Implement List Mode Content Fetch ⚡️ (#40)

* Implement List Mode Content Fetch ⚡️
- Support returning all List resource References in result
- Add Unit Tests

plugins/src/main/java/com/google/fhir/gateway/plugin/AccessGrantedAndUpdateList.java

@@ -76,7 +76,8 @@ public boolean canAccess() {
   }
 
   @Override
-  public String postProcess(HttpResponse response) throws IOException {
+  public String postProcess(RequestDetailsReader request, HttpResponse response)
+      throws IOException {
     Preconditions.checkState(HttpUtil.isResponseValid(response));
     String content = CharStreams.toString(HttpUtil.readerFromEntity(response.getEntity()));
     IParser parser = fhirContext.newJsonParser();

plugins/src/main/java/com/google/fhir/gateway/plugin/OpenSRPSyncAccessDecision.java

@@ -15,7 +15,12 @@
  */
 package com.google.fhir.gateway.plugin;
 
+import static com.google.fhir.gateway.plugin.PermissionAccessChecker.Factory.PROXY_TO_ENV;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.parser.IParser;
 import ca.uhn.fhir.rest.api.RequestTypeEnum;
+import ca.uhn.fhir.rest.client.api.IGenericClient;
 import ca.uhn.fhir.rest.server.servlet.ServletRequestDetails;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.fhir.gateway.ProxyConstants;
@@ -36,7 +41,11 @@
 import org.apache.commons.lang3.tuple.ImmutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.http.HttpResponse;
+import org.apache.http.impl.client.BasicResponseHandler;
 import org.apache.http.util.TextUtils;
+import org.hl7.fhir.instance.model.api.IBaseResource;
+import org.hl7.fhir.r4.model.Bundle;
+import org.hl7.fhir.r4.model.ListResource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -56,6 +65,10 @@ public class OpenSRPSyncAccessDecision implements AccessDecision {
 
   private final List<String> organizationIds;
   private IgnoredResourcesConfig config;
+  private Gson gson = new Gson();
+
+  private FhirContext fhirR4Context = FhirContext.forR4();
+  private IParser fhirR4JsonParser = fhirR4Context.newJsonParser();
 
   public OpenSRPSyncAccessDecision(
       String applicationId,
@@ -133,8 +146,58 @@ private void addSyncFilters(
   }
 
   @Override
-  public String postProcess(HttpResponse response) throws IOException {
-    return null;
+  public String postProcess(RequestDetailsReader request, HttpResponse response)
+      throws IOException {
+
+    String resultContent = null;
+    String listMode = request.getHeader(Constants.FHIR_GATEWAY_MODE);
+
+    switch (listMode) {
+      case Constants.LIST_ENTRIES:
+        resultContent = postProcessModeListEntries(response);
+      default:
+        break;
+    }
+    return resultContent;
+  }
+
+  /**
+   * Generates a Bundle result from making a batch search request with the contained entries in the
+   * List as parameters
+   *
+   * @param response HTTPResponse
+   * @return String content of the result Bundle
+   */
+  private String postProcessModeListEntries(HttpResponse response) throws IOException {
+
+    String resultContent = null;
+    IBaseResource responseResource =
+        fhirR4JsonParser.parseResource((new BasicResponseHandler().handleResponse(response)));
+
+    if (responseResource instanceof ListResource && ((ListResource) responseResource).hasEntry()) {
+
+      Bundle requestBundle = new Bundle();
+      requestBundle.setType(Bundle.BundleType.BATCH);
+      Bundle.BundleEntryComponent bundleEntryComponent;
+
+      for (ListResource.ListEntryComponent listEntryComponent :
+          ((ListResource) responseResource).getEntry()) {
+
+        bundleEntryComponent = new Bundle.BundleEntryComponent();
+        bundleEntryComponent.setRequest(
+            new Bundle.BundleEntryRequestComponent()
+                .setMethod(Bundle.HTTPVerb.GET)
+                .setUrl(listEntryComponent.getItem().getReference()));
+
+        requestBundle.addEntry(bundleEntryComponent);
+      }
+
+      Bundle responseBundle =
+          createFhirClientForR4().transaction().withBundle(requestBundle).execute();
+
+      resultContent = fhirR4JsonParser.encodeResourceToString(responseBundle);
+    }
+    return resultContent;
   }
 
