const {
  JWT_SECRETS,
  JWT_SECRET,
  JWT_ALG
} = require('./config');

const debug = require('debug')('talk:secrets');
const jwt = require('./services/jwt');

if (JWT_SECRETS) {
  if (!Array.isArray(JWT_SECRETS)) {
    throw new Error('TALK_JWT_SECRETS must be a JSON array in the form [{"kid": kid, ["secret": secret | "private": private, "public": public]}, ...]');
  }

  if (JWT_SECRETS.length === 0) {
    throw new Error('TALK_JWT_SECRETS must be a JSON array with non zero length');
  }

  // Wrap a multi-secret around the available secrets.
  module.exports.jwt = new jwt.MultiSecret(JWT_SECRETS.map((secret) => {
    if (!('kid' in secret)) {
      throw new Error('when multiple keys are specified, kid\'s must be specified');
    }

    if (typeof secret.kid !== 'string' || secret.kid.length === 0) {
      throw new Error('kid must be a unique string');
    }

    // HMAC secrets do not have public/private keys.
    if (JWT_ALG.startsWith('HS')) {
      return new jwt.SharedSecret(secret, JWT_ALG);
    }

    if (!('public' in secret)) {
      throw new Error('all symetric keys must provide a PEM encoded public key');
    }

    return new jwt.AsymmetricSecret(secret, JWT_ALG);
  }));

  debug(`loaded ${JWT_SECRETS.length} ${JWT_ALG.startsWith('HS') ? 'shared' : 'asymmetric'} secrets`);
} else if (JWT_SECRET) {
  if (JWT_ALG.startsWith('HS')) {
    module.exports.jwt = new jwt.SharedSecret({
      secret: JWT_SECRET
    }, JWT_ALG);
  } else {
    module.exports.jwt = new jwt.AsymmetricSecret(JSON.parse(JWT_SECRET), JWT_ALG);
  }

  debug(`loaded a ${JWT_ALG.startsWith('HS') ? 'shared' : 'asymmetric'} secret`);
}