// frontend/utils/handlers/guideHandler.js
// 引导记录 handler（分组型，含保留规则）
// spec §3.4.2: 保留当前 uid 的 + 全局 key；其他用户组仅在登录态可清

import { getCurrentUid } from '@/utils/draftStorage'  // 复用
import { listGuideKeys, extractUidFromGuideKey } from './guideKeys'

const GLOBAL_PROTECTED_KEYS = new Set(['guide_debug_mode', 'guide_first_show'])

function isGlobalKey(key) {
  // guide_shown_xxx 是无 uid 段（但有 configKey）
  if (GLOBAL_PROTECTED_KEYS.has(key)) return true
  if (key.startsWith('guide_shown_')) return true
  return false
}

function bytesOf(keys) {
  let total = 0
  for (const k of keys) {
    try { const v = uni.getStorageSync(k); if (v != null) total += JSON.stringify(v).length } catch (e) {}
  }
  return total
}

export default {
  id: 'guide',
  label: '引导记录',
  description: '新手引导完成标记',
  warning: false,

  async computeSize() {
    const keys = listGuideKeys()
    return { sizeBytes: bytesOf(keys), keyCount: keys.length }
  },

  async computeBreakdown() {
    const currentUid = getCurrentUid()
    const allKeys = listGuideKeys()
    const groups = []
    const isLoggedIn = !!currentUid

    // 1. 我的（currentUid）— 保留不可清
    if (currentUid) {
      const myKeys = allKeys.filter((k) => extractUidFromGuideKey(k) === currentUid)
      groups.push({
        uid: currentUid, displayUid: currentUid, isCurrent: true,
        sizeBytes: bytesOf(myKeys), keyCount: myKeys.length,
        canClean: false, disabledReason: 'guide-current',
      })
    }

    // 2. 其他用户（按 uid 聚合）— 仅登录态可清；未登录态保留展示但按钮置灰
    const otherUidKeys = new Map()
    for (const k of allKeys) {
      const uid = extractUidFromGuideKey(k)
      if (!uid || uid === currentUid) continue
      if (!otherUidKeys.has(uid)) otherUidKeys.set(uid, [])
      otherUidKeys.get(uid).push(k)
    }
    for (const [uid, keys] of otherUidKeys) {
      groups.push({
        uid, displayUid: uid, isCurrent: false,
        sizeBytes: bytesOf(keys), keyCount: keys.length,
        canClean: isLoggedIn && keys.length > 0,
        disabledReason: isLoggedIn ? (keys.length === 0 ? 'empty' : null) : 'logged-out',
      })
    }

    // 3. 全局 guide_*（无 uid 段）— 永远不可清
    const globalKeys = allKeys.filter(isGlobalKey)
    if (globalKeys.length > 0) {
      groups.push({
        uid: '__global__', displayUid: '全局标记', isCurrent: false,
        sizeBytes: bytesOf(globalKeys), keyCount: globalKeys.length, global: true,
        canClean: false, disabledReason: 'guide-global',
      })
    }

    // 按 sizeBytes 降序（spec §4.3.2 要求）
    return groups.sort((a, b) => b.sizeBytes - a.sizeBytes)
  },

  async cleanGroup({ uid }) {
    const currentUid = getCurrentUid()
    const allKeys = listGuideKeys()

    // 保留：当前 uid 的 + 全局 key
    const reserved = new Set()
    if (currentUid) {
      for (const k of allKeys) if (extractUidFromGuideKey(k) === currentUid) reserved.add(k)
    }
    for (const k of allKeys) if (isGlobalKey(k)) reserved.add(k)

    let targetKeys = []
    if (uid === 'self') {
      // 不允许清自己的（保留规则）
      return { freedBytes: 0, keyCount: 0 }
    } else if (uid === null) {
      // 其他用户聚合（不含全局）
      targetKeys = allKeys.filter((k) => {
        if (reserved.has(k)) return false
        const u = extractUidFromGuideKey(k)
        return u && u !== currentUid
      })
    } else if (uid === '__global__') {
      // 全局 key 也不允许清
      return { freedBytes: 0, keyCount: 0 }
    } else {
      // 具体其他 uid
      targetKeys = allKeys.filter((k) => {
        if (reserved.has(k)) return false  // defensive
        return extractUidFromGuideKey(k) === uid
      })
    }

    // 逐 key：先量后删（per-key 精确值，避免 approximation）
    let freed = 0
    let count = 0
    for (const k of targetKeys) {
      let valueBytes = 0
      try {
        const v = uni.getStorageSync(k)
        if (v != null) valueBytes = JSON.stringify(v).length
      } catch (e) {
        console.warn('[guideHandler] read failed:', k, e.message)
        continue
      }
      try {
        uni.removeStorageSync(k)
        freed += valueBytes
        count++
      } catch (e) {
        console.warn('[guideHandler] remove failed:', k, e.message)
      }
    }
    return { freedBytes: freed, keyCount: count }
  },
}