Cache the list of friends

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);
 }