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Refactor SDSFilter for readability #354

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Merged
MartinWheelerMT merged 2 commits into from
Sep 9, 2026
Merged

Refactor SDSFilter for readability #354

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a14c03f
Refactor `SdsFilter` for readabilty
MartinWheelerMT Sep 8, 2026
8abb27c
* Refactor `prepareLookupUri` to use regex matching for readability.
MartinWheelerMT Sep 8, 2026
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153 changes: 90 additions & 63 deletions service/src/main/java/uk/nhs/adaptors/gpc/consumer/filters/SdsFilter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,8 @@
import java.util.Objects;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static uk.nhs.adaptors.gpc.consumer.gpc.InteractionIds.DOCUMENT_MIGRATE_ID;
import static uk.nhs.adaptors.gpc.consumer.gpc.InteractionIds.DOCUMENT_READ_ID;
Expand Down Expand Up @@ -70,6 +72,23 @@ public class SdsFilter implements GlobalFilter, Ordered {
private final SdsClient sdsClient;
private Map<String, BiFunction<String, String, Mono<SdsClient.SdsResponseData>>> sdsRequestFunctions;

@Override
public int getOrder() {
return RouteToRequestUrlFilter.ROUTE_TO_URL_FILTER_ORDER + 1;
}

@PostConstruct
public void initializeSdsRequestFunctions() {
sdsRequestFunctions = Map.of(
STRUCTURED_ID, sdsClient::callForGetStructuredRecord,
PATIENT_SEARCH_ID, sdsClient::callForPatientSearchAccessDocument,
DOCUMENT_SEARCH_ID, sdsClient::callForSearchForDocumentRecord,
DOCUMENT_READ_ID, sdsClient::callForRetrieveDocumentRecord,
DOCUMENT_MIGRATE_ID, sdsClient::callForMigrateDocumentRecord,
MIGRATE_STRUCTURED_ID, sdsClient::callForMigrateStructuredRecord
);
}

@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
return getGpcProviderEndpointDetails(exchange)
Expand All @@ -82,18 +101,18 @@ public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
}

private Mono<SdsClient.SdsResponseData> getGpcProviderEndpointDetails(ServerWebExchange exchange) {

return performGpcProviderSdsLookup(exchange)
.doOnNext(v -> {
if (exchange.getRequest().getPath().value().endsWith(DOCUMENT_REFERENCE_SUFFIX)) {
QueryParamsEncoder.encodeQueryParams(exchange);
}
});
.doOnNext(v -> encodeQueryParamsToUrlWhenDocumentRequest(exchange));
}

private static void encodeQueryParamsToUrlWhenDocumentRequest(ServerWebExchange exchange) {
if (exchange.getRequest().getPath().value().endsWith(DOCUMENT_REFERENCE_SUFFIX)) {
QueryParamsEncoder.encodeQueryParams(exchange);
}
}

@NotNull
private Mono<SdsClient.SdsResponseData> performGpcProviderSdsLookup(ServerWebExchange exchange) {

LoggingUtil.info(LOGGER, exchange, "Using SDS API for GP connect provider service lookup");

var id = extractHeaderValueOrThrowSdsException(exchange.getRequest().getHeaders(), SSP_INTERACTION_ID);
Expand All @@ -107,22 +126,34 @@ private String extractHeaderValueOrThrowSdsException(HttpHeaders httpHeaders, St
}

private Mono<SdsClient.SdsResponseData> performGpcProviderSdsLookup(ServerWebExchange exchange, String interactionId) {

ServerHttpRequest serverHttpRequest = exchange.getRequest();
String organisation = extractOdsCode(serverHttpRequest.getPath());
var sspTraceId = extractHeaderValueOrThrowSdsException(exchange.getRequest().getHeaders(), SSP_TRACE_ID);

return performRequestAccordingToInteractionId(interactionId, organisation, sspTraceId, exchange)
.switchIfEmpty(Mono.error(new SdsException(
String.format("No endpoint found in SDS for GP Connect endpoint InteractionId=%s OdsCode=%s",
interactionId,
organisation)))
).doOnNext(response -> {
LoggingUtil.info(LOGGER, exchange, "Found GP connect provider endpoint in sds: {}", response.getAddress());
prepareLookupUri(response.getAddress(), serverHttpRequest)
.ifPresent(uri -> exchange.getAttributes()
.put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, uri));
});
.switchIfEmpty(buildNoEndpointFoundError(interactionId, organisation)
).doOnNext(response -> updateGatewayRequestUrlIfEndpointFound(
exchange,
response,
serverHttpRequest
));
}

private void updateGatewayRequestUrlIfEndpointFound(
ServerWebExchange exchange,
SdsClient.SdsResponseData response,
ServerHttpRequest serverHttpRequest
) {
LoggingUtil.info(LOGGER, exchange, "Found GP connect provider endpoint in sds: {}", response.getAddress());
URI lookupUri = prepareLookupUri(response.getAddress(), serverHttpRequest);
exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, lookupUri);
}

private static @NotNull Mono<SdsClient.SdsResponseData> buildNoEndpointFoundError(String interactionId, String organisation) {
return Mono.error(new SdsException(
"No endpoint found in SDS for GP Connect endpoint InteractionId=%s OdsCode=%s".formatted(
interactionId,
organisation)));
}

private Mono<Void> appendSspHeadersToExchangeIfRequired(
Expand Down Expand Up @@ -157,21 +188,31 @@ private Mono<? extends Void> addMissingSspHeaders(
String spineCode = mapWebClientExceptionToSpineCode(e);
String fhirCode = mapSpineCodeToFhirCode(spineCode);

