const cloud = require('wx-server-sdk')
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })
const db = cloud.database()
const _ = db.command

exports.main = async (event, context) => {
  const { OPENID } = cloud.getWXContext()
  const { type = 'following', userId } = event
  const targetId = userId || OPENID

  try {
    let followIds = []

    if (type === 'following') {
      const res = await db.collection('follows')
        .where({ followerId: targetId })
        .field({ followeeId: true })
        .get()
      followIds = res.data.map(f => f.followeeId)
    } else {
      const res = await db.collection('follows')
        .where({ followeeId: targetId })
        .field({ followerId: true })
        .get()
      followIds = res.data.map(f => f.followerId)
    }

    if (followIds.length === 0) {
      return { code: 0, data: [] }
    }

    const usersRes = await db.collection('users')
      .where({ openid: _.in(followIds) })
      .field({ nickName: true, openid: true, avatarUrl: true, bio: true, location: true, isOnline: true, lastSeen: true, pets: true, stats: true })
      .get()

    // check if current user follows each
    const myFollowsRes = await db.collection('follows')
      .where({ followerId: OPENID, followeeId: _.in(followIds) })
      .field({ followeeId: true })
      .get()
    const myFollowSet = new Set(myFollowsRes.data.map(f => f.followeeId))

    return {
      code: 0,
      data: usersRes.data.map(u => ({ ...u, _id: u._id, isFollowing: myFollowSet.has(u.openid) })),
    }
  } catch (e) {
    return { code: -1, message: e.message }
  }
}