import { Buffer } from "buffer"
import { createHmac } from "crypto"

const decode = (str: string):string => Buffer.from(str, 'base64').toString('binary');
const encode = (str: string):string => Buffer.from(str, 'binary').toString('base64');
const secret = process.env.JWT_SECRET ? process.env.JWT_SECRET : ""

interface tokenData {
  // eslint-disable-next-line
  data: any,
  maxAge: number
}

export function createToken({data, maxAge}: tokenData) {
  const tokenData = data
  tokenData.maxAge = maxAge
  const header = encode(JSON.stringify({"alg":"HS256", "typ":"jwt"})) 
  const body = encode(JSON.stringify(tokenData))
  const signature = createHmac('sha256',secret).update(header + "." + body).digest('hex')
  return header + "." + body + "." + signature
}

export function validateToken(token: string) {
  const rawData = token.split(".")
  const header = rawData[0]
  const body = rawData[1]
  const signature = rawData[2]

  const calculatedSignature = createHmac('sha256',secret).update(header + "." + body).digest('hex')
  return signature == calculatedSignature
}

export function decryptToken(token: string) {
  const rawData = token.split(".")
  const body = rawData[1]
  return JSON.parse(decode(body))
}