Tolerates discrepancies in the swap amount crosschecks. To ensure we
calculate the send/receive amounts correctly we apply a check, using
amount inversion. The inversion is not exact up to +-1 due to used
floor and ceil functions in the methods. They are not invertible,
which is why we relax the check to off-by-ones.
- document SwapManager._get_recv_amount and SwapManager._get_send_amount
- change calculations so that they match the boltz-backend
- note that in the reverse swap case, the server does not care about the on-chain claim tx the client
needs to pay for. This introduced some implicit hacks and inconsistencies in the code in the past,
it is still a bit ugly but at least this is now explicit.
- SwapManager._get_recv_amount and SwapManager._get_send_amount are now proper inverses of each other
-----
Here are some code snippets to play around with in Qt console.
For the forward swap case:
```
from electrum import ecc; lnworker = wallet.lnworker; sm = lnworker.swap_manager
invoice = network.run_from_another_thread(lnworker.create_invoice(amount_msat=3000000*1000, message="swap", expiry=86400))[1]; request_data = {"type": "submarine", "pairId": "BTC/BTC", "orderSide": "sell", "invoice": invoice, "refundPublicKey": ecc.GENERATOR.get_public_key_bytes().hex()}
network.send_http_on_proxy('post', sm.api_url + '/createswap', json=request_data, timeout=30)
sm.get_send_amount(3000000, is_reverse=False)
sm.get_recv_amount(3026730, is_reverse=False)
```
For the reverse swap case:
```
from electrum import ecc; import os; lnworker = wallet.lnworker; sm = lnworker.swap_manager
request_data = {"type": "reversesubmarine", "pairId": "BTC/BTC", "orderSide": "buy", "invoiceAmount": 3000000, "preimageHash": os.urandom(32).hex(), "claimPublicKey": ecc.GENERATOR.get_public_key_bytes().hex()}
network.send_http_on_proxy('post', sm.api_url + '/createswap', json=request_data, timeout=30)
sm.get_recv_amount(3000000, is_reverse=True)
sm.get_send_amount(2974443, is_reverse=True)
```
In a normal (forward) swap (onchain->offchain):
send_amount = receive_amount * (1 + service_percentage) + normal_fee ,
and vice versa:
receive_amount = (send_amount + normal_fee) / (1 + service_percentage) ,
i.e., the service fee is charged on the received offchain amount.
ThomasV
SomberNight
bitromortac