Four rule statement with multiple criterias (Formula?, macro?, IDK??)

I need to create a formula for the following rules.
(Document attached)
help.xlsx

1)If previous months index is greater than the previous months (base + previous months max) then display previous months index.
If not then display previous months base

2)If previous months index is less than the previous months (base + previous months min)
Then display previous months index
If not then display previous months base

3)If previous months index is greater than the previous months ceiling
Then display ceiling
If not, then display either the index or base using rules #1 & #2

4)If previous months index is less than the previous months floor
Then display floor
If not, then display either the index or base using rules #1 & #2

F G H I J K L
Month Base Index Min Max Floor Ceiling
Jan 600 $622 -30 30 400 700
Feb $607 -30 30 400 700
Mar $609 -30 30 400 700
Apr $598 -30 30 400 700
May $575 -30 30 400 700
June $550 -30 30 400 700
July $800 -30 30 400 700
August $300 -30 30 400 700
September $450 -30 30 400 700
October $560 -30 30 400 700
November $570 -30 30 400 700

I have no idea where to start and any help would be appreciated

I could not figure out how to attach a new file but i pasted an example column below. The formula you provided doesn't provide the calculation I'm looking for but I appreciate it.




F G H I J K L
Month Base EXAMPLE ROW Index Min Max Floor Ceiling
Jan 600 600 $622 -30 30 400 700
Feb 600 $607 -30 30 400 700
Mar 600 $609 -30 30 400 700
Apr 600 $598 -30 30 400 700
May 600 $650 -30 30 400 700
June 650 $750 -30 30 400 700
July 700 $300 -30 30 400 700
August 400 $480 -30 30 400 700
September 480 $420 -30 30 400 700
October 420 $450 -30 30 400 700
November 420 $430 -30 30 400 700
December 420