com.metreeca.rdf4j.assets.GraphTerms Maven / Gradle / Ivy

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/*
 * Copyright © 2013-2021 Metreeca srl
 *
 * 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 com.metreeca.rdf4j.assets;

import com.metreeca.json.Shape;
import com.metreeca.json.queries.Terms;
import com.metreeca.rest.assets.Engine;

import org.eclipse.rdf4j.model.*;
import org.eclipse.rdf4j.model.vocabulary.OWL;
import org.eclipse.rdf4j.model.vocabulary.RDFS;
import org.eclipse.rdf4j.query.*;

import java.math.BigInteger;
import java.util.*;

import static com.metreeca.json.Values.*;
import static com.metreeca.json.shapes.And.and;
import static com.metreeca.rdf4j.SPARQLScribe.*;
import static com.metreeca.rdf4j.assets.Graph.graph;
import static com.metreeca.rest.Context.asset;
import static com.metreeca.rest.Scribe.indent;
import static com.metreeca.rest.Scribe.text;
import static com.metreeca.rest.Scribe.*;

final class GraphTerms extends GraphFacts {

	private final Options options=options();

	private final Graph graph=asset(graph());


	GraphTerms(final Options options) {
		super(options);
	}


	Collection process(final IRI resource, final Terms terms) {

		final Shape shape=terms.shape();
		final List path=terms.path();
		final int offset=terms.offset();
		final int limit=terms.limit();

		final Shape filter=shape
				.filter(resource)
				.resolve(resource); // .filter() may introduce focus values › resolve afterwards

		final Shape convey=shape
				.convey()
				.resolve(resource);

		final Shape select=and(filter, path(convey, path)).label(this::label); // requires path to exist in convey

		final String hook=hook(select, path);

		final Collection model=new LinkedHashSet<>();

		evaluate(() -> graph.exec(connection -> {
			connection.prepareTupleQuery(compile(() -> code(list(

					comment("terms query"),

					prefix(OWL.NS),
					prefix(RDFS.NS),

					space(select(), where(

							space(block(

									space(select(space(indent(
											as("value", var(hook)),
											as("count", count(true, var(root)))
									)))),

									space(where(

											space(tree(select, true))

											// !!! sampling w/ options.stats()

									)),

									space(
											line(group(var(hook))),
											line(having(gt(count(var(root)), text(0)))),
											line(order(desc(var("count")), var("value"))),
											line(offset(offset)),
											line(limit(limit))
									)

							)),

							space(
									line(optional(edge(var("value"), "rdfs:label", var("label")))),
									line(optional(edge(var("value"), "rdfs:comment", var("notes"))))
							)

					))

			)))).evaluate(new AbstractTupleQueryResultHandler() {
				@Override public void handleSolution(final BindingSet bindings) throws TupleQueryResultHandlerException {

					// ;(virtuoso) counts are returned as xsd:int… cast to stay consistent

					final Value value=bindings.getValue("value");
					final Value count=literal(integer(bindings.getValue("count")).orElse(BigInteger.ZERO));

					final Value label=bindings.getValue("label");
					final Value notes=bindings.getValue("notes");

					final BNode term=bnode(md5(format(value)));

					model.add(statement(resource, Engine.terms, term));

					model.add(statement(term, Engine.value, value));
					model.add(statement(term, Engine.count, count));

					if ( label != null ) { model.add(statement((Resource)value, RDFS.LABEL, label)); }
					if ( notes != null ) { model.add(statement((Resource)value, RDFS.COMMENT, notes)); }

				}
			});
		}));

		return model;
	}

}