import CryptoJS from 'crypto-js'

const encryptionPrefix = 'contexted|'
const salt = 'salt'

export const calculateClientKey = (passphrase: string): ClientKey => {
  return CryptoJS.PBKDF2(passphrase, salt, { keySize: 256 / 32 }).toString()
}

export const decrypt = (encryptedMessage: string, key: string): string => {
  const decryptedMessage = CryptoJS.AES.decrypt(encryptedMessage, key).toString(CryptoJS.enc.Utf8)
  if (!decryptedMessage.startsWith(encryptionPrefix))
    throw new Error("Message doesn't have valid encryption")
  return decryptedMessage.substring(encryptionPrefix.length)
}

export const encrypt = (unencryptedMessage: string, key: string): string => {
  return CryptoJS.AES.encrypt(encryptionPrefix + unencryptedMessage, key).toString()
}

export const generateEncryptionKey = () => {
  return CryptoJS.lib.WordArray.random(16).toString(CryptoJS.enc.Hex)
}