/// <summary>
/// Returns how many plan periods are due.
/// </summary>
/// <param name="plan">The payment plan to calculate.</param>
/// <param name="currentDate">The current date, ensuring all calculations are done using the exact same date.</param>
/// <returns>The amount of periods to pay.</returns>
private decimal CalcPeriodQty(ApiPaymentPlan plan, DateTimeOffset currentDate)
{
var loopDate = new[] { plan.StartDate, plan.PaidUntilDate, plan.DateAdded }.Max() ?? MovePeriodDate(plan, plan.NextChargeDate !.Value, -1);
var qtyTotal = 0m;
var qtyTrial = 0m;
var count = 0;
while (GetPlanPeriod(plan, loopDate, currentDate, out var periodStart, out var periodEnd) &&
(plan.TransactionsLeft == null || count < plan.TransactionsLeft))
{
count++;
var fullPeriod = periodEnd - periodStart;
var billPeriod = periodEnd - loopDate;
if (plan.EndDate.HasValue)
{
billPeriod -= (periodEnd - plan.EndDate.Value);
}
// Calculate period by period.
var qty = (decimal)billPeriod.Ticks / fullPeriod.Ticks;
// Trial period will only be billed once we've completed a billing cycle afterwards.
if (plan.PeriodUnit == PaymentPeriodUnit.MonthPostpaidTrial && billPeriod.TotalDays <= (plan.PeriodQty ?? _config.Value.DefaultTrialDays))
{
qtyTrial += qty;
}
else
{
qtyTotal += qty + qtyTrial;
qtyTrial = 0;
}
loopDate = periodEnd;
}
return(qtyTotal);
}
/// <summary>
/// Moves the date by specified number of full billing periods.
/// </summary>
/// <param name="plan">The plan containing billing period info.</param>
/// <param name="datePlan">The date to move.</param>
/// <param name="qty">The amount of full periods to add or remove to the date.</param>
/// <returns>The date for a different billing period.</returns>
private static DateTimeOffset MovePeriodDate(ApiPaymentPlan plan, DateTimeOffset datePlan, int qty)
{
return(plan.PeriodUnit switch
{
PaymentPeriodUnit.MonthPostpaid => datePlan.AddMonths(1 * qty),
PaymentPeriodUnit.MonthPostpaidTrial => datePlan.AddMonths(1 * qty),
PaymentPeriodUnit.Day => datePlan.AddDays((plan.PeriodQty ?? 1) * qty),
PaymentPeriodUnit.Week => datePlan.AddDays(7 * (plan.PeriodQty ?? 1) * qty),
PaymentPeriodUnit.Month => datePlan.AddMonths((plan.PeriodQty ?? 1) * qty),
PaymentPeriodUnit.Year => datePlan.AddYears((plan.PeriodQty ?? 1) * qty),
_ => throw new InvalidOperationException(Res.GetPlanPeriodUnrecognizedUnit)
});
/// <summary>
/// Calculates the start and end dates of a period, and returns whether the period end is past and due to be paid.
/// </summary>
/// <param name="plan">The payment plan to calculate.</param>
/// <param name="planDate">The date to calculate period start and end dates for.</param>
/// <param name="currentDate">The current date, ensuring all calculations are done using the exact same date.</param>
/// <param name="periodStart">Returns the period start date.</param>
/// <param name="periodEnd">Returns the period end date.</param>
/// <returns>Whether endDate is past and due to be paid.</returns>
private bool GetPlanPeriod(ApiPaymentPlan plan, DateTimeOffset planDate, DateTimeOffset currentDate, out DateTimeOffset periodStart, out DateTimeOffset periodEnd)
{
if (plan.PeriodUnit == PaymentPeriodUnit.MonthPostpaid || plan.PeriodUnit == PaymentPeriodUnit.MonthPostpaidTrial)
{
periodStart = new DateTimeOffset(planDate.Year, planDate.Month, 1, 0, 0, 0, TimeSpan.Zero);
}
else
{
periodStart = planDate;
}
periodEnd = MovePeriodDate(plan, periodStart, 1);
return(periodEnd <= currentDate.AddHours(_config.Value.PayHoursAhead));
}
