import JwksRsa = require('jwks-rsa');
import jwksClient from 'jwks-rsa';
import * as jsonwebtoken from 'jsonwebtoken';
import { Injectable } from '@nestjs/common';
import { AppLogger } from '../../../logger';
import { DecodeMicroServiceAccessTokenDto } from '../../dto';
import { MicroServiceSub } from '../../enums';
import {MicroServiceGuardModuleConfig} from '../micro-service.guard.module';

@Injectable()
export class MicroServiceGuardService {
  private readonly TAG: string = `${this.constructor.name}`;

  constructor(private readonly config: MicroServiceGuardModuleConfig) {
    AppLogger.log('Init', this.TAG);
  }

  public getMicroServiceSub(microServiceAllowed: MicroServiceSub): string {
    return '';
  }

  public async verify(token: string, microServiceAllowed: string): Promise<boolean> {
    const client: JwksRsa.JwksClient = jwksClient({
      jwksUri: this.config.jwksRoute,
    });

    function getKey(header, callback) {
      client.getSigningKey(header.kid, (err, key) => {
        if (err) {
          AppLogger.error(err, 'MicroServiceGuard');
          return callback(null, null);
        }
        const signingKey = key['publicKey'] || key['rsaPublicKey'];
        callback(null, signingKey);
      });
    }

    return new Promise((resolve, reject) => {
      jsonwebtoken.verify(token, getKey, {}, (err, decoded: DecodeMicroServiceAccessTokenDto) => {
        if (err) {
          AppLogger.error(err, this.TAG);
          reject(false);
          return;
        } else {
          if (microServiceAllowed === decoded.sub) {
            resolve(true);
            return;
          }
          AppLogger.log('Failed to authenticate micro service access token');
          reject(false);
          return;
        }
      });
    });
  }

}