Case nestled inside another case

Question

I’m very doubtful about CASE NESTED I have to perform an interest calculation that depends on some variables and I’m not able to build this case, so I need your help to assemble it.

1º IF GETDATE()-1 is a minor (<) that E1_VENCREA the code must stop and put the value ZERO ( 0 ) because you still have time to pay, otherwise you should continue to SECOND QUESTION.

---

2º If the result of FIRST QUESTION for FALSE (meaning greater) should be verified whether CONVERT(VARCHAR,CONVERT(DATETIME, E1_BAIXA),103 is different (<>) of '01/01/1900'.

---

3º If the result of SECOND QUESTION for TRUE another check shall be made whether CONVERT(VARCHAR,CONVERT(DATETIME, E1_BAIXA),103) is larger (>) that CONVERT(VARCHAR,CONVERT(DATETIME,E1_VENCREA),103)

---

4º If the result of THIRD QUESTION for TRUE perform the following calculation SUM((E1_PORCJUR/100)*BALANCE)*DATEDIFF(DAY,E1_BAIXA,GETDATE())) if the THIRD QUESTION for PHONY perform that other calculation SUM(((E1_PORCJUR/100)*BALANCE)*DATEDIFF(DAY,E1_VENCREA,GETDATE()))

---

5th Now here goes back to the end of the SECOND QUESTION if he goes PHONY perform the following calculation SUM(((E1_PORCJUR/100)*BALANCE)*DATEDIFF(DAY,E1_VENCREA,GETDATE()))

---

6th Ready! Now the questions are over, just name the column with the name of INTEREST.

---

DATABASE IS SQL SERVER, TABLE STRUCTURE HERE DOWNLOAD DROPBOX TABLES