const express = require('express');
const router = express.Router();
const cozeChatService = require('../services/cozeChatService');
const arkChatService = require('../services/arkChatService');
const ToolExecutor = require('../services/toolExecutor');
const { shouldForceKnowledgeRoute } = require('../services/realtimeDialogRouting');
const db = require('../db');

// 存储文字对话的会话状态（sessionId -> session）
const chatSessions = new Map();

const BRAND_HARMFUL_PATTERN = /传销|骗局|骗子公司|非法集资|非法经营|不正规|不合法|庞氏骗局|老鼠会|拉人头的|割韭菜/;
const BRAND_SAFE_REPLY = '德国PM是一家1993年成立于德国的合法直销公司，获得邓白氏AAA+认证，业务覆盖100多个国家和地区。如果你想了解更多，可以问我关于PM公司的详细介绍哦。';

function normalizeAssistantText(text) {
  let result = String(text || '')
    .replace(/\r/g, ' ')
    .replace(/\n{2,}/g, '。')
    .replace(/\n/g, ' ')
    .replace(/。{2,}/g, '。')
    .replace(/([！？；，])\1+/g, '$1')
    .replace(/([。！？；，])\s*([。！？；，])/g, '$2')
    .replace(/\s+/g, ' ')
    .trim();
  if (BRAND_HARMFUL_PATTERN.test(result)) {
    console.warn(`[Chat][SafeGuard] blocked harmful content: ${JSON.stringify(result.slice(0, 200))}`);
    return BRAND_SAFE_REPLY;
  }
  return result;
}

async function loadHandoffMessages(sessionId, voiceSubtitles = []) {
  let voiceMessages = [];
  try {
    const dbHistory = await db.getHistoryForLLM(sessionId, 20);
    if (dbHistory.length > 0) {
      voiceMessages = dbHistory;
      console.log(`[Chat] Loaded ${dbHistory.length} messages from DB for session ${sessionId}`);
    }
  } catch (e) { console.warn('[DB] getHistoryForLLM failed:', e.message); }

  if (voiceMessages.length === 0 && voiceSubtitles.length > 0) {
    const recentSubtitles = voiceSubtitles.slice(-10);
    for (const sub of recentSubtitles) {
      voiceMessages.push({
        role: sub.role === 'user' ? 'user' : 'assistant',
        content: sub.text,
      });
    }
  }

  return voiceMessages;
}

async function buildChatSessionState(sessionId, voiceSubtitles = []) {
  const voiceMessages = await loadHandoffMessages(sessionId, voiceSubtitles);
  let handoffSummary = '';
  try {
    handoffSummary = await arkChatService.summarizeContextForHandoff(voiceMessages, 3);
  } catch (error) {
    console.warn('[Chat] summarizeContextForHandoff failed:', error.message);
  }
  return {
    userId: `user_${sessionId.slice(0, 12)}`,
    conversationId: null,
    voiceMessages,
    handoffSummary,
    handoffSummaryUsed: false,
    createdAt: Date.now(),
    lastActiveAt: Date.now(),
    fromVoice: voiceSubtitles.length > 0 || voiceMessages.length > 0,
  };
}

function buildInitialContextMessages(session) {
  const summary = String(session?.handoffSummary || '').trim();
  const extraMessages = [];
  if (summary && !session?.handoffSummaryUsed) {
    extraMessages.push({ role: 'assistant', content: `会话交接摘要：${summary}` });
  }
  if (Array.isArray(session?.voiceMessages) && session.voiceMessages.length > 0) {
    extraMessages.push(...session.voiceMessages.slice(-6));
  }
  return extraMessages;
}

async function buildKnowledgeContextMessages(sessionId, session) {
  const recentMessages = await db.getRecentMessages(sessionId, 20).catch(() => []);
  const scopedMessages = session?.fromVoice && session?.handoffSummaryUsed
    ? recentMessages.filter((item) => !/^voice_/i.test(String(item?.source || '')))
    : recentMessages;
  const dbHistory = scopedMessages
    .filter((item) => item && (item.role === 'user' || item.role === 'assistant'))
    .map((item) => ({ role: item.role, content: item.content }));
  const summary = String(session?.handoffSummary || '').trim();
  if (!summary || session?.handoffSummaryUsed) {
    return dbHistory;
  }
  return [
    { role: 'assistant', content: `会话交接摘要：${summary}` },
    ...dbHistory,
  ];
}

