[WIP] Federated cloud firestore platform interface

packages/cloud_firestore/cloud_firestore/example/.flutter-plugins-dependencies

@@ -0,0 +1 @@
+{"_info":"// This is a generated file; do not edit or check into version control.","dependencyGraph":[{"name":"cloud_firestore","dependencies":["firebase_core"]},{"name":"firebase_core","dependencies":[]}]}

packages/cloud_firestore/cloud_firestore/lib/cloud_firestore.dart

@@ -9,6 +9,8 @@ import 'dart:convert';
 import 'dart:typed_data';
 import 'dart:ui' show hashValues, hashList;
 
+import 'package:cloud_firestore_platform_interface/cloud_firestore_platform_interface.dart';
+
 import 'package:collection/collection.dart';
 import 'package:firebase_core/firebase_core.dart';
 import 'package:flutter/foundation.dart' show ReadBuffer, WriteBuffer;

packages/cloud_firestore/cloud_firestore/lib/src/document_reference.dart

@@ -48,15 +48,7 @@ class DocumentReference {
   /// If [merge] is true, the provided data will be merged into an
   /// existing document instead of overwriting.
   Future<void> setData(Map<String, dynamic> data, {bool merge = false}) {
-    return Firestore.channel.invokeMethod<void>(
-      'DocumentReference#setData',
-      <String, dynamic>{
-        'app': firestore.app.name,
-        'path': path,
-        'data': data,
-        'options': <String, bool>{'merge': merge},
-      },
-    );
+    return Firestore.platform.setDocumentReferenceData(firestore.app.name, path: path, data: data, options: <String, bool>{'merge': merge},);
   }
 
   /// Updates fields in the document referred to by this [DocumentReference].
@@ -66,29 +58,16 @@ class DocumentReference {
   ///
   /// If no document exists yet, the update will fail.
   Future<void> updateData(Map<String, dynamic> data) {
-    return Firestore.channel.invokeMethod<void>(
-      'DocumentReference#updateData',
-      <String, dynamic>{
-        'app': firestore.app.name,
-        'path': path,
-        'data': data,
-      },
-    );
+    return Firestore.platform.updateDocumentReferenceData(firestore.app.name, path: path, data: data,);
   }
 
   /// Reads the document referenced by this [DocumentReference].
   ///
   /// If no document exists, the read will return null.
   Future<DocumentSnapshot> get({Source source = Source.serverAndCache}) async {
     final Map<String, dynamic> data =
-        await Firestore.channel.invokeMapMethod<String, dynamic>(
-      'DocumentReference#get',
-      <String, dynamic>{
-        'app': firestore.app.name,
-        'path': path,
-        'source': _getSourceString(source),
-      },
-    );
+        await Firestore.platform.getDocumentReference(firestore.app.name, path: path, source: _getSourceString(source),);
+
     return DocumentSnapshot._(
       data['path'],
       _asStringKeyedMap(data['data']),
@@ -100,10 +79,7 @@ class DocumentReference {
 
   /// Deletes the document referred to by this [DocumentReference].
   Future<void> delete() {
-    return Firestore.channel.invokeMethod<void>(
-      'DocumentReference#delete',
-      <String, dynamic>{'app': firestore.app.name, 'path': path},
-    );
+    return Firestore.platform.deleteDocumentReference(firestore.app.name, path: path,);
   }
 
   /// Returns the reference of a collection contained inside of this
@@ -124,24 +100,15 @@ class DocumentReference {
     StreamController<DocumentSnapshot> controller; // ignore: close_sinks
     controller = StreamController<DocumentSnapshot>.broadcast(
       onListen: () {
-        _handle = Firestore.channel.invokeMethod<int>(
-          'DocumentReference#addSnapshotListener',
-          <String, dynamic>{
-            'app': firestore.app.name,
-            'path': path,
-            'includeMetadataChanges': includeMetadataChanges,
-          },
-        ).then<int>((dynamic result) => result);
+        _handle = Firestore.platform.addDocumentReferenceSnapshotListener(firestore.app.name, path: path, includeMetadataChanges: includeMetadataChanges,)
+          .then<int>((dynamic result) => result);
         _handle.then((int handle) {
           Firestore._documentObservers[handle] = controller;
         });
       },
       onCancel: () {
         _handle.then((int handle) async {
-          await Firestore.channel.invokeMethod<void>(
-            'removeListener',
-            <String, dynamic>{'handle': handle},
-          );
+          await Firestore.platform.removeListener(handle);
           Firestore._documentObservers.remove(handle);
         });
       },

