Hoist validation from SetAssigneeOp into PutAssignee

Performing validation of the new asignee inside the operation isn't
necessary; it can be validated in the REST API handler as its parsing
the input object and preparing the operation object.  This
signficantly cleans up the operation object, making it easier to
follow the logic.

This change also makes it easier to later refactor the check "can new
assignee see the target branch", before the operation is even started.

Change-Id: I3c8f3459300a670e8c76edff1262399de704933b

gerrit-server/src/main/java/com/google/gerrit/server/api/changes/ChangeApiImpl.java

@@ -492,7 +492,7 @@ class ChangeApiImpl implements ChangeApi {
   @Override
   public AccountInfo setAssignee(AssigneeInput input) throws RestApiException {
     try {
-      return putAssignee.apply(change, input).value();
+      return putAssignee.apply(change, input);
     } catch (UpdateException | IOException | OrmException e) {
       throw new RestApiException("Cannot set assignee", e);
     }

gerrit-server/src/main/java/com/google/gerrit/server/change/PutAssignee.java

@@ -22,12 +22,14 @@ import com.google.gerrit.extensions.client.ReviewerState;
 import com.google.gerrit.extensions.common.AccountInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.BadRequestException;
-import com.google.gerrit.extensions.restapi.Response;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.extensions.restapi.RestModifyView;
+import com.google.gerrit.extensions.restapi.UnprocessableEntityException;
 import com.google.gerrit.extensions.webui.UiAction;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountLoader;
+import com.google.gerrit.server.account.AccountsCollection;
 import com.google.gerrit.server.change.PostReviewers.Addition;
 import com.google.gerrit.server.update.BatchUpdate;
 import com.google.gerrit.server.update.UpdateException;
@@ -41,6 +43,7 @@ import java.io.IOException;
 public class PutAssignee
     implements RestModifyView<ChangeResource, AssigneeInput>, UiAction<ChangeResource> {
 
+  private final AccountsCollection accounts;
   private final SetAssigneeOp.Factory assigneeFactory;
   private final BatchUpdate.Factory batchUpdateFactory;
   private final Provider<ReviewDb> db;
@@ -49,11 +52,13 @@ public class PutAssignee
 
   @Inject
   PutAssignee(
+      AccountsCollection accounts,
       SetAssigneeOp.Factory assigneeFactory,
       BatchUpdate.Factory batchUpdateFactory,
       Provider<ReviewDb> db,
       PostReviewers postReviewers,
       AccountLoader.Factory accountLoaderFactory) {
+    this.accounts = accounts;
     this.assigneeFactory = assigneeFactory;
     this.batchUpdateFactory = batchUpdateFactory;
     this.db = db;
@@ -62,7 +67,7 @@ public class PutAssignee
   }
 
   @Override
-  public Response<AccountInfo> apply(ChangeResource rsrc, AssigneeInput input)
+  public AccountInfo apply(ChangeResource rsrc, AssigneeInput input)
       throws RestApiException, UpdateException, OrmException, IOException {
     if (!rsrc.getControl().canEditAssignee()) {
       throw new AuthException("Changing Assignee not permitted");
@@ -71,20 +76,30 @@ public class PutAssignee
       throw new BadRequestException("missing assignee field");
     }
 
+    IdentifiedUser assignee = accounts.parse(input.assignee.trim());
+    if (!assignee.getAccount().isActive()) {
+      throw new UnprocessableEntityException(
+          String.format("Account of %s is not active", input.assignee));
+    }
+    if (!rsrc.getControl().forUser(assignee).isRefVisible()) {
+      throw new AuthException(
+          String.format("Change %s is not visible to %s.", rsrc.getId(), input.assignee));
+    }
+
     try (BatchUpdate bu =
         batchUpdateFactory.create(
             db.get(),
             rsrc.getChange().getProject(),
             rsrc.getControl().getUser(),
             TimeUtil.nowTs())) {
-      SetAssigneeOp op = assigneeFactory.create(input.assignee);
+      SetAssigneeOp op = assigneeFactory.create(assignee);
       bu.addOp(rsrc.getId(), op);
 
       PostReviewers.Addition reviewersAddition = addAssigneeAsCC(rsrc, input.assignee);
       bu.addOp(rsrc.getId(), reviewersAddition.op);
 
       bu.execute();
-      return Response.ok(accountLoaderFactory.create(true).fillOne(op.getNewAssignee()));
+      return accountLoaderFactory.create(true).fillOne(assignee.getAccountId());
     }
   }
 

gerrit-server/src/main/java/com/google/gerrit/server/change/SetAssigneeOp.java

@@ -17,16 +17,12 @@ package com.google.gerrit.server.change;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.gerrit.extensions.registration.DynamicSet;
-import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.extensions.restapi.RestApiException;
-import com.google.gerrit.extensions.restapi.UnprocessableEntityException;
-import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.ChangeMessage;
 import com.google.gerrit.server.ChangeMessagesUtil;
 import com.google.gerrit.server.IdentifiedUser;
-import com.google.gerrit.server.account.AccountsCollection;
 import com.google.gerrit.server.extensions.events.AssigneeChanged;
 import com.google.gerrit.server.mail.send.SetAssigneeSender;
 import com.google.gerrit.server.notedb.ChangeUpdate;
@@ -46,93 +42,74 @@ public class SetAssigneeOp implements BatchUpdateOp {
   private static final Logger log = LoggerFactory.getLogger(SetAssigneeOp.class);
 
   public interface Factory {
-    SetAssigneeOp create(String assignee);
+    SetAssigneeOp create(IdentifiedUser assignee);
   }
 
