const cloud = require('wx-server-sdk')

cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })
const db = cloud.database()
const _ = db.command

async function safeGet(collection, where, limit = 200) {
  try {
    return await db.collection(collection).where(where).limit(limit).get()
  } catch (e) {
    return { data: [] }
  }
}

function formatTimeText(ts) {
  const diff = Date.now() - ts
  const mins = Math.floor(diff / 60000)
  if (mins < 1) return '刚刚'
  if (mins < 60) return `${mins} 分钟前`
  const hours = Math.floor(mins / 60)
  if (hours < 24) return `${hours} 小时前`
  const days = Math.floor(hours / 24)
  if (days === 1) return '昨天'
  if (days < 7) return `${days} 天前`
  const d = new Date(ts)
  return `${d.getMonth() + 1}月${d.getDate()}日`
}

function isCloudFileId(value) {
  return typeof value === 'string' && value.startsWith('cloud://')
}

function extractMediaUrl(media) {
  if (!media) return ''
  if (typeof media === 'string') return media
  return media.url || media.fileId || media.fileID || ''
}

async function resolveTempUrlMap(urls) {
  const fileIds = [...new Set(urls.filter(isCloudFileId))]
  if (!fileIds.length) return new Map()

  try {
    const result = await cloud.getTempFileURL({ fileList: fileIds })
    const fileList = Array.isArray(result.fileList) ? result.fileList : []
    return new Map(fileList.map(file => [
      file.fileID || file.fileId,
      file.tempFileURL || file.tempFileUrl || ''
    ]).filter(([fileId, tempUrl]) => fileId && tempUrl))
  } catch (e) {
    return new Map()
  }
}

function readableUrl(url, tempUrlMap) {
  if (!url) return ''
  if (!isCloudFileId(url)) return url
  return tempUrlMap.get(url) || ''
}

// List a user's own posts. Defaults to the caller; pass authorId to view
// another user (only public posts are returned for others).
exports.main = async event => {
  const { OPENID } = cloud.getWXContext()
  if (!OPENID) throw new Error('no openid in wx context')
  const pageSize = Math.max(1, Math.min(Number(event.pageSize || 20), 50))

  let authorOpenid = OPENID
  let viewingSelf = true
  if (event.authorId) {
    const u = await db.collection('users').doc(event.authorId).get().catch(() => null)
    if (!u || !u.data) return { list: [] }
    authorOpenid = u.data.openid
    viewingSelf = authorOpenid === OPENID
  }

  const where = { authorOpenid }
  if (!viewingSelf) where.visibility = 'public'
  const cursor = Number(event.cursor || 0)
  if (Number.isFinite(cursor) && cursor > 0) where.createdAt = _.lt(cursor)

  const res = await db.collection('posts')
    .where(where)
    .orderBy('createdAt', 'desc')
    .limit(pageSize + 1)
    .get()

  if (!res.data.length) return { list: [], nextCursor: '' }

  const page = res.data.slice(0, pageSize)
  const nextCursor = res.data.length > pageSize && page[page.length - 1]
    ? String(page[page.length - 1].createdAt || '')
    : ''

  const authorRes = await db.collection('users').where({ openid: authorOpenid }).limit(1).get().catch(() => null)
  const authorUser = authorRes && authorRes.data ? authorRes.data[0] : null

  // Real presence: author has a recent, visible location (same signal as 附近).
  const ONLINE_WINDOW_MS = 5 * 60 * 1000
  const locRes = await safeGet('locations', { openid: authorOpenid }, 1)
  const authorLoc = locRes.data[0]
  const authorOnline = Boolean(
    authorLoc && authorLoc.visible && authorLoc.updatedAt && Date.now() - authorLoc.updatedAt < ONLINE_WINDOW_MS
  )
  const postIds = page.map(p => p._id)
  const likedRes = await safeGet('postLikes', { openid: OPENID, postId: _.in(postIds) })
  const likedSet = new Set(likedRes.data.map(l => l.postId))
  const assetUrls = [
    authorUser?.avatarUrl || '',
    ...page.flatMap(post => Array.isArray(post.media) ? post.media.map(extractMediaUrl) : [])
  ]
  const tempUrlMap = await resolveTempUrlMap(assetUrls)

  const list = page.map(post => ({
    _id: post._id,
    author: {
      id: post.authorId || '',
      name: post.authorSnapshot?.name || '用户',
      avatarKey: authorUser?.avatarKey || post.authorSnapshot?.avatarKey || 'gradient-avatar-1',
      avatarUrl: readableUrl(authorUser?.avatarUrl || post.authorSnapshot?.avatarUrl || '', tempUrlMap),
      online: authorOnline
    },
    pet: post.petSnapshot || { name: '', breed: '' },
    body: post.content || '',
    topics: post.topics || [],
    visibility: post.visibility || 'public',
    media: Array.isArray(post.media)
      ? post.media
        .map(extractMediaUrl)
        .map(url => readableUrl(url, tempUrlMap))
        .filter(Boolean)
      : [],
    mediaTone: post.mediaTone || 'pet-1',
    sticker: post.sticker || undefined,
    locationText: post.locationText || '',
    timeText: formatTimeText(post.createdAt || Date.now()),
    counts: {
      likes: post.counts?.likes || 0,
      comments: post.counts?.comments || 0
    },
    likedByMe: likedSet.has(post._id)
  }))

  return { list, nextCursor }
}