find and replace - Script for modifying file content in specified files

I tried searching previous questions but none worked, or I couldn't adapt them to my needs.

I want to write a script that asks for:

• folder


• criteria


• old string


• new string

And replace every file in the specified folder and subfolders (and force user to type one) with specific criteria (for example, it must be a ".cue" file), and:

1. If the file is read-only, disable it.


2. Search for specified old string in the file content and replace it with new string , and save changes in same file.


3. If the file was read-only, enable it again.

I have this code so far, but I don't know what to do in the do part:

@echo off 

setLocal enableDELAYedexpansion

:START
set "var2="
set /P var2="type folder "

if "%var2%"=="" goto ERROR

set /p old="old string ? "
set /p new="new string ? "
set /p files="what criteria ? "
echo modifying files...

for /r "%var2%" %%v in (%%files) do (

???

)
pause

goto START

:ERROR
echo type something!!
goto START