From cf6ccc7a462d0f7eb7c5ef15c36300f8bb63c9df Mon Sep 17 00:00:00 2001
From: Brian Chen <chenbrian@google.com>
Date: Wed, 10 Jun 2020 17:17:30 -0700
Subject: [PATCH] fix: update delete to return sentinel

---
 .../google/cloud/firestore/BulkWriter.java    |  7 ++++---
 .../google/cloud/firestore/UpdateBuilder.java | 21 +++++++++++++------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/BulkWriter.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/BulkWriter.java
index a42302f21..62bda8fd3 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/BulkWriter.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/BulkWriter.java
@@ -148,8 +148,8 @@ public ApiFuture<WriteResult> delete(@Nonnull DocumentReference documentReferenc
    *
    * @param documentReference The DocumentReference to delete.
    * @param precondition Precondition to enforce for this delete.
-   * @return An ApiFuture containing the result of the delete. Contains an error if the delete
-   *     fails.
+   * @return An ApiFuture containing a sentinel value (Timestamp(0)) for the delete operation.
+   *     Contains an error if the delete fails.
    */
   @Nonnull
   public ApiFuture<WriteResult> delete(
@@ -167,7 +167,8 @@ public ApiFuture<WriteResult> delete(
    *
    * @param documentReference A reference to the document to be set.
    * @param fields A map of the fields and values for the document.
-   * @return An ApiFuture containing the result of the write. Contains an error if the write fails.
+   * @return An ApiFuture containing a sentinel value (Timestamp(0)) for the delete operation.
+   *     Contains an error if the delete fails.
    */
   @Nonnull
   public ApiFuture<WriteResult> set(
diff --git a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/UpdateBuilder.java b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/UpdateBuilder.java
index fa98c8951..08a53aa3c 100644
--- a/google-cloud-firestore/src/main/java/com/google/cloud/firestore/UpdateBuilder.java
+++ b/google-cloud-firestore/src/main/java/com/google/cloud/firestore/UpdateBuilder.java
@@ -697,12 +697,21 @@ public List<BatchWriteResult> apply(BatchWriteResponse batchWriteResponse) {
             for (int i = 0; i < writeResults.size(); ++i) {
               com.google.firestore.v1.WriteResult writeResult = writeResults.get(i);
               com.google.rpc.Status status = statuses.get(i);
-              result.add(
-                  new BatchWriteResult(
-                      writeResult.hasUpdateTime()
-                          ? Timestamp.fromProto(writeResult.getUpdateTime())
-                          : null,
-                      Status.fromCodeValue(status.getCode())));
+              Timestamp updateTime = null;
+
+              // Since delete operations currently do not have write times, use a
+              // sentinel Timestamp value.
+              // TODO(b/158502664): Use actual delete timestamp.
+              boolean isSuccessfulDelete =
+                  !writeResult.hasUpdateTime()
+                      && Status.fromCodeValue(status.getCode()) == Status.OK;
+              Timestamp DELETE_TIMESTAMP_SENTINEL = Timestamp.ofTimeSecondsAndNanos(0, 0);
+              if (isSuccessfulDelete) {
+                updateTime = DELETE_TIMESTAMP_SENTINEL;
+              } else if (writeResult.hasUpdateTime()) {
+                updateTime = Timestamp.fromProto(writeResult.getUpdateTime());
+              }
+              result.add(new BatchWriteResult(updateTime, Status.fromCodeValue(status.getCode())));
             }
 
             return result;