public async Task <(IBitcoinBasedTransaction, byte[])> CreateSwapPaymentTxAsync(
BitcoinBasedCurrency currency,
long amount,
IEnumerable <string> fromWallets,
string refundAddress,
string toAddress,
DateTimeOffset lockTime,
byte[] secretHash,
int secretSize,
ITxOutputSource outputsSource)
{
var availableOutputs = (await outputsSource
.GetAvailableOutputsAsync(fromWallets)
.ConfigureAwait(false))
.ToList();
if (!availableOutputs.Any())
{
throw new Exception($"Insufficient funds. Available 0.");
}
var feeInSatoshi = 0L;
ITxOutput[] selectedOutputs = null;
for (var i = 1; i <= availableOutputs.Count; ++i)
{
selectedOutputs = availableOutputs
.Take(i)
.ToArray();
var estimatedSigSize = BitcoinBasedCurrency.EstimateSigSize(selectedOutputs);
var selectedInSatoshi = selectedOutputs.Sum(o => o.Value);
if (selectedInSatoshi < amount) // insufficient funds
{
continue;
}
var maxFeeInSatoshi = selectedInSatoshi - amount;
var estimatedTx = currency
.CreateHtlcP2PkhScriptSwapPaymentTx(
unspentOutputs: selectedOutputs,
aliceRefundAddress: refundAddress,
bobAddress: toAddress,
lockTime: lockTime,
secretHash: secretHash,
secretSize: secretSize,
amount: amount,
fee: maxFeeInSatoshi,
redeemScript: out _);
var estimatedTxVirtualSize = estimatedTx.VirtualSize();
var estimatedTxSize = estimatedTxVirtualSize + estimatedSigSize;
var estimatedTxSizeWithChange = estimatedTxVirtualSize + estimatedSigSize + BitcoinBasedCurrency.OutputSize;
var estimatedFeeInSatoshi = (long)(estimatedTxSize * currency.FeeRate);
if (estimatedFeeInSatoshi > maxFeeInSatoshi) // insufficient funds
{
continue;
}
var estimatedChangeInSatoshi = selectedInSatoshi - amount - estimatedFeeInSatoshi;
// if estimated change is dust
if (estimatedChangeInSatoshi >= 0 && estimatedChangeInSatoshi < currency.GetDust())
{
feeInSatoshi = estimatedFeeInSatoshi + estimatedChangeInSatoshi;
break;
}
// if estimated change > dust
var estimatedFeeWithChangeInSatoshi = (long)(estimatedTxSizeWithChange * currency.FeeRate);
if (estimatedFeeWithChangeInSatoshi > maxFeeInSatoshi) // insufficient funds
{
continue;
}
var esitmatedNewChangeInSatoshi = selectedInSatoshi - amount - estimatedFeeWithChangeInSatoshi;
// if new estimated change is dust
if (esitmatedNewChangeInSatoshi >= 0 && esitmatedNewChangeInSatoshi < currency.GetDust())
{
feeInSatoshi = estimatedFeeWithChangeInSatoshi + esitmatedNewChangeInSatoshi;
break;
}
// if new estimated change > dust
feeInSatoshi = estimatedFeeWithChangeInSatoshi;
break;
}
if (selectedOutputs == null || feeInSatoshi == 0L)
{
throw new Exception($"Insufficient funds. Available {availableOutputs.Sum(o => o.Value)}");
}
var tx = currency
.CreateHtlcP2PkhScriptSwapPaymentTx(
unspentOutputs: selectedOutputs,
aliceRefundAddress: refundAddress,
bobAddress: toAddress,
lockTime: lockTime,
secretHash: secretHash,
secretSize: secretSize,
amount: amount,
fee: feeInSatoshi,
redeemScript: out var redeemScript);
return(tx, redeemScript);
}
public async Task <IBitcoinBasedTransaction> CreateSwapPaymentTxAsync(
BitcoinBasedCurrency currency,
ClientSwap swap,
IEnumerable <string> fromWallets,
string refundAddress,
string toAddress,
DateTimeOffset lockTime,
byte[] secretHash,
int secretSize,
ITxOutputSource outputsSource)
{
var availableOutputs = (await outputsSource
.GetAvailableOutputsAsync(currency, fromWallets)
.ConfigureAwait(false))
.ToList();
var fee = 0L;
var orderAmount = (long)(AmountHelper.QtyToAmount(swap.Side, swap.Qty, swap.Price) *
currency.DigitsMultiplier);
var requiredAmount = orderAmount + fee;
long usedAmount;
IList <ITxOutput> usedOutputs;
IBitcoinBasedTransaction tx;
do
{
usedOutputs = availableOutputs
.SelectOutputsForAmount(requiredAmount)
.ToList();
usedAmount = usedOutputs.Sum(o => o.Value);
if (usedAmount < requiredAmount)
{
throw new Exception($"Insufficient funds. Available {usedAmount}, required {requiredAmount}");
}
var estimatedSigSize = EstimateSigSize(usedOutputs);
tx = currency.CreateHtlcP2PkhSwapPaymentTx(
unspentOutputs: usedOutputs,
aliceRefundAddress: refundAddress,
bobAddress: toAddress,
lockTime: lockTime,
secretHash: secretHash,
secretSize: secretSize,
amount: orderAmount,
fee: fee);
var txSize = tx.VirtualSize();
fee = (long)(currency.FeeRate * (txSize + estimatedSigSize));
requiredAmount = orderAmount + fee;
} while (usedAmount < requiredAmount);
tx = currency.CreateHtlcP2PkhSwapPaymentTx(
unspentOutputs: usedOutputs,
aliceRefundAddress: refundAddress,
bobAddress: toAddress,
lockTime: lockTime,
secretHash: secretHash,
secretSize: secretSize,
amount: orderAmount,
fee: fee);
return(tx);
}