// AddOutput adds a standard pay to public key hash output to a payment transaction.
func (p *Payment) AddOutput(addrHash []byte, value uint64) error {
s, err := script.PayToPubKeyHash(addrHash)
if err != nil {
return err
}
p.tx.AddOutput(&messages.TxOutput{
Value: value,
Script: s,
})
return nil
}
// AddInputsAndFee to payment adds spendable inputs from the account until
// the value of the inputs matches or surpases the outputs. If the inputs
// become larger than the outputs, a change output from the account is added.
// No more outputs should be added after calling this.
func (p *Payment) AddInputsAndFee(fee uint64) error {
a := p.account
required := fee
for _, outs := range p.tx.Outputs {
required += outs.Value
}
// Get a list of unspent outputs that this account can spend.
spendables := a.SpendableOutputs()
count := duplicateCountNeeded(spendables, required)
if count <= 0 {
return fmt.Errorf("No enough funds to send: %d", required)
}
for i := 0; i < count; i++ {
// Make a new copy of the transaction we've set up so far,
// including all outputs.
tx := *p.tx
// Add inputs to transaction until it has enough.
var total uint64
for _, spend := range spendables {
// For payments from multiple unconfirmed duplicates
// we're assuming we only need splits from a single
// duplicated transactions. If we end up using splits
// from more than one, we'll be in a situation where we
// rely on the splits with the same "index" gets
// confirmed for all duplicated transactions.
index := 0
if len(spend.outputs) > 1 {
index = i
}
output := spend.outputs[index]
total += output.Value
tx.AddInput(&messages.TxInput{
PreviousOutput: &messages.OutPoint{
Hash: []byte(output.TxHash()),
Index: output.Index(),
},
Sequence: 0xffffffff,
// Temporarily store the subscript needed to
// sign tx in signature.
Signature: output.Script,
})
// Add keys in same order as inputs are added. This is
// a bit hacky, but works since we control the order
// the transactions are signed.
p.keys = append(p.keys, spend.key)
if total >= required {
break
}
}
if total > required {
// Add change output for the excess satoshis.
s, err := script.PayToPubKeyHash(a.NextChangeAddress())
if err != nil {
return fmt.Errorf("Failed to add change output: %v", err)
}
tx.AddOutput(&messages.TxOutput{
Value: total - required,
Script: s,
})
}
// Append completed transaction to list.
p.transactions = append(p.transactions, &tx)
}
return nil
}