import re
s = "I want to get [samsung](brand) within [1 week](duration) to be happy.";
print(re.split(r'⦅([^⦅⦆]+)⦆', re.sub(r'\[([^][]*)]\(([^()]*)\)', r'⦅\1:\2⦆', s)))
aW1wb3J0IHJlCnMgPSAiSSB3YW50IHRvIGdldCBbc2Ftc3VuZ10oYnJhbmQpIHdpdGhpbiBbMSB3ZWVrXShkdXJhdGlvbikgdG8gYmUgaGFwcHkuIjsKcHJpbnQocmUuc3BsaXQocifvvZ8oW17vvZ/vvaBdKynvvaAnLCByZS5zdWIocidcWyhbXl1bXSopXVwoKFteKCldKilcKScsIHIn772fXDE6XDLvvaAnLCBzKSkp