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 { targetId } = event
  if (!targetId || targetId === OPENID) return { code: -1, message: '参数错误' }

  try {
    const existRes = await db.collection('follows')
      .where({ followerId: OPENID, followeeId: targetId })
      .count()

    if (existRes.total > 0) {
      // unfollow
      await db.collection('follows')
        .where({ followerId: OPENID, followeeId: targetId })
        .remove()
      await Promise.all([
        db.collection('users').where({ openid: OPENID }).update({ data: { 'stats.friends': _.inc(-1) } }),
        db.collection('users').where({ openid: targetId }).update({ data: { 'stats.friends': _.inc(-1) } }),
      ])
      return { code: 0, data: { following: false } }
    } else {
      // follow
      await db.collection('follows').add({
        data: { followerId: OPENID, followeeId: targetId, createdAt: db.serverDate() },
      })
      await Promise.all([
        db.collection('users').where({ openid: OPENID }).update({ data: { 'stats.friends': _.inc(1) } }),
        db.collection('users').where({ openid: targetId }).update({ data: { 'stats.friends': _.inc(1) } }),
      ])
      return { code: 0, data: { following: true } }
    }
  } catch (e) {
    return { code: -1, message: e.message }
  }
}