const DB_COLLECTION = 'plank_data'
const ENV_ID = 'cloudbase-d1g56kl2q8f4f7d8a'

let _db = null
let _pushTimer = null
let _enabled = false
let _docId = null  // cache doc id after first successful query

const getDb = () => {
  if (!_enabled) return null
  if (!_db) {
    try { _db = wx.cloud.database({ env: ENV_ID }) } catch (e) { _enabled = false }
  }
  return _db
}

const init = () => {
  try {
    wx.cloud.init({ env: ENV_ID, traceUser: true })
    _enabled = true
  } catch (e) {
    _enabled = false
  }
}

const pullAll = async () => {
  const db = getDb()
  if (!db) return null
  try {
    // First try cached doc id
    if (_docId) {
      try {
        const res = await db.collection(DB_COLLECTION).doc(_docId).get()
        if (res && res.data) return res.data
      } catch (e) {
        _docId = null  // doc deleted or inaccessible
      }
    }
    // Query: rely on security rules to scope to current user
    const res = await db.collection(DB_COLLECTION).limit(1).get()
    if (res && res.data && res.data.length > 0) {
      _docId = res.data[0]._id
      return res.data[0]
    }
    return null
  } catch (e) {
    return null
  }
}

const pushAll = () => {
  if (!_enabled) return
  if (_pushTimer) clearTimeout(_pushTimer)
  _pushTimer = setTimeout(() => _doPush(), 2000)
}

const _doPush = async () => {
  const db = getDb()
  if (!db) return
  try {
    const storage = require('./storage')
    const themeMod = require('./theme')

    const data = {
      records: storage.getRecords(),
      settings: storage.getSettings(),
      streak: storage.getStreak(),
      customPlans: storage.getCustomPlans(),
      themeId: themeMod.getCurrentTheme().id,
      updatedAt: db.serverDate()
    }

    // Use cached doc id if available
    if (_docId) {
      try {
        await db.collection(DB_COLLECTION).doc(_docId).update({ data })
        return
      } catch (e) {
        _docId = null  // doc may have been deleted
      }
    }

    // Query for existing doc (relies on security rules to scope to current user)
    const existing = await db.collection(DB_COLLECTION).limit(1).get()
    if (existing && existing.data && existing.data.length > 0) {
      _docId = existing.data[0]._id
      await db.collection(DB_COLLECTION).doc(_docId).update({ data })
    } else {
      const res = await db.collection(DB_COLLECTION).add({ data })
      if (res && res._id) _docId = res._id
    }
  } catch (e) {
    // Silently retry on next write
  }
}

const clearAll = async () => {
  const db = getDb()
  if (!db) return
  try {
    if (_docId) {
      try {
        await db.collection(DB_COLLECTION).doc(_docId).remove()
        _docId = null
        return
      } catch (e) {
        _docId = null
      }
    }
    const existing = await db.collection(DB_COLLECTION).limit(1).get()
    if (existing && existing.data && existing.data.length > 0) {
      await db.collection(DB_COLLECTION).doc(existing.data[0]._id).remove()
    }
    _docId = null
  } catch (e) {
    // Nothing to clear
  }
}

module.exports = { init, pullAll, pushAll, clearAll, get enabled() { return _enabled } }