'use strict';

class UserCache {
  constructor(options) {
    this.users = options.users;
    this.redis = options.redis;
  }

  flush(user, callback) {
    this.redis.del('cached:' + user, () => callback());
  }

  get(user, key, defaultValue, callback) {
    this.redis.hget('cached:' + user, key, (err, value) => {
      if (err) {
        return callback(err);
      }

      if (value) {
        return callback(null, Number(value));
      }

      this.users.collection('users').findOne(
        {
          _id: user
        },
        {
          projection: {
            [key]: true
          }
        },
        (err, userData) => {
          if (err) {
            return callback(err);
          }

          if (!userData) {
            return callback(null, defaultValue);
          }

          value = userData[key] || defaultValue;
          this.redis.hset('cached:' + user, key, value, err => {
            if (err) {
              return callback(err);
            }
            return callback(null, value);
          });
        }
      );
    });
  }
}

module.exports = UserCache;