const config = global.yoho.config;
const session = require('yoho-express-session');
const _ = require('lodash');
const uuid = require('uuid');

const cookieSession = require('client-sessions');
const connectRedis = require('connect-redis');
const RedisStore = connectRedis(session);
const monitor = global.yoho.monitorSender;
const monitorType = _.get(monitor, 'type.REDIS');

/**
 * 该中间件主要把 express-session 和 client-session 集中起来处理，如果 redis 出错了，使用 cookie session
 * @param opts.backSession cookieSession 的键名
 * @returns {function(*=, *=, *)}
 */
function yohoSession(opts) {
    return (req, res, next) => {
        let notUseRedis = _.get(req.app.locals.wap, 'session.removeMemcached', false);

        opts.backSession = opts.backSession || 'session2';

        if (req.session && !req.session.degrage && !notUseRedis) {
            // 如果存在session并且没有被降级，且移除redis开关没开，则继续使用session redis
            req.sessionError = false;
        } else {
            // 重建 session
            res.emit('sessionError');
            req.sessionError = true;

            req.sessionID = req.sessionID || uuid.v4();
            req.session = new session.Session(req, req[opts.backSession].sessionBack);
            req.session.cookie = new session.Cookie({
                domain: 'yohobuy.com',
                httpOnly: true
            });
        }

        Object.defineProperty(req.session, 'reset', {
            configurable: true,
            enumerable: false,
            value: function() {
                req.session.destroy();
                req[opts.backSession].reset();
            },
            writable: false
        });

        // 备份数据
        req[opts.backSession].sessionBack = req.session;

        next();
    };
}

module.exports = (app) => {
    app.use(session({  // eslint-disable-line
        proxy: true,
        resave: false,
        saveUninitialized: true,
        unset: 'destroy',
        secret: '82dd7e724f2c6870472c89dfa43cf48d',
        name: 'yohobuy_session',
        genid() {
            return uuid.v4();
        },
        cookie: {
            domain: 'yohobuy.com',
            httpOnly: true
        },
        store: new RedisStore(Object.assign(config.redis.session, {
            logErrors: (e) => {
                // 上报redis session错误
                monitor && monitor.tallyFail(monitorType, e);
            }
        }))
    }));

    app.use(cookieSession({ // eslint-disable-line
        requestKey: 'session2',
        cookieName: 'yohobuy_session_cookie',
        secret: '82dd7e724f2c6870472c89dfa43cf48d',
        cookie: {
            domain: 'yohobuy.com',
            ephemeral: true,
            httpOnly: true
        }
    }));

    app.use(yohoSession({
        backSession: 'session2'
    }));
};