Is it possible to perform sequential row calculations in presto sql? - sql

Question

I have user_cost information and hourly discount information.
I am trying to get the below result using below two tables.
The discount_per_time is applied every time of user_cost, and the users of the same time shares the discount.
Discounts are applied sequentially for each row, and are performed until no more discounts are available.
I thought it would be possible using presto's window function, so I tried it for a few days but couldn't do it. Can I create the below result through query?
table: user_cost
time user_id cost
1 aaa 20
1 bbb 5
2 aaa 11
2 bbb 5
3 aaa 15
4 aaa 1
4 bbb 1
table: discount_per_time
discount_id cost
d-1 10
d-2 5
RESULT:
time user_id type cost discount_id discounted_cost
1 aaa discount d-1 10
1 aaa discount d-2 5
1 aaa usage 5
1 bbb usage 5
2 aaa discount d-1 10
2 aaa discount d-2 1
2 bbb discount d-2 4
2 bbb usage 1
3 aaa discount d-1 10
3 aaa discount d-2 5
4 aaa discount d-1 1
4 bbb discount d-1 1
+ add:
You should be able to see which discounts apply to which users and how much per time.
The discounted_cost per time cannot be greater than the usage cost and the discountable cost.
If all of the cost of the time is discounted, "usage" is not displayed (instead, the value before discount can be inferred through discounted_cost).
e.g.
User 'aaa' uses a cost of 20 and user 'bbb' uses a cost of 5 in a time.
Both the 10 discount of d-1 and the 5 discount of d-2 are applied to aaa, so the final cost of aaa becomes 5. All discounts are applied to aaa, so the final cost of bbb is still 5.
aaa uses 11 and bbb uses 5. d-1 gives aaa a discount of 10, d-2 gives a discount of 1 so aaa does not charge. 4 out of 5 of d-2 left. This can be applied to bbbs. So the final cost of bbb is 1.
When both users' cost is 1, those are discounted by using only 2 out of 10 of d-1. There is no final usage for both users.