/**
 * 会话模块
 * @author yutent<yutent.io@gmail.com>
 * @date 2020/09/24 11:18:23
 */

import { uuid, sha1 } from 'crypto.js'

import RedisStore from './lib/redis-store.js'

const DEFAULT_CONFIG = {
  ttl: 3600 * 24 * 7,
  domain: '', // NODESSID域, 默认等于domain
  level: 0, // 校验级别, 0: 不校验客户端, 2: ua, 4: ip, 6: ua + ip
  db: {
    host: '127.0.0.1',
    port: 6379,
    db: 0
  }
}

// 会话安装包
export const SessionModule = {
  name: 'session',
  install(conf = {}) {
    if (!conf.domain) {
      throw new Error('Please make sure to set the `domain` field')
    }
    let session = Object.assign({}, DEFAULT_CONFIG, conf)
    this.set({ session })
    // 这里只创建session的存储器, 而初始化操作在中间件中进行
    return new RedisStore(session)
  }
}

// 会话中间件
export function createSession() {
  return function (req, res, next) {
    let opt = this.get('session')
    let cache = req.cookie('NODESSID')
    let deviceID = ''
    let ssid

    // options请求不处理会话
    if (req.method === 'OPTIONS') {
      return next()
    }

    // 校验UA
    if (opt.level & 2) {
      deviceID += req.header('user-agent')
    }

    // 校验IP
    if (opt.level & 4) {
      deviceID += req.ip()
    }

    if (deviceID) {
      deviceID = sha1(deviceID)

      // ssid 最后16位是指纹
      if (cache) {
        if (cache.slice(-16) === deviceID.slice(-16)) {
          ssid = cache
        } else {
          ssid = uuid('') + deviceID.slice(-16)
        }
      }
    } else {
      ssid = cache || sha1(uuid())
    }

    res.cookie('NODESSID', ssid, {
      maxAge: opt.ttl,
      httpOnly: true,
      domain: opt.domain
    })
    // 缓存ssid到req上
    req.ssid = ssid
    this.$$session.update(ssid)

    next()
  }
}