packages/cloud_firestore/cloud_firestore/lib/src/firestore.dart

@@ -10,28 +10,6 @@ part of cloud_firestore;
 class Firestore {
   Firestore({FirebaseApp app}) : app = app ?? FirebaseApp.instance {
     if (_initialized) return;
-    channel.setMethodCallHandler((MethodCall call) async {
-      if (call.method == 'QuerySnapshot') {
-        final QuerySnapshot snapshot = QuerySnapshot._(call.arguments, this);
-        _queryObservers[call.arguments['handle']].add(snapshot);
-      } else if (call.method == 'DocumentSnapshot') {
-        final DocumentSnapshot snapshot = DocumentSnapshot._(
-          call.arguments['path'],
-          _asStringKeyedMap(call.arguments['data']),
-          SnapshotMetadata._(call.arguments['metadata']['hasPendingWrites'],
-              call.arguments['metadata']['isFromCache']),
-          this,
-        );
-        _documentObservers[call.arguments['handle']].add(snapshot);
-      } else if (call.method == 'DoTransaction') {
-        final int transactionId = call.arguments['transactionId'];
-        final Transaction transaction = Transaction(transactionId, this);
-        final dynamic result =
-            await _transactionHandlers[transactionId](transaction);
-        await transaction._finish();
-        return result;
-      }
-    });
     _initialized = true;
   }
 
@@ -46,21 +24,11 @@ class Firestore {
   static bool _initialized = false;
 
   @visibleForTesting
-  static const MethodChannel channel = MethodChannel(
-    'plugins.flutter.io/cloud_firestore',
-    StandardMethodCodec(FirestoreMessageCodec()),
-  );
-
-  static final Map<int, StreamController<QuerySnapshot>> _queryObservers =
-      <int, StreamController<QuerySnapshot>>{};
+  static CloudFirestorePlatform platform = CloudFirestorePlatform.instance;
 
   static final Map<int, StreamController<DocumentSnapshot>> _documentObservers =
       <int, StreamController<DocumentSnapshot>>{};
 
-  static final Map<int, TransactionHandler> _transactionHandlers =
-      <int, TransactionHandler>{};
-  static int _transactionHandlerId = 0;
-
   @override
   bool operator ==(dynamic o) => o is Firestore && o.app == app;
 
@@ -123,39 +91,33 @@ class Firestore {
       {Duration timeout = const Duration(seconds: 5)}) async {
     assert(timeout.inMilliseconds > 0,
         'Transaction timeout must be more than 0 milliseconds');
-    final int transactionId = _transactionHandlerId++;
-    _transactionHandlers[transactionId] = transactionHandler;
-    final Map<String, dynamic> result = await channel
-        .invokeMapMethod<String, dynamic>(
-            'Firestore#runTransaction', <String, dynamic>{
-      'app': app.name,
-      'transactionId': transactionId,
-      'transactionTimeout': timeout.inMilliseconds
-    });
+
+    // Wrap the transactionHandler into something that can be passed to the Platform implementation
+    final PlatformTransactionHandler handler = (int transactionId) async {
+      Transaction transaction = Transaction(transactionId, this);
+      final dynamic result = await transactionHandler(transaction);
+      await transaction._finish();
+      return result;
+    };
+
+    // Move to a runTransaction method in the method channel!
+    final Map<String, dynamic> result = await platform.runTransaction(app.name, transactionHandler: handler, transactionTimeout: timeout.inMilliseconds,);
     return result ?? <String, dynamic>{};
   }
 
   @deprecated
   Future<void> enablePersistence(bool enable) async {
     assert(enable != null);
-    await channel
-        .invokeMethod<void>('Firestore#enablePersistence', <String, dynamic>{
-      'app': app.name,
-      'enable': enable,
-    });
+    await platform.enablePersistence(app.name, enable: enable,);
   }
 
