[firestore] feat: support firestore aggregate query

firestore_flutter/_pubspec_overrides.yaml

@@ -0,0 +1,5 @@
+dependency_overrides:
+  tekartik_firebase_flutter:
+    path: ../firebase_flutter
+  tekartik_firebase_firestore:
+    path: ../../firebase_firestore.dart/firestore

firestore_flutter/lib/src/aggregate_query_flutter.dart

@@ -0,0 +1,91 @@
+import 'package:tekartik_firebase_firestore_flutter/src/firestore_flutter.dart';
+
+import 'import_firestore.dart';
+import 'import_native.dart' as native;
+
+class AggregateQueryFlutter implements AggregateQuery {
+  final QueryFlutter queryFlutter;
+  late final native.AggregateQuery nativeInstance;
+
+  native.AggregateField _convertField(AggregateField field) {
+    if (field is AggregateFieldCount) {
+      return native.count();
+    } else if (field is AggregateFieldAverage) {
+      return native.average(field.field);
+    } else if (field is AggregateFieldSum) {
+      return native.sum(field.field);
+    } else {
+      throw ArgumentError(field);
+    }
+  }
+
+  native.AggregateField? _convertFieldAt(
+      List<AggregateField> fields, int index) {
+    if (index < fields.length) {
+      return _convertField(fields[index]);
+    }
+    return null;
+  }
+
+  AggregateQueryFlutter(this.queryFlutter, List<AggregateField> fields) {
+    var i = 0;
+    nativeInstance = queryFlutter.nativeInstance.aggregate(
+      _convertFieldAt(fields, i++)!,
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+      _convertFieldAt(fields, i++),
+    );
+  }
+
+  @override
+  Future<AggregateQuerySnapshot> get() async {
+    var nativeSnapshot = await nativeInstance.get();
+    return AggregateQuerySnapshotFlutter(this, nativeSnapshot);
+  }
+}
+
+class AggregateQuerySnapshotFlutter implements AggregateQuerySnapshot {
+  final AggregateQueryFlutter aggregateQueryFlutter;
+  late final native.AggregateQuerySnapshot nativeInstance;
+
+  AggregateQuerySnapshotFlutter(
+      this.aggregateQueryFlutter, this.nativeInstance);
+
+  @override
+  int? get count => nativeInstance.count;
+
+  @override
+  double? getAverage(String field) => nativeInstance.getAverage(field);
+
+  @override
+  double? getSum(String field) => nativeInstance.getSum(field);
+
+  @override
+  Query get query => aggregateQueryFlutter.queryFlutter;
+}

firestore_flutter/lib/src/firestore_flutter.dart

@@ -5,6 +5,7 @@ import 'package:meta/meta.dart';
 import 'package:path/path.dart';
 import 'package:tekartik_firebase_flutter/src/firebase_flutter.dart'; // ignore: implementation_imports
 
+import 'aggregate_query_flutter.dart';
 import 'document_snapshot_flutter.dart';
 import 'import.dart';
 import 'import_firestore.dart';
@@ -62,6 +63,9 @@ class FirestoreServiceFlutter
 
   @override
   bool get supportsTrackChanges => true;
+
+  @override
+  bool get supportsAggregateQueries => true;
 }
 
 class FirestoreFlutter with FirestoreDefaultMixin implements Firestore {
@@ -394,6 +398,11 @@ class QueryFlutter
             whereIn: toNativeValues(whereIn),
             isNull: isNull));
   }
+
+  @override
+  AggregateQuery aggregate(List<AggregateField> fields) {
+    return AggregateQueryFlutter(this, fields);
+  }
 }
 
 mixin PathReferenceFlutterMixin {

firestore_flutter/lib/src/import_native.dart

@@ -0,0 +1,4 @@
+export 'package:cloud_firestore/cloud_firestore.dart';
+// ignore: depend_on_referenced_packages
+export 'package:cloud_firestore_platform_interface/cloud_firestore_platform_interface.dart'
+    show AggregateField;

firestore_flutter/pubspec.yaml

@@ -16,7 +16,7 @@ dependencies:
       url: https://github.com/tekartik/firebase_firestore.dart
       path: firestore
       ref: dart3a
-    version: '>=1.1.1'
+    version: '>=1.1.6'
   tekartik_firebase_flutter:
     git:
       url: https://github.com/tekartik/firebase_flutter