You can't have mandatory ceilings and enable products by other means

[chrisjrn]

If you have a mandatory ceiling for a product, then you can't use vouchers or other non-mandatory conditions to selectively enable the product. The mandatory/non-mandatory approach might need some work.

[chrisjrn]

Design for a fix:

1. Ditch the "mandatory/non-mandatory" approach, as it doesn't make sense if you need both.
2. Add two condition types: ENABLED_IF_TRUE, and DISABLED_IF_FALSE
3. If there's an ENABLED_IF_TRUE condition attached to a product, at least one must be met before the product will be displayed (this is the same as old non-mandatory)
4. If there's a DISABLED_IF_FALSE condition attached to a product, the product will not be displayed if any condition is not med (this is the same as old mandatory)
5. If ENABLED_IF_TRUE and DISABLED_IF_FALSE conditions are both present, then all DISABLED_IF_FALSE conditions must be met as well as at least one ENABLED_IF_TRUE condition.

Here's the use case:

• We have a ceiling of 600 items from Ticket category.
• We have a Sponsor Ticket product that is enabled by the user holding one of a number of applicable voucher codes.
• We only show the Sponsor Ticket product if one of the valid voucher codes is entered, and fewer than 600 Ticket products have been reserved.
• Create a TimeOrStockLimitFlag with a limit of 600; set it as DISABLED_IF_FALSE
• Create a VoucherFlag for each voucher code; set it as ENABLED_IF_TRUE