   /**
@@ -214,7 +277,6 @@ private boolean isResourceTypeRequest(String requestPath) {
   protected IgnoredResourcesConfig getIgnoredResourcesConfigFileConfiguration(String configFile) {
     if (configFile != null && !configFile.isEmpty()) {
       try {
-        Gson gson = new Gson();
         config = gson.fromJson(new FileReader(configFile), IgnoredResourcesConfig.class);
         if (config == null || config.entries == null) {
           throw new IllegalArgumentException("A map with a single `entries` array expected!");
@@ -286,6 +348,10 @@ private boolean shouldSkipDataFiltering(ServletRequestDetails servletRequestDeta
     return false;
   }
 
+  private IGenericClient createFhirClientForR4() {
+    return fhirR4Context.newRestfulGenericClient(System.getenv(PROXY_TO_ENV));
+  }
+
   @VisibleForTesting
   protected void setSkippedResourcesConfig(IgnoredResourcesConfig config) {
     this.config = config;
@@ -308,4 +374,19 @@ public String toString() {
           + '}';
     }
   }
+
+  @VisibleForTesting
+  protected void setFhirR4Context(FhirContext fhirR4Context) {
+    this.fhirR4Context = fhirR4Context;
+  }
+
+  @VisibleForTesting
+  protected void setFhirR4JsonParser(IParser fhirR4JsonParser) {
+    this.fhirR4JsonParser = fhirR4JsonParser;
+  }
+
+  public static final class Constants {
+    public static final String FHIR_GATEWAY_MODE = "fhir-gateway-mode";
+    public static final String LIST_ENTRIES = "list-entries";
+  }
 }

plugins/src/test/java/com/google/fhir/gateway/plugin/AccessGrantedAndUpdateListTest.java

@@ -18,6 +18,7 @@
 import ca.uhn.fhir.context.FhirContext;
 import com.google.common.io.Resources;
 import com.google.fhir.gateway.HttpFhirClient;
+import com.google.fhir.gateway.interfaces.RequestDetailsReader;
 import java.io.IOException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
@@ -39,6 +40,9 @@ public class AccessGrantedAndUpdateListTest {
   @Mock(answer = Answers.RETURNS_DEEP_STUBS)
   private HttpResponse responseMock;
 
+  @Mock(answer = Answers.RETURNS_DEEP_STUBS)
+  private RequestDetailsReader requestDetailsMock;
+
   private static final FhirContext fhirContext = FhirContext.forR4();
 
   private AccessGrantedAndUpdateList testInstance;
@@ -55,14 +59,14 @@ public void postProcessNewPatientPut() throws IOException {
     testInstance =
         AccessGrantedAndUpdateList.forPatientResource(
             TEST_LIST_ID, httpFhirClientMock, fhirContext);
-    testInstance.postProcess(responseMock);
+    testInstance.postProcess(requestDetailsMock, responseMock);
   }
 
   @Test
   public void postProcessNewPatientPost() throws IOException {
     testInstance =
         AccessGrantedAndUpdateList.forPatientResource(
             TEST_LIST_ID, httpFhirClientMock, fhirContext);
-    testInstance.postProcess(responseMock);
+    testInstance.postProcess(requestDetailsMock, responseMock);
   }
 }

plugins/src/test/java/com/google/fhir/gateway/plugin/OpenSRPSyncAccessDecisionTest.java

@@ -15,22 +15,39 @@
  */
 package com.google.fhir.gateway.plugin;
 
+import static com.google.fhir.gateway.plugin.PermissionAccessChecker.Factory.PROXY_TO_ENV;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+
+import ca.uhn.fhir.context.FhirContext;
 import ca.uhn.fhir.rest.api.RequestTypeEnum;
 import ca.uhn.fhir.rest.api.RestOperationTypeEnum;
+import ca.uhn.fhir.rest.client.api.IGenericClient;
+import ca.uhn.fhir.rest.gclient.ITransaction;
+import ca.uhn.fhir.rest.gclient.ITransactionTyped;
 import ca.uhn.fhir.rest.server.servlet.ServletRequestDetails;
 import com.google.common.collect.Maps;
 import com.google.common.io.Resources;
+import com.google.fhir.gateway.HttpFhirClient;
 import com.google.fhir.gateway.ProxyConstants;
+import com.google.fhir.gateway.interfaces.RequestDetailsReader;
 import java.io.IOException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import org.apache.commons.lang3.StringUtils;
+import org.apache.http.HttpResponse;
+import org.hl7.fhir.r4.model.Bundle;
 import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Answers;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.junit.MockitoJUnitRunner;
 
