/// <summary>
/// Add recipients to the <see cref="TransactionBuilder"/>.
/// </summary>
/// <param name="context">The context associated with the current transaction being built.</param>
/// <remarks>
/// Add outputs to the <see cref="TransactionBuilder"/> based on the <see cref="Recipient"/> list.
/// </remarks>
protected virtual void AddRecipients(TransactionBuildContext context)
{
if (context.Recipients.Any(a => a.Amount == Money.Zero))
{
throw new WalletException("No amount specified.");
}
if (context.Recipients.Any(a => a.SubtractFeeFromAmount))
{
throw new NotImplementedException("Substracting the fee from the recipient is not supported yet.");
}
foreach (Recipient recipient in context.Recipients)
{
context.TransactionBuilder.Send(recipient.ScriptPubKey, recipient.Amount);
}
}
/// <summary>
/// Find the next available change address.
/// </summary>
/// <param name="context">The context associated with the current transaction being built.</param>
protected void FindChangeAddress(TransactionBuildContext context)
{
if (context.ChangeAddress == null)
{
// If no change address is supplied, get a new address to send the change to.
context.ChangeAddress = this.walletManager.GetUnusedChangeAddress(new WalletAccountReference(context.AccountReference.WalletName, context.AccountReference.AccountName));
}
if (context.UseSegwitChangeAddress)
{
context.TransactionBuilder.SetChange(new BitcoinWitPubKeyAddress(context.ChangeAddress.Bech32Address, this.network).ScriptPubKey);
}
else
{
context.TransactionBuilder.SetChange(context.ChangeAddress.ScriptPubKey);
}
}
/// <inheritdoc />
public Transaction BuildTransaction(TransactionBuildContext context)
{
this.InitializeTransactionBuilder(context);
const int maxRetries = 5;
int retryCount = 0;
TransactionPolicyError[] errors = null;
while (retryCount <= maxRetries)
{
if (context.Shuffle)
{
context.TransactionBuilder.Shuffle();
}
Transaction transaction = context.TransactionBuilder.BuildTransaction(false);
if (context.Sign)
{
ICoin[] coinsSpent = context.TransactionBuilder.FindSpentCoins(transaction);
// TODO: Improve this as we already have secrets when running a retry iteration.
this.AddSecrets(context, coinsSpent);
context.TransactionBuilder.SignTransactionInPlace(transaction);
}
if (context.TransactionBuilder.Verify(transaction, out errors))
{
return(transaction);
}
// Retry only if error is of type 'FeeTooLowPolicyError'
if (!errors.Any(e => e is FeeTooLowPolicyError))
{
break;
}
retryCount++;
}
string errorsMessage = string.Join(" - ", errors.Select(s => s.ToString()));
this.logger.LogError($"Build transaction failed: {errorsMessage}");
throw new WalletException($"Could not build the transaction. Details: {errorsMessage}");
}
/// <summary>
/// Find all available outputs (UTXO's) that belong to <see cref="WalletAccountReference.AccountName"/>.
/// Then add them to the <see cref="TransactionBuildContext.UnspentOutputs"/>.
/// </summary>
/// <param name="context">The context associated with the current transaction being built.</param>
protected void AddCoins(TransactionBuildContext context)
{
context.UnspentOutputs = this.walletManager.GetSpendableTransactionsInAccount(context.AccountReference, context.MinConfirmations).ToList();
if (context.UnspentOutputs.Count == 0)
{
throw new WalletException("No spendable transactions found.");
}
// Get total spendable balance in the account.
long balance = context.UnspentOutputs.Sum(t => t.Transaction.Amount);
long totalToSend = context.Recipients.Sum(s => s.Amount);
if (balance < totalToSend)
{
throw new WalletException("Not enough funds.");
}
Money sum = 0;
var coins = new List <Coin>();
if (context.SelectedInputs != null && context.SelectedInputs.Any())
{
// 'SelectedInputs' are inputs that must be included in the
// current transaction. At this point we check the given
// input is part of the UTXO set and filter out UTXOs that are not
// in the initial list if 'context.AllowOtherInputs' is false.
Dictionary <OutPoint, UnspentOutputReference> availableHashList = context.UnspentOutputs.ToDictionary(item => item.ToOutPoint(), item => item);
if (!context.SelectedInputs.All(input => availableHashList.ContainsKey(input)))
{
throw new WalletException("Not all the selected inputs were found on the wallet.");
}
if (!context.AllowOtherInputs)
{
foreach (KeyValuePair <OutPoint, UnspentOutputReference> unspentOutputsItem in availableHashList)
{
if (!context.SelectedInputs.Contains(unspentOutputsItem.Key))
{
context.UnspentOutputs.Remove(unspentOutputsItem.Value);
}
}
}
foreach (OutPoint outPoint in context.SelectedInputs)
{
UnspentOutputReference item = availableHashList[outPoint];
coins.Add(new Coin(item.Transaction.Id, (uint)item.Transaction.Index, item.Transaction.Amount, item.Transaction.ScriptPubKey));
sum += item.Transaction.Amount;
}
}
foreach (UnspentOutputReference item in context.UnspentOutputs
.OrderByDescending(a => a.Confirmations > 0)
.ThenByDescending(a => a.Transaction.Amount))
{
if (context.SelectedInputs?.Contains(item.ToOutPoint()) ?? false)
{
continue;
}
// If the total value is above the target
// then it's safe to stop adding UTXOs to the coin list.
// The primary goal is to reduce the time it takes to build a trx
// when the wallet is bloated with UTXOs.
// Get to our total, and then check that we're a little bit over to account for tx fees.
// If it gets over totalToSend but doesn't hit this break, that's fine too.
// The TransactionBuilder will have a go with what we give it, and throw NotEnoughFundsException accurately if it needs to.
if (sum > totalToSend + PretendMaxFee)
{
break;
}
coins.Add(new Coin(item.Transaction.Id, (uint)item.Transaction.Index, item.Transaction.Amount, item.Transaction.ScriptPubKey));
sum += item.Transaction.Amount;
}
// All the UTXOs are added to the builder without filtering.
// The builder then has its own coin selection mechanism
// to select the best UTXO set for the corresponding amount.
// To add a custom implementation of a coin selection override
// the builder using builder.SetCoinSelection().
context.TransactionBuilder.AddCoins(coins);
}
/// <inheritdoc />
public Money EstimateFee(TransactionBuildContext context)
{
this.InitializeTransactionBuilder(context);
return(context.TransactionFee);
}