// {app_root}/config/plugin.js
exports.session = true; // enable by default

// config/plugin.js
exports.redis = {
  enable: true,
  package: 'egg-redis',
};

// config/config.default.js
exports.redis = {
  // your redis configurations
};

// app.js

module.exports = app => {
  // set redis session store
  // session store must have 3 methods
  // define sessionStore in `app.js` so you can access `app.redis`
  app.sessionStore = {
    async get(key) {
      const res = await app.redis.get(key);
      if (!res) return null;
      return JSON.parse(res);
    },

    async set(key, value, maxAge) {
      // maxAge not present means session cookies
      // we can't exactly know the maxAge and just set an appropriate value like one day
      if (!maxAge) maxAge = 24 * 60 * 60 * 1000;
      value = JSON.stringify(value);
      await app.redis.set(key, value, 'PX', maxAge);
    },

    async destroy(key) {
      await app.redis.del(key);
    },
  };

  // session store can be a session store class
  // app.sessionStore = class Store {
  //   constructor(app) {
  //     this.app = app;
  //   }
  //   async get() {}
  //   async set() {}
  //   async destroy() {}
  // };
};