'use strict';

const logger = require('./logger')('RsaJwt');
const NodeRSA = require('node-rsa');
const jwt = require('jsonwebtoken');
const fs = require('fs');

class rsaJwt {
  constructor(keyPath) {
    this.keyPath = keyPath;

    if(this.keyPath && fs.existsSync(this.keyPath)) {
      logger.debug('Loading private and public key for JWT sessions...');
      const keyPair = new NodeRSA();
      this.privateKey = fs.readFileSync(keyPath, 'utf-8');
      keyPair.importKey(privateKey, 'private');
      this.publicKey = keyPair.exportKey('public');
      logger.success('Done');

      this.resetInvalidation();
    }
    else this.generateNewKeyPair();
  }

  resetInvalidation() {
      this.invalidationCounterByUserUuid = {};
      this.invalidBefore = Math.floor(new Date().getTime()/1000);
  }

  generateNewKeyPair() {
    logger.debug('Generating private and public key for JWT sessions...');
    const keyPair = new NodeRSA({ b: 2048 });
    this.privateKey = keyPair.exportKey('private');
    this.publicKey = keyPair.exportKey('public');
    if(this.keyPath) fs.writeFileSync(this.keyPath, this.privateKey, 'utf-8');
    logger.success('Done');

    this.resetInvalidation();
  }

  sign(payload) {
    payload.invalidationCounter = this.invalidationCounterByUserUuid[payload.userUuid] || 0;
    return jwt.sign(payload, this.privateKey, { algorithm:'RS256' });
  }

  verify(token) {
    try {
      const payload = jwt.verify(token, this.publicKey, { algorithm: ['RS256'] });
      const notInvalidated = !this.invalidationCounterByUserUuid[payload.userUuid] || payload.invalidationCounter === this.invalidationCounterByUserUuid[payload.userUuid];
      const hasValidIat = payload.iat >= this.invalidBefore;
      return (notInvalidated && hasValidIat) ? payload : false;
    }
    catch(error) {
      logger.warning(error);
      return false;
    }
  }

  invalidateUserTokens(userUuid) {
    this.invalidationCounterByUserUuid[userUuid] = ++this.invalidationCounterByUserUuid[userUuid] || 1;
  }
}

module.exports = rsaJwt;