/*
 *  Copyright 2016 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.model;

import org.onosproject.cluster.ControllerNode;
import org.onosproject.cluster.NodeId;
import org.onosproject.cluster.RoleInfo;
import org.onosproject.event.EventDispatcher;
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.region.Region;
import org.onosproject.net.region.RegionId;
import org.onosproject.ui.model.ServiceBundle;
import org.onosproject.ui.model.topo.UiClusterMember;
import org.onosproject.ui.model.topo.UiDevice;
import org.onosproject.ui.model.topo.UiElement;
import org.onosproject.ui.model.topo.UiHost;
import org.onosproject.ui.model.topo.UiLink;
import org.onosproject.ui.model.topo.UiLinkId;
import org.onosproject.ui.model.topo.UiRegion;
import org.onosproject.ui.model.topo.UiTopology;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Set;

import static org.onosproject.net.DefaultEdgeLink.createEdgeLink;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.CLUSTER_MEMBER_ADDED_OR_UPDATED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.CLUSTER_MEMBER_REMOVED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.DEVICE_ADDED_OR_UPDATED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.DEVICE_REMOVED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.HOST_ADDED_OR_UPDATED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.HOST_MOVED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.HOST_REMOVED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.LINK_ADDED_OR_UPDATED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.LINK_REMOVED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.REGION_ADDED_OR_UPDATED;
import static org.onosproject.ui.impl.topo.model.UiModelEvent.Type.REGION_REMOVED;
import static org.onosproject.ui.model.topo.UiLinkId.uiLinkId;

/**
 * UI Topology Model cache.
 */
class ModelCache {

    private static final String E_NO_ELEMENT = "Tried to remove non-member {}: {}";

    private static final Logger log = LoggerFactory.getLogger(ModelCache.class);

    private final ServiceBundle services;
    private final EventDispatcher dispatcher;
    private final UiTopology uiTopology = new UiTopology();

    ModelCache(ServiceBundle services, EventDispatcher eventDispatcher) {
        this.services = services;
        this.dispatcher = eventDispatcher;
    }

    @Override
    public String toString() {
        return "ModelCache{" + uiTopology + "}";
    }

    private void postEvent(UiModelEvent.Type type, UiElement subject) {
        dispatcher.post(new UiModelEvent(type, subject));
    }

    void clear() {
        uiTopology.clear();
    }

    /**
     * Create our internal model of the global topology. An assumption we are
     * making is that the topology is empty to start.
     */
    void load() {
        loadClusterMembers();
        loadRegions();
        loadDevices();
        loadLinks();
        loadHosts();
    }


    // === CLUSTER MEMBERS

    private UiClusterMember addNewClusterMember(ControllerNode n) {
        UiClusterMember member = new UiClusterMember(uiTopology, n);
        uiTopology.add(member);
        return member;
    }

    private void updateClusterMember(UiClusterMember member) {
        ControllerNode.State state = services.cluster().getState(member.id());
        member.setState(state);
        member.setMastership(services.mastership().getDevicesOf(member.id()));
        // NOTE: 'UI-attached' is session-based data, not global, so will
        //       be set elsewhere
    }

    private void loadClusterMembers() {
        for (ControllerNode n : services.cluster().getNodes()) {
            UiClusterMember member = addNewClusterMember(n);
            updateClusterMember(member);
        }
    }

    // invoked from UiSharedTopologyModel cluster event listener
    void addOrUpdateClusterMember(ControllerNode cnode) {
        NodeId id = cnode.id();
        UiClusterMember member = uiTopology.findClusterMember(id);
        if (member == null) {
            member = addNewClusterMember(cnode);
        }
        updateClusterMember(member);

        postEvent(CLUSTER_MEMBER_ADDED_OR_UPDATED, member);
    }

    // package private for unit test access
    UiClusterMember accessClusterMember(NodeId id) {
        return uiTopology.findClusterMember(id);
    }

    // invoked from UiSharedTopologyModel cluster event listener
    void removeClusterMember(ControllerNode cnode) {
        NodeId id = cnode.id();
        UiClusterMember member = uiTopology.findClusterMember(id);
        if (member != null) {
            uiTopology.remove(member);
            postEvent(CLUSTER_MEMBER_REMOVED, member);
        } else {
            log.warn(E_NO_ELEMENT, "cluster node", id);
        }
    }


    // === MASTERSHIP CHANGES

    // invoked from UiSharedTopologyModel mastership listener
    void updateMasterships(DeviceId deviceId, RoleInfo roleInfo) {
        // To think about:: do we need to store mastership info?
        //  or can we rely on looking it up live?
        // TODO: store the updated mastership information
        // TODO: post event
    }


    // === REGIONS

    private UiRegion addNewRegion(Region r) {
        UiRegion region = new UiRegion(uiTopology, r);
        uiTopology.add(region);
        return region;
    }

    private void updateRegion(UiRegion region) {
        Set<DeviceId> devs = services.region().getRegionDevices(region.id());
        region.reconcileDevices(devs);
    }

    private void loadRegions() {
        for (Region r : services.region().getRegions()) {
            UiRegion region = addNewRegion(r);
            updateRegion(region);
        }
    }

    // invoked from UiSharedTopologyModel region listener
    void addOrUpdateRegion(Region region) {
        RegionId id = region.id();
        UiRegion uiRegion = uiTopology.findRegion(id);
        if (uiRegion == null) {
            uiRegion = addNewRegion(region);
        }
        updateRegion(uiRegion);

        postEvent(REGION_ADDED_OR_UPDATED, uiRegion);
    }

    // invoked from UiSharedTopologyModel region listener
    void removeRegion(Region region) {
        RegionId id = region.id();
        UiRegion uiRegion = uiTopology.findRegion(id);
        if (uiRegion != null) {
            uiTopology.remove(uiRegion);
            postEvent(REGION_REMOVED, uiRegion);
        } else {
            log.warn(E_NO_ELEMENT, "region", id);
        }
    }


    // === DEVICES

    private UiDevice addNewDevice(Device d) {
        UiDevice device = new UiDevice(uiTopology, d);
        uiTopology.add(device);
        return device;
    }

    private void updateDevice(UiDevice device) {
        device.setRegionId(services.region().getRegionForDevice(device.id()).id());
    }

    private void loadDevices() {
        for (Device d : services.device().getDevices()) {
            UiDevice device = addNewDevice(d);
            updateDevice(device);
        }
    }

    // invoked from UiSharedTopologyModel device listener
    void addOrUpdateDevice(Device device) {
        DeviceId id = device.id();
        UiDevice uiDevice = uiTopology.findDevice(id);
        if (uiDevice == null) {
            uiDevice = addNewDevice(device);
        }
        updateDevice(uiDevice);

        postEvent(DEVICE_ADDED_OR_UPDATED, uiDevice);
    }

    // invoked from UiSharedTopologyModel device listener
    void removeDevice(Device device) {
        DeviceId id = device.id();
        UiDevice uiDevice = uiTopology.findDevice(id);
        if (uiDevice != null) {
            uiTopology.remove(uiDevice);
            postEvent(DEVICE_REMOVED, uiDevice);
        } else {
            log.warn(E_NO_ELEMENT, "device", id);
        }
    }


    // === LINKS

    private UiLink addNewLink(UiLinkId id) {
        UiLink uiLink = new UiLink(uiTopology, id);
        uiTopology.add(uiLink);
        return uiLink;
    }

    private void updateLink(UiLink uiLink, Link link) {
        uiLink.attachBackingLink(link);
    }

    private void loadLinks() {
        for (Link link : services.link().getLinks()) {
            UiLinkId id = uiLinkId(link);

            UiLink uiLink = uiTopology.findLink(id);
            if (uiLink == null) {
                uiLink = addNewLink(id);
            }
            updateLink(uiLink, link);
        }
    }

    // invoked from UiSharedTopologyModel link listener
    void addOrUpdateLink(Link link) {
        UiLinkId id = uiLinkId(link);
        UiLink uiLink = uiTopology.findLink(id);
        if (uiLink == null) {
            uiLink = addNewLink(id);
        }
        updateLink(uiLink, link);

        postEvent(LINK_ADDED_OR_UPDATED, uiLink);
    }

    // invoked from UiSharedTopologyModel link listener
    void removeLink(Link link) {
        UiLinkId id = uiLinkId(link);
        UiLink uiLink = uiTopology.findLink(id);
        if (uiLink != null) {
            boolean remaining = uiLink.detachBackingLink(link);
            if (remaining) {
                postEvent(LINK_ADDED_OR_UPDATED, uiLink);
            } else {
                uiTopology.remove(uiLink);
                postEvent(LINK_REMOVED, uiLink);
            }
        } else {
            log.warn(E_NO_ELEMENT, "link", id);
        }
    }


    // === HOSTS

    private UiHost addNewHost(Host h) {
        UiHost host = new UiHost(uiTopology, h);
        uiTopology.add(host);

        UiLink edgeLink = addNewEdgeLink(host);
        host.setEdgeLinkId(edgeLink.id());

        return host;
    }

    private void removeOldEdgeLink(UiHost uiHost) {
        UiLink old = uiTopology.findLink(uiHost.edgeLinkId());
        if (old != null) {
            uiTopology.remove(old);
        }
    }

    private UiLink addNewEdgeLink(UiHost uiHost) {
        EdgeLink elink = createEdgeLink(uiHost.backingHost(), true);
        UiLinkId elinkId = UiLinkId.uiLinkId(elink);
        UiLink uiLink = addNewLink(elinkId);
        uiLink.attachEdgeLink(elink);
        return uiLink;
    }

    private void updateHost(UiHost uiHost, Host h) {
        removeOldEdgeLink(uiHost);
        HostLocation hloc = h.location();
        uiHost.setLocation(hloc.deviceId(), hloc.port());
        addNewEdgeLink(uiHost);
    }

    private void loadHosts() {
        for (Host h : services.host().getHosts()) {
            UiHost host = addNewHost(h);
            updateHost(host, h);
        }
    }

    // invoked from UiSharedTopologyModel host listener
    void addOrUpdateHost(Host host) {
        HostId id = host.id();
        UiHost uiHost = uiTopology.findHost(id);
        if (uiHost == null) {
            uiHost = addNewHost(host);
        }
        updateHost(uiHost, host);

        postEvent(HOST_ADDED_OR_UPDATED, uiHost);
    }

    // invoked from UiSharedTopologyModel host listener
    void moveHost(Host host, Host prevHost) {
        UiHost uiHost = uiTopology.findHost(prevHost.id());
        updateHost(uiHost, host);

        postEvent(HOST_MOVED, uiHost);
    }

    // invoked from UiSharedTopologyModel host listener
    void removeHost(Host host) {
        HostId id = host.id();
        UiHost uiHost = uiTopology.findHost(id);
        if (uiHost != null) {
            uiTopology.remove(uiHost);
            removeOldEdgeLink(uiHost);
            postEvent(HOST_REMOVED, uiHost);
        } else {
            log.warn(E_NO_ELEMENT, "host", id);
        }
    }


    // === CACHE STATISTICS

    /**
     * Returns the number of members in the cluster.
     *
     * @return number of cluster members
     */
    public int clusterMemberCount() {
        return uiTopology.clusterMemberCount();
    }

    /**
     * Returns the number of regions in the topology.
     *
     * @return number of regions
     */
    public int regionCount() {
        return uiTopology.regionCount();
    }
}