Show cached conversations list before getting list from the server

lib/helpers/conversations_helper.dart

@@ -43,6 +43,13 @@ class ConversationsHelper {
     }
   }
 
+  /// Get the local list of conversations
+  Future<ConversationsList> getCachedList() async {
+    final list = await _conversationsDatabaseHelper.getAll();
+    list.sort();
+    return list;
+  }
+
   /// Get the name of a [conversation]. This requires information about the
   /// users of this conversation
   static String getConversationName(

lib/helpers/database/conversations_database_helper.dart

@@ -1,5 +1,6 @@
 import 'package:comunic/helpers/database/database_contract.dart';
 import 'package:comunic/helpers/database/model_database_helper.dart';
+import 'package:comunic/lists/conversations_list.dart';
 import 'package:comunic/models/conversation.dart';
 
 /// Conversations database helper
@@ -17,4 +18,12 @@ class ConversationsDatabaseHelper extends ModelDatabaseHelper<Conversation> {
     return ConversationTableContract.TABLE_NAME;
   }
 
+  @override
+  Future<ConversationsList> getAll() async {
+    ConversationsList list = ConversationsList();
+    list.addAll(await super.getAll());
+    return list;
+  }
+
+
 }

lib/helpers/database/model_database_helper.dart

@@ -36,8 +36,8 @@ abstract class ModelDatabaseHelper<T extends CacheModel> {
   /// Returns null if none found
   Future<T> get(int id) async {
     List<Map> maps = await (await DatabaseHelper.get()).query(
-      UserTableContract.TABLE_NAME,
-      where: '${UserTableContract.C_ID} = ?',
+      tableName(),
+      where: '${BaseTableContract.C_ID} = ?',
       whereArgs: [id],
     );
 
@@ -46,6 +46,12 @@ abstract class ModelDatabaseHelper<T extends CacheModel> {
     return null;
   }
 
+  /// Get all the entries from the table
+  Future<List<T>> getAll() async {
+    List<Map> maps = await(await DatabaseHelper.get()).query(tableName());
+    return maps.map((f) => initializeFromMap(f)).toList();
+  }
+
   /// Empty the table
   Future<void> clearTable() async {
     await (await DatabaseHelper.get()).execute("DELETE FROM ${tableName()}");

lib/models/conversation.dart

@@ -7,7 +7,7 @@ import 'package:meta/meta.dart';
 ///
 /// @author Pierre HUBERT
 
-class Conversation extends CacheModel {
+class Conversation extends CacheModel implements Comparable {
   final int ownerID;
   final int lastActive;
   final String name;
@@ -56,4 +56,9 @@ class Conversation extends CacheModel {
       ConversationTableContract.C_MEMBERS: members.join(","),
     };
   }
+
+  @override
+  int compareTo(other) {
+    return other.lastActive.compareTo(this.lastActive);
+  }
 }

lib/ui/screens/conversations_screen.dart

@@ -33,23 +33,34 @@ class _ConversationScreenState extends State<ConversationsScreen> {
 
   void setLoading(bool loading) => setState(() => _loading = loading);
 
+  /// Get the list of conversations, once from the cache, once from the server
+  Future<void> _loadConversations() async {
+    await _loadConversationsList(true);
+    await _loadConversationsList(false);
+  }
+
   void _gotLoadingError() {
     setLoading(false);
     setError(_list == null ? LoadErrorLevel.MAJOR : LoadErrorLevel.MINOR);
   }
 
   /// Load the list of conversations
-  Future<void> _loadConversations() async {
+  Future<void> _loadConversationsList(bool cached) async {
     setError(LoadErrorLevel.NONE);
     setLoading(true);
 
-    //Process the list of conversations
-    final list = await _conversationsHelper.downloadList();
+    //Get the list of conversations
+    var list;
+    if(cached)
+      list = await _conversationsHelper.getCachedList();
+    else
+      list = await _conversationsHelper.downloadList();
+
     if (list == null) return _gotLoadingError();
 
     //Get information about the members of the conversations
     list.users = await _usersHelper.getUsersInfo(list.allUsersID);
-    if(list.users == null) return _gotLoadingError();
+    if (list.users == null) return _gotLoadingError();
 
     //Save list
     setState(() {
@@ -65,7 +76,7 @@ class _ConversationScreenState extends State<ConversationsScreen> {
       tr("Could not retrieve the list of conversations!"),
       actions: <Widget>[
         FlatButton(
-          onPressed: _loadConversations,
+          onPressed: () => _loadConversationsList(true),
           child: Text(
             tr("Retry").toUpperCase(),
             style: TextStyle(
@@ -83,14 +94,39 @@ class _ConversationScreenState extends State<ConversationsScreen> {
     if (_list == null) return buildCenteredProgressBar();
 
     // Show the list of conversations
-    return ListView.builder(
-      itemBuilder: (context, index) {
-        return ConversationTile(
-          conversation: _list.elementAt(index),
-          usersList: _list.users,
-        );
-      },
-      itemCount: _list.length,
+    return Stack(
+      children: <Widget>[
+        Column(
+          children: <Widget>[
+            Container(
+              child: _error == LoadErrorLevel.MINOR ? _buildErrorCard() : null,
+            ),
+            Expanded(
+              child: ListView.builder(
+                itemBuilder: (context, index) {
+                  return ConversationTile(
+                    conversation: _list.elementAt(index),
+                    usersList: _list.users,
+                  );
+                },
+                itemCount: _list.length,
+              ),
+            ),
+          ],
+        ),
+        Positioned(
+          top: 8.0,
+          left: 0.0,
+          right: 0.0,
+          child: Container(
+            child: !_loading
+                ? null
+                : Center(
+                    child: CircularProgressIndicator(),
+                  ),
+          ),
+        )
+      ],
     );
   }
 }