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){},
          )),
        ),

      ],
    );
  }
}