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

cloud.init()
const db = cloud.database()
const _ = db.command
const $ = db.command.aggregate

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

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

    return {
      list: managers.list,
      next_page_token: event.page_token + managers.list.length,
      status: 'OK'
    }
  } else if (event.follow) {
    const publishers = await db.collection('publisher')
      .aggregate()
      .lookup({
        from: 'follow',
        let: {
          pub_id: '$_id'
        },
        pipeline: $.pipeline()
          .match(_.expr($.and([
            $.eq(['$user_id', OPENID]),
            $.eq(['$pub_id', '$$pub_id'])
          ])))
          .project({
            _id: 0,
            follow_time: 1
          }).done(),
        as: 'follow'
      })
      .unwind('$follow')
      .skip(event.page_token)
      .limit(event.page_size)
      .end()

    return {
      list: publishers.list,
      next_page_token: event.page_token + publishers.list.length,
      status: 'OK'
    }
  } else {
    const publishers = await db.collection('publisher')
      .aggregate()
      .skip(event.page_token)
      .limit(event.page_size)
      .end()

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