Per Wallet Implementation: transfer with crypto fee spanning multiple lots with FIFO fails

[macanudo527]

We are currently working on the per wallet implementation PR #138

Since there are a lot of complicated issues in the two threads that already exist, I thought I would post something separate here. I wrote this test:

            # Test for transfer with crypto fee spanning multiple lots with FIFO
            _Test(
                description="Transfer with crypto fee spanning multiple lots (FIFO)",
                input=[
                    InTransactionDescriptor("1", 1, 1, "Coinbase", "Bob", 100, 5),
                    InTransactionDescriptor("2", 2, 2, "Coinbase", "Bob", 110, 3),
                    # Send 4 BTC with 3 BTC fee = 7 total, spans both lots with FIFO
                    IntraTransactionDescriptor("3", 3, 3, "Coinbase", "Bob", "Kraken", "Bob", 120, 7, 4),
                ],
                want_per_wallet_transactions={
                    Account("Coinbase", "Bob"): [
                        InTransactionDescriptor("1", 1, 1, "Coinbase", "Bob", 100, 5, 
                            to_lot_unique_ids={Account("Kraken", "Bob"): ["3/-1"]}),
                        InTransactionDescriptor("2", 2, 2, "Coinbase", "Bob", 110, 3, 
                            to_lot_unique_ids={Account("Kraken", "Bob"): ["3/-2"]}),
                        IntraTransactionDescriptor("3", 3, 3, "Coinbase", "Bob", "Kraken", "Bob", 120, 7, 4),
                    ],
                    Account("Kraken", "Bob"): [
                        InTransactionDescriptor("3/-1", 3, -1, "Kraken", "Bob", 100, 4, 
                            from_lot_unique_id="1", cost_basis_day=1),
                        # Note: With fee, only 4 BTC received but 7 BTC sent (5 from lot 1, 2 from lot 2)
                        # FIFO takes from lot 1 first for the 4 BTC received
                    ],
                },
                want_amounts={
                    Account(exchange='Coinbase', holder='Bob'): {'1': 0, '2': 1},
                    Account(exchange='Kraken', holder='Bob'): {},
                },
                want_error="",
            ), 

It fails because the current resolver attempts to take the fee out of the last lot only and doesn't account for splitting across lots. As you can see in the following lines:

rp2/src/rp2/transfer_analyzer.py

Lines 290 to 321 in 046dfe9

	while True:
	current_in_lot_and_amount = self.__transfer_semantics.seek_non_exhausted_acquired_lot(
	from_per_wallet_transactions.in_transactions, transaction.crypto_received
	)
	if current_in_lot_and_amount is None:
	raise RP2ValueError(
	f"Insufficient balance on {from_account} to send funds (amount {amount_left_to_transfer + fee} {transaction.asset}): {transaction}"
	)
	original_actual_amounts[current_in_lot_and_amount.acquired_lot] = current_in_lot_and_amount.amount
	if current_in_lot_and_amount.amount >= amount_left_to_transfer + fee:
	# Pay the fee only in the last lot.
	self._process_remaining_transfer_amount(
	wallet_2_per_wallet_transactions,
	current_in_lot_and_amount,
	transaction,
	amount_left_to_transfer,
	fee,
	)
	if transaction.is_self_transfer():
	from_per_wallet_transactions.in_transactions.reset_partial_amounts(self.__transfer_semantics, original_actual_amounts)
	break
	self._process_remaining_transfer_amount(
	wallet_2_per_wallet_transactions,
	current_in_lot_and_amount,
	transaction,
	current_in_lot_and_amount.amount,
	ZERO,
	)
	amount_left_to_transfer -= current_in_lot_and_amount.amount
	else:
	raise RP2ValueError(f"Internal error: invalid transaction class: {transaction}")

I think this can be fixed by tracking both the remaining amount of the transfer and remaining amount of the fee. I tried to fix it, but I might not have the time. If anyone could help it would be much appreciated.

[macanudo527]

@eprbell
Is this test correct? I just want to double-check before spending more time on it. Tks.

[jayr0d]

I am in the middle of some serious work stuff at the moment. Not sure when I can get around to it, or if I can even help, but I will try once I can.

Are you still working out of https://github.com/eprbell/rp2/tree/per_wallet_application or do you have your own branch with some changes?

[eprbell]

I can confirm that unfortunately I won't have much time to work on this (and on RP2 in general) for the foreseeable future, due to heavy workload at my job. I don't think I'll be able to get any free cycles before Tax Day.

All the work done so far is on this is at #138

[jayr0d]

@macanudo527 can you push your work in progress changes into a branch so I can try to look into this further?