bitcoinjs-lib/ts_src/templates/scripthash/input.ts

// <scriptSig> {serialized scriptPubKey script}

import * as bscript from '../../script';
import * as p2ms from '../multisig';
import * as p2pk from '../pubkey';
import * as p2pkh from '../pubkeyhash';
import * as p2wpkho from '../witnesspubkeyhash/output';
import * as p2wsho from '../witnessscripthash/output';

export function check(
  script: Buffer | Array<number | Buffer>,
  allowIncomplete?: boolean,
): boolean {
  const chunks = bscript.decompile(script)!;
  if (chunks.length < 1) return false;

  const lastChunk = chunks[chunks.length - 1];
  if (!Buffer.isBuffer(lastChunk)) return false;

  const scriptSigChunks = bscript.decompile(
    bscript.compile(chunks.slice(0, -1)),
  )!;
  const redeemScriptChunks = bscript.decompile(lastChunk);

  // is redeemScript a valid script?
  if (!redeemScriptChunks) return false;

  // is redeemScriptSig push only?
  if (!bscript.isPushOnly(scriptSigChunks)) return false;

  // is witness?
  if (chunks.length === 1) {
    return (
      p2wsho.check(redeemScriptChunks) || p2wpkho.check(redeemScriptChunks)
    );
  }

  // match types
  if (
    p2pkh.input.check(scriptSigChunks) &&
    p2pkh.output.check(redeemScriptChunks)
  )
    return true;

  if (
    p2ms.input.check(scriptSigChunks, allowIncomplete) &&
    p2ms.output.check(redeemScriptChunks)
  )
    return true;

  if (
    p2pk.input.check(scriptSigChunks) &&
    p2pk.output.check(redeemScriptChunks)
  )
    return true;

  return false;
}
check.toJSON = (): string => {
  return 'scriptHash input';
};