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The RMLMapper executes RML rules to generate high quality Linked Data from multiple originally (semi-)structured data sources.
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package be.ugent.rml.conformer;

import be.ugent.idlab.knows.dataio.access.DatabaseType;
import be.ugent.rml.NAMESPACES;
import be.ugent.rml.Utils;
import be.ugent.rml.store.QuadStore;

import be.ugent.rml.term.Literal;
import be.ugent.rml.term.NamedNode;
import be.ugent.rml.term.Term;

import java.util.Map;

import static be.ugent.rml.NAMESPACES.*;

/**
 * Converts InputStream of R2RML or RML mapping files to RML mapping files.
 * convert() can fail with an Exception
 * No support for quoted database identifiers
 * Uses the first "a d2rq:Database" it finds as source
 */
public class R2RMLConverter implements Converter {

    private QuadStore store;

    R2RMLConverter(QuadStore store) {
        this.store = store;
    }

    /**
     * Tries to convert R2RML TriplesMap to rml by:
     * - renaming logicalTable to logicalSource
     * - adding referenceFormulation: CSV
     * - adding sqlVersion: SQL2008
     * - renaming rr:sqlQuery to rml:query
     * - renaming all rr:column properties to rml:reference
     * - removing all rr:logicalTable nodes, leaving rml:logicalSource to take their place
     * - moving rest over from logicalTable to logicalSource
     *
     * @param triplesMap rr:TriplesMap
     */
    public void convert(Map mappingOptions) throws Exception {
        for (Term triplesMap: Utils.getSubjectsFromQuads(store.getQuads(null, new NamedNode(RML2 + "subjectMap"), null))) {
            // UNSAFE store changes not yet allowed; check if all required properties are present
            Term logicalTable;

            // Get logical table
            try {
                logicalTable = store
                        .getQuad(triplesMap, new NamedNode(RR + "logicalTable"), null)
                        .getObject();
            } catch (Exception e) {
                // Also not R2RML
                throw new UnsupportedOperationException("Mapping is either RML without logicalSource or R2RML without logicalTable");
            }

            Term database;

            // SAFE store changes allowed
            database = new NamedNode(triplesMap.getValue() + "_database");

            if (mappingOptions != null) {
                store.addQuad(database, new NamedNode(RDF + "type"), new NamedNode(D2RQ + "Database"));

                for (Map.Entry entry : mappingOptions.entrySet()) {
                    String removePrefix = entry.getKey();
                    store.addQuad(database, new NamedNode(D2RQ + removePrefix), new Literal(entry.getValue()));

                    if (removePrefix.equals("jdbcDSN")) {
                        DatabaseType type = DatabaseType.getDBtype(entry.getValue());
                        String driver = type.getDriver();

                        store.addQuad(database, new NamedNode(D2RQ + "jdbcDriver"), new Literal(driver));
                    }
                }
            }

            // Add logical source
            String logicalSourceIRI = triplesMap.getValue() + "_logicalSource";
            Term logicalSource = new NamedNode(logicalSourceIRI);

            store.addQuad(triplesMap, new NamedNode(RML + "logicalSource"), logicalSource, null);
            store.addQuad(logicalSource, new NamedNode(RML + "referenceFormulation"),
                    new NamedNode(NAMESPACES.QL + "CSV")
            );

            // Also add old R2RML for AccessFactory property
            store.addQuad(logicalSource, new NamedNode(RML + "source"),
                    database
            );
            store.tryPropertyTranslation(logicalTable, new NamedNode(RR + "sqlQuery"), logicalSource, new NamedNode(RML + "query"));
            store.tryPropertyTranslation(logicalTable, new NamedNode(RR + "tableName"), logicalSource, new NamedNode(RR + "tableName"));
            store.tryPropertyTranslation(logicalTable, new NamedNode(RR + "sqlVersion"), logicalSource, new NamedNode(RR + "sqlVersion"));

            // Rename on whole store instead of deep search in TriplesMap Resource
            store.renameAllPredicates(new NamedNode(RR + "column"), new NamedNode(RML + "reference"));
            store.removeQuads(triplesMap, new NamedNode(RR + "logicalTable"), null);
        }
    }
}