Arabic letter replacment

[hu ma]

Hi,
I need to do some search and replace in arabic sentences.
Which is maybe hard to explain, I don’t know if the arabic characters will show to your screen, but I’m gonna say it anyway.

Arabic words are sometimes attached sometimes deattached, depending on the word it self. Different forms but one letter

For example we will take the letter س
*In the begaining of the word initial form ﺳ
Example سوف
*In the middle of the word form ﺴ
Example حسن
*In the end of the word attached form ﺲ
Example ليس
*In the end of the word isolated form ﺱ
Example ناس
*In the middle of the word but again in initial form ﺳ
Example ناسي

All these form are witten with one key by the keyboard which is ﺱ . The isolated form.

What i want to do is replace each form of the letter with different letter,
Let’s say

Form ﺳ replaced with a

Form ﺴ replaced with b

Form ﺲ replaced with c

Form ﺱ replaced with d

How can this be possible?

[hu ma]

Well, it appears that i have to convert the hole text with Arabic presentation form-b coding in order to achieve what I want, luckly I found a tool to do that for me, also i have to reverse the text RTL, which is not hard to do.