What would be a way to assign a code word inside a contract (such as a promotional / coupon style code word) so that you could let people know "send this message/code word to this contract address and it will issue out a token".
The use case is during certain times of the week (say between 1pm and 2pm on Wednesday) I'd like to issue a code word, which friends would then send this code word to the contract, and it will issue out a token for them.
Double points for help with creating a timing regulation within the contract that's editable at a later date (eg I can set this week's code word to be valid between X and Y time on Wednesday).
Thank you.