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

// 项目暂未建立独立的通知集合，这里通过聚合"我的动态"收到的点赞 / 评论
// 实时合成通知列表；已读状态通过用户文档上的 lastReadNotificationsAt 时间戳比对得出
exports.main = async (event, context) => {
  const { OPENID } = cloud.getWXContext()

  try {
    const meRes = await db.collection('users').where({ openid: OPENID }).get()
    if (meRes.data.length === 0) return { code: 0, data: [] }
    const me = meRes.data[0]
    const lastRead = me.lastReadNotificationsAt ? new Date(me.lastReadNotificationsAt).getTime() : 0

    const myPostsRes = await db.collection('posts')
      .where({ authorId: OPENID })
      .field({ _id: true })
      .orderBy('createdAt', 'desc')
      .limit(50)
      .get()
    const myPostIds = myPostsRes.data.map(p => p._id)

    const items = []

    if (myPostIds.length) {
      const [likesRes, commentsRes] = await Promise.all([
        db.collection('likes')
          .where({ postId: _.in(myPostIds), userId: _.neq(OPENID) })
          .orderBy('createdAt', 'desc')
          .limit(20)
          .get(),
        db.collection('comments')
          .where({ postId: _.in(myPostIds), authorId: _.neq(OPENID) })
          .orderBy('createdAt', 'desc')
          .limit(20)
          .get(),
      ])

      likesRes.data.forEach(l => items.push({
        _id: `like_${l._id}`,
        fromId: l.userId,
        postId: l.postId,
        action: '点赞',
        target: '动态',
        createdAt: l.createdAt,
      }))

      commentsRes.data.forEach(c => items.push({
        _id: `comment_${c._id}`,
        fromId: c.authorId,
        postId: c.postId,
        action: '评论',
        target: '动态',
        createdAt: c.createdAt,
      }))
    }

    items.sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime())
    const sliced = items.slice(0, 30)

    const fromIds = [...new Set(sliced.map(i => i.fromId).filter(Boolean))]
    const usersRes = fromIds.length
      ? await db.collection('users').where({ openid: _.in(fromIds) }).field({ openid: true, nickName: true }).get()
      : { data: [] }
    const nickMap = {}
    usersRes.data.forEach(u => { nickMap[u.openid] = u.nickName })

    const result = sliced.map(i => ({
      ...i,
      fromNick: nickMap[i.fromId] || '一位用户',
      isRead: new Date(i.createdAt).getTime() <= lastRead,
    }))

    return { code: 0, data: result }
  } catch (e) {
    return { code: -1, message: e.message }
  }
}