/// <summary>
        /// Deletes the selected Account from  Accounts Database and update the data in ListView
        /// </summary>
        /// <param name="sender">Button Control</param>
        /// <param name="e">Evenet handler delegate</param>
        private void DeleteButton_Click(object sender, RoutedEventArgs e)
        {
            // Create an Account object from the selected item of the ListView
            Account selectedAccount = AccountList.SelectedItem as Account;

            // Get the Account Id property
            int accountID = selectedAccount.Id;

            // Create new DataContext object
            using (AccountsDataContext accountsDataBase = new AccountsDataContext())
            {
                // Get from the Database the Account which had the same Id as the Account selected in ListView
                Account accountToDelete = accountsDataBase.Accounts.SingleOrDefault(item => item.Id == accountID);

                // Delete the Account from Accounts Databse
                accountsDataBase.Accounts.DeleteOnSubmit(accountToDelete);

                // Submit changes into Accounts Database
                accountsDataBase.SubmitChanges();
            }

            // Reset window to default state
            ResetWindow();

            // Display message for user about the succefull completion of transacton
            MessageBox.Show("Account is successfully removed from the list.", "Success",
                            MessageBoxButton.OK, MessageBoxImage.Information);
        }
        /// <summary>
        /// Updates the selected Account from ListView in Database with new data in respective Textboxes.
        /// </summary>
        /// <param name="sender">Button Control</param>
        /// <param name="e">Evenet handler delegate</param>
        private void UpdateButton_Click(object sender, RoutedEventArgs e)
        {
            // Create an Account object from the selected item of the ListView
            Account selectedAccount = AccountList.SelectedItem as Account;

            // Get the Account Id property
            int accountID = selectedAccount.Id;

            // Get the updated data from respective TextBoxes
            string firstName  = FirstNameTextBox.Text;
            string lastName   = LastNameTextBox.Text;
            string passportID = PassportTextBox.Text;

            // Create new DataContext object
            using (AccountsDataContext accountsDataBase = new AccountsDataContext())
            {
                // Get from the Database the Account which had the same Id as the Account selected in ListView
                Account newAccountInstance = accountsDataBase.Accounts.SingleOrDefault(item => item.Id == accountID);

                // Updated the Account in Databse
                newAccountInstance.First_Name = firstName;
                newAccountInstance.Last_Name  = lastName;
                newAccountInstance.Passport   = passportID;

                // Submit changes into Accounts Database
                accountsDataBase.SubmitChanges();
            }

            // Reset window to default state
            ResetWindow();

            // Display message for user about the succefull completion of transacton
            MessageBox.Show("Account data is successfully updated .", "Success",
                            MessageBoxButton.OK, MessageBoxImage.Information);
        }
        /// <summary>
        /// Gets the text input from TextBoxes, creates an Account Entity and inserts it into Accounts Database
        /// </summary>
        /// <param name="sender">Button Control</param>
        /// <param name="e">Evenet handler delegate</param>
        private void CreateButton_Click(object sender, RoutedEventArgs e)
        {
            // Show warning message in case not all the required textboxes contain data
            if (String.IsNullOrEmpty(FirstNameTextBox.Text) || String.IsNullOrEmpty(LastNameTextBox.Text) || String.IsNullOrEmpty(PassportTextBox.Text))
            {
                MessageBox.Show("Please, complete the form.", "Incomplete data",
                                MessageBoxButton.OK, MessageBoxImage.Warning);
            }
            // If all textboces contain data, create a new Account object with the data from textboxes
            else
            {
                // Create variables with the filled-in text from respective TextBoxes
                string firstName  = FirstNameTextBox.Text;
                string lastName   = LastNameTextBox.Text;
                string passportID = PassportTextBox.Text;

                // Create AccountsDataContext class instance
                using (AccountsDataContext accountsDataBase = new AccountsDataContext())
                {
                    // Create a new Account instance that should be inserted into Accounts Database
                    Account accountToInsert = new Account
                    {
                        First_Name = firstName,
                        Last_Name  = lastName,
                        Passport   = passportID
                    };

                    // Insert the created Account instance into Acocunts Table
                    accountsDataBase.Accounts.InsertOnSubmit(accountToInsert);

                    // Submit changes into Accounts Database
                    accountsDataBase.SubmitChanges();
                }

                // Reset window to default state
                ResetWindow();
            }
        }