// 云函数入口文件
const cloud = require('wx-server-sdk')

cloud.init()
const db = cloud.database()

// 云函数入口函数
exports.main = async (event, context) => {
  const {
    OPENID
  } = cloud.getWXContext()

  const notifications = await db.collection('notification')
    .aggregate()
    .match({
      user_id: OPENID
    })
    .skip(event.page_token)
    .limit(event.page_size)
    .lookup({
      from: 'message',
      localField: 'msg_id',
      foreignField: '_id',
      as: 'message'
    })
    .unwind('$message')
    .lookup({
      from: 'publisher',
      localField: 'message.pub_id',
      foreignField: '_id',
      as: 'message.publisher'
    })
    .unwind('$message.publisher')
    .end()

  return {
    list: notifications.list,
    next_page_token: event.page_token + notifications.list.length,
    status: 'OK'
  }
}