// Collects up to maxTotal coins of tx outs between minInput and maxInput coins in size.
// - inMPK: Set inMPK to hotMPK to move funds offline from the hot wallet.
// - minInput, maxInput: Range of permittable input transaction sizes.
// - maxTotal: Maximum amount of coins to collect.
// NOTE: should be deterministic, because of dryRun options.
func CollectSweepInputs(coin string, inMPK *bitcoin.MPK, minInput, maxInput, maxTotal uint64, maxNumInputs int) ([]*bitcoin.Payment, uint64, error) {
reqHeight := bitcoin.ReqHeight(coin)
if minInput < bitcoin.MinerFee(coin) {
return nil, 0, NewError("minInput must be at least as large as the miner fee for %v: %v", coin, maxMinerFeeForCoin(coin))
}
// Gather oldest spendable inputs in range until maxTotal.
candidates := bitcoin.LoadOldestSpendablePaymentsBetween(inMPK.Id, coin, minInput, maxInput, maxNumInputs, reqHeight)
inputs := []*bitcoin.Payment{}
total := uint64(0)
for _, payment := range candidates {
if total+payment.Amount > maxTotal {
continue
}
total += payment.Amount
inputs = append(inputs, payment)
}
// total must meet some threshold for sweep to be worth it.
if total < maxMinerFeeForCoin(coin) {
return nil, 0, NewError("Could not gather enough inputs. Needed at least %v, only got %v", maxMinerFeeForCoin(coin), total)
}
return inputs, total, nil
}
// Finds payments & constructs transaction to satisfy the given output amounts.
// This function could fail, in which case we'll call it again later.
// This means that this function should be largely side-effect free.
// However, note that 'outputs' may be modified to account for
// fees & change addresses.
func ComputeWithdrawalTransaction(coin string, outputs map[string]uint64) (string, []*bitcoin.Payment, uint64, string, error) {
returnErr := func(err error) (string, []*bitcoin.Payment, uint64, string, error) { return "", nil, 0, "", err }
reqHeight := bitcoin.ReqHeight(coin)
payments := []*bitcoin.Payment{}
changeAddress := createNewChangeAddress(coin)
sumAmount := int64(0)
for _, amount := range outputs {
sumAmount += int64(amount)
}
// Add base fees to sumAmount. Be generous, we'll adjust later.
sumAmount += int64(bitcoin.MinerFee(coin)) * MAX_BASE_FEES
sumAmountCopy := sumAmount
// Then load payments greater than remainder
for sumAmountCopy > 0 {
// We shouldn't use too many inputs.
if len(payments) > len(outputs)*2 {
return returnErr(NewError("[%v] Too many inputs required for %v", coin, sumAmount))
}
// Try to do it with one input
payment := bitcoin.LoadSmallestSpendablePaymentGreaterThan(hotMPK.Id, coin, uint64(sumAmountCopy), reqHeight, payments)
if payment == nil {
// Try to fill it as much as possible
payment = bitcoin.LoadLargestSpendablePaymentLessThan(hotMPK.Id, coin, uint64(sumAmountCopy), reqHeight, payments)
}
if payment == nil {
return returnErr(NewError("[%v] Unable to gather enough inputs for %v", coin, sumAmount))
}
sumAmountCopy -= int64(payment.Amount)
payments = append(payments, payment)
}
// If we need to create a change address, do so.
if sumAmountCopy != 0 {
outputs[changeAddress] = uint64(-1 * sumAmountCopy)
}
// Adjust miner fees & collect private keys
privKeys := map[string]string{}
minerFee, err := adjustMinerFee(coin, payments, outputs, changeAddress, privKeys)
if err != nil {
return returnErr(err)
}
// Sign transaction
s := rpc.CreateSignedRawTransaction(coin, bitcoin.ToRPCPayments(payments), outputs, privKeys)
return s, payments, minerFee, changeAddress, nil
}
func maxMinerFeeForCoin(coin string) uint64 {
return uint64(bitcoin.MinerFee(coin)) * MAX_BASE_FEES
}