   Future<void> settings(
       {bool persistenceEnabled,
       String host,
       bool sslEnabled,
       int cacheSizeBytes}) async {
-    await channel.invokeMethod<void>('Firestore#settings', <String, dynamic>{
-      'app': app.name,
-      'persistenceEnabled': persistenceEnabled,
-      'host': host,
-      'sslEnabled': sslEnabled,
-      'cacheSizeBytes': cacheSizeBytes,
-    });
+    await platform.settings(app.name, persistenceEnabled: persistenceEnabled,
+        host: host, sslEnabled: sslEnabled,
+        cacheSizeBytes: cacheSizeBytes);
   }
 }

packages/cloud_firestore/cloud_firestore/lib/src/query.dart

@@ -52,54 +52,17 @@ class Query {
   // TODO(jackson): Reduce code duplication with [DocumentReference]
   Stream<QuerySnapshot> snapshots({bool includeMetadataChanges = false}) {
     assert(includeMetadataChanges != null);
-    Future<int> _handle;
-    // It's fine to let the StreamController be garbage collected once all the
-    // subscribers have cancelled; this analyzer warning is safe to ignore.
-    StreamController<QuerySnapshot> controller; // ignore: close_sinks
-    controller = StreamController<QuerySnapshot>.broadcast(
-      onListen: () {
-        _handle = Firestore.channel.invokeMethod<int>(
-          'Query#addSnapshotListener',
-          <String, dynamic>{
-            'app': firestore.app.name,
-            'path': _path,
-            'isCollectionGroup': _isCollectionGroup,
-            'parameters': _parameters,
-            'includeMetadataChanges': includeMetadataChanges,
-          },
-        ).then<int>((dynamic result) => result);
-        _handle.then((int handle) {
-          Firestore._queryObservers[handle] = controller;
-        });
-      },
-      onCancel: () {
-        _handle.then((int handle) async {
-          await Firestore.channel.invokeMethod<void>(
-            'removeListener',
-            <String, dynamic>{'handle': handle},
-          );
-          Firestore._queryObservers.remove(handle);
-        });
-      },
-    );
-    return controller.stream;
+
+    return Firestore.platform.snapshots(firestore.app.name, path: _path, isCollectionGroup: _isCollectionGroup, parameters: _parameters, includeMetadataChanges: includeMetadataChanges,)
+    .map((dynamic data) => QuerySnapshot._(data, firestore));
   }
 
   /// Fetch the documents for this query
   Future<QuerySnapshot> getDocuments(
       {Source source = Source.serverAndCache}) async {
     assert(source != null);
     final Map<dynamic, dynamic> data =
-        await Firestore.channel.invokeMapMethod<String, dynamic>(
-      'Query#getDocuments',
-      <String, dynamic>{
-        'app': firestore.app.name,
-        'path': _path,
-        'isCollectionGroup': _isCollectionGroup,
-        'parameters': _parameters,
-        'source': _getSourceString(source),
-      },
-    );
+        await Firestore.platform.getQueryDocuments(firestore.app.name, path: _path, isCollectionGroup: _isCollectionGroup, parameters: _parameters, source: _getSourceString(source),);
     return QuerySnapshot._(data, firestore);
   }
 

packages/cloud_firestore/cloud_firestore/lib/src/transaction.dart

@@ -23,12 +23,8 @@ class Transaction {
   }
 
   Future<DocumentSnapshot> _get(DocumentReference documentReference) async {
-    final Map<String, dynamic> result = await Firestore.channel
-        .invokeMapMethod<String, dynamic>('Transaction#get', <String, dynamic>{
-      'app': _firestore.app.name,
-      'transactionId': _transactionId,
-      'path': documentReference.path,
-    });
+    final Map<String, dynamic> result = await Firestore.platform.getTransaction(_firestore.app.name, transactionId: _transactionId, path: documentReference.path,);
+
     if (result != null) {
       return DocumentSnapshot._(
           documentReference.path,
@@ -52,12 +48,7 @@ class Transaction {
   }
 
