DeFiCh/jellyfish

import { OP_CODES, OP_PUSHDATA, Script } from '@defichain/jellyfish-transaction'
import { getNetwork, NetworkName } from '@defichain/jellyfish-network'
import { DecodedBase58Check, toBase58Check } from './Base58Check'

function isScriptP2SH (script: Script): boolean {
  return script.stack.length === 3 &&
    script.stack[0].type === OP_CODES.OP_HASH160.type &&
    script.stack[1].type === 'OP_PUSHDATA' && (script.stack[1] as OP_PUSHDATA).length() === 20 &&
    script.stack[2].type === OP_CODES.OP_EQUAL.type
}

export function fromScriptP2SH (script: Script, network: NetworkName): string | undefined {
  if (!isScriptP2SH(script)) {
    return undefined
  }

  const hash = script.stack[1] as OP_PUSHDATA
  const buffer = Buffer.from(hash.hex, 'hex')
  const prefix = getNetwork(network).scriptHashPrefix
  return toBase58Check(buffer, prefix)
}

function isBase58CheckP2SH (decoded: DecodedBase58Check, network: NetworkName): boolean {
  return decoded.prefix === getNetwork(network).scriptHashPrefix &&
    decoded.buffer.length === 20
}

export function fromBase58CheckP2SH (decoded: DecodedBase58Check, network: NetworkName): Script | undefined {
  if (!isBase58CheckP2SH(decoded, network)) {
    return undefined
  }

  return {
    stack: [
      OP_CODES.OP_HASH160,
      OP_CODES.OP_PUSHDATA(Buffer.from(decoded.buffer), 'little'),
      OP_CODES.OP_EQUAL
    ]
  }
}