        ArrayNode labelsT = arrayNode();

        pathNodeT.put("class", "secondary").put("traffic", true);
        pathNodeT.set("links", linksNodeT);
        pathNodeT.set("labels", labelsT);
        paths.add(pathNodeT);

        Map<LinkKey, BiLink> biLinks = consolidateLinks(linkService.getLinks());
        addEdgeLinks(biLinks);
        for (BiLink link : biLinks.values()) {
            boolean bi = link.two != null;
            if (type == FLOW) {
                link.addLoad(getLinkLoad(link.one));
                link.addLoad(bi ? getLinkLoad(link.two) : null);
            } else if (type == PORT) {
                //For a bi-directional traffic links, use
                //the max link rate of either direction
                link.addLoad(portStatsService.load(link.one.src()),
                             BPS_THRESHOLD,
                             portStatsService.load(link.one.dst()),
                             BPS_THRESHOLD);
            }
            if (link.hasTraffic) {
                linksNodeT.add(compactLinkString(link.one));
                labelsT.add(type == PORT ?
                                    formatBitRate(link.rate) + "ps" :
                                    formatBytes(link.bytes));
            } else {
                linksNodeN.add(compactLinkString(link.one));
                labelsN.add("");
            }
        }
        return JsonUtils.envelope(SHOW_HIGHLIGHTS, 0, payload);
    }

    private Load getLinkLoad(Link link) {
        if (link.src().elementId() instanceof DeviceId) {
            return flowStatsService.load(link);
        }
        return null;
    }

    private void addEdgeLinks(Map<LinkKey, BiLink> biLinks) {
        hostService.getHosts().forEach(host -> {
            addLink(biLinks, createEdgeLink(host, true));
            addLink(biLinks, createEdgeLink(host, false));
        });
    }

    private Map<LinkKey, BiLink> consolidateLinks(Iterable<Link> links) {
        Map<LinkKey, BiLink> biLinks = new HashMap<>();
        for (Link link : links) {
            addLink(biLinks, link);
        }
        return biLinks;
    }

    // Produces JSON message to trigger flow overview visualization
    protected ObjectNode flowSummaryMessage(Set<Device> devices) {
        ObjectNode payload = objectNode();
        ArrayNode paths = arrayNode();
        payload.set("paths", paths);

        for (Device device : devices) {
            Map<Link, Integer> counts = getFlowCounts(device.id());
            for (Link link : counts.keySet()) {
                addLinkFlows(link, paths, counts.get(link));
            }
        }
        return JsonUtils.envelope(SHOW_HIGHLIGHTS, 0, payload);
    }

    private void addLinkFlows(Link link, ArrayNode paths, Integer count) {
        ObjectNode pathNode = objectNode();
        ArrayNode linksNode = arrayNode();
        ArrayNode labels = arrayNode();
        boolean noFlows = count == null || count == 0;
        pathNode.put("class", noFlows ? "secondary" : "primary");
        pathNode.put("traffic", false);
        pathNode.set("links", linksNode.add(compactLinkString(link)));
        pathNode.set("labels", labels.add(noFlows ? "" : (count.toString() +
                (count == 1 ? " flow" : " flows"))));
        paths.add(pathNode);
    }


    // Produces JSON message to trigger traffic visualization
    protected ObjectNode trafficMessage(TrafficClass... trafficClasses) {
        ObjectNode payload = objectNode();
        ArrayNode paths = arrayNode();
        payload.set("paths", paths);

        // Classify links based on their traffic traffic first...
        Map<LinkKey, BiLink> biLinks = classifyLinkTraffic(trafficClasses);

