Renaming files (jpg) in the folders to sequential numbers order starting with 1 in every folder

sequential_rename.applescript

set text item delimiters to "."
tell application "Finder"
	set the_folder to choose folder
	set the_subfolders to every folder in the_folder
	repeat with index from 1 to the count of the_subfolders
		set this_folder to item index of the_subfolders
		set img_files to (every file in this_folder whose name ends with ".jpg")
		repeat with indexf from 1 to (the count of img_files)
			set this_file to item indexf of img_files
			set file_name_count to text items of (get name of this_file)
			
			if number of file_name_count is 1 then
				set file_extension to ""
			else
				set file_extension to "." & item -1 of file_name_count
			end if
			
			set the name of this_file to indexf & file_extension as string
		end repeat
	end repeat
end tell