Port `SnapshotVersion` for the rest Firestore modulo (#1185)

* remove conversions in `Local` and `Remote`

* replace `FSTSnapshotVersion` in `Model`

* replace `FSTSnapshotVersion` in the rest

* let test check equal with C++ equal

* fix newly added code

* address changes

3 files changed, 10 insertions, 10 deletions

diff --git a/Firestore/Source/Local/FSTLocalSerializer.mm b/Firestore/Source/Local/FSTLocalSerializer.mm
index 652fa5f..8fa1278 100644
--- a/Firestore/Source/Local/FSTLocalSerializer.mm
+++ b/Firestore/Source/Local/FSTLocalSerializer.mm
@@ -103,8 +103,8 @@ using firebase::firestore::model::SnapshotVersion;
   FSTSerializerBeta *remoteSerializer = self.remoteSerializer;
 
   FSTObjectValue *data = [remoteSerializer decodedFields:document.fields];
-  const DocumentKey key = [remoteSerializer decodedDocumentKey:document.name];
-  const SnapshotVersion version = [remoteSerializer decodedVersion:document.updateTime];
+  DocumentKey key = [remoteSerializer decodedDocumentKey:document.name];
+  SnapshotVersion version = [remoteSerializer decodedVersion:document.updateTime];
   return [FSTDocument documentWithData:data key:key version:version hasLocalMutations:NO];
 }
 
@@ -122,8 +122,8 @@ using firebase::firestore::model::SnapshotVersion;
 - (FSTDeletedDocument *)decodedDeletedDocument:(FSTPBNoDocument *)proto {
   FSTSerializerBeta *remoteSerializer = self.remoteSerializer;
 
-  const DocumentKey key = [remoteSerializer decodedDocumentKey:proto.name];
-  const SnapshotVersion version = [remoteSerializer decodedVersion:proto.readTime];
+  DocumentKey key = [remoteSerializer decodedDocumentKey:proto.name];
+  SnapshotVersion version = [remoteSerializer decodedVersion:proto.readTime];
   return [FSTDeletedDocument documentWithKey:key version:version];
 }
 
@@ -188,7 +188,7 @@ using firebase::firestore::model::SnapshotVersion;
 
   FSTTargetID targetID = target.targetId;
   FSTListenSequenceNumber sequenceNumber = target.lastListenSequenceNumber;
-  const SnapshotVersion version = [remoteSerializer decodedVersion:target.snapshotVersion];
+  SnapshotVersion version = [remoteSerializer decodedVersion:target.snapshotVersion];
   NSData *resumeToken = target.resumeToken;
 
   FSTQuery *query;
diff --git a/Firestore/Source/Local/FSTLocalStore.mm b/Firestore/Source/Local/FSTLocalStore.mm
index a3c447f..3a324cd 100644
--- a/Firestore/Source/Local/FSTLocalStore.mm
+++ b/Firestore/Source/Local/FSTLocalStore.mm
@@ -318,8 +318,9 @@ NS_ASSUME_NONNULL_BEGIN
       } else {
         FSTLog(
             @"FSTLocalStore Ignoring outdated watch update for %s. "
-             "Current version: %@  Watch version: %@",
-            key.ToString().c_str(), existingDoc.version, doc.version);
+             "Current version: %s  Watch version: %s",
+            key.ToString().c_str(), existingDoc.version.timestamp().ToString().c_str(),
+            doc.version.timestamp().ToString().c_str());
       }
 
       // The document might be garbage because it was unreferenced by everything.
@@ -331,8 +332,7 @@ NS_ASSUME_NONNULL_BEGIN
     // events when we get permission denied errors while trying to resolve the state of a locally
     // cached document that is in limbo.
     const SnapshotVersion &lastRemoteVersion = [self.queryCache lastRemoteSnapshotVersion];
-    // TODO(zxu): convert to reference once SnapshotVersion is used in RemoteEvent.
-    const SnapshotVersion remoteVersion = remoteEvent.snapshotVersion;
+    const SnapshotVersion &remoteVersion = remoteEvent.snapshotVersion;
     if (remoteVersion != SnapshotVersion::None()) {
       FSTAssert(remoteVersion >= lastRemoteVersion,
                 @"Watch stream reverted to previous snapshot?? (%s < %s)",
diff --git a/Firestore/Source/Local/FSTQueryData.mm b/Firestore/Source/Local/FSTQueryData.mm
index 456d42a..e352101 100644
--- a/Firestore/Source/Local/FSTQueryData.mm
+++ b/Firestore/Source/Local/FSTQueryData.mm
@@ -74,7 +74,7 @@ NS_ASSUME_NONNULL_BEGIN
 
   FSTQueryData *other = (FSTQueryData *)object;
   return [self.query isEqual:other.query] && self.targetID == other.targetID &&
-         self.purpose == other.purpose && [self.snapshotVersion isEqual:other.snapshotVersion] &&
+         self.purpose == other.purpose && self.snapshotVersion == other.snapshotVersion &&
          [self.resumeToken isEqual:other.resumeToken];
 }