function extractKnowledgeReply(result) {
  if (result && result.results && Array.isArray(result.results)) {
    return result.results.map((item) => item.content || JSON.stringify(item)).join('\n');
  }
  if (result && result.error) {
    return result.error;
  }
  return typeof result === 'string' ? result : '';
}

function buildFastGreetingReply(message) {
  const text = String(message || '').trim();
  if (!/^(喂|你好|您好|嗨|哈喽|hello|hi|在吗|在不在|早上好|中午好|下午好|晚上好|早安|晚安)[，,！。？?~～\s]*[啊呀吧呢哦嗯嘛哈的了]*[！。？?~～]*$/i.test(text)) {
    return '';
  }
  return '你好😊！我是大沃智能助手。你可以直接问我一成系统、德国PM产品、招商合作、营养科普等问题，我会尽量快速给你准确回复。';
}

async function tryKnowledgeReply(sessionId, session, message) {
  const text = String(message || '').trim();
  if (!text) return null;
  const context = await buildKnowledgeContextMessages(sessionId, session);
  if (!shouldForceKnowledgeRoute(text, context)) {
    return null;
  }
  const result = await ToolExecutor.execute('search_knowledge', { query: text }, context);
  if (!result?.hit) {
    return null;
  }
  const content = normalizeAssistantText(extractKnowledgeReply(result));
  if (!content) {
    return null;
  }
  return {
    content,
    meta: {
      route: 'search_knowledge',
      original_text: text,
      tool_name: 'search_knowledge',
      tool_args: { query: text },
      source: result?.source || null,
      original_query: result?.original_query || text,
      rewritten_query: result?.rewritten_query || null,
      selected_dataset_ids: result?.selected_dataset_ids || null,
      selected_kb_routes: result?.selected_kb_routes || null,
      hit: typeof result?.hit === 'boolean' ? result.hit : null,
      reason: result?.reason || null,
      error_type: result?.errorType || null,
      latency_ms: result?.latency_ms || null,
    },
  };
}

/**
 * POST /api/chat/start
 * 创建文字对话会话，可选传入语音通话的历史字幕
 */
router.post('/start', async (req, res) => {
  const { sessionId, voiceSubtitles = [] } = req.body;

  if (!sessionId) {
    return res.status(400).json({ success: false, error: 'sessionId is required' });
  }

  if (!cozeChatService.isConfigured()) {
    return res.status(500).json({ success: false, error: 'Coze 智能体未配置，请设置 COZE_API_TOKEN 和 COZE_BOT_ID' });
  }

  const sessionState = await buildChatSessionState(sessionId, voiceSubtitles);

  // 更新数据库会话模式为 chat
  try { await db.createSession(sessionId, `user_${sessionId.slice(0, 12)}`, 'chat'); } catch (e) {}

  chatSessions.set(sessionId, sessionState);

  console.log(`[Chat] Session started: ${sessionId}, fromVoice: ${sessionState.fromVoice}, voiceMessages: ${sessionState.voiceMessages.length}, summary: ${sessionState.handoffSummary ? 'yes' : 'no'}`);

  res.json({
    success: true,
    data: {
      sessionId,
      messageCount: sessionState.voiceMessages.length,
      fromVoice: sessionState.fromVoice,
    },
  });
});

/**
 * POST /api/chat/send
 * 发送文字消息并获取 Coze 智能体回复（非流式）
 */
router.post('/send', async (req, res) => {
  try {
    const { sessionId, message } = req.body;

    if (!sessionId || !message) {
      return res.status(400).json({ success: false, error: 'sessionId and message are required' });
    }

    let session = chatSessions.get(sessionId);

    // 自动创建会话（如果不存在）
    if (!session) {
      session = await buildChatSessionState(sessionId, []);
      chatSessions.set(sessionId, session);
    }
    session.lastActiveAt = Date.now();

    console.log(`[Chat] User(${sessionId}): ${message}`);

    // 写入数据库：用户消息
    db.addMessage(sessionId, 'user', message, 'chat_user').catch(e => console.warn('[DB] addMessage failed:', e.message));

    const fastGreetingReply = buildFastGreetingReply(message);
    if (fastGreetingReply) {
      db.addMessage(sessionId, 'assistant', fastGreetingReply, 'chat_bot').