/// <summary>
        /// Adds the plan to the DataBase and plans listbox after filling
        /// the plan description in PlanDescription Window
        /// </summary>
        private void addButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                plan = new PlanDescription();
                plan.DeadLine_datepicker.SelectedDate = DateTime.Today;
                bool? result = plan.ShowDialog();

                if (result.Value == true)
                {
                    if (String.IsNullOrEmpty(plan.descriptionTextBox.Text) == false &&
                            plan.DeadLine_datepicker.SelectedDate != null &&
                                InputLanguageManager.Current.CurrentInputLanguage.Name == "en-US")
                    {
                        MainWindow.Connection.Open();
                        cmd = new SqlCommand("Insert into [Plan] (User_login, Description, IsCompleted, DeadLine, Date) values (@User_login, @Description, 'N', @DeadLine, @Date)", MainWindow.Connection);
                        cmd.Parameters.AddWithValue("@User_login", MainWindow.CurrentUser);
                        cmd.Parameters.AddWithValue("@Description", plan.descriptionTextBox.Text);
                        cmd.Parameters.AddWithValue("@DeadLine", plan.DeadLine_datepicker.SelectedDate);
                        cmd.Parameters.AddWithValue("@Date", DateTime.Now);
                        cmd.ExecuteNonQuery();
                        MainWindow.Connection.Close();

                        plansListBox.Items.Add(plan.descriptionTextBox.Text + ": (Till " + plan.DeadLine_datepicker.SelectedDate.Value.ToShortDateString() + ")");
                    }
                    else
                        MessageBox.Show("Description can't be empty or written in Russian (Write in English)", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
                }
            }
            catch (SqlException ex)
            {
                MessageBox.Show(ex.Message, "Error!", MessageBoxButton.OK, MessageBoxImage.Error);
                MainWindow.Connection.Close();
            }
            catch (Exception except)
            {
                MessageBox.Show(except.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error);
                MainWindow.Connection.Close();
            }
        }
        /// <summary>
        /// Allows the user to edit the selected plan after pressing 
        /// the "Edit" button
        /// </summary>
        private void editButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                if (plansListBox.SelectedItem != null)
                {
                    plan = new PlanDescription();
                    plan.descriptionTextBox.Text = plansListBox.SelectedItem.ToString().Split(':')[0];
                    plan.DeadLine_datepicker.SelectedDate = GetDeadLineDate(MainWindow.Connection, CurrentPlanId);

                    bool? result = plan.ShowDialog();

                    if (result.Value == true)
                    {
                        if (string.IsNullOrEmpty(plan.descriptionTextBox.Text) == false &&
                                InputLanguageManager.Current.CurrentInputLanguage.Name == "en-US")
                        {
                            MainWindow.Connection.Open();
                            cmd = new SqlCommand(@"update [Plan] set Description='" + plan.descriptionTextBox.Text + "', "
                                + "DeadLine='" + plan.DeadLine_datepicker.SelectedDate + "' where Id like " + CurrentPlanId, MainWindow.Connection);
                            cmd.ExecuteNonQuery();
                            MainWindow.Connection.Close();

                            MainWindow.GetTasks(MainWindow.Connection, plansListBox, "N");
                        }
                        else
                            MessageBox.Show("The description field can't be empty or written in Russian!", "Description", MessageBoxButton.OK, MessageBoxImage.Information);
                    }
                }
                else
                    MessageBox.Show("Select the plan you want to edit!", "Select the plan", MessageBoxButton.OK, MessageBoxImage.Information);
            }
            catch (SqlException ex)
            {
                MessageBox.Show(ex.Message, "Error!", MessageBoxButton.OK, MessageBoxImage.Error);
                MainWindow.Connection.Close();
            }
            catch (Exception except)
            {
                MessageBox.Show(except.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error);
                MainWindow.Connection.Close();
            }
        }