ResponseEntity<String> errorResponse = OperationOutcomes.buildErrorResponse(status, spineCode, fhirCode, e.getMessage());
ServerHttpResponse response = exchange.getResponse();
byte[] bytes = buildResponseBodyAsUtf8Bytes(e, status, spineCode, fhirCode, response);

DataBuffer buffer = response.bufferFactory().wrap(bytes);
return response.writeWith(Mono.just(buffer));
}

private static byte @NotNull [] buildResponseBodyAsUtf8Bytes(
Exception e,
HttpStatus status,
String spineCode,
String fhirCode,
ServerHttpResponse response
) {
ResponseEntity<String> errorResponse = OperationOutcomes.buildErrorResponse(status, spineCode, fhirCode, e.getMessage());
response.setStatusCode(errorResponse.getStatusCode());
response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
String body = Objects.requireNonNullElse(errorResponse.getBody(), "");
byte[] bytes = body.getBytes(StandardCharsets.UTF_8);
DataBuffer buffer = response.bufferFactory().wrap(bytes);
return response.writeWith(Mono.just(buffer));
return body.getBytes(StandardCharsets.UTF_8);
}

private static HttpStatus mapExceptionToHttpStatus(Exception e) {
return switch (e) {
case WebClientRequestException ignored -> HttpStatus.BAD_GATEWAY;
case WebClientResponseException webClientResponseEx ->
HttpStatus.resolve(webClientResponseEx.getStatusCode().value());
case WebClientResponseException webClientResponseEx -> HttpStatus.resolve(webClientResponseEx.getStatusCode().value());
default -> HttpStatus.INTERNAL_SERVER_ERROR;
};
}
Expand Down Expand Up @@ -225,58 +266,44 @@ private ServerWebExchange appendSspHeaderWhenAbsent(ServerWebExchange exchange,
return exchange.mutate().request(mutateRequest).build();
}


@Override
public int getOrder() {
return RouteToRequestUrlFilter.ROUTE_TO_URL_FILTER_ORDER + 1;
}

@PostConstruct
@SuppressWarnings("unused")
public void initializeSdsRequestFunctions() {
sdsRequestFunctions = Map.of(
STRUCTURED_ID, sdsClient::callForGetStructuredRecord,
PATIENT_SEARCH_ID, sdsClient::callForPatientSearchAccessDocument,
DOCUMENT_SEARCH_ID, sdsClient::callForSearchForDocumentRecord,
DOCUMENT_READ_ID, sdsClient::callForRetrieveDocumentRecord,
DOCUMENT_MIGRATE_ID, sdsClient::callForMigrateDocumentRecord,
MIGRATE_STRUCTURED_ID, sdsClient::callForMigrateStructuredRecord
);
}

private Mono<SdsClient.SdsResponseData> performRequestAccordingToInteractionId(
String interactionId,
String organisation,
String sspTraceId,
ServerWebExchange exchange
) {
if (sdsRequestFunctions.containsKey(interactionId)) {
LoggingUtil.info(LOGGER, exchange, "Performing request with organisation \"{}\" and NHS service endpoint id \"{}\"",
organisation, interactionId);
return sdsRequestFunctions.get(interactionId)
.apply(organisation, sspTraceId);
LoggingUtil.info(
LOGGER,
exchange,
"Performing request with organisation \"{}\" and NHS service endpoint id \"{}\"",
organisation,
interactionId
);
return sdsRequestFunctions.get(interactionId).apply(organisation, sspTraceId);
}
throw new IllegalArgumentException(String.format("Not recognised InteractionId %s", interactionId));
}

private Optional<URI> prepareLookupUri(String serviceRootUrl, ServerHttpRequest originalRequest) {
var originalRequestPath = originalRequest.getPath();
var originalRequestPathValues = originalRequestPath.elements().stream()
.map(PathContainer.Element::value)
.toList();
int indexOfPatientInFhirPath = originalRequestPathValues.lastIndexOf("Patient");
int indexOfBinaryInFhirPath = originalRequestPathValues.lastIndexOf("Binary");
int indexOfStartOfFhirPath = Math.max(indexOfPatientInFhirPath, indexOfBinaryInFhirPath);
if (indexOfStartOfFhirPath < 0) {
throw new SdsFilterException("Unable to detect a supported FHIR path in the original request");
}
String fhirRequestPathPart = originalRequest.getPath().subPath(indexOfStartOfFhirPath - 1)
.toString();
String uriWithoutQueryParameters = serviceRootUrl + fhirRequestPathPart;
URI constructedUri = UriComponentsBuilder.fromUriString(uriWithoutQueryParameters)
private URI prepareLookupUri(String serviceRootUrl, ServerHttpRequest originalRequest) {
var path = getEitherBinaryOrPatientFhirPathOrThrow(originalRequest);

return UriComponentsBuilder.fromUriString(serviceRootUrl + path)
.queryParams(originalRequest.getQueryParams())
.build()
.toUri();
return Optional.of(constructedUri);

}

private static @NotNull String getEitherBinaryOrPatientFhirPathOrThrow(ServerHttpRequest originalRequest) {
var pattern = Pattern.compile("Patient|Binary");
Matcher matcher = pattern.matcher(originalRequest.getPath().toString());

if (!matcher.find()) {
throw new SdsFilterException("Unable to detect a supported FHIR path in the original request");
}

var startIndex = Math.max(0, matcher.start() - 1);
return originalRequest.getPath().toString().substring(startIndex);
}
}
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