public async Task HandleAsync(RefundPointsCommand command, CancellationToken cancellationToken)
{
await commandValidator.ValidateAndThrowAsync(command, cancellationToken : cancellationToken).ConfigureAwait(false);
try
{
using (var context = dbContextFactory.CreateDbContext())
{
var consumptionEvent = await context.PointsConsumedEvents.FirstAsync(e => e.TransactionId == command.TransactionId).ConfigureAwait(false);
var points = consumptionEvent.PointChange;
var transactionId = command.TransactionId;
context.PointsRefundedEvents.Add(new PointsRefundedEvent
{
PointChange = points,
Reason = $"Refunded {points} points consumed by transaction {transactionId}.",
UtcDateTimeRecorded = DateTime.UtcNow,
UserId = consumptionEvent.UserId,
TransactionId = command.TransactionId
});
await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
}
}
catch (DbUpdateException ex) when(ex.IsUniqueConstraintViolationError())
{
// This means this consumption has already been refunded, can be ignored.
return;
}
}
public async Task HandleAsync(EarnPointsCommand command, CancellationToken cancellationToken)
{
commandValidator.ValidateAndThrow(command);
try
{
using (var context = dbContextFactory.CreateDbContext())
{
context.PointsEarnedEvents.Add(new PointsEarnedEvent
{
PointChange = command.Points,
Reason = EarnPointsReason,
UtcDateTimeRecorded = DateTime.UtcNow,
UserId = command.UserId,
TransactionId = command.TransactionId
});
await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
}
}
catch (DbUpdateException ex) when(ex.IsUniqueConstraintViolationError())
{
// This means this earning has already been registered, can be ignored.
return;
}
}
public async Task HandleAsync(ConsumePointsCommand command, CancellationToken cancellationToken)
{
await commandValidator.ValidateAndThrowAsync(command, cancellationToken : cancellationToken).ConfigureAwait(false);
try
{
using (var context = dbContextFactory.CreateDbContext())
{
context.PointsConsumedEvents.Add(new PointsConsumedEvent
{
PointChange = command.Points,
UtcDateTimeRecorded = DateTime.UtcNow,
UserId = command.UserId,
TransactionId = command.TransactionId,
Reason = ConsumePointsReason,
});
// Assume optimistic concurrency so that points aren't changed between retrieving the sum and adding the consume record.
await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
}
}
catch (DbUpdateException ex) when(ex.IsUniqueConstraintViolationError())
{
// This means this consumption has already been registered, can be ignored.
return;
}
}
public async Task <int> CalculateTotalAsync(int userId, CancellationToken cancellationToken)
{
using (var context = dbContextFactory.CreateDbContext())
{
var totalEarned = await context.PointsEarnedEvents.Where(evt => evt.UserId == userId).SumAsync(e => e.PointChange).ConfigureAwait(false);
var totalRefunded = await context.PointsRefundedEvents.Where(evt => evt.UserId == userId).SumAsync(e => e.PointChange).ConfigureAwait(false);
var totalConsumed = await context.PointsConsumedEvents.Where(evt => evt.UserId == userId).SumAsync(e => e.PointChange).ConfigureAwait(false);
var total = totalEarned + totalRefunded - totalConsumed;
return(total);
}
}
public RefundPointsCommandValidator(ILoyaltyDbContextFactory dbContextFactory)
{
RuleFor(cmd => cmd.TransactionId)
.NotEmpty()
.WithMessage(CommonValidationMessages.CannotBeNullOrEmpty)
.DependentRules(() =>
{
RuleFor(cmd => cmd.TransactionId)
.MustAsync(async(string transactionId, CancellationToken cancellationToken) =>
{
using (var context = dbContextFactory.CreateDbContext())
{
var consumptionEvent = await context
.PointsConsumedEvents
.FirstOrDefaultAsync(e => e.TransactionId == transactionId).ConfigureAwait(false);
return(consumptionEvent != null);
}
})
.WithMessage(ValidationMessages.PointsConsumptionNotFound);
});
}