linux script(for loop) as below formate, this script needs to run daily Eg:1 Actual file

In a source directory, i have 200 files those files i have to rename using linux script(for loop) as below formate, this script needs to run daily Eg:1 Actual file name : abcd.071220.dat Rename files like : Apple_abcd_071220.dat Eg:2 Actual file name : xyz.071220.dat