/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.jena.sparql.core.assembler;

import static org.apache.jena.assembler.JA.data;
import static org.apache.jena.query.DatasetFactory.createTxnMem;
import static org.apache.jena.query.ReadWrite.WRITE;
import static org.apache.jena.riot.RDFDataMgr.read;
import static org.apache.jena.sparql.core.assembler.AssemblerUtils.setContext;
import static org.apache.jena.sparql.core.assembler.DatasetAssemblerVocab.pGraphName;
import static org.apache.jena.sparql.core.assembler.DatasetAssemblerVocab.pNamedGraph;
import static org.apache.jena.sparql.util.graph.GraphUtils.getAsStringValue;
import static org.apache.jena.sparql.util.graph.GraphUtils.multiValueResource;

import org.apache.jena.assembler.Assembler;
import org.apache.jena.assembler.Mode;
import org.apache.jena.assembler.assemblers.AssemblerBase;
import org.apache.jena.query.Dataset;
import org.apache.jena.rdf.model.Resource;

/**
 * An {@link Assembler} that creates in-memory {@link Dataset}s.
 */
public class InMemDatasetAssembler extends AssemblerBase implements Assembler {

    public static Resource getType() {
        return DatasetAssemblerVocab.tDatasetTxnMem ;
    }
    
	@Override
	public Dataset open(final Assembler assembler, final Resource root, final Mode mode) {
		checkType(root, DatasetAssemblerVocab.tDatasetTxnMem);
		final Dataset dataset = createTxnMem();
		setContext(root, dataset.getContext());

		dataset.begin(WRITE);

		// load data into the default graph
		if (root.hasProperty(data)) {
		    multiValueResource(root, data)
				.forEach(defaultGraphDocument -> read(dataset, defaultGraphDocument.getURI()));
		}

		// load data into named graphs
		multiValueResource(root, pNamedGraph).forEach(namedGraphResource -> {
			final String graphName = getAsStringValue(namedGraphResource, pGraphName);
			if (namedGraphResource.hasProperty(data)) {
			    multiValueResource(namedGraphResource, data)
			        .forEach(namedGraphData -> read(dataset.getNamedModel(graphName), namedGraphData.getURI()));
			}
		});

		dataset.commit();
		dataset.end();
		return dataset;
	}
}