import { compareSync, hashSync } from 'bcryptjs'
import { HttpException, HttpStatus } from '@nestjs/common'

import { Patient } from '../../../models/patient.model'

export const AUTH_TOKEN_LENGTH = 5

export type AuthToken = {
  code: string
  encryptedCode: string
}

export const USER_HAS_NOT_TOKEN = 'User has not token'
export const USERS_TOKEN_EXPIRED = "User's token expired"
export const INVALID_TOKEN = 'Invalid token'

export class AuthTokenHelper {
  static authTokenIsValid(patient: Patient, token: string): boolean {
    if (!patient.hasAuthToken()) {
      throw new HttpException({ message: USER_HAS_NOT_TOKEN }, HttpStatus.NOT_FOUND)
    }

    if (patient.hasExpiredAuthToken()) {
      throw new HttpException({ message: USERS_TOKEN_EXPIRED }, HttpStatus.UNAUTHORIZED)
    }

    if (!this.tokenMatch(token, patient.auth_token)) {
      throw new HttpException({ message: INVALID_TOKEN }, HttpStatus.UNAUTHORIZED)
    }

    return true
  }

  static buildAuthToken(givenCode?: string): AuthToken {
    const code = givenCode || this.generate(AUTH_TOKEN_LENGTH)

    return {
      code,
      encryptedCode: this.encrypt(code),
    }
  }

  private static generate(chars: number): string {
    let token = ''

    for (let index = 0; index < chars; index++) {
      token += Math.floor(Math.random() * 9).toString()
    }

    return token
  }

  private static encrypt(decrypted: any, salt = 10): string {
    return hashSync(decrypted, salt)
  }

  private static tokenMatch(decrypted: any, encrypted: string): boolean {
    return compareSync(decrypted, encrypted)
  }
}