//! AI 事件监听与分发 — startListener/stopListener/handleEvent 及其辅助函数
//!
//! 模块级私有状态(不进 reactive):
//! - _unlistenAiEvent / _unlistenConvChanged: 已注册的 unlistener
//! - _startPromise: startListener 并发去重(防 onMounted 与 sendMessage 首发竞态重复注册)
//!
//! 耦合:
//! - handleEvent 调 useAiConversations.loadConversations、useAiSend.drainQueue、
//!   useAiStream.{resetStreamWatchdog,clearStreamWatchdog}、本模块 flushCurrentText/findToolCall/notifyConversationChanged
//! - nextMsgId 已下沉到 aiShared(原为本模块导出,useAiStream 亦依赖之构成循环依赖,故抽出)

import { listen, emit } from '@tauri-apps/api/event'
import { aiApi } from '../../api'
import { useAppSettingsStore } from '../../stores/appSettings'
import { state } from '../../stores/ai'
import i18n from '../../i18n'
import { nextMsgId } from './aiShared'
import { resetStreamWatchdog, clearStreamWatchdog } from './useAiStream'
import { drainQueue } from './useAiSend'
import { loadConversations } from './useAiConversations'
import type { AiChatEvent, AiToolCallInfo } from '../../api/types'

// composable 内非组件上下文(无 setup),用 vue-i18n 全局实例的 t 而非 useI18n()。
// 通过 any 中转规避 vue-i18n 深度 message schema 泛型导致的 TS2589(类型实例化过深)。
const t = ((i18n as any).global.t as (key: string) => string).bind((i18n as any).global)

let _unlistenAiEvent: (() => void) | null = null
let _unlistenConvChanged: (() => void) | null = null
// startListener 并发去重:防 onMounted 与 sendMessage 首发竞态下重复注册 listener
// (两回调写同一 state.currentText → 流式文字双倍)
let _startPromise: Promise<void> | null = null

const appSettings = useAppSettingsStore()

/** 通知会话列表发生变化(供 newConversation/deleteConversation/rename/archive 等触发刷新侧栏) */
export function notifyConversationChanged() {
  emit('ai-conversation-changed', {})
}

/** 后端原始错误转用户友好提示 */
export function friendlyError(raw: string): string {
  if (/404|not\s*found/i.test(raw)) return t('ai.errorNotFound')
  if (/401|403|unauthorized|api[_\s-]?key/i.test(raw)) return t('ai.errorAuth')
  if (/timeout|超时/i.test(raw)) return t('ai.errorTimeout')
  if (/network|connection|ECONN|网络|连接/i.test(raw)) return t('ai.errorNetwork')
  return raw
}

/** 把流式累积的 currentText 回填到最后一条 assistant 消息(AiAgentRound/AiCompleted 收尾共用) */
export function flushCurrentText() {
  if (!state.currentText) return
  const last = state.messages[state.messages.length - 1]
  if (last && last.role === 'assistant') last.content = state.currentText
}

/**
 * 在全部消息中查找指定 id 的工具调用卡片(用于状态流转)
 *
 * 扫描策略:从尾部反向遍历并提前退出。tool_result/approval/completed
 * 通常对应最近触发的 tool_use(agent 顺序执行工具并尽快回填结果),
 * 反向扫描使其命中落在尾部 → 平均 O(1)、最坏 O(n)。(原正向全量扫描为 O(n²),
 * 每条 tool_result 都从头扫整条历史。)
 *
 * 注:未引入 Map<id, tc> 索引。state.messages 在 newConversation /
 * switchConversation / deleteConversation 等处被整体替换(且这些操作散落在
 * useAiEvents 之外),独立索引极易与响应式数组失配形成"陈旧引用"——状态卡
 * 片读到已不存在的对象。反向扫描零额外状态、改动最小且行为完全一致。
 */
export function findToolCall(id: string): AiToolCallInfo | undefined {
  for (let i = state.messages.length - 1; i >= 0; i--) {
    const toolCalls = state.messages[i].toolCalls
    if (!toolCalls) continue
    // 同一消息内工具调用通常很少,沿用正向扫描;命中即返回
    for (let j = 0; j < toolCalls.length; j++) {
      if (toolCalls[j].id === id) return toolCalls[j]
    }
  }
  return undefined
}

/** token 用量展示开关(读 appSettings,与 Settings.vue 共享 key `df-show-token-usage`) */
function isShowTokenUsage(): boolean {
  return appSettings.get<boolean>('df-show-token-usage', false)
}

/** 后端事件分发:按 conversation_id 路由,流式累积文本,工具状态流转,看门狗联动 */
export function handleEvent(event: AiChatEvent) {
  const convId = event.conversation_id
  // 首次收到事件时同步当前对话 id(后端自动建对话的场景)
  // 同步写 appSettings(SQLite):刷新页面后 loadConversations 据此恢复上次会话
  if (convId && !state.activeConversationId) {
    state.activeConversationId = convId
    void appSettings.set('df-ai-active-conv', convId)
  }
  // 事件不属于当前展示对话(生成中切走了)→ 不污染当前视图,仅完成/错误时刷新侧边栏
  const isCurrent = !convId || convId === state.activeConversationId
  if (!isCurrent) {
    if (event.type === 'AiCompleted' || event.type === 'AiError') {
      state.generatingConvId = null
      void loadConversations()
    }
    return
  }
  // 标记正在生成的对话(完成/错误事件除外)
  if (convId && event.type !== 'AiCompleted' && event.type !== 'AiError') {
    state.generatingConvId = convId
  }
  // 流式看门狗:活跃事件(delta/工具/新轮/审批结果)重置;审批等待/完成/错误在 case 内 clear
  if (!['AiApprovalRequired', 'AiCompleted', 'AiError'].includes(event.type)) {
    resetStreamWatchdog()
  }
  switch (event.type) {
    case 'AiTextDelta':
      state.currentText += event.delta
      break

