Get conversation message

lib/ui/screens/conversation_screen.dart

@@ -0,0 +1,94 @@
+import 'package:comunic/helpers/conversations_helper.dart';
+import 'package:comunic/helpers/users_helper.dart';
+import 'package:comunic/lists/conversation_messages_list.dart';
+import 'package:comunic/lists/users_list.dart';
+import 'package:comunic/ui/tiles/conversation_message_tile.dart';
+import 'package:comunic/utils/intl_utils.dart';
+import 'package:comunic/utils/list_utils.dart';
+import 'package:comunic/utils/ui_utils.dart';
+import 'package:flutter/material.dart';
+
+/// Conversation screen
+///
+/// @author Pierre HUBERT
+
+enum ErrorLevel { NONE, MINOR, MAJOR }
+
+class ConversationScreen extends StatefulWidget {
+  final int conversationID;
+
+  const ConversationScreen({Key key, this.conversationID})
+      : assert(conversationID != null),
+        super(key: key);
+
+  @override
+  State<StatefulWidget> createState() => _ConversationScreenState();
+}
+
+class _ConversationScreenState extends State<ConversationScreen> {
+  final ConversationsHelper _conversationsHelper = ConversationsHelper();
+  final UsersHelper _usersHelper = UsersHelper();
+  ConversationMessagesList _messages;
+  UsersList _usersInfo = UsersList();
+  ErrorLevel _error = ErrorLevel.NONE;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    _loadMessages();
+  }
+
+  void _setError(ErrorLevel err) => setState(() => _error = err);
+
+  /// Method called when an error occurred while loading messages
+  void _errorLoading() {
+    _setError(_messages == null ? ErrorLevel.MAJOR : ErrorLevel.MINOR);
+  }
+
+  /// Load a list of messages
+  Future<void> _loadMessages() async {
+    //First, get the messages
+    final messages = await _conversationsHelper
+        .downloadNewMessagesSingle(widget.conversationID);
+
+    if (messages == null) return _errorLoading();
+
+    //Then get information about users
+    final usersToGet =
+        findMissingFromList(_usersInfo.usersID, messages.getUsersID());
+
+    final users = await _usersHelper.getUsersInfo(usersToGet);
+
+    if (users == null) _errorLoading();
+
+    // Save the new list of messages
+    setState(() {
+      _usersInfo.addAll(users);
+      if (_messages == null)
+        _messages = messages;
+      else
+        _messages.addAll(messages);
+    });
+  }
+
+  /// Error handling
+  Widget _buildError() {
+    return buildErrorCard(tr("Could not load the list of messages!"));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (_error == ErrorLevel.MAJOR) return _buildError();
+
+    if (_messages == null) return buildCenteredProgressBar();
+
+    return ListView.builder(
+        itemCount: _messages.length,
+        itemBuilder: (c, i) {
+          return ConversationMessageTile(
+            message: _messages.elementAt(i),
+            userInfo: _usersInfo.getUser(_messages[i].userID),
+          );
+        });
+  }
+}