Cache the list of friends

lib/helpers/database/database_contract.dart

@@ -45,4 +45,14 @@ abstract class ConversationsMessagesTableContract {
   static const C_TIME_INSERT = "time_insert";
   static const C_MESSAGE = "message";
   static const C_IMAGE_URL = "image_url";
+}
+
+/// Friends table contract
+abstract class FriendsListTableContract {
+  static const TABLE_NAME = "friends";
+  static const C_ID = BaseTableContract.C_ID;
+  static const C_ACCEPTED = "accepted";
+  static const C_LAST_ACTIVE = "last_active";
+  static const C_FOLLOWING = "following";
+  static const C_CAN_POST_TEXTS = "can_post_texts";
 }

lib/helpers/database/database_helper.dart

@@ -45,6 +45,10 @@ abstract class DatabaseHelper {
     await db.execute(
         "DROP TABLE IF EXISTS ${ConversationsMessagesTableContract.TABLE_NAME}");
 
+    // Drop friends list table
+    await db.execute(
+        "DROP TABLE IF EXISTS ${FriendsListTableContract.TABLE_NAME}");
+
     // Initialize database again
     await _initializeDatabase(db, newVersion);
   }
@@ -82,5 +86,14 @@ abstract class DatabaseHelper {
         "${ConversationsMessagesTableContract.C_MESSAGE} TEXT, "
         "${ConversationsMessagesTableContract.C_IMAGE_URL} TEXT"
         ")");
+
+    // Friends list table
+    await db.execute("CREATE TABLE ${FriendsListTableContract.TABLE_NAME} ("
+        "${FriendsListTableContract.C_ID} INTEGER PRIMARY KEY, "
+        "${FriendsListTableContract.C_ACCEPTED} INTEGER, "
+        "${FriendsListTableContract.C_LAST_ACTIVE} INTEGER, "
+        "${FriendsListTableContract.C_FOLLOWING} INTEGER, "
+        "${FriendsListTableContract.C_CAN_POST_TEXTS} INTEGER"
+        ")");
   }
 }

lib/helpers/database/friends_database_helper.dart

@@ -0,0 +1,15 @@
+import 'package:comunic/helpers/database/database_contract.dart';
+import 'package:comunic/helpers/database/model_database_helper.dart';
+import 'package:comunic/models/friend.dart';
+
+/// Friends database helper
+///
+/// @author Pierre HUBERT
+
+class FriendsDatabaseHelper extends ModelDatabaseHelper<Friend> {
+  @override
+  Friend initializeFromMap(Map<String, dynamic> map) => Friend.fromMap(map);
+
+  @override
+  String tableName() => FriendsListTableContract.TABLE_NAME;
+}

lib/helpers/friends_helper.dart

@@ -1,17 +1,22 @@
+import 'package:comunic/helpers/database/friends_database_helper.dart';
 import 'package:comunic/lists/friends_list.dart';
 import 'package:comunic/models/api_request.dart';
 import 'package:comunic/models/friend.dart';
+import 'package:meta/meta.dart';
 
 /// Friends helper
 ///
 /// @author Pierre HUBERT
 
 class FriendsHelper {
-  /// Get the list of friends of the user
+
+  final FriendsDatabaseHelper _friendsDatabaseHelper = FriendsDatabaseHelper();
+
+  /// Get the list of friends of the user from the server
   ///
   /// Returns the list of friends in case of success, or null if an error
   /// occurred
-  Future<FriendsList> downloadList() async {
+  Future<FriendsList> _downloadList() async {
     final response = await APIRequest(
       uri: "friends/getList",
       needLogin: true,
@@ -36,9 +41,23 @@ class FriendsHelper {
               ),
         );
 
+    // Save the list of friends
+    _friendsDatabaseHelper.clearTable();
+    _friendsDatabaseHelper.insertAll(list);
+
     return list;
   }
 
