Use the conversation messages cache before going online

lib/helpers/conversations_helper.dart

@@ -176,9 +176,16 @@ class ConversationsHelper {
   /// the conversation.
   /// Otherwise [lastMessageID] contains the ID of the last known message
   Future<ConversationMessagesList> getNewMessages(
-      {@required int conversationID, int lastMessageID = 0}) async {
+      {@required int conversationID,
-    return await _downloadNewMessagesSingle(conversationID,
+      int lastMessageID = 0,
-        lastMessageID: lastMessageID);
+      bool online = true}) async {
+    if (online)
+      return await _downloadNewMessagesSingle(conversationID,
+          lastMessageID: lastMessageID);
+    else
+      return await _conversationMessagesDatabaseHelper
+          .getAllMessagesConversations(conversationID,
+              lastMessageID: lastMessageID);
   }
 
   /// Send a new message to the server

lib/helpers/database/conversation_messages_database_helper.dart

@@ -1,13 +1,14 @@
 import 'package:comunic/helpers/database/database_contract.dart';
 import 'package:comunic/helpers/database/model_database_helper.dart';
+import 'package:comunic/lists/conversation_messages_list.dart';
 import 'package:comunic/models/conversation_message.dart';
 
 /// Conversation messages database helper
 ///
 /// @author Pierre HUBERT
 
-class ConversationMessagesDatabaseHelper extends ModelDatabaseHelper<ConversationMessage> {
+class ConversationMessagesDatabaseHelper
-
+    extends ModelDatabaseHelper<ConversationMessage> {
   @override
   ConversationMessage initializeFromMap(Map<String, dynamic> map) {
     return ConversationMessage.fromMap(map);
@@ -18,4 +19,19 @@ class ConversationMessagesDatabaseHelper extends ModelDatabaseHelper<Conversatio
     return ConversationsMessagesTableContract.TABLE_NAME;
   }
 
-}
+  /// Get all the message cached for a given conversation
+  Future<ConversationMessagesList> getAllMessagesConversations(
+      int conversationID,
+      {int lastMessageID = 0}) async {
+    final list = await getMultiple(
+      where: "${ConversationsMessagesTableContract.C_CONVERSATION_ID} = ? "
+          "AND ${BaseTableContract.C_ID} > ?",
+      whereArgs: [conversationID, lastMessageID],
+    );
+
+    // Turn the list into a conversation messages list
+    ConversationMessagesList finalList = ConversationMessagesList();
+    finalList.addAll(list);
+    return finalList;
+  }
+}

lib/helpers/database/model_database_helper.dart

@@ -48,7 +48,33 @@ abstract class ModelDatabaseHelper<T extends CacheModel> {
 
   /// Get all the entries from the table
   Future<List<T>> getAll() async {
-    List<Map> maps = await(await DatabaseHelper.get()).query(tableName());
+    List<Map> maps = await (await DatabaseHelper.get()).query(tableName());
+    return maps.map((f) => initializeFromMap(f)).toList();
+  }
+
+  /// Get some entries from the table based on some conditions
+  Future<List<T>> getMultiple(
+      {bool distinct,
+      List<String> columns,
+      String where,
+      List<dynamic> whereArgs,
+      String groupBy,
+      String having,
+      String orderBy,
+      int limit,
+      int offset}) async {
+    List<Map> maps = await (await DatabaseHelper.get()).query(
+      tableName(),
+      distinct: distinct,
+      columns: columns,
+      where: where,
+      whereArgs: whereArgs,
+      groupBy: groupBy,
+      having: having,
+      orderBy: orderBy,
+      limit: limit,
+      offset: offset,
+    );
     return maps.map((f) => initializeFromMap(f)).toList();
   }
 

lib/ui/screens/conversation_screen.dart

@@ -43,7 +43,7 @@ class _ConversationScreenState extends State<ConversationScreen> {
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
-    _loadMessages();
+    _initializeLoading();
   }
 
   void _setError(ErrorLevel err) => setState(() => _error = err);
@@ -55,15 +55,27 @@ class _ConversationScreenState extends State<ConversationScreen> {
     _setError(_messages == null ? ErrorLevel.MAJOR : ErrorLevel.MINOR);
   }
 
+  /// Load the first conversations
+  Future<void> _initializeLoading() async {
+    await _loadMessages(false);
+    await _loadMessages(true);
+  }
+
   /// Load a list of messages
-  Future<void> _loadMessages() async {
+  Future<void> _loadMessages(bool online) async {
     //First, get the messages
     final messages = await _conversationsHelper.getNewMessages(
         conversationID: widget.conversationID,
-        lastMessageID: _messages == null ? 0 : _messages.lastMessageID);
+        lastMessageID: _messages == null ? 0 : _messages.lastMessageID,
+        online: online);
 
     if (messages == null) return _errorLoading();
 
+    // In case we are offline and we did not get any message we do not do
+    // anything (we wait for the online request)
+    if(messages.length == 0 && !online)
+      return;
+
     //Then get information about users
     final usersToGet =
         findMissingFromList(_usersInfo.usersID, messages.getUsersID());
@@ -254,6 +266,9 @@ class _ConversationScreenState extends State<ConversationScreen> {
 
     return Column(
       children: <Widget>[
+        Container(
+          child: _error == ErrorLevel.MINOR ? _buildError() : null,
+        ),
         _buildMessagesList(),
         Divider(),
         _buildSendMessageForm()