Set revision to policy when it can be derived from the entity tag contained in the response headers

Signed-off-by: Yannic Klem <Yannic.Klem@bosch.io>

Author: Yannic92

java/src/main/java/org/eclipse/ditto/client/policies/internal/PoliciesImpl.java

@@ -20,6 +20,10 @@
 
 import javax.annotation.Nonnull;
 
+import org.eclipse.ditto.base.model.acks.AcknowledgementLabel;
+import org.eclipse.ditto.base.model.acks.DittoAcknowledgementLabel;
+import org.eclipse.ditto.base.model.headers.DittoHeaders;
+import org.eclipse.ditto.base.model.headers.entitytag.EntityTag;
 import org.eclipse.ditto.client.internal.AbstractHandle;
 import org.eclipse.ditto.client.internal.OutgoingMessageFactory;
 import org.eclipse.ditto.client.internal.bus.PointerBus;
@@ -28,12 +32,10 @@
 import org.eclipse.ditto.client.policies.Policies;
 import org.eclipse.ditto.json.JsonObject;
 import org.eclipse.ditto.json.JsonValue;
-import org.eclipse.ditto.base.model.acks.AcknowledgementLabel;
-import org.eclipse.ditto.base.model.acks.DittoAcknowledgementLabel;
 import org.eclipse.ditto.policies.model.PoliciesModelFactory;
 import org.eclipse.ditto.policies.model.Policy;
 import org.eclipse.ditto.policies.model.PolicyId;
-import org.eclipse.ditto.protocol.TopicPath;
+import org.eclipse.ditto.policies.model.PolicyRevision;
 import org.eclipse.ditto.policies.model.signals.commands.modify.CreatePolicy;
 import org.eclipse.ditto.policies.model.signals.commands.modify.CreatePolicyResponse;
 import org.eclipse.ditto.policies.model.signals.commands.modify.DeletePolicy;
@@ -42,6 +44,7 @@
 import org.eclipse.ditto.policies.model.signals.commands.modify.PolicyModifyCommandResponse;
 import org.eclipse.ditto.policies.model.signals.commands.query.RetrievePolicy;
 import org.eclipse.ditto.policies.model.signals.commands.query.RetrievePolicyResponse;
+import org.eclipse.ditto.protocol.TopicPath;
 
 /**
  * Default implementation for {@link Policies}.
@@ -75,14 +78,44 @@ public static PoliciesImpl newInstance(final MessagingProvider messagingProvider
         return new PoliciesImpl(messagingProvider, outgoingMessageFactory, bus);
     }
 
+    private static Optional<PolicyRevision> getRevisionFromDittoHeaders(final DittoHeaders dittoHeaders) {
+        return dittoHeaders
+                .getETag()
+                .map(EntityTag::getOpaqueTag)
+                .filter(tag -> tag.contains("rev:"))
+                .map(tag -> tag.replace("rev:", "").replaceAll("\"", ""))
+                .map(Long::parseLong)
+                .map(PolicyRevision::newInstance);
+    }
+
+    private static Policy setRevisionToPolicy(final PolicyRevision policyRevision, final Policy policy) {
+        return policy.toBuilder()
+                .setRevision(policyRevision)
+                .build();
+    }
+
+    private static Policy appendRevisionFromHeadersIfNeeded(final Policy policy, final DittoHeaders dittoHeaders) {
+        final Policy policyWithRevision;
+        final Optional<PolicyRevision> revisionFromPolicy = policy.getRevision();
+        policyWithRevision = revisionFromPolicy
+                .map(policyRevision -> setRevisionToPolicy(policyRevision, policy))
+                .orElseGet(() -> getRevisionFromDittoHeaders(dittoHeaders)
+                        .map(revisionFromHeaders -> setRevisionToPolicy(revisionFromHeaders, policy))
+                        .orElse(policy));
+        return policyWithRevision;
+    }
+
     @Override
     public CompletionStage<Policy> create(final Policy policy, final Option<?>... options) {
         argumentNotNull(policy);
         assertThatPolicyHasId(policy);
 
         final CreatePolicy command = outgoingMessageFactory.createPolicy(policy, options);
         return askPolicyCommand(command, CreatePolicyResponse.class,
-                response -> response.getPolicyCreated().orElse(null));
+                response -> response.getPolicyCreated()
+                        .map(policyFromResponse -> appendRevisionFromHeadersIfNeeded(policyFromResponse,
+                                response.getDittoHeaders()))
+                        .orElse(null));
     }
 
     @Override
@@ -104,6 +137,8 @@ public CompletionStage<Optional<Policy>> put(final Policy policy, final Option<?
                 response -> response.getEntity(response.getImplementedSchemaVersion())
                         .map(JsonValue::asObject)
                         .map(PoliciesModelFactory::newPolicy)
+                        .map(policyFromResponse -> appendRevisionFromHeadersIfNeeded(policyFromResponse,
+                                response.getDittoHeaders()))
         );
     }
 
@@ -143,7 +178,10 @@ public CompletionStage<Void> delete(final PolicyId policyId, final Option<?>...
     @Override
     public CompletionStage<Policy> retrieve(PolicyId policyId) {
         final RetrievePolicy command = outgoingMessageFactory.retrievePolicy(policyId);
-        return askPolicyCommand(command, RetrievePolicyResponse.class, RetrievePolicyResponse::getPolicy);
+        return askPolicyCommand(command, RetrievePolicyResponse.class, response -> {
+            final Policy policyFromResponse = response.getPolicy();
+            return appendRevisionFromHeadersIfNeeded(policyFromResponse, response.getDittoHeaders());
+        });
     }
 
     private static void assertThatPolicyHasId(final Policy policy) {