import Parse from 'parse/node';
import LRU from 'lru-cache';
import logger from '../logger';

function userForSessionToken(sessionToken){
  var q = new Parse.Query("_Session");
  q.equalTo("sessionToken", sessionToken);
  return q.first({useMasterKey:true}).then(function(session){
    if(!session){
      return Parse.Promise.error("No session found for session token");
    }
    return session.get("user");
  });
}

class SessionTokenCache {
  cache: Object;

  constructor(timeout: number = 30 * 24 * 60 * 60 * 1000, maxSize: number = 10000) {
    this.cache = new LRU({
      max: maxSize,
      maxAge: timeout
    });
  }

  getUserId(sessionToken: string): any {
    if (!sessionToken) {
      return Parse.Promise.error('Empty sessionToken');
    }
    const userId = this.cache.get(sessionToken);
    if (userId) {
      logger.verbose('Fetch userId %s of sessionToken %s from Cache', userId, sessionToken);
      return Parse.Promise.as(userId);
    }
    return userForSessionToken(sessionToken).then((user) => {
      logger.verbose('Fetch userId %s of sessionToken %s from Parse', user.id, sessionToken);
      const userId = user.id;
      this.cache.set(sessionToken, userId);
      return Parse.Promise.as(userId);
    }, (error) => {
      logger.error('Can not fetch userId for sessionToken %j, error %j', sessionToken, error);
      return Parse.Promise.error(error);
    });
  }
}

export {
  SessionTokenCache
}