Display the list of friends of the user

lib/ui/screens/friends_list_screen.dart

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+import 'package:comunic/helpers/friends_helper.dart';
+import 'package:comunic/helpers/users_helper.dart';
+import 'package:comunic/lists/friends_list.dart';
+import 'package:comunic/lists/users_list.dart';
+import 'package:comunic/ui/tiles/accepted_friend_tile.dart';
+import 'package:comunic/ui/tiles/pending_friend_tile.dart';
+import 'package:comunic/ui/widgets/safe_state.dart';
+import 'package:comunic/utils/intl_utils.dart';
+import 'package:comunic/utils/ui_utils.dart';
+import 'package:flutter/material.dart';
+
+/// Friends list screen
+///
+/// Display the list of friends of the current user
+///
+/// @author Pierre HUBERT
+
+enum _ErrorsLevel { NONE, MINOR, MAJOR }
+
+class FriendsListScreen extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => _FriendsListScreenState();
+}
+
+class _FriendsListScreenState extends SafeState<FriendsListScreen> {
+  /// Helpers
+  final _friendsHelper = FriendsHelper();
+  final _usersHelper = UsersHelper();
+
+  /// Widget members
+  _ErrorsLevel _error = _ErrorsLevel.NONE;
+  FriendsList _friendsList;
+  UsersList _usersInfo;
+  bool _loading = true;
+
+  /// Useful setters
+  set error(_ErrorsLevel err) => setState(() => _error = err);
+
+  set loading(bool loading) => setState(() => _loading = loading);
+
+  void _gotError() =>
+      error = _friendsList == null ? _ErrorsLevel.MAJOR : _ErrorsLevel.MINOR;
+
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    _loadList();
+  }
+
+  /// Load the list of friends
+  Future<void> _loadList() async {
+    error = _ErrorsLevel.NONE;
+    loading = true;
+
+    // Get the list of friends
+    final list = await _friendsHelper.downloadList();
+
+    // Check for errors
+    if (list == null) return _gotError();
+
+    // Get information about related users
+    final users = await _usersHelper.getUsersInfo(list.usersId);
+
+    // Check for errors
+    if (users == null) return _gotError();
+
+    // Apply new information
+    setState(() {
+      _friendsList = list;
+      _usersInfo = users;
+    });
+    loading = false;
+    error = _ErrorsLevel.NONE;
+  }
+
+  /// Build and return loading error
+  Widget _buildError() =>
+      buildErrorCard(
+        tr("Could not load your list of friends!"),
+        actions: [
+          FlatButton(
+            onPressed: _loadList,
+            child: Text(
+              tr("Retry").toUpperCase(),
+              style: TextStyle(color: Colors.white),
+            ),
+          ),
+        ],
+      );
+
+  @override
+  Widget build(BuildContext context) {
+    if (_error == _ErrorsLevel.MAJOR) return _buildError();
+    if (_friendsList == null) return buildCenteredProgressBar();
+
+    return Column(
+      children: <Widget>[
+
+        // Check for errors
+        Container(child: _error != _ErrorsLevel.NONE ? _buildError() : null),
+
+        // Check if loading
+        Container(child: _loading ? CircularProgressIndicator() : null),
+
+        // List of friends
+        Expanded(
+          child: ListView.builder(itemCount: _friendsList.length, itemBuilder: (c, i) =>
+          _friendsList[i].accepted ? AcceptedFriendTile(
+            friend: _friendsList[i],
+            user: _usersInfo.getUser(_friendsList[i].id),
+          ) : PendingFriendTile(
+            friend: _friendsList[i],
+            user: _usersInfo.getUser(_friendsList[i].id),
+            onRespond: (friend, accept){},
+          )),
+        ),
+
+      ],
+    );
+  }
+}