    case 'AiAgentRound': {
      // Agent 循环新一轮：保存当前文本到上一条 assistant 消息，新建空 assistant 消息
      flushCurrentText()
      state.currentText = ''
      state.messages.push({
        id: `ai-${nextMsgId()}`,
        role: 'assistant',
        content: '',
        timestamp: Date.now(),
      })
      break
    }

    case 'AiHeartbeat':
      // 心跳事件:仅维持看门狗(已在上方 reset),无需额外处理;显式 case 防 switch 穿透
      break

    case 'AiToolCallStarted': {
      const info: AiToolCallInfo = {
        id: event.id,
        name: event.name,
        args: event.args,
        status: 'running',
      }
      const lastMsg = state.messages[state.messages.length - 1]
      if (lastMsg && lastMsg.role === 'assistant') {
        lastMsg.toolCalls = lastMsg.toolCalls || []
        lastMsg.toolCalls.push(info)
      }
      break
    }

    case 'AiToolCallCompleted': {
      const tc = findToolCall(event.id)
      if (tc) {
        tc.status = 'completed'
        tc.result = event.result
      }
      state.pendingApprovals = state.pendingApprovals.filter(p => p.id !== event.id)
      break
    }

    case 'AiApprovalRequired': {
      clearStreamWatchdog() // 等用户审批,不计超时
      const info: AiToolCallInfo = {
        id: event.id,
        name: event.name,
        args: event.args,
        status: 'pending_approval',
      }
      state.pendingApprovals.push(info)
      const tc = findToolCall(event.id)
      if (tc) {
        tc.status = 'pending_approval'
        tc.reason = event.reason
      }
      break
    }

    case 'AiApprovalResult': {
      if (!event.approved) {
        const tc = findToolCall(event.id)
        if (tc) {
          tc.status = 'rejected'
          // 与后端落库一致：拒绝结果回填卡片，供 UI 展示拒绝原因
          tc.result = '用户拒绝了此操作'
        }
        state.pendingApprovals = state.pendingApprovals.filter(p => p.id !== event.id)
      }
      break
    }

    case 'AiCompleted': {
      clearStreamWatchdog()
      flushCurrentText()
      state.currentText = ''
      state.streaming = false
      state.generatingConvId = null
      // token 用量记录(开关开时):lastTokenUsage 供当前回复展示,convTokenTotal 累加对话总量
      if (isShowTokenUsage()) {
        state.lastTokenUsage = {
          prompt: event.prompt_tokens,
          completion: event.completion_tokens,
          total: event.total_tokens,
        }
        if (state.convTokenTotal) {
          state.convTokenTotal.prompt += event.prompt_tokens
          state.convTokenTotal.completion += event.completion_tokens
          state.convTokenTotal.total += event.total_tokens
        } else {
          state.convTokenTotal = { prompt: event.prompt_tokens, completion: event.completion_tokens, total: event.total_tokens }
        }
      }
      // 清理分离窗口生成态快照
      localStorage.removeItem('df-ai-gen')
      localStorage.removeItem('df-ai-text')
      void loadConversations()
      notifyConversationChanged()
      // 队列续发：当前完成后自动发下一条（后端 generating 已复位，不会被"正在生成中"拒绝）
      drainQueue()
      break
    }

    case 'AiError': {
      clearStreamWatchdog()
      state.streaming = false
      state.generatingConvId = null
      state.currentText = ''
      state.queue = [] // B-32:错误收尾清队列,防生成中入队的消息被静默丢失(drainQueue 仅 AiCompleted 触发)
      localStorage.removeItem('df-ai-gen')
      localStorage.removeItem('df-ai-text')
      state.messages.push({
        id: `err-${nextMsgId()}`,
        role: 'assistant',
        content: friendlyError(event.error),
        isError: true,
        timestamp: Date.now(),
      })
      break
    }
  }
}

/** 启动事件监听(幂等 + 并发去重,onMounted 与 sendMessage 首发竞态不会重复注册) */
export async function startListener() {
  // 已注册 → 直接复用(幂等;sendMessage 每次调用不重复注册)
  if (_unlistenAiEvent && _unlistenConvChanged) return
  // 并发去重:防 onMounted 与 sendMessage 首发竞态重复注册 listener → 文字双倍
  if (_startPromise) return _startPromise
  _startPromise = (async () => {
    _unlistenAiEvent = await aiApi.onEvent(handleEvent)
    _unlistenConvChanged = await listen('ai-conversation-changed', () => { void loadConversations() })
  })()
  try {
    await _startPromise
  } finally {
    _startPromise = null
  }
}

/** 停止事件监听(卸载时调用,释放后端 listener) */
function stopListener() {
  _unlistenAiEvent?.()
  _unlistenConvChanged?.()
  _unlistenAiEvent = null
  _unlistenConvChanged = null
}

export function useAiEvents() {
  return {
    startListener,
    stopListener,
    handleEvent,
    flushCurrentText,
    findToolCall,
    friendlyError,
    notifyConversationChanged,
  }
}