Rename a JPG, a PSD and a CR2 file having the same filename to a new same-filename

Question

Hello,
The question is regarding my archives that I need to re-name.
Say within a folder I have:
IMG_4146.JPG
IMG_4147.JPG
IMG_4147.CR2
IMG_4147.PSD
IMG_4148.JPG
IMG_4149.JPG
I wish to rename the above as
IMG_4146.JPG  becomes 2000.JPG
IMG_4147.JPG  becomes 2001.JPG
IMG_4147.CR2  becomes 2001.CR2
IMG_4147.PSD  becomes 2001.PSD
IMG_4148.JPG  becomes 2002.JPG
IMG_4149.JPG  becomes 2003.JPG
and so on..
Basically, can I get Bridge to rename all files with the same filename but different extensions, to a new filename which is also the same. As of now I rename all the JPG files in a folder sequentially, and then manually change the filename of the CR2 and PSD files to match to the filename of their JPG versions.
Note that every JPG does not have a corresponding CR2 and PSD. Hence I cannot use the sequential filename feature to rename the CR2 and PSD files.
Hope I've been clear in explaining what I need. And many thanks in advance for any help

Answer 1

Ah, I was in a bit of a rush this morning, the scipt should have decremented the number by 2146 in the filename.
This should do the same but remove the characters before the numbers giving a numeric filename only...
#target bridge
var sels = app.document.selections;
for(var a in sels){
sels[a].spec.rename(sels[a].name.replace(/\d{4}/,sels[a].name.match(/(.{4})(\d{4})/)[2]-2146).replace(/^.{4}/,''));