        // Then separate the links into their respective classes and send them out.
        Map<String, ObjectNode> pathNodes = new HashMap<>();
        for (BiLink biLink : biLinks.values()) {
            boolean hasTraffic = biLink.hasTraffic;
            String tc = (biLink.classes() + (hasTraffic ? " animated" : "")).trim();
            ObjectNode pathNode = pathNodes.get(tc);
            if (pathNode == null) {
                pathNode = objectNode()
                        .put("class", tc).put("traffic", hasTraffic);
                pathNode.set("links", arrayNode());
                pathNode.set("labels", arrayNode());
                pathNodes.put(tc, pathNode);
                paths.add(pathNode);
            }
            ((ArrayNode) pathNode.path("links")).add(compactLinkString(biLink.one));
            ((ArrayNode) pathNode.path("labels")).add(hasTraffic ? formatBytes(biLink.bytes) : "");
        }

        return JsonUtils.envelope(SHOW_HIGHLIGHTS, 0, payload);
    }

    // Classifies the link traffic according to the specified classes.
    private Map<LinkKey, BiLink> classifyLinkTraffic(TrafficClass... trafficClasses) {
        Map<LinkKey, BiLink> biLinks = new HashMap<>();
        for (TrafficClass trafficClass : trafficClasses) {
            for (Intent intent : trafficClass.intents) {
                boolean isOptical = intent instanceof OpticalConnectivityIntent;
                List<Intent> installables = intentService.getInstallableIntents(intent.key());
                if (installables != null) {
                    for (Intent installable : installables) {
                        String type = isOptical ? trafficClass.type + " optical" : trafficClass.type;
                        if (installable instanceof PathIntent) {
                            classifyLinks(type, biLinks, trafficClass.showTraffic,
                                          ((PathIntent) installable).path().links());
                        } else if (installable instanceof FlowRuleIntent) {
                            classifyLinks(type, biLinks, trafficClass.showTraffic,
                                          linkResources(installable));
                        } else if (installable instanceof LinkCollectionIntent) {
                            classifyLinks(type, biLinks, trafficClass.showTraffic,
                                          ((LinkCollectionIntent) installable).links());
                        } else if (installable instanceof OpticalPathIntent) {
                            classifyLinks(type, biLinks, trafficClass.showTraffic,
                                          ((OpticalPathIntent) installable).path().links());
                        }
                    }
                }
            }
        }
        return biLinks;
    }

    // Extracts links from the specified flow rule intent resources
    private Collection<Link> linkResources(Intent installable) {
        ImmutableList.Builder<Link> builder = ImmutableList.builder();
        for (NetworkResource r : installable.resources()) {
            if (r instanceof Link) {
                builder.add((Link) r);
            }
        }
        return builder.build();
    }


    // Adds the link segments (path or tree) associated with the specified
    // connectivity intent
    private void classifyLinks(String type, Map<LinkKey, BiLink> biLinks,
                               boolean showTraffic, Iterable<Link> links) {
        if (links != null) {
            for (Link link : links) {
                BiLink biLink = addLink(biLinks, link);
                if (showTraffic) {
                    biLink.addLoad(getLinkLoad(link));
                }
                biLink.addClass(type);
            }
        }
    }


    static BiLink addLink(Map<LinkKey, BiLink> biLinks, Link link) {
        LinkKey key = canonicalLinkKey(link);
        BiLink biLink = biLinks.get(key);
        if (biLink != null) {
            biLink.setOther(link);
        } else {
            biLink = new BiLink(key, link);
            biLinks.put(key, biLink);
        }
        return biLink;
    }

    // Poor-mans formatting to get the labels with byte counts looking nice.
    private String formatBytes(long bytes) {
        String unit;
        double value;
        if (bytes > GIGA) {
            value = bytes / GIGA;
            unit = GBYTES_UNIT;
        } else if (bytes > MEGA) {
            value = bytes / MEGA;
            unit = MBYTES_UNIT;
        } else if (bytes > KILO) {
            value = bytes / KILO;
            unit = KBYTES_UNIT;
        } else {
            value = bytes;
            unit = BYTES_UNIT;
        }
        DecimalFormat format = new DecimalFormat("#,###.##");
        return format.format(value) + " " + unit;
    }

    // Poor-mans formatting to get the labels with bit rate looking nice.
    private String formatBitRate(long bytes) {
        String unit;
        double value;
        //Convert to bits
        long bits = bytes * 8;
        if (bits > GIGA) {
            value = bits / GIGA;
            unit = GBITS_UNIT;

