Provide ported draft comments via a separate REST endpoint

All other REST endpoints for comments have a clear separation between
published comments and draft comments. We follow the same approach for
ported comments and hence introduce a dedicated REST endpoint for
ported draft comments.

The existing tests for ported comments also cover most code paths for
ported draft comments as a large amount of the code is shared. We only
add additional tests for varying aspects or those which are outside of
the shared code.

Change-Id: If8802a4f94540284cc1303b278f7f38d120593eb

java/com/google/gerrit/extensions/api/changes/RevisionApi.java

@@ -108,6 +108,8 @@ public interface RevisionApi {
 
   Map<String, List<CommentInfo>> portedComments() throws RestApiException;
 
+  Map<String, List<CommentInfo>> portedDrafts() throws RestApiException;
+
   /**
    * Applies the indicated fix by creating a new change edit or integrating the fix with the
    * existing change edit. If no change edit exists before this call, the fix must refer to the
@@ -300,6 +302,11 @@ public interface RevisionApi {
       throw new NotImplementedException();
     }
 
+    @Override
+    public Map<String, List<CommentInfo>> portedDrafts() throws RestApiException {
+      throw new NotImplementedException();
+    }
+
     @Override
     public EditInfo applyFix(String fixId) throws RestApiException {
       throw new NotImplementedException();

java/com/google/gerrit/server/api/changes/RevisionApiImpl.java

@@ -80,6 +80,7 @@ import com.google.gerrit.server.restapi.change.GetPatch;
 import com.google.gerrit.server.restapi.change.GetRelated;
 import com.google.gerrit.server.restapi.change.GetRevisionActions;
 import com.google.gerrit.server.restapi.change.ListPortedComments;
+import com.google.gerrit.server.restapi.change.ListPortedDrafts;
 import com.google.gerrit.server.restapi.change.ListRevisionComments;
 import com.google.gerrit.server.restapi.change.ListRevisionDrafts;
 import com.google.gerrit.server.restapi.change.ListRobotComments;
@@ -132,6 +133,7 @@ class RevisionApiImpl implements RevisionApi {
   private final ListRevisionComments listComments;
   private final ListRobotComments listRobotComments;
   private final ListPortedComments listPortedComments;
+  private final ListPortedDrafts listPortedDrafts;
   private final ApplyFix applyFix;
   private final GetFixPreview getFixPreview;
   private final Fixes fixes;
@@ -178,6 +180,7 @@ class RevisionApiImpl implements RevisionApi {
       ListRevisionComments listComments,
       ListRobotComments listRobotComments,
       ListPortedComments listPortedComments,
+      ListPortedDrafts listPortedDrafts,
       ApplyFix applyFix,
       GetFixPreview getFixPreview,
       Fixes fixes,
@@ -223,6 +226,7 @@ class RevisionApiImpl implements RevisionApi {
     this.robotComments = robotComments;
     this.listRobotComments = listRobotComments;
     this.listPortedComments = listPortedComments;
+    this.listPortedDrafts = listPortedDrafts;
     this.applyFix = applyFix;
     this.getFixPreview = getFixPreview;
     this.fixes = fixes;
@@ -466,6 +470,15 @@ class RevisionApiImpl implements RevisionApi {
     }
   }
 
+  @Override
+  public Map<String, List<CommentInfo>> portedDrafts() throws RestApiException {
+    try {
+      return listPortedDrafts.apply(revision).value();
+    } catch (Exception e) {
+      throw asRestApiException("Cannot retrieve ported draft comments", e);
+    }
+  }
+
   @Override
   public EditInfo applyFix(String fixId) throws RestApiException {
     try {

java/com/google/gerrit/server/restapi/change/ListPortedDrafts.java

@@ -0,0 +1,72 @@
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.restapi.change;
+
+import com.google.common.collect.ImmutableList;
+import com.google.gerrit.entities.HumanComment;
+import com.google.gerrit.entities.PatchSet;
+import com.google.gerrit.extensions.common.CommentInfo;
+import com.google.gerrit.extensions.restapi.Response;
+import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.server.CommentsUtil;
+import com.google.gerrit.server.change.RevisionResource;
+import com.google.gerrit.server.patch.PatchListNotAvailableException;
+import com.google.gerrit.server.permissions.PermissionBackendException;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.Singleton;
+import java.util.List;
+import java.util.Map;
+
+@Singleton
+public class ListPortedDrafts implements RestReadView<RevisionResource> {
+
+  private final CommentsUtil commentsUtil;
+  private final CommentPorter commentPorter;
+  private final Provider<CommentJson> commentJson;
+
+  @Inject
+  public ListPortedDrafts(
+      Provider<CommentJson> commentJson, CommentsUtil commentsUtil, CommentPorter commentPorter) {
+    this.commentJson = commentJson;
+    this.commentsUtil = commentsUtil;
+    this.commentPorter = commentPorter;
+  }
+
+  @Override
+  public Response<Map<String, List<CommentInfo>>> apply(RevisionResource revisionResource)
+      throws PermissionBackendException, PatchListNotAvailableException {
+    PatchSet targetPatchset = revisionResource.getPatchSet();
+
+    List<HumanComment> draftComments =
+        commentsUtil.draftByChangeAuthor(
+            revisionResource.getNotes(), revisionResource.getAccountId());
+    ImmutableList<HumanComment> portedDraftComments =
+        commentPorter.portComments(revisionResource.getNotes(), targetPatchset, draftComments);
+    return Response.ok(format(portedDraftComments));
+  }
+
+  private Map<String, List<CommentInfo>> format(List<HumanComment> comments)
+      throws PermissionBackendException {
+    return commentJson
+        .get()
+        // Always unset for draft comments as only draft comments of the requesting user are
+        // returned.
+        .setFillAccounts(false)
+        .setFillPatchSet(true)
+        .newHumanCommentFormatter()
+        .format(comments);
+  }
+}

java/com/google/gerrit/server/restapi/change/Module.java

@@ -173,6 +173,7 @@ public class Module extends RestApiModule {
     get(FIX_KIND, "preview").to(GetFixPreview.class);
 
     get(REVISION_KIND, "ported_comments").to(ListPortedComments.class);
+    get(REVISION_KIND, "ported_drafts").to(ListPortedDrafts.class);
 
     child(REVISION_KIND, "files").to(Files.class);
     put(FILE_KIND, "reviewed").to(PutReviewed.class);