-  private final AccountsCollection accounts;
   private final ChangeMessagesUtil cmUtil;
   private final DynamicSet<AssigneeValidationListener> validationListeners;
-  private final String assignee;
+  private final IdentifiedUser newAssignee;
   private final AssigneeChanged assigneeChanged;
   private final SetAssigneeSender.Factory setAssigneeSenderFactory;
   private final Provider<IdentifiedUser> user;
   private final IdentifiedUser.GenericFactory userFactory;
 
   private Change change;
-  private Account newAssignee;
+  private IdentifiedUser oldAssignee;
-  private Account oldAssignee;
 
   @Inject
   SetAssigneeOp(
-      AccountsCollection accounts,
       ChangeMessagesUtil cmUtil,
       DynamicSet<AssigneeValidationListener> validationListeners,
       AssigneeChanged assigneeChanged,
       SetAssigneeSender.Factory setAssigneeSenderFactory,
       Provider<IdentifiedUser> user,
       IdentifiedUser.GenericFactory userFactory,
-      @Assisted String assignee) {
+      @Assisted IdentifiedUser newAssignee) {
-    this.accounts = accounts;
     this.cmUtil = cmUtil;
     this.validationListeners = validationListeners;
     this.assigneeChanged = assigneeChanged;
     this.setAssigneeSenderFactory = setAssigneeSenderFactory;
     this.user = user;
     this.userFactory = userFactory;
-    this.assignee = checkNotNull(assignee);
+    this.newAssignee = checkNotNull(newAssignee, "assignee");
   }
 
   @Override
   public boolean updateChange(ChangeContext ctx) throws OrmException, RestApiException {
     change = ctx.getChange();
-    ChangeUpdate update = ctx.getUpdate(change.currentPatchSetId());
+    if (newAssignee.getAccountId().equals(change.getAssignee())) {
-    IdentifiedUser newAssigneeUser = accounts.parse(assignee);
-    newAssignee = newAssigneeUser.getAccount();
-    IdentifiedUser oldAssigneeUser = null;
-    if (change.getAssignee() != null) {
-      oldAssigneeUser = userFactory.create(change.getAssignee());
-      oldAssignee = oldAssigneeUser.getAccount();
-      if (newAssignee.equals(oldAssignee)) {
       return false;
     }
-    }
-    if (!newAssignee.isActive()) {
-      throw new UnprocessableEntityException(
-          String.format("Account of %s is not active", assignee));
-    }
-    if (!ctx.getControl().forUser(newAssigneeUser).isRefVisible()) {
-      throw new AuthException(
-          String.format("Change %s is not visible to %s.", change.getChangeId(), assignee));
-    }
     try {
       for (AssigneeValidationListener validator : validationListeners) {
-        validator.validateAssignee(change, newAssignee);
+        validator.validateAssignee(change, newAssignee.getAccount());
       }
     } catch (ValidationException e) {
       throw new ResourceConflictException(e.getMessage());
     }
+
+    if (change.getAssignee() != null) {
+      oldAssignee = userFactory.create(change.getAssignee());
+    }
+
+    ChangeUpdate update = ctx.getUpdate(change.currentPatchSetId());
     // notedb
-    update.setAssignee(newAssignee.getId());
+    update.setAssignee(newAssignee.getAccountId());
     // reviewdb
-    change.setAssignee(newAssignee.getId());
+    change.setAssignee(newAssignee.getAccountId());
-    addMessage(ctx, update, oldAssigneeUser, newAssigneeUser);
+    addMessage(ctx, update);
     return true;
   }
 
-  private void addMessage(
+  private void addMessage(ChangeContext ctx, ChangeUpdate update) throws OrmException {
-      ChangeContext ctx,
-      ChangeUpdate update,
-      IdentifiedUser previousAssignee,
-      IdentifiedUser newAssignee)
-      throws OrmException {
     StringBuilder msg = new StringBuilder();
     msg.append("Assignee ");
-    if (previousAssignee == null) {
+    if (oldAssignee == null) {
       msg.append("added: ");
       msg.append(newAssignee.getNameEmail());
     } else {
       msg.append("changed from: ");
-      msg.append(previousAssignee.getNameEmail());
+      msg.append(oldAssignee.getNameEmail());
       msg.append(" to: ");
       msg.append(newAssignee.getNameEmail());
     }
@@ -145,16 +122,17 @@ public class SetAssigneeOp implements BatchUpdateOp {
   public void postUpdate(Context ctx) throws OrmException {
     try {
       SetAssigneeSender cm =
-          setAssigneeSenderFactory.create(change.getProject(), change.getId(), newAssignee.getId());
+          setAssigneeSenderFactory.create(
+              change.getProject(), change.getId(), newAssignee.getAccountId());
       cm.setFrom(user.get().getAccountId());
       cm.send();
     } catch (Exception err) {
       log.error("Cannot send email to new assignee of change " + change.getId(), err);
     }
-    assigneeChanged.fire(change, ctx.getAccount(), oldAssignee, ctx.getWhen());
+    assigneeChanged.fire(
-  }
+        change,
-
+        ctx.getAccount(),
-  public Account.Id getNewAssignee() {
+        oldAssignee != null ? oldAssignee.getAccount() : null,
-    return newAssignee != null ? newAssignee.getId() : null;
+        ctx.getWhen());
   }
 }