Problems in `spend_from_wallet`

[KnowWhoami]

• [ ] Take fee_rate instead of fee:

  • fee is always calculated from fee_rate & weight of tx and that's done after the creation of tx -> thus it's rational to take fee_rate instead of fee in the parameters.

• [ ] check whether it's feasible to spend given amount.

  • when send_amount= SendAmount::Amount , then we directly consider the given amount as utxo output value and we do not check whether it's feasible to send that amount or not.

  • If the change amount i.e (remaining= total_input_value- fee-amount - amount) > minimal_dust_amt -> then a change utxo is created while deducting fee from remaining.

  • But there are two edges :

  amount ~= total_input_value && amount> total_input_value:

  • created utxo value= amount even if it is practically not possible to do so.
  • 1'st case: remaining < minimal_dust_amt -> no fee deducted.
  • 2'nd case -> (total_input_value < amount) -> panic occurs due to overflow

[mojoX911]

Take fee_rate instead of fee:

Probably better to just to stick with fee. Refer https://github.com/citadel-tech/coinswap/pull/244#discussion_r1751555639

Rest are good fixes.