   Future<void> _delete(DocumentReference documentReference) async {
-    return Firestore.channel
-        .invokeMethod<void>('Transaction#delete', <String, dynamic>{
-      'app': _firestore.app.name,
-      'transactionId': _transactionId,
-      'path': documentReference.path,
-    });
+    return Firestore.platform.deleteTransaction(_firestore.app.name, transactionId: _transactionId, path: documentReference.path,);
   }
 
   /// Updates fields in the document referred to by [documentReference].
@@ -74,13 +65,7 @@ class Transaction {
 
   Future<void> _update(
       DocumentReference documentReference, Map<String, dynamic> data) async {
-    return Firestore.channel
-        .invokeMethod<void>('Transaction#update', <String, dynamic>{
-      'app': _firestore.app.name,
-      'transactionId': _transactionId,
-      'path': documentReference.path,
-      'data': data,
-    });
+    return Firestore.platform.updateTransaction(_firestore.app.name, transactionId: _transactionId, path: documentReference.path, data: data);
   }
 
   /// Writes to the document referred to by the provided [DocumentReference].
@@ -98,12 +83,6 @@ class Transaction {
 
   Future<void> _set(
       DocumentReference documentReference, Map<String, dynamic> data) async {
-    return Firestore.channel
-        .invokeMethod<void>('Transaction#set', <String, dynamic>{
-      'app': _firestore.app.name,
-      'transactionId': _transactionId,
-      'path': documentReference.path,
-      'data': data,
-    });
+    return Firestore.platform.setTransaction(_firestore.app.name, transactionId: _transactionId, path: documentReference.path, data: data,);
   }
 }

packages/cloud_firestore/cloud_firestore/lib/src/write_batch.dart

@@ -12,8 +12,7 @@ part of cloud_firestore;
 /// nor can it be committed again.
 class WriteBatch {
   WriteBatch._(this._firestore)
-      : _handle = Firestore.channel.invokeMethod<dynamic>(
-            'WriteBatch#create', <String, dynamic>{'app': _firestore.app.name});
+      : _handle = Firestore.platform.createWriteBatch(_firestore.app.name);
 
   final Firestore _firestore;
   Future<dynamic> _handle;
@@ -29,8 +28,7 @@ class WriteBatch {
     if (!_committed) {
       _committed = true;
       await Future.wait<dynamic>(_actions);
-      await Firestore.channel.invokeMethod<void>(
-          'WriteBatch#commit', <String, dynamic>{'handle': await _handle});
+      await Firestore.platform.commitWriteBatch(handle: await _handle);
     } else {
       throw StateError("This batch has already been committed.");
     }
@@ -41,14 +39,7 @@ class WriteBatch {
     if (!_committed) {
       _handle.then((dynamic handle) {
         _actions.add(
-          Firestore.channel.invokeMethod<void>(
-            'WriteBatch#delete',
-            <String, dynamic>{
-              'app': _firestore.app.name,
-              'handle': handle,
-              'path': document.path,
-            },
-          ),
+          Firestore.platform.deleteWriteBatch(_firestore.app.name, handle: handle, path: document.path,),
         );
       });
     } else {
@@ -68,16 +59,7 @@ class WriteBatch {
     if (!_committed) {
       _handle.then((dynamic handle) {
         _actions.add(
-          Firestore.channel.invokeMethod<void>(
-            'WriteBatch#setData',
-            <String, dynamic>{
-              'app': _firestore.app.name,
-              'handle': handle,
-              'path': document.path,
-              'data': data,
-              'options': <String, bool>{'merge': merge},
-            },
-          ),
+          Firestore.platform.setWriteBatchData(_firestore.app.name, handle: handle, path: document.path, data: data, options: <String, bool>{'merge': merge},),
         );
       });
     } else {
@@ -93,15 +75,7 @@ class WriteBatch {
     if (!_committed) {
       _handle.then((dynamic handle) {
         _actions.add(
-          Firestore.channel.invokeMethod<void>(
-            'WriteBatch#updateData',
-            <String, dynamic>{
-              'app': _firestore.app.name,
-              'handle': handle,
-              'path': document.path,
-              'data': data,
-            },
-          ),
+          Firestore.platform.updateWriteBatchData(_firestore.app.name, handle: handle, path: document.path, data: data,),
         );
       });
     } else {