Include character in regex only if another character is there

I have this regular expression for finding time:

/ (\[|\(|)([0-1]?[0-9]|2[0-3])(:)[0-5][0-9](:[0-5][0-9])?(( ?am| ?pm|))(\]|\)|)/gi

Currently, it correctly identifies:

11:32
11:32 am
11:32 Am
11:32 AM
(11:32)
[11:32 am]

The only thing that doesn’t work is that it includes the right bracket even if the left bracket is not there, for example it would include:

11:32) 

Which I don’t want.

How can I solve this issue?

>Solution :

I’ve "simplified" your question to match:

x
(x)
[x]

while ignoring:

x)
x]
(x
[x
[x)
(x]

I’ve come up with the following:

(?:^(?:(?=[^)\]]+$)|\[(?=.*\]$)|\((?=.*\)$)))x[)\]]?$

See regex101‘s demo, and Debuggex‘s diagram:

A tad hairy!