Make use of cached user information

lib/helpers/users_helper.dart

@@ -11,14 +11,13 @@ import 'package:comunic/models/user.dart';
 /// @author Pierre HUBERT
 
 class UsersHelper {
-
   final UsersDatabaseHelper _usersDatabaseHelper = UsersDatabaseHelper();
 
   /// Download information about some given users ID
   ///
   /// Return the list of users information in case of success, null in case of
   /// failure
-  Future<UsersList> downloadInfo(List<int> users) async {
+  Future<UsersList> _downloadInfo(List<int> users) async {
     // Execute the request
     final response = await APIRequest(
         uri: "user/getInfoMultiple", args: {"usersID": users.join(",")}).exec();
@@ -51,4 +50,35 @@ class UsersHelper {
 
     return list;
   }
+
+  /// Get users information
+  ///
+  /// If [forceDownload] is set to true, the data will always be retrieved from
+  /// the server, otherwise cached data will be used if available
+  Future<UsersList> getUsersInfo(List<int> users,
+      {bool forceDownload = false}) async {
+
+    List<int> toDownload = List();
+    UsersList list = UsersList();
+
+    // Check cache
+    for(int userID in users){
+      if(!forceDownload && await _usersDatabaseHelper.has(userID))
+        list.add(await _usersDatabaseHelper.get(userID));
+      else
+        toDownload.add(userID);
+    }
+
+    // Process download if required
+    if(toDownload.length > 0) {
+      final downloadedList = await _downloadInfo(toDownload);
+
+      if(downloadedList == null)
+        return null;
+
+      list.addAll(downloadedList);
+    }
+
+    return list;
+  }
 }

lib/ui/screens/conversations_screen.dart

@@ -48,7 +48,7 @@ class _ConversationScreenState extends State<ConversationsScreen> {
     if (list == null) return _gotLoadingError();
 
     //Get information about the members of the conversations
-    list.users = await _usersHelper.downloadInfo(list.allUsersID);
+    list.users = await _usersHelper.getUsersInfo(list.allUsersID);
     if(list.users == null) return _gotLoadingError();
 
     //Save list