merge origin/develop into ref/segregate-api-layer

Signed-off-by: Sahil Kumar <[email protected]>

packages/stream_chat_flutter_core/lib/src/better_stream_builder.dart

@@ -0,0 +1,109 @@
+import 'dart:async';
+
+import 'package:flutter/widgets.dart';
+
+/// A more efficient [StreamBuilder]
+/// It requires [initialData] and will rebuild
+/// only when the new data is different than the current data
+/// The [comparator] is used to check if the new data is different
+class BetterStreamBuilder<T> extends StatefulWidget {
+  /// Creates a new BetterStreamBuilder
+  const BetterStreamBuilder({
+    required this.stream,
+    required this.initialData,
+    required this.builder,
+    this.loadingBuilder,
+    this.errorBuilder,
+    this.comparator,
+    Key? key,
+  }) : super(key: key);
+
+  /// The stream to listen to
+  final Stream<T>? stream;
+
+  /// The initial data available
+  final T initialData;
+
+  /// Comparator used to check if the new data is different than the last one
+  final bool Function(T?, T)? comparator;
+
+  /// Builder that builds based on the new snapshot
+  final Widget Function(BuildContext context, T data) builder;
+
+  /// Builder that builds when the data is null
+  final Widget Function(BuildContext context)? loadingBuilder;
+
+  /// Builder used when there is an error
+  final Widget Function(BuildContext context, Object error)? errorBuilder;
+
+  @override
+  _BetterStreamBuilderState createState() => _BetterStreamBuilderState<T>();
+}
+
+class _BetterStreamBuilderState<T> extends State<BetterStreamBuilder<T>> {
+  T? _lastEvent;
+  StreamSubscription? _subscription;
+  Object? _lastError;
+
+  @override
+  Widget build(BuildContext context) {
+    if (_lastError != null) {
+      return widget.errorBuilder!(context, _lastError!);
+    }
+
+    if (_lastEvent == null) {
+      return widget.loadingBuilder?.call(context) ?? const Offstage();
+    }
+    return widget.builder(context, _lastEvent ?? widget.initialData);
+  }
+
+  @override
+  void initState() {
+    _lastEvent = widget.initialData;
+    _subscription = widget.stream?.listen(
+      _onEvent,
+      onError: _onError,
+    );
+    super.initState();
+  }
+
+  @override
+  void didUpdateWidget(covariant BetterStreamBuilder<T> oldWidget) {
+    if (oldWidget.stream != widget.stream) {
+      _subscription?.cancel();
+      _subscription = widget.stream?.listen(
+        _onEvent,
+        onError: _onError,
+      );
+    }
+    super.didUpdateWidget(oldWidget);
+  }
+
+  @override
+  void dispose() {
+    _subscription?.cancel();
+    super.dispose();
+  }
+
+  void _onError(error) {
+    if (widget.errorBuilder != null && error != _lastError) {
+      if (mounted) {
+        setState(() {});
+      }
+      _lastError = error;
+    }
+  }
+
+  void _onEvent(T event) {
+    _lastError = null;
+    final isEqual = widget.comparator != null
+        ? widget.comparator!(_lastEvent, event)
+        : event == _lastEvent;
+    if (!isEqual) {
+      if (mounted) {
+        setState(() {});
+      }
+      _lastEvent = event;
+    }
+  }
+}

packages/stream_chat_flutter_core/lib/src/message_list_core.dart

@@ -1,9 +1,11 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter_core/src/better_stream_builder.dart';
 import 'package:stream_chat_flutter_core/src/stream_channel.dart';
 import 'package:stream_chat_flutter_core/src/typedef.dart';
 
@@ -127,6 +129,10 @@ class MessageListCoreState extends State<MessageListCore> {
             .map((threads) => threads[widget.parentMessage!.id])
         : _streamChannel!.channel.state?.messagesStream;
 
+    final initialData = _isThreadConversation
+        ? _streamChannel!.channel.state?.threads[widget.parentMessage!.id]
+        : _streamChannel!.channel.state?.messages;
+
     bool defaultFilter(Message m) {
       final isMyMessage = m.user?.id == _currentUser?.id;
       final isDeletedOrShadowed = m.isDeleted == true || m.shadowed == true;
@@ -134,28 +140,27 @@ class MessageListCoreState extends State<MessageListCore> {
       return true;
     }
 
-    return StreamBuilder<List<Message>?>(
-      stream: messagesStream?.map((messages) =>
-          messages?.where(widget.messageFilter ?? defaultFilter).toList(
-                growable: false,
-              )),
-      builder: (context, snapshot) {
-        if (snapshot.hasError) {
-          return widget.errorWidgetBuilder(context, snapshot.error!);
-        } else if (!snapshot.hasData) {
-          return widget.loadingBuilder(context);
-        } else {
-          final messageList =
-              snapshot.data?.reversed.toList(growable: false) ?? [];
-          if (messageList.isEmpty && !_isThreadConversation) {
-            if (_upToDate) {
-              return widget.emptyBuilder(context);
-            }
-          } else {
-            _messages = messageList;
+    return BetterStreamBuilder<List<Message>?>(
+      initialData: initialData,
+      comparator: const ListEquality().equals,
+      stream: messagesStream!.map(
+        (messages) =>
+            messages?.where(widget.messageFilter ?? defaultFilter).toList(
+                  growable: false,
+                ),
+      ),
+      errorBuilder: widget.errorWidgetBuilder,
+      loadingBuilder: widget.loadingBuilder,
+      builder: (context, data) {
+        final messageList = data?.reversed.toList(growable: false) ?? [];
+        if (messageList.isEmpty && !_isThreadConversation) {
+          if (_upToDate) {
+            return widget.emptyBuilder(context);
           }
-          return widget.messageListBuilder(context, _messages);
+        } else {
+          _messages = messageList;
         }
+        return widget.messageListBuilder(context, _messages);
       },
     );
   }

packages/stream_chat_flutter_core/lib/stream_chat_flutter_core.dart

@@ -3,6 +3,7 @@ library stream_chat_flutter_core;
 export 'package:connectivity_plus/connectivity_plus.dart';
 export 'package:stream_chat/stream_chat.dart';
 
+export 'src/better_stream_builder.dart';
 export 'src/channel_list_core.dart' hide ChannelListCoreState;
 export 'src/channels_bloc.dart';
 export 'src/lazy_load_scroll_view.dart';