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/models/notification.dart' as n;
import 'package:comunic/ui/widgets/account_image_widget.dart';
import 'package:comunic/utils/date_utils.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: _buildBody(), onRefresh: _loadList),
        )
      ],
    );
  }

  /// Build body
  Widget _buildBody() {
    if (_status == _Status.ERROR || _list.length == 0)
      return SingleChildScrollView(
        physics: AlwaysScrollableScrollPhysics(),
        child: _buildSingleChildCases(),
      );

    return ListView(
      children: _list
          .map((f) => _NotificationTile(
                notification: f,
                usersList: _users,
                groupsList: _groups,
              ))
          .toList(),
    );
  }

  Widget _buildSingleChildCases() {
    // 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.")),
        ),
      );
  }
}

class _NotificationTile extends StatelessWidget {
  final n.Notification notification;
  final UsersList usersList;
  final GroupsList groupsList;

  const _NotificationTile({
    Key key,
    @required this.notification,
    @required this.usersList,
    @required this.groupsList,
  })  : assert(notification != null),
        super(key: key);

  @override
  Widget build(BuildContext context) {
    final srcUser = usersList.getUser(notification.fromUser);

    String message = "${srcUser.fullName} ";

    switch (notification.type) {
      // Comment
      case n.NotificationType.COMMENT_CREATED:
        message += tr("posted a comment");
        break;

      // Friendship requests
      case n.NotificationType.SENT_FRIEND_REQUEST:
        message += tr("sent you a friendship request.");
        break;

      case n.NotificationType.ACCEPTED_FRIEND_REQUEST:
        message += tr("accepted your friendship request.");
        break;

      case n.NotificationType.REJECTED_FRIEND_REQUEST:
        message += tr("rejected your friendship request.");
        break;

      // Groups membership
      case n.NotificationType.SENT_GROUP_MEMBERSHIP_INVITATION:
        message += tr("invited you to join the group");
        break;

      case n.NotificationType.ACCEPTED_GROUP_MEMBERSHIP_INVITATION:
        message += tr("accepted his invitation to join the group");
        break;

      case n.NotificationType.REJECTED_GROUP_MEMBERSHIP_INVITATION:
        message += tr("rejected his invitation to join the group");
        break;

      case n.NotificationType.SENT_GROUP_MEMBERSHIP_REQUEST:
        message += tr("sent a request to join the group");
        break;

      case n.NotificationType.ACCEPTED_GROUP_MEMBERSHIP_REQUEST:
        message += tr("accepted you request to join the group");
        break;

      case n.NotificationType.REJECTED_GROUP_MEMBERSHIP_REQUEST:
        message += tr("rejected your request to join the group");
        break;

      // Generic element creation
      case n.NotificationType.ELEM_CREATED:
        if (notification.onElemType == n.NotificationElementType.POST)
          message += tr("created a new post");
        break;

      case n.NotificationType.ELEM_UPDATED:
        // Operation not implemented
        break;
    }

    // Separator
    message += " ";

    // Notification target

    // User page
    if (notification.fromContainerType == n.NotificationElementType.USER_PAGE) {
      if (notification.fromUser == notification.fromContainerId)
        message += tr("on his / her page");
      else
        message += tr("on %user_name%'s page", args: {
          "user_name": usersList.getUser(notification.fromContainerId).fullName
        });
    }

    // Group page
    if (notification.fromContainerType ==
        n.NotificationElementType.GROUP_PAGE) {
      message += tr("on the group %group%.", args: {
        "group": groupsList[notification.fromContainerId].displayName
      });
    }

    // Group membership
    if (notification.onElemType == n.NotificationElementType.GROUP_MEMBERSHIP)
      message += groupsList[notification.onElemId].displayName;

    return ListTile(
      leading: AccountImageWidget(
        user: srcUser,
      ),
      title: Text(message),
      subtitle: Text(diffTimeFromNowToStr(notification.timeCreate)),
    );
  }
}