/// <summary>
/// Generate an email content based on the time and the bill statement.
/// </summary>
/// <param name="bill"></param>
/// <param name="month"></param>
/// <param name="year"></param>
/// <returns></returns>
public Email GenerateEmail(BillStatement bill, int month, int year)
{
string emailTemplate = DomainResources.BILLING_STATEMENT_EMAIL_TEMPLATE;
string subject = $"Billing statement for {month}-{year}";
string content = emailTemplate
.Replace("{name}", bill.Customer.Name)
.Replace("{address}", bill.Customer.Address)
.Replace("{city}", bill.Customer.City)
.Replace("{state}", bill.Customer.Address)
.Replace("{zip}", bill.Customer.Address)
.Replace("{bill_month}", month + "-" + year)
.Replace("{amount_due}", bill.AmountDue.ToString("C"));
return(new Email(subject, content, bill.Customer, bill));
}
/// <summary>
/// Generate the bill for a customer.
/// Note:
/// this action is idempotent. If the bill is generated, it will be retrieved.
/// </summary>
/// <param name="cust"></param>
/// <param name="month"></param>
/// <param name="year"></param>
/// <returns></returns>
public BillStatement GenerateBill(Customer cust, int month, int year)
{
string billedCustomerKey = $"{month}_{year}_{cust.CustomerId}";
// if the bill is not generated, create it
if (billedCustomerByTime[billedCustomerKey] == null)
{
decimal? amountDue = GetAmountDue(cust, month, year);
BillStatement bill = new BillStatement(cust, month, year, amountDue.GetValueOrDefault());
cust.MonthlyStatements.Add(bill);
customerRepository.SaveOrUpdate(cust);
//remember customer bill statement for the month
billedCustomerByTime[billedCustomerKey] = bill;
return(bill);
}
// if the bill has been generated, just retrieve it.
return(billedCustomerByTime[billedCustomerKey]);
}
/// <summary>
/// Generate and send the bill to all active customers for the month and year.
/// Note:
/// This action is idempotent. If customer has already been emailed, the system will not send duplicate email.
/// </summary>
/// <param name="month">the month to bill customer.</param>
/// <param name="year">the year to bill customer.</param>
public void SendBillToActiveCustomers(int month, int year)
{
// Billing service does not support future date
if (!DateTimeHelper.IsInFuture(month, year))
{
ISet <Email> emails = new HashSet <Email>();
string datetimeStamp = $"{month}_{year}";
IList <Customer> allActiveCustomers = this.customerRepository.GetAllActiveCustomers();
foreach (Customer customer in allActiveCustomers)
{
try
{
BillStatement bill = GenerateBill(customer, month, year);
// only send email if we have not done that.
string emailedCustomerKey = $"{customer.CustomerId}_{month}_{year}";
if (!emailedCustomerByTime.ContainsKey(emailedCustomerKey))
{
Email email = GenerateEmail(bill, month, year);
// remember the customer who was emailed
emailedCustomerByTime[emailedCustomerKey] = email;
emails.Add(email);
}
}
//Should not block the whole billing cycle if a customer failed
catch (Exception ex)
{
Logger.Error(ex);
Logger.Error($"Unable to generate bill for {customer.CustomerId}:{customer.Name} for the {month}-{year}");
}
}
//storing the generated email for reporting purpose
invoiceGeneratedByTime[datetimeStamp] = emails;
emailRepository.SendMultiple(emails);
}
}