/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.aai.serialization.engines.query;

import static org.onap.aai.edges.enums.AAIDirection.*;
import static org.onap.aai.edges.enums.EdgeField.PRIVATE;
import static org.onap.aai.edges.enums.EdgeProperty.CONTAINS;
import static org.onap.aai.edges.enums.EdgeProperty.DELETE_OTHER_V;

import java.util.List;
import java.util.Set;

import org.apache.tinkerpop.gremlin.process.traversal.Order;
import org.apache.tinkerpop.gremlin.process.traversal.P;
import org.apache.tinkerpop.gremlin.process.traversal.Path;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.Tree;
import org.apache.tinkerpop.gremlin.structure.Direction;
import org.apache.tinkerpop.gremlin.structure.Edge;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.onap.aai.db.props.AAIProperties;
import org.onap.aai.edges.enums.EdgeField;
import org.onap.aai.edges.enums.EdgeProperty;
import org.onap.aai.introspection.Loader;
import org.onap.aai.logging.StopWatch;

/*
 * This class needs some big explanation despite its compact size.
 * This controls all the queries performed by the CRUD API in A&AI.
 * findParents, findChildren, and findDeletable require special attention
 *   These methods use 'repeat'. You cannot use 'emit' with repeat currently
 *   as it is extremely buggy as of tinkerpop-3.0.1-incubating. The way around
 *   it (for now) is to sideEffect all the vertices we traverse into an ArrayList.
 *
 */
public class GraphTraversalQueryEngine extends QueryEngine {

    /**
     * Instantiates a new graph traversal query engine.
     *
     * @param g graph traversal source to traverse the graph
     */
    public GraphTraversalQueryEngine(GraphTraversalSource g) {
        super(g);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findParents(Vertex start) {
        try {
            StopWatch.conditionalStart();

            @SuppressWarnings("unchecked")
            final GraphTraversal<Vertex, Vertex> pipe = this.g.V(start).emit(v -> true)
                    .repeat(__.union(__.inE().has(CONTAINS.toString(), OUT.toString()).outV(),
                            __.outE().has(CONTAINS.toString(), IN.toString()).inV()));
            return pipe.toList();
        } finally {
            dbTimeMsecs += StopWatch.stopIfStarted();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findParents(String[] uris) {
        try {
            StopWatch.conditionalStart();
            final GraphTraversal<Vertex, Vertex> pipe =
                    this.g.V().has(AAIProperties.AAI_URI, P.within(uris)).order().by(AAIProperties.AAI_URI, Order.decr);
            return pipe.toList();
        } finally {
            dbTimeMsecs += StopWatch.stopIfStarted();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findAllChildren(Vertex start) {

        @SuppressWarnings("unchecked")
        GraphTraversal<Vertex, Vertex> pipe = this.g.V(start).emit(v -> true)
                .repeat(__.union(__.outE().has(CONTAINS.toString(), OUT.toString()).inV(),
                        __.inE().has(CONTAINS.toString(), IN.toString()).outV()));

        return pipe.toList();

    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findChildrenOfType(Vertex start, String type) {
        @SuppressWarnings("unchecked")
        GraphTraversal<Vertex, Vertex> pipe = this.g.V(start)
                .union(__.outE().has(CONTAINS.toString(), OUT.toString()).inV(),
                        __.inE().has(CONTAINS.toString(), IN.toString()).outV())
                .has(AAIProperties.NODE_TYPE, type).dedup();

        return pipe.toList();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findChildren(Vertex start) {
        @SuppressWarnings("unchecked")
        GraphTraversal<Vertex, Vertex> pipe = this.g.V(start).union(__.outE().has(CONTAINS.toString(), OUT.toString()),
                __.inE().has(CONTAINS.toString(), IN.toString())).otherV().dedup();

        return pipe.toList();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findDeletable(Vertex start) {
        try {
            StopWatch.conditionalStart();
            @SuppressWarnings("unchecked")
            GraphTraversal<Vertex, Vertex> pipe = this.g.V(start).emit(v -> true)
                    .repeat(__.union(__.outE().has(DELETE_OTHER_V.toString(), OUT.toString()).inV(),
                            __.inE().has(DELETE_OTHER_V.toString(), IN.toString()).outV()))
                    .dedup();

