import * as crypto from 'crypto'
import { IPasswordHasher } from './IPasswordHasher'

export type Pbkdf2Algorithm = 'hmac-sha1' | 'hmac-sha256' | 'hmac-sha512'

export class Pbkdf2PasswordHasher implements IPasswordHasher {
  constructor(private algorithm: Pbkdf2Algorithm, private iterations: number, private length: number) {}

  public async hash(
    password: string,
    algorithm?: Pbkdf2Algorithm,
    iterations?: number,
    length?: number,
    salt?: Buffer
  ): Promise<string> {
    const algorithm2 = algorithm || this.algorithm
    const iterations2 = iterations || this.iterations
    const length2 = length || this.length
    const salt2 =
      salt ||
      (await new Promise<Buffer>((resolve, reject) =>
        crypto.randomBytes(32, (err, buf) => (err ? reject(err) : resolve(buf)))
      ))

    const hash = await new Promise<Buffer>((resolve, reject) =>
      crypto.pbkdf2(
        password,
        salt2,
        iterations2,
        Math.ceil(length2 / 8),
        algorithm2.substr(5),
        (err, buf) => (err ? reject(err) : resolve(buf))
      )
    )

    return (
      algorithm2 +
      ':' +
      iterations2.toString() +
      ':' +
      length2.toString() +
      ':' +
      salt2.toString('base64') +
      ':' +
      hash.toString('base64')
    )
  }

  public async verify(password: string, passwordHash: string): Promise<boolean> {
    const match = passwordHash.match(/^([^:]+):([^:]+):([^:]+):([^:]+):([^:]+)$/)
    if (match) {
      const [_all, algorithm, iterationsString, lengthString, saltString, _hashString] = match
      return (
        passwordHash ===
        (await this.hash(
          password,
          algorithm as Pbkdf2Algorithm,
          parseInt(iterationsString, 10),
          parseInt(lengthString, 10),
          new Buffer(saltString, 'base64')
        ))
      )
    } else {
      return false
    }
  }
}