SQL Server 2012 :: Create A Function That Take A Value And Run Some Logic And Output The Value?

I would like to create a function that take a value and run some logic and output the value

I have a table like this

Table A
value
*
001
004.00
3.0
1.22

Logic I want to run is

The value that you are passing is numeric and numeric with only decimal 0 value, and then convert it to integer otherwise leave as it is

So if I run a query something like this

Select value, fn_convertointerger(value) as converted_value from TableA

I will get

Value converted_value
* *
001 1
004.00 4
3.0 3
1.22 1.22
2.02 2.02
4.000 4
Jkil& Jkil&

How can I create a function like this to convert specific numeric value?