            return pipe.toList();
        } finally {
            dbTimeMsecs += StopWatch.stopIfStarted();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findDeletable(List<Vertex> startVertexes) {
        try {
            StopWatch.conditionalStart();
            Vertex[] vertices = new Vertex[startVertexes.size()];
            vertices = startVertexes.toArray(vertices);
            GraphTraversal<Vertex, Vertex> pipe = this.g.V(vertices).emit(v -> true)
                    .repeat(__.union(__.outE().has(DELETE_OTHER_V.toString(), OUT.toString()).inV(),
                            __.inE().has(DELETE_OTHER_V.toString(), IN.toString()).outV()))
                    .dedup();

            return pipe.toList();
        } finally {
            dbTimeMsecs += StopWatch.stopIfStarted();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Vertex> findRelatedVertices(Vertex start, Direction direction, String label, String nodeType) {
        GraphTraversal<Vertex, Vertex> pipe = this.g.V(start);
        switch (direction) {
            case OUT:
                pipe.out(label);
                break;
            case IN:
                pipe.in(label);
                break;
            case BOTH:
                pipe.both(label);
                break;
            default:
                break;
        }

        pipe.has(AAIProperties.NODE_TYPE, nodeType).dedup();
        return pipe.toList();
    }

    @Override
    public Tree<Element> findSubGraph(Vertex start, int iterations, boolean nodeOnly) {
        final GraphTraversal<Vertex, ?> t = this.g.V(start).emit(v -> true).times(iterations)
                .repeat(__.union(__.outE().has(CONTAINS.toString(), OUT.toString()).inV(),
                        __.inE().has(CONTAINS.toString(), IN.toString()).outV()));

        if (!nodeOnly) {
            t.union(__.identity(), __.bothE().has(CONTAINS.toString(), NONE.toString()).dedup().otherV());
        }
        t.tree();
        if (t.hasNext()) {
            return (Tree) t.next();
        } else {
            return new Tree();
        }
    }

    @Override
    public List<Edge> findEdgesForVersion(Vertex start, Loader loader) {
        // From the given start vertex find both the
        // out edges that has property CONTAINS set to NONE
        // whose in vertexes has an object that is declared in the oxm
        // And do the same thing vice versa to get a list of edges
        // Then check that the edge should not have the property private set to true
        // and remove the duplicates and return the list of edges
        final Set<String> objects = loader.getAllObjects().keySet();
        GraphTraversal<Vertex, Edge> pipeline = this.g.V(start)
                .union(__.inE().has(CONTAINS.toString(), NONE.toString())
                        .where(__.outV().has(AAIProperties.NODE_TYPE, P.within(objects))),
                        __.outE().has(CONTAINS.toString(), NONE.toString())
                                .where(__.inV().has(AAIProperties.NODE_TYPE, P.within(objects))))
                .not(__.has("private", true)).dedup();

        return pipeline.toList();
    }

    @Override
    public List<Vertex> findCousinVertices(Vertex start, String... labels) {
        // Start at the given vertex
        // Do a union to copy the start vertex to be run against all
        // so for the start vertex it gets all of in edges that contains other v set to none
        // and also all the other out edges with contains other v set to none
        // And filter the edges based on the property private not set
        // so that means it will be a regular edge
        // and find the other end of the vertex so if setup like this:
        // v2 -> e1 -> v3
        // It will return v3
        GraphTraversal<Vertex, Vertex> pipeline = this.g.V(start)
                .union(__.inE(labels).has(CONTAINS.toString(), NONE.toString()),
                        __.outE(labels).has(CONTAINS.toString(), NONE.toString()))
                .not(__.has(PRIVATE.toString(), true)).otherV().dedup();

        return pipeline.toList();
    }

    public List<Path> findCousinsAsPath(Vertex start) {
        return this.g.V(start).bothE().where(__.and(__.has(EdgeProperty.CONTAINS.toString(), NONE.toString()),
                __.not(__.has(EdgeField.PRIVATE.toString(), true)))).otherV().path().toList();
    }

    public double getDBTimeMsecs() {
        return (dbTimeMsecs);
    }
}