const {
  bech32,
  derivePrivate,
  derivePublic,
  getPubKeyBlake2b224Hash,
  mnemonicToRootKeypair,
  packBaseAddress,
  // tslint:disable-next-line:no-var-requires
} = require('cardano-crypto.js')
import { ADA_DERIVATION_PATH, ADA_DERIVATION_SCHEME, HARDENED_THRESHOLD } from '../constants'

/**
 * Generate an Ada key for the standard derivation path
 * @param mnemonic mnemonic seed to use
 * @returns the key buffer
 */
const generateKey = async (mnemonic: string): Promise<Buffer> => {
  const walletSecret = await mnemonicToRootKeypair(mnemonic, ADA_DERIVATION_SCHEME)
  return ADA_DERIVATION_PATH.split('/')
    .slice(1)
    .map((index) => (index.slice(-1) === "'" ? HARDENED_THRESHOLD + parseInt(index.slice(0, -1)) : parseInt(index)))
    .reduce((secret, index) => derivePrivate(secret, index, ADA_DERIVATION_SCHEME), walletSecret)
}

/**
 * Generate an Ada private key for the standard derivation path
 * @param mnemonic mnemonic seed to use
 * @param i derivation index of private key to generate
 * @returns the (extended) private key string
 */
export const generatePrivateKey = async (mnemonic: string, i: number): Promise<string> => {
  // /0/i
  return derivePrivate(derivePrivate(await generateKey(mnemonic), 0, ADA_DERIVATION_SCHEME), i, ADA_DERIVATION_SCHEME).toString('hex')
}

/**
 * Generate an Ada public key for the standard derivation path
 * @param mnemonic mnemonic seed to use
 * @returns the extended public key string (spend + stake)
 */
export const generateXPublicKey = async (mnemonic: string): Promise<string> => {
  const root = await generateKey(mnemonic)
  // /0
  const spendXPub = derivePrivate(root, 0, ADA_DERIVATION_SCHEME).slice(64, 128).toString('hex')
  // /2/0
  const stakeXPub = derivePrivate(derivePrivate(root, 2, ADA_DERIVATION_SCHEME), 0, ADA_DERIVATION_SCHEME).slice(64, 128).toString('hex')
  return spendXPub + stakeXPub
}

function xpub2blake2b224Hash(xpub: string) {
  return getPubKeyBlake2b224Hash(Buffer.from(xpub, 'hex').slice(0, 32))
}

/**
 * Generate Carnado address
 * @param testnet extended public key to generate address from
 * @param xpub extended public key to generate address from
 * @param i derivation index of address to generate. Up to 2^31 addresses can be generated.
 * @returns blockchain address
 */
export const generateAddress = async (testnet: boolean, xpub: string, i: number): Promise<string> => {
  const spendXPub = derivePublic(Buffer.from(xpub.substr(0, 128), 'hex'), i, ADA_DERIVATION_SCHEME)
  const stakeXPub = xpub.substr(128, 128)
  return bech32.encode(
    testnet ? 'addr_test' : 'addr',
    packBaseAddress(xpub2blake2b224Hash(spendXPub), xpub2blake2b224Hash(stakeXPub), testnet ? 0 : 1)
  )
}