From 17f284a9acae6357b26c52ad8fa9cafdce583f96 Mon Sep 17 00:00:00 2001
From: hunteraraujo <hunter_araujo@msn.com>
Date: Wed, 6 Sep 2023 15:05:26 -0700
Subject: [PATCH] Add auto-scroll behavior to chat message list

Implemented auto-scrolling in the chat message list to ensure that the view scrolls down to the most recent message when a new chat is added. This behavior only triggers if the user is already at the bottom of the list, providing a seamless user experience.
---
 frontend/lib/views/chat/chat_view.dart | 38 ++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/frontend/lib/views/chat/chat_view.dart b/frontend/lib/views/chat/chat_view.dart
index 565ff2854..42d33590f 100644
--- a/frontend/lib/views/chat/chat_view.dart
+++ b/frontend/lib/views/chat/chat_view.dart
@@ -19,16 +19,45 @@ class ChatView extends StatefulWidget {
 }
 
 class _ChatViewState extends State<ChatView> {
+  final ScrollController _scrollController = ScrollController();
+  bool _isAtBottom = true;
+
   @override
   void initState() {
     super.initState();
 
+    // Listen for scroll events and determine whether the scroll is at the bottom
+    _scrollController.addListener(() {
+      if (_scrollController.position.atEdge) {
+        if (_scrollController.position.pixels == 0) {
+          _isAtBottom = false;
+        } else {
+          _isAtBottom = true;
+        }
+      }
+    });
+
     // Schedule the fetchTasks call for after the initial build
     WidgetsBinding.instance.addPostFrameCallback((_) {
       widget.viewModel.fetchChatsForTask();
     });
   }
 
+  @override
+  void dispose() {
+    // Dispose of the ScrollController when the widget is removed
+    _scrollController.dispose();
+    super.dispose();
+  }
+
+  void _scrollToBottom() {
+    _scrollController.animateTo(
+      _scrollController.position.maxScrollExtent,
+      duration: const Duration(milliseconds: 200),
+      curve: Curves.easeOut,
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     // TODO: Do we want to have a reference to task view model in this class?
@@ -39,9 +68,18 @@ class _ChatViewState extends State<ChatView> {
           // Chat messages list
           Expanded(
             child: ListView.builder(
+              controller: _scrollController,
               itemCount: widget.viewModel.chats.length,
               itemBuilder: (context, index) {
                 final chat = widget.viewModel.chats[index];
+
+                // If the last message has been built and we're at the bottom of the list, scroll down
+                if (index == widget.viewModel.chats.length - 1 && _isAtBottom) {
+                  WidgetsBinding.instance.addPostFrameCallback((_) {
+                    _scrollToBottom();
+                  });
+                }
+
                 if (chat.messageType == MessageType.user) {
                   return UserMessageTile(message: chat.message);
                 } else {