import 'package:comunic/helpers/groups_helper.dart';
import 'package:comunic/helpers/notifications_helper.dart';
import 'package:comunic/helpers/users_helper.dart';
import 'package:comunic/lists/groups_list.dart';
import 'package:comunic/lists/notifications_list.dart';
import 'package:comunic/lists/users_list.dart';
import 'package:comunic/utils/intl_utils.dart';
import 'package:comunic/utils/ui_utils.dart';
import 'package:flutter/material.dart';

/// Notifications screen
///
/// @author Pierre HUBERT

enum _Status { LOADING, ERROR, NONE }

class NotificationsScreen extends StatefulWidget {
  @override
  _NotificationsScreenState createState() => _NotificationsScreenState();
}

class _NotificationsScreenState extends State<NotificationsScreen> {
  NotificationsList _list;
  UsersList _users;
  GroupsList _groups;
  _Status _status = _Status.LOADING;

  void setStatus(_Status s) => setState(() => _status = s);

  Future<void> _loadList() async {
    setStatus(_Status.LOADING);

    try {
      final list = await NotificationsHelper().getUnread();

      final users = await UsersHelper().getListWithThrow(list.usersIds);

      final groups = await GroupsHelper().getListOrThrow(list.groupsIds);

      setState(() {
        _list = list;
        _users = users;
        _groups = groups;
      });

      setStatus(_Status.NONE);
    } on Exception catch (e) {
      print("Exception while getting the list of notifications!");
      print(e);
    } on Error catch (e) {
      print("Error while getting the list of notifications!");
      print(e.stackTrace);
    }
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _loadList();
  }

  @override
  Widget build(BuildContext context) {
    // Loading status
    if (_list == null || _status == _Status.LOADING)
      return Center(
        child: CircularProgressIndicator(),
      );

    return Column(
      children: [
        Expanded(
          child: RefreshIndicator(
              child: SingleChildScrollView(
                physics: AlwaysScrollableScrollPhysics(),
                child: _buildBody(),
              ),
              onRefresh: _loadList),
        )
      ],
    );
  }

  /// Build body
  Widget _buildBody() {
    // In case of error
    if (_status == _Status.ERROR)
      return buildErrorCard(tr("Could not get the list of notifications!"),
          actions: [
            MaterialButton(
              onPressed: () => _loadList(),
              child: Text(tr("Try again".toUpperCase())),
            )
          ]);

    // When there is no notification
    if (_list.length == 0)
      return Padding(
        padding: const EdgeInsets.all(8.0),
        child: Center(
          child: Text(tr("You do not have any notification now.")),
        ),
      );
  }
}