// This file was copied from https://github.com/RaisinTen/aes-crypto-js/blob/2978af8e004d47539d767e751def003fe134b6e2/index.js
// and modified slightly for TS compatibility.
import crypto from 'crypto'

// Refs: https://github.com/brix/crypto-js/issues/468#issuecomment-2060562277
export function aesEncrypt(plainText: string, secret: string) {
  const salt = crypto.randomBytes(8)
  const password = Buffer.concat([Buffer.from(secret), salt])
  const hash = []
  let digest = password
  for (let i = 0; i < 3; i++) {
    hash[i] = crypto.createHash('md5').update(digest).digest()
    digest = Buffer.concat([hash[i], password])
  }
  const keyDerivation = Buffer.concat(hash)
  const key = keyDerivation.subarray(0, 32)
  const iv = keyDerivation.subarray(32)
  const cipher = crypto.createCipheriv('aes-256-cbc', key, iv)
  return Buffer.concat([
    Buffer.from('Salted__', 'utf8'),
    salt,
    cipher.update(plainText),
    cipher.final(),
  ]).toString('base64')
}

// Refs: https://github.com/brix/crypto-js/issues/468#issuecomment-1783351942
export function aesDecrypt(encryptedText: string, secret: string) {
  // From https://gist.github.com/schakko/2628689?permalink_comment_id=3321113#gistcomment-3321113
  // From https://gist.github.com/chengen/450129cb95c7159cb05001cc6bdbf6a1
  const cypher = Buffer.from(encryptedText, 'base64')
  const salt = cypher.slice(8, 16)
  const password = Buffer.concat([Buffer.from(secret), salt])
  const md5Hashes = []
  let digest = password
  for (let i = 0; i < 3; i++) {
    md5Hashes[i] = crypto.createHash('md5').update(digest).digest()
    digest = Buffer.concat([md5Hashes[i], password])
  }
  const key = Buffer.concat([md5Hashes[0], md5Hashes[1]])
  const iv = md5Hashes[2]
  const contents = cypher.slice(16)
  const decipher = crypto.createDecipheriv('aes-256-cbc', key, iv)

  return Buffer.concat([decipher.update(contents), decipher.final()]).toString('utf8')
}