001/*-
002 * #%L
003 * HAPI FHIR Storage api
004 * %%
005 * Copyright (C) 2014 - 2024 Smile CDR, Inc.
006 * %%
007 * Licensed under the Apache License, Version 2.0 (the "License");
008 * you may not use this file except in compliance with the License.
009 * You may obtain a copy of the License at
010 *
011 *      http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 * #L%
019 */
020package ca.uhn.fhir.storage;
021
022import ca.uhn.fhir.jpa.api.dao.IFhirResourceDao;
023import ca.uhn.fhir.rest.api.server.SystemRequestDetails;
024import ca.uhn.fhir.rest.server.exceptions.ResourceGoneException;
025import org.hl7.fhir.instance.model.api.IBaseResource;
026import org.hl7.fhir.instance.model.api.IIdType;
027
028import java.util.Optional;
029
030public class PreviousVersionReader<T extends IBaseResource> {
031        private final IFhirResourceDao<T> myDao;
032
033        public PreviousVersionReader(IFhirResourceDao<T> theDao) {
034                myDao = theDao;
035        }
036
037        public Optional<T> readPreviousVersion(T theResource) {
038                return readPreviousVersion(theResource, false);
039        }
040
041        public Optional<T> readPreviousVersion(T theResource, boolean theDeletedOk) {
042                Long currentVersion = theResource.getIdElement().getVersionIdPartAsLong();
043                if (currentVersion == null || currentVersion == 1L) {
044                        return Optional.empty();
045                }
046                long previousVersion = currentVersion - 1L;
047                IIdType previousId = theResource.getIdElement().withVersion(Long.toString(previousVersion));
048                try {
049                        return Optional.ofNullable(myDao.read(previousId, new SystemRequestDetails(), theDeletedOk));
050                } catch (ResourceGoneException e) {
051                        // This will only happen in the case where theDeleteOk = false
052                        return Optional.empty();
053                }
054        }
055}