 @RunWith(MockitoJUnitRunner.class)
@@ -44,6 +61,8 @@ public class OpenSRPSyncAccessDecisionTest {
 
   private OpenSRPSyncAccessDecision testInstance;
 
+  @Mock private HttpFhirClient httpFhirClientMock;
+
   @Test
   public void preprocessShouldAddAllFiltersWhenIdsForLocationsOrganisationsAndCareTeamsAreProvided()
       throws IOException {
@@ -300,6 +319,84 @@ public void preProcessShouldSkipAddingFiltersWhenResourceInSyncFilterIgnoredReso
     }
   }
 
+  @Test
+  public void testPostProcessWithListModeHeaderShouldFetchListEntriesBundle() throws IOException {
+    locationIds.add("Location-1");
+    testInstance = Mockito.spy(createOpenSRPSyncAccessDecisionTestInstance());
+
+    FhirContext fhirR4Context = mock(FhirContext.class);
+    IGenericClient iGenericClient = mock(IGenericClient.class);
+    ITransaction iTransaction = mock(ITransaction.class);
+    ITransactionTyped<Bundle> iClientExecutable = mock(ITransactionTyped.class);
+
+    Mockito.when(fhirR4Context.newRestfulGenericClient(System.getenv(PROXY_TO_ENV)))
+        .thenReturn(iGenericClient);
+    Mockito.when(iGenericClient.transaction()).thenReturn(iTransaction);
+    Mockito.when(iTransaction.withBundle(any(Bundle.class))).thenReturn(iClientExecutable);
+
+    Bundle resultBundle = new Bundle();
+    resultBundle.setType(Bundle.BundleType.BATCHRESPONSE);
+    resultBundle.setId("bundle-result-id");
+
+    Mockito.when(iClientExecutable.execute()).thenReturn(resultBundle);
+
+    ArgumentCaptor<Bundle> bundleArgumentCaptor = ArgumentCaptor.forClass(Bundle.class);
+
+    testInstance.setFhirR4Context(fhirR4Context);
+
+    RequestDetailsReader requestDetailsSpy = Mockito.mock(RequestDetailsReader.class);
+
+    Mockito.when(requestDetailsSpy.getHeader(OpenSRPSyncAccessDecision.Constants.FHIR_GATEWAY_MODE))
+        .thenReturn(OpenSRPSyncAccessDecision.Constants.LIST_ENTRIES);
+
+    URL listUrl = Resources.getResource("test_list_resource.json");
+    String testListJson = Resources.toString(listUrl, StandardCharsets.UTF_8);
+
+    HttpResponse fhirResponseMock = Mockito.mock(HttpResponse.class, Answers.RETURNS_DEEP_STUBS);
+
+    TestUtil.setUpFhirResponseMock(fhirResponseMock, testListJson);
+
+    String resultContent = testInstance.postProcess(requestDetailsSpy, fhirResponseMock);
+
+    Mockito.verify(iTransaction).withBundle(bundleArgumentCaptor.capture());
+    Bundle requestBundle = bundleArgumentCaptor.getValue();
+
+    // Verify modified request to the server
+    Assert.assertNotNull(requestBundle);
+    Assert.assertEquals(Bundle.BundleType.BATCH, requestBundle.getType());
+    List<Bundle.BundleEntryComponent> requestBundleEntries = requestBundle.getEntry();
+    Assert.assertEquals(2, requestBundleEntries.size());
+
+    Assert.assertEquals(Bundle.HTTPVerb.GET, requestBundleEntries.get(0).getRequest().getMethod());
+    Assert.assertEquals(
+        "Group/proxy-list-entry-id-1", requestBundleEntries.get(0).getRequest().getUrl());
+
+    Assert.assertEquals(Bundle.HTTPVerb.GET, requestBundleEntries.get(1).getRequest().getMethod());
+    Assert.assertEquals(
+        "Group/proxy-list-entry-id-2", requestBundleEntries.get(1).getRequest().getUrl());
+
+    // Verify returned result content from the server request
+    Assert.assertNotNull(resultContent);
+    Assert.assertEquals(
+        "{\"resourceType\":\"Bundle\",\"id\":\"bundle-result-id\",\"type\":\"batch-response\"}",
+        resultContent);
+  }
+
+  @Test
+  public void testPostProcessWithoutListModeHeaderShouldShouldReturnNull() throws IOException {
+    testInstance = createOpenSRPSyncAccessDecisionTestInstance();
+
+    RequestDetailsReader requestDetailsSpy = Mockito.mock(RequestDetailsReader.class);
+    Mockito.when(requestDetailsSpy.getHeader(OpenSRPSyncAccessDecision.Constants.FHIR_GATEWAY_MODE))
+        .thenReturn("");
+
+    String resultContent =
+        testInstance.postProcess(requestDetailsSpy, Mockito.mock(HttpResponse.class));
+
+    // Verify no special Post-Processing happened
+    Assert.assertNull(resultContent);
+  }
+
   private OpenSRPSyncAccessDecision createOpenSRPSyncAccessDecisionTestInstance() {
     OpenSRPSyncAccessDecision accessDecision =
         new OpenSRPSyncAccessDecision(

