import type { Transaction } from "@solana/web3.js";

function shortvecEncodeLength(bytes: Array<number>, len: number) {
  let rem_len = len;
  for (;;) {
    let elem = rem_len & 0x7f;
    rem_len >>= 7;
    if (rem_len === 0) {
      bytes.push(elem);
      break;
    } else {
      elem |= 0x80;
      bytes.push(elem);
    }
  }
}

/**
 * Calculates transaction size. If the transaction is too large, it does not throw.
 * @param tx
 * @returns
 */
export const calculateTxSizeUnsafe = (tx: Transaction): number => {
  // check if fee payer signed.
  const { feePayer } = tx;
  const hasFeePayerSigned =
    feePayer && tx.signatures.find((s) => s.publicKey.equals(feePayer));
  const signData = tx.serializeMessage();
  const numSigners = tx.signatures.length + (hasFeePayerSigned ? 1 : 0);
  const signatureCount: number[] = [];
  shortvecEncodeLength(signatureCount, numSigners);
  return signatureCount.length + numSigners * 64 + signData.length;
};