import { err, ok, Result } from 'neverthrow'

export type TransactionIdentifierT = Readonly<{
  __witness: 'isTXId'
  __hex: string
  toPrimitive: () => string
  equals: (other: TransactionIdentifierT) => boolean
}>

const isTransactionIdentifier = (
  something: unknown,
): something is TransactionIdentifierT => {
  const inspection = something as TransactionIdentifierT
  return inspection.__hex !== undefined && inspection.__witness === 'isTXId'
}

const create = (
  bytes: Buffer | string,
): Result<TransactionIdentifierT, Error> => {
  const buffer = typeof bytes === 'string' ? Buffer.from(bytes, 'hex') : bytes
  const length = 32
  if (buffer.length !== length) {
    return err(
      new Error(`Expected #${length} bytes, but got #${buffer.length}`),
    )
  }

  const asString = buffer.toString('hex')

  return ok({
    __witness: 'isTXId',
    __hex: asString,
    toPrimitive: () => asString,
    equals: (other: TransactionIdentifierT) => other.toPrimitive() === asString,
  })
}

export const TransactionIdentifier = {
  is: isTransactionIdentifier,
  create,
}