Function createCoinPsbt

src/btc/btc-coin-tx.ts:7–59

(
  privateKey: ECPairInterface,
  utxos: IUtxo[],
  to: ISendToAddress[],
  change: string, // Change address
  network: bitcoin.Network,
  fee = 1000 // Assume a fee of 1000
)

// Create a transaction to pay any number of addresses using P2WPKH or P2TR UTXOs
export function createCoinPsbt(
  privateKey: ECPairInterface,
  utxos: IUtxo[],
  to: ISendToAddress[],
  change: string, // Change address
  network: bitcoin.Network,
  fee = 1000 // Assume a fee of 1000
) {
  const psbt = new bitcoin.Psbt({network});
  const totalInput = addPsbtPayUtxos(privateKey, psbt, utxos, network);

  // Send all to one address
  if (to.length === 1 && Number(to[0]!.amount) === totalInput) {
    const value = totalInput - fee;
    if (value < MIN_SATOSHIS) {
      throw new Error("Insufficient fund");
    }
    psbt.addOutput({
      address: to[0]!.address,
      value: value,
    });
  } else {
    let totalOutput = 0;
    for (const item of to) {
      psbt.addOutput({
        address: item.address,
        value: Number(item.amount),
      });
      totalOutput += Number(item.amount);
    }

    const value = totalInput - totalOutput - fee;
    if (value < 0) throw new Error("NoFund");
    if (value > MIN_SATOSHIS) {
      psbt.addOutput({
        address: change,
        value: value,
      });
    }
  }

  // Sign each input
  for (let i = 0; i < psbt.inputCount; i++) {
    const privateKeyWif = utxos[i]?.privateKeyWif;
    if (privateKeyWif) {
      signPsbtInput(ECPair.fromWIF(privateKeyWif, network), psbt, i);
    } else {
      signPsbtInput(privateKey, psbt, i);
    }
  }
  psbt.finalizeAllInputs();
  return psbt.extractTransaction();
}