# RdfQueryService.java

    /*
     * Copyright 2008 Alin Dreghiciu.
     *
     * 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 org.qi4j.index.rdf.query;

    import java.util.Map;
    import org.openrdf.query.QueryLanguage;
    import org.qi4j.api.composite.Composite;
    import org.qi4j.api.entity.EntityReference;
    import org.qi4j.api.injection.scope.Service;
    import org.qi4j.api.injection.scope.This;
    import org.qi4j.api.mixin.Mixins;
    import org.qi4j.api.query.grammar.OrderBy;
    import org.qi4j.api.query.grammar.QuerySpecification;
    import org.qi4j.api.service.ServiceComposite;
    import org.qi4j.functional.Specification;
    import org.qi4j.spi.query.EntityFinder;
    import org.qi4j.spi.query.EntityFinderException;

    /**
     * JAVADOC Add JavaDoc
     */
    @Mixins( { RdfQueryService.RdfEntityFinderMixin.class } )
    public interface RdfQueryService
        extends EntityFinder, RdfQueryParserFactory, ServiceComposite
    {
        /**
         * JAVADOC Add JavaDoc
         */
        public static class RdfEntityFinderMixin
            implements EntityFinder
        {

            private static final QueryLanguage language = QueryLanguage.SPARQL;

            @Service
            private RdfQueryParserFactory queryParserFactory;

            @This
            TupleQueryExecutor tupleExecutor;

            @Override
            public Iterable<EntityReference> findEntities( Class<?> resultType,
                                                           Specification<Composite> whereClause,
                                                           OrderBy[] orderBySegments,
                                                           Integer firstResult,
                                                           Integer maxResults,
                                                           Map<String, Object> variables
            )
                throws EntityFinderException
            {
                CollectingQualifiedIdentityResultCallback collectingCallback = new CollectingQualifiedIdentityResultCallback();

                if( QuerySpecification.isQueryLanguage( "SERQL", whereClause ))
                {
                    String query = ((QuerySpecification)whereClause).query();
                    tupleExecutor.performTupleQuery( QueryLanguage.SERQL, query, variables, collectingCallback );
                    return collectingCallback.entities();

                } else
                {
                    RdfQueryParser rdfQueryParser = queryParserFactory.newQueryParser( language );
                    String query = rdfQueryParser.constructQuery( resultType, whereClause, orderBySegments, firstResult, maxResults, variables );

                    tupleExecutor.performTupleQuery( language, query, variables, collectingCallback );
                    return collectingCallback.entities();
                }
            }

            @Override
            public EntityReference findEntity( Class<?> resultType, Specification<Composite> whereClause, Map<String, Object> variables )
                throws EntityFinderException
            {
                final SingleQualifiedIdentityResultCallback singleCallback = new SingleQualifiedIdentityResultCallback();

                if (QuerySpecification.isQueryLanguage( "SERQL", whereClause))
                {
                    String query = ((QuerySpecification)whereClause).query();
                    tupleExecutor.performTupleQuery( QueryLanguage.SERQL, query, variables, singleCallback );
                    return singleCallback.qualifiedIdentity();
                } else
                {
                    RdfQueryParser rdfQueryParser = queryParserFactory.newQueryParser( language );
                    String query = rdfQueryParser.constructQuery( resultType, whereClause, null, null, null, variables );
                    tupleExecutor.performTupleQuery( QueryLanguage.SPARQL, query, variables, singleCallback );
                    return singleCallback.qualifiedIdentity();
                }
            }

            @Override
            public long countEntities( Class<?> resultType, Specification<Composite> whereClause, Map<String, Object> variables )
                throws EntityFinderException
            {
                if (QuerySpecification.isQueryLanguage( "SERQL", whereClause ))
                {
                    String query = ((QuerySpecification)whereClause).query();
                    return tupleExecutor.performTupleQuery( QueryLanguage.SERQL, query, variables, null );

                } else
                {
                    RdfQueryParser rdfQueryParser = queryParserFactory.newQueryParser( language );
                    String query = rdfQueryParser.constructQuery( resultType, whereClause, null, null, null, variables );
                    return tupleExecutor.performTupleQuery( language, query, variables, null );
                }
            }
        }
    }