            // NOTE: temporary hack to clip rate at 10.0 Gbps
            //  Added for the CORD Fabric demo at ONS 2015
            if (value > 10.0) {
                value = 10.0;
            }

        } else if (bits > MEGA) {
            value = bits / MEGA;
            unit = MBITS_UNIT;
        } else if (bits > KILO) {
            value = bits / KILO;
            unit = KBITS_UNIT;
        } else {
            value = bits;
            unit = BITS_UNIT;
        }
        DecimalFormat format = new DecimalFormat("#,###.##");
        return format.format(value) + " " + unit;
    }

    // Produces compact string representation of a link.
    private static String compactLinkString(Link link) {
        return String.format(COMPACT, link.src().elementId(), link.src().port(),
                             link.dst().elementId(), link.dst().port());
    }

    // translates the property panel into JSON, for returning to the client
    protected ObjectNode json(PropertyPanel pp) {
        ObjectNode result = objectNode()
                .put("title", pp.title())
                .put("type", pp.typeId())
                .put("id", pp.id());

        ObjectNode pnode = objectNode();
        ArrayNode porder = arrayNode();
        for (PropertyPanel.Prop p : pp.properties()) {
            porder.add(p.key());
            pnode.put(p.key(), p.value());
        }
        result.set("propOrder", porder);
        result.set("props", pnode);

        ArrayNode buttons = arrayNode();
        for (ButtonId b : pp.buttons()) {
            buttons.add(b.id());
        }
        result.set("buttons", buttons);
        return result;
    }


    // Produces canonical link key, i.e. one that will match link and its inverse.
    static LinkKey canonicalLinkKey(Link link) {
        String sn = link.src().elementId().toString();
        String dn = link.dst().elementId().toString();
        return sn.compareTo(dn) < 0 ?
                linkKey(link.src(), link.dst()) : linkKey(link.dst(), link.src());
    }

    // Representation of link and its inverse and any traffic data.
    static class BiLink {
        public final LinkKey key;
        public final Link one;
        public Link two;
        public boolean hasTraffic = false;
        public long bytes = 0;

        private Set<String> classes = new HashSet<>();
        private long rate;

        BiLink(LinkKey key, Link link) {
            this.key = key;
            this.one = link;
        }

        void setOther(Link link) {
            this.two = link;
        }

        void addLoad(Load load) {
            addLoad(load, 0);
        }

        void addLoad(Load load, double threshold) {
            if (load != null) {
                this.hasTraffic = hasTraffic || load.rate() > threshold;
                this.bytes += load.latest();
                this.rate += load.rate();
            }
        }

        void addLoad(Load srcLinkLoad,
                     double srcLinkThreshold,
                     Load dstLinkLoad,
                     double dstLinkThreshold) {
            //use the max of link load at source or destination
            if (srcLinkLoad != null) {
                this.hasTraffic = hasTraffic || srcLinkLoad.rate() > srcLinkThreshold;
                this.bytes = srcLinkLoad.latest();
                this.rate = srcLinkLoad.rate();
            }

            if (dstLinkLoad != null) {
                if (dstLinkLoad.rate() > this.rate) {
                    this.bytes = dstLinkLoad.latest();
                    this.rate = dstLinkLoad.rate();
                    this.hasTraffic = hasTraffic || dstLinkLoad.rate() > dstLinkThreshold;
                }
            }
        }

        void addClass(String trafficClass) {
            classes.add(trafficClass);
        }

        String classes() {
            StringBuilder sb = new StringBuilder();
            classes.forEach(c -> sb.append(c).append(" "));
            return sb.toString().trim();
        }
    }


    // TODO: move this to traffic overlay component
    // Auxiliary carrier of data for requesting traffic message.
    static class TrafficClass {
        public final boolean showTraffic;
        public final String type;
        public final Iterable<Intent> intents;

        TrafficClass(String type, Iterable<Intent> intents) {
            this(type, intents, false);
        }

        TrafficClass(String type, Iterable<Intent> intents, boolean showTraffic) {
            this.type = type;
            this.intents = intents;
            this.showTraffic = showTraffic;
        }
    }

}