[Feat] Add bundler implementation to Firestore SSR Serialization feature branch

packages/firestore/src/api/snapshot.ts

@@ -520,6 +520,13 @@ export class DocumentSnapshot<
       document.data.value.mapValue.fields,
       'previous'
     );
+    if (this.metadata.hasPendingWrites) {
+      throw new FirestoreError(
+        Code.FAILED_PRECONDITION,
+        'DocumentSnapshot.toJSON attempted to serialize a document with pending writes. ' +
+          'Await `waitForPendingWrites()` before invoking `toJSON()`.'
+      );
+    }
     builder.addBundleDocument(
       documentToDocumentSnapshotBundleData(
         this.ref.path,
@@ -703,6 +710,13 @@ export class QuerySnapshot<
         doc._document.data.value.mapValue.fields,
         'previous'
       );
+      if (this.metadata.hasPendingWrites) {
+        throw new FirestoreError(
+          Code.FAILED_PRECONDITION,
+          'QuerySnapshot.toJSON attempted to serialize a document with pending writes. ' +
+            'Await `waitForPendingWrites()` before invoking `toJSON()`.'
+        );
+      }
       docBundleDataArray.push(
         documentToDocumentSnapshotBundleData(
           doc.ref.path,

packages/firestore/src/remote/serializer.ts

@@ -226,7 +226,10 @@ export function toTimestamp(
   }
 }
 
-function fromTimestamp(date: ProtoTimestamp): Timestamp {
+/**
+ * Returns a Timestamp typed object given protobuf timestamp value.
+ */
+export function fromTimestamp(date: ProtoTimestamp): Timestamp {
   const timestamp = normalizeTimestamp(date);
   return new Timestamp(timestamp.seconds, timestamp.nanos);
 }

packages/firestore/src/util/bundle_builder_impl.ts

@@ -17,6 +17,7 @@
 
 import {
   JsonProtoSerializer,
+  fromTimestamp,
   toName,
   toQueryTarget,
   toTimestamp
@@ -45,8 +46,6 @@ import {
 } from '../protos/firestore_proto_api';
 import { AutoId } from '../util/misc';
 
-import { debugAssert } from './assert';
-
 const BUNDLE_VERSION = 1;
 
 /**
@@ -99,35 +98,37 @@ export class BundleBuilder {
   ): void {
     const originalDocument = this.documents.get(docBundleData.documentPath);
     const originalQueries = originalDocument?.metadata.queries;
+    const docReadTime: Timestamp | undefined = docBundleData.readTime;
+    const origDocReadTime: Timestamp | null = !!originalDocument?.metadata
+      .readTime
+      ? fromTimestamp(originalDocument.metadata.readTime)
+      : null;
 
-    const readTime = docBundleData.readTime;
-    // Update with document built from `snap` because it is newer.
-    if (
-      !originalDocument ||
-      (!readTime && !originalDocument.metadata.readTime) ||
-      (readTime && originalDocument.metadata.readTime! < readTime)
-    ) {
+    const neitherHasReadTime: boolean = !docReadTime && origDocReadTime == null;
+    const docIsNewer: boolean =
+      docReadTime !== undefined &&
+      (origDocReadTime == null || origDocReadTime < docReadTime);
+    if (neitherHasReadTime || docIsNewer) {
+      // Store document.
       this.documents.set(docBundleData.documentPath, {
         document: this.toBundleDocument(docBundleData),
         metadata: {
           name: toName(this.serializer, docBundleData.documentKey),
-          readTime: !!readTime
-            ? toTimestamp(this.serializer, readTime)
+          readTime: !!docReadTime
+            ? toTimestamp(this.serializer, docReadTime) // Convert Timestamp to proto format.
             : undefined,
           exists: docBundleData.documentExists
         }
       });
     }
+    if (docReadTime && docReadTime > this.latestReadTime) {
+      this.latestReadTime = docReadTime;
+    }
     // Update `queries` to include both original and `queryName`.
     if (queryName) {
       const newDocument = this.documents.get(docBundleData.documentPath)!;
       newDocument.metadata.queries = originalQueries || [];
-      if (queryName) {
-        newDocument.metadata.queries!.push(queryName);
-      }
-    }
-    if (readTime && readTime > this.latestReadTime) {
-      this.latestReadTime = readTime;
+      newDocument.metadata.queries!.push(queryName);
     }
   }
 
@@ -175,12 +176,6 @@ export class BundleBuilder {
   private toBundleDocument(
     docBundleData: DocumentSnapshotBundleData
   ): ProtoDocument {
-    // TODO handle documents that have mutations
-    debugAssert(
-      !docBundleData.documentData.hasLocalMutations,
-      "Can't serialize documents with mutations."
-    );
-
     // a parse context is typically used for validating and parsing user data, but in this
     // case we are using it internally to convert DocumentData to Proto3 JSON
     const context = this.userDataReader.createContext(