+  /// Get the list, either from an online or an offline source
+  Future<FriendsList> getList({@required bool online}) async {
+
+    if(online)
+      return await _downloadList();
+
+    else
+      return FriendsList()..addAll(await _friendsDatabaseHelper.getAll());
+  }
+
   /// Respond to friendship request
   Future<bool> respondRequest(int friendID, bool accept) async {
     final response = await APIRequest(

lib/models/friend.dart

@@ -1,3 +1,5 @@
+import 'package:comunic/helpers/database/database_contract.dart';
+import 'package:comunic/models/cache_model.dart';
 import 'package:comunic/utils/date_utils.dart';
 import 'package:meta/meta.dart';
 
@@ -5,15 +7,14 @@ import 'package:meta/meta.dart';
 ///
 /// @author Pierre HUBERT
 
-class Friend {
-  final int id;
+class Friend extends CacheModel implements Comparable<Friend> {
   final bool accepted;
   final int lastActive;
   final bool following;
   final bool canPostTexts;
 
-  Friend({
-    @required this.id,
+  const Friend({
+    @required int id,
     @required this.accepted,
     @required this.lastActive,
     @required this.following,
@@ -22,8 +23,29 @@ class Friend {
         assert(accepted != null),
         assert(lastActive != null),
         assert(following != null),
-        assert(canPostTexts != null);
+        assert(canPostTexts != null),
+        super(id: id);
 
   /// Check out whether friend is connected or not
   bool get isConnected => time() - 30 < lastActive;
+
+  @override
+  int compareTo(Friend other) => other.lastActive.compareTo(lastActive);
+
+  @override
+  Map<String, dynamic> toMap() => {
+        FriendsListTableContract.C_ID: id.toString(),
+        FriendsListTableContract.C_ACCEPTED: accepted ? 1 : 0,
+        FriendsListTableContract.C_LAST_ACTIVE: lastActive,
+        FriendsListTableContract.C_FOLLOWING: following ? 1 : 0,
+        FriendsListTableContract.C_CAN_POST_TEXTS: canPostTexts ? 1 : 0
+      };
+
+  Friend.fromMap(Map<String, dynamic> map)
+      : assert(map != null),
+        accepted = map[FriendsListTableContract.C_ACCEPTED] == 1,
+        lastActive = map[FriendsListTableContract.C_LAST_ACTIVE],
+        following = map[FriendsListTableContract.C_FOLLOWING] == 1,
+        canPostTexts = map[FriendsListTableContract.C_CAN_POST_TEXTS] == 1,
+        super.fromMap(map);
 }

lib/ui/screens/friends_list_screen.dart

@@ -47,7 +47,13 @@ class _FriendsListScreenState extends SafeState<FriendsListScreen> {
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
-    _loadList();
+    _getList();
+  }
+
+  /// Initialize list retrieving
+  Future<void> _getList() async {
+    await _loadList(false);
+    await _loadList(true);
   }
 
   /// Refresh the list of friends
@@ -56,11 +62,14 @@ class _FriendsListScreenState extends SafeState<FriendsListScreen> {
   }
 
   /// Load the list of friends
-  Future<void> _loadList() async {
+  Future<void> _loadList(bool online) async {
     error = _ErrorsLevel.NONE;
 
     // Get the list of friends
-    final list = await _friendsHelper.downloadList();
+    final list = await _friendsHelper.getList(online: online);
+
+    // Check if there is no cache yet
+    if(!online && list.isEmpty) return;
 
     // Check for errors
     if (list == null) return _gotError();
@@ -73,7 +82,7 @@ class _FriendsListScreenState extends SafeState<FriendsListScreen> {
 
     // Apply new information
     setState(() {
-      _friendsList = list;
+      _friendsList = list..sort();
       _usersInfo = users;
     });
     error = _ErrorsLevel.NONE;
@@ -107,7 +116,7 @@ class _FriendsListScreenState extends SafeState<FriendsListScreen> {
         Expanded(
           child: RefreshIndicator(
             key: _refreshIndicatorKey,
-            onRefresh: _loadList,
+            onRefresh: () => _loadList(true),
             child: ListView.builder(
                 physics: AlwaysScrollableScrollPhysics(),
                 itemCount: _friendsList.length,