Validate a string with a regex -

i need write regular expression handle below constraints:

names can contain letters, numbers, hyphens (-), dollar signs, brackets ([ , ]), , underscores (_). single periods (.) allowed inside of internal name (abc.de), not @ beginning or end of internal name (.abc or def.). spaces , other special characters not listed here not supported.

i wrote this:

(^[^\.])([a-za-z0-9\.\$\[\]\_\-])*[^.] 

but still can put 1 sign like: ! or @ or %

^(?!\.)([a-za-z0-9\.\$\[\]\_\-])+(?<!\.)$ 

you need anchors .also [^\.] can accept other ..so lookaheads , lookbehinds advised.

see demo.

https://regex101.com/r/sj9gm7/78