plugins/src/test/resources/test_list_resource.json

@@ -0,0 +1,35 @@
+{
+  "resourceType": "List",
+  "id": "proxy-test-list-id",
+  "identifier": [
+    {
+      "use": "official",
+      "value": "proxy-test-list-id"
+    }
+  ],
+  "status": "current",
+  "mode": "working",
+  "title": "Proxy Test List",
+  "code": {
+    "coding": [
+      {
+        "system": "http://ona.io",
+        "code": "supply-chain",
+        "display": "Proxy Test List"
+      }
+    ],
+    "text": "My Proxy Test List"
+  },
+  "entry": [
+    {
+      "item": {
+        "reference": "Group/proxy-list-entry-id-1"
+      }
+    },
+    {
+      "item": {
+        "reference": "Group/proxy-list-entry-id-2"
+      }
+    }
+  ]
+}

server/src/main/java/com/google/fhir/gateway/BearerAuthorizationInterceptor.java

@@ -290,7 +290,7 @@ public boolean authorizeRequest(RequestDetails requestDetails) {
       if (HttpUtil.isResponseValid(response)) {
         try {
           // For post-processing rationale/example see b/207589782#comment3.
-          content = outcome.postProcess(response);
+          content = outcome.postProcess(new RequestDetailsToReader(requestDetails), response);
         } catch (Exception e) {
           // Note this is after a successful fetch/update of the FHIR store. That success must be
           // passed to the client even if the access related post-processing fails.

server/src/main/java/com/google/fhir/gateway/CapabilityPostProcessor.java

@@ -66,7 +66,8 @@ public boolean canAccess() {
   }
 
   @Override
-  public String postProcess(HttpResponse response) throws IOException {
+  public String postProcess(RequestDetailsReader requestDetails, HttpResponse response)
+      throws IOException {
     Preconditions.checkState(HttpUtil.isResponseValid(response));
     String content = CharStreams.toString(HttpUtil.readerFromEntity(response.getEntity()));
     IParser parser = fhirContext.newJsonParser();

server/src/main/java/com/google/fhir/gateway/interfaces/AccessDecision.java

@@ -56,5 +56,6 @@ public interface AccessDecision {
    *     reads the response; otherwise null. Note that we should try to avoid reading the whole
    *     content in memory whenever it is not needed for post-processing.
    */
-  String postProcess(HttpResponse response) throws IOException;
+  String postProcess(RequestDetailsReader requestDetailsReader, HttpResponse response)
+      throws IOException;
 }

server/src/main/java/com/google/fhir/gateway/interfaces/NoOpAccessDecision.java

@@ -37,7 +37,7 @@ public boolean canAccess() {
   }
 
   @Override
-  public String postProcess(HttpResponse response) {
+  public String postProcess(RequestDetailsReader requestDetailsReader, HttpResponse response) {
     return null;
   }
 

server/src/test/java/com/google/fhir/gateway/BearerAuthorizationInterceptorTest.java

@@ -381,7 +381,9 @@ public RequestMutation getRequestMutation(RequestDetailsReader requestDetailsRea
             return RequestMutation.builder().queryParams(paramMutations).build();
           }
 
-          public String postProcess(HttpResponse response) throws IOException {
+          @Override
+          public String postProcess(
+              RequestDetailsReader requestDetailsReader, HttpResponse response) throws IOException {
             return null;
           }
         };