io.telicent.jena.graphql.fetchers.telicent.graph.StartingStatesFetcher Maven / Gradle / Ivy

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/**
 * Copyright (C) Telicent Ltd
 *
 * 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 io.telicent.jena.graphql.fetchers.telicent.graph;

import graphql.schema.DataFetcher;
import graphql.schema.DataFetchingEnvironment;
import io.telicent.jena.graphql.execution.telicent.graph.TelicentExecutionContext;
import io.telicent.jena.graphql.schemas.telicent.graph.TelicentGraphSchema;
import io.telicent.jena.graphql.schemas.telicent.graph.models.State;
import org.apache.jena.graph.Node;
import org.apache.jena.sparql.core.DatasetGraph;
import org.apache.jena.sparql.core.Quad;
import org.apache.jena.vocabulary.RDF;

import java.util.List;
import java.util.stream.Collectors;

/**
 * A GraphQL {@link DataFetcher} that finds the starting states for a states query
 */
public class StartingStatesFetcher implements DataFetcher> {

    /**
     * Creates a fetcher that finds the states associated with a given URI
     */
    public StartingStatesFetcher() {

    }

    @Override
    public List get(DataFetchingEnvironment environment) {
        TelicentExecutionContext context = environment.getLocalContext();
        DatasetGraph dsg = context.getDatasetGraph();
        Node node = StartingNodesFetcher.parseStart(environment.getArgument(TelicentGraphSchema.ARGUMENT_URI));

        return IesFetchers.STATE_PREDICATES.stream()
                                           .flatMap(p -> dsg.stream(Node.ANY, Node.ANY, p, node)
                                                .filter(q -> (q.getSubject().isURI() || q.getSubject()
                                                                                         .isBlank()) && dsg.contains(
                                                        Node.ANY, q.getSubject(), RDF.type.asNode(), Node.ANY))
                                                .map(Quad::getSubject)
                                                .distinct()
                                                .map(n -> new State(n, p, node)))
                                           .collect(Collectors.toList());
    }
}