/*
 * Copyright 2014-present Open Networking Foundation
 *
 * 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.net.topology;

import org.onlab.util.GuavaCollectors;
import org.onosproject.event.Event;
import org.onosproject.net.ConnectPoint;
import org.onosproject.net.DeviceId;
import org.onosproject.net.Link;
import org.onosproject.net.Path;
import org.onosproject.net.DisjointPath;
import org.onosproject.net.provider.ProviderId;
import org.onosproject.store.Store;

import java.util.List;
import java.util.Set;
import java.util.stream.Stream;
import java.util.Map;

/**
 * Manages inventory of topology snapshots; not intended for direct use.
 */
public interface TopologyStore extends Store<TopologyEvent, TopologyStoreDelegate> {

    /**
     * Returns the current topology snapshot.
     *
     * @return current topology descriptor
     */
    Topology currentTopology();

    /**
     * Indicates whether the topology is the latest.
     *
     * @param topology topology descriptor
     * @return true if topology is the most recent one
     */
    boolean isLatest(Topology topology);

    /**
     * Returns the immutable graph view of the current topology.
     *
     * @param topology topology descriptor
     * @return graph view
     */
    TopologyGraph getGraph(Topology topology);

    /**
     * Returns the set of topology SCC clusters.
     *
     * @param topology topology descriptor
     * @return set of clusters
     */
    Set<TopologyCluster> getClusters(Topology topology);

    /**
     * Returns the cluster of the specified topology.
     *
     * @param topology  topology descriptor
     * @param clusterId cluster identity
     * @return topology cluster
     */
    TopologyCluster getCluster(Topology topology, ClusterId clusterId);

    /**
     * Returns the cluster of the specified topology.
     *
     * @param topology topology descriptor
     * @param cluster  topology cluster
     * @return set of cluster links
     */
    Set<DeviceId> getClusterDevices(Topology topology, TopologyCluster cluster);

    /**
     * Returns the cluster of the specified topology.
     *
     * @param topology topology descriptor
     * @param cluster  topology cluster
     * @return set of cluster links
     */
    Set<Link> getClusterLinks(Topology topology, TopologyCluster cluster);

    /**
     * Returns the set of pre-computed shortest paths between src and dest.
     *
     * @param topology topology descriptor
     * @param src      source device
     * @param dst      destination device
     * @return set of shortest paths
     */
    Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst);

    /**
     * Computes and returns the set of shortest paths between src and dest.
     *
     * @param topology topology descriptor
     * @param src      source device
     * @param dst      destination device
     * @param weigher  link weight function
     * @return set of shortest paths
     */
    Set<Path> getPaths(Topology topology, DeviceId src, DeviceId dst,
                       LinkWeigher weigher);

    /**
     * Computes and returns the k-shortest paths between source and
     * destination devices.
     *
     * The first {@code maxPaths} paths will be returned
     * in ascending order according to the provided {@code weigher}
     *
     * @param topology topology descriptor
     * @param src    source device
     * @param dst    destination device
     * @param weigher edge-weight entity
     * @param maxPaths maximum number of paths (k)
     * @return set of k-shortest paths
     */
    default Set<Path> getKShortestPaths(Topology topology,
                                        DeviceId src, DeviceId dst,
                                        LinkWeigher weigher,
                                        int maxPaths) {
        return getKShortestPaths(topology, src, dst, weigher)
                .limit(maxPaths)
                .collect(GuavaCollectors.toImmutableSet());
    }

    /**
     * Computes and returns the k-shortest paths between source and
     * destination devices.
     *
     * @param topology topology descriptor
     * @param src    source device
     * @param dst    destination device
     * @param weigher edge-weight entity
     * @return stream of k-shortest paths
     */
    default Stream<Path> getKShortestPaths(Topology topology,
                                        DeviceId src, DeviceId dst,
                                        LinkWeigher weigher) {
        return getPaths(topology, src, dst, weigher).stream();
    }

    /**
     * Computes and returns the set of disjoint shortest path pairs
     * between src and dst.
     *
     * @param topology topology descriptor
     * @param src      source device
     * @param dst      destination device
     * @param weigher  link weight function
     * @return set of shortest paths
     */
    Set<DisjointPath> getDisjointPaths(Topology topology, DeviceId src, DeviceId dst,
                                       LinkWeigher weigher);

    /**
     * Computes and returns the set of disjoint shortest path pairs
     * between src and dst.
     *
     * @param topology topology descriptor
     * @param src      source device
     * @param dst      destination device
     * @return set of shortest paths
     */
    Set<DisjointPath> getDisjointPaths(Topology topology, DeviceId src, DeviceId dst);

    /**
     * Computes and returns the set of SRLG disjoint shortest path pairs between source
     * and dst, given a mapping of edges to SRLG risk groups.
     *
     * @param topology    topology descriptor
     * @param src         source device
     * @param dst         destination device
     * @param weigher     link weight function
     * @param riskProfile map of edges to objects. Edges that map to the same object will
     * be treated as if they were in the same risk group.
     * @return set of shortest paths
     */
    Set<DisjointPath> getDisjointPaths(Topology topology, DeviceId src, DeviceId dst,
                                       LinkWeigher weigher, Map<Link, Object> riskProfile);

    /**
     * Returns the set of pre-computed SRLG shortest paths between src and dest.
     *
     * @param topology    topology descriptor
     * @param src         source device
     * @param dst         destination device
     * @param riskProfile map of edges to objects. Edges that map to the same object will
     * be treated as if they were in the same risk group.
     * @return set of shortest paths
     */
    Set<DisjointPath> getDisjointPaths(Topology topology, DeviceId src, DeviceId dst,
                                       Map<Link, Object> riskProfile);


    /**
     * Indicates whether the given connect point is part of the network fabric.
     *
     * @param topology     topology descriptor
     * @param connectPoint connection point
     * @return true if infrastructure; false otherwise
     */
    boolean isInfrastructure(Topology topology, ConnectPoint connectPoint);

    /**
     * Indicates whether broadcast is allowed for traffic received on the
     * given connection point.
     *
     * @param topology     topology descriptor
     * @param connectPoint connection point
     * @return true if broadcast allowed; false otherwise
     */
    boolean isBroadcastPoint(Topology topology, ConnectPoint connectPoint);

    /**
     * Generates a new topology snapshot from the specified description.
     *
     * @param providerId       provider identification
     * @param graphDescription topology graph description
     * @param reasons          list of events that triggered the update
     * @return topology update event or null if the description is old
     */
    TopologyEvent updateTopology(ProviderId providerId,
                                 GraphDescription graphDescription,
                                 List<Event> reasons);
}