Apply Taxes and Discounts to Kasir Object about kasir

[risangbaskoro]

Example for double discount in percentage:

Given a gross amount of Rp10000

The transaction have two discounts:

• discount #1: 20%
• discount #2: 10%

First, we're doing Rp10000 - 20%, so it would be Rp8000.
Then, the final amount would be Rp8000 - 10%, which is Rp7200.

This also applies with taxes, and multiple discounts and taxes.

[risangbaskoro]

Keeping an index of how many discounts or taxes has been applied would be helpful.

If it's the first index, the discount or tax will be calculated normally from gross amount. If it's not, calculate the discount or tax from the previous result of applied discount or tax.

[risangbaskoro]

Generally, taxes are applied after discounts are applied. By this nature, we can prevent $kasir->tax()->discount() to apply taxes before the discounts is applied.

We can approach this by reversing taxes, do the discount calculation for the gross_amount, and then reapply the taxes.