Immunization Interceptor Example

ImmunizationInterceptor.java

package ca.onfhir.interceptor;

import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.interceptor.api.Hook;
import ca.uhn.fhir.interceptor.api.Interceptor;
import ca.uhn.fhir.interceptor.api.Pointcut;
import ca.uhn.fhir.jpa.api.dao.DaoRegistry;
import ca.uhn.fhir.jpa.api.dao.IFhirResourceDao;
import ca.uhn.fhir.jpa.searchparam.SearchParameterMap;
import ca.uhn.fhir.rest.api.server.IBundleProvider;
import ca.uhn.fhir.rest.api.server.RequestDetails;
import ca.uhn.fhir.rest.api.server.storage.TransactionDetails;
import ca.uhn.fhir.rest.client.api.IGenericClient;
import ca.uhn.fhir.rest.client.impl.BaseClient;
import ca.uhn.fhir.rest.param.*;
import ca.uhn.fhir.rest.server.servlet.ServletRequestDetails;
import ca.uhn.fhir.util.BundleBuilder;
import org.apache.commons.collections4.SetUtils;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.r4.model.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Arrays;
import java.util.Set;

@Interceptor
public class ImmunizationInterceptor {

	private static final String IMMUNIZATION = "Immunization";
	public static final String SYSTEM_CVX = "http://hl7.org/fhir/sid/cvx";

	private static Logger log = LoggerFactory.getLogger(ImmunizationInterceptor.class);

	/**
	 * Two-dose COVID vaccine codes as defined by CDC https://www2a.cdc.gov/vaccines/iis/iisstandards/vaccines.asp?rpt=cvx
	 */
	private static Set<String> covidImmunizationCodes = SetUtils.unmodifiableSet("207", "208", "210");

	private FhirContext fhirContext;

	private DaoRegistry daoRegistry;

	private String issuerServerBase;

	@Hook(Pointcut.STORAGE_PRECOMMIT_RESOURCE_CREATED)
	public void notifyCredentialsIssuer(IBaseResource resource, RequestDetails request, ServletRequestDetails servletRequest, TransactionDetails txDetails) {
		if (!IMMUNIZATION.equals(fhirContext.getResourceType(resource))) {
			return;
		}

		Immunization immunization = (Immunization) resource;
		if (!isCovidImmunization(immunization)) {
			log.debug("Immunization resource {} is not COVID-19 immunization type", immunization);
			return;
		}

		Patient patient = getPatientFromRef(immunization.getPatient());
		Immunization previousImmunization = getPreviousCovidImmunization(patient, immunization);
		if (previousImmunization == null) {
			log.debug("Previous COVID immunization is not found for {}", toJson(patient));
			return;
		}

		String telecom = patient.getTelecomFirstRep().getValue();
		patient.getTelecom().clear();
		BundleBuilder builder = new BundleBuilder(fhirContext);
		for (DomainResource r : Arrays.asList(patient, previousImmunization, immunization)) {
			builder.addCollectionEntry(clear(r));
		}

		IGenericClient client = fhirContext.newRestfulGenericClient(getIssuerServerBase());
		((BaseClient) client).setDontValidateConformance(true);

		Bundle bundle = (Bundle) builder.getBundle();
		Bundle response = (Bundle) client.transaction()
			.withBundle(bundle)
			.withAdditionalHeader("Patient-Name", patient.getNameFirstRep().getNameAsSingleString())
			.withAdditionalHeader("Patient-Email", telecom)
			.execute();
		log.debug("Published vaccination info with result {}", toJson(response));
	}

	private DomainResource clear(DomainResource resource) {
		resource.setText(null);
		resource.setMeta(null);
		return resource;
	}

	private String toJson(IBaseResource resource) {
		return fhirContext.newJsonParser().encodeResourceToString(resource);
	}

	private Immunization getPreviousCovidImmunization(Patient patient, Immunization immunization) {
		SearchParameterMap params = new SearchParameterMap();
		params.add("patient", new ReferenceParam(patient.getId()));
		params.add("date", new DateParam(ParamPrefixEnum.LESSTHAN, immunization.getOccurrenceDateTimeType()));
		params.add("vaccine-code", new TokenOrListParam(SYSTEM_CVX, covidImmunizationCodes.toArray(new String[0])));
		params.add("status", new TokenParam(Immunization.ImmunizationStatus.COMPLETED.getSystem(),
			Immunization.ImmunizationStatus.COMPLETED.toCode()));

		IFhirResourceDao<Immunization> resourceDao = getDaoRegistry().getResourceDao(Immunization.class);
		IBundleProvider search = resourceDao.search(params);
		if (search.isEmpty()) {
			return null;
		}
		return (Immunization) search.getResources(0, 1).get(0);
	}

	private Patient getPatientFromRef(Reference ref) {
		IFhirResourceDao<Patient> resourceDao = getDaoRegistry().getResourceDao(Patient.class);
		return resourceDao.read(ref.getReferenceElement());
	}

	private boolean isCovidImmunization(Immunization immunization) {
		return immunization.getVaccineCode().getCoding()
			.stream()
			.filter(c -> SYSTEM_CVX.equals(c.getSystem()))
			.anyMatch(c -> covidImmunizationCodes.contains(c.getCode()));
	}

	public FhirContext getFhirContext() {
		return fhirContext;
	}

	public void setFhirContext(FhirContext fhirContext) {
		this.fhirContext = fhirContext;
	}

	public DaoRegistry getDaoRegistry() {
		return daoRegistry;
	}

	public void setDaoRegistry(DaoRegistry daoRegistry) {
		this.daoRegistry = daoRegistry;
	}

	public String getIssuerServerBase() {
		return issuerServerBase;
	}

	public void setIssuerServerBase(String issuerServerBase) {
		this.issuerServerBase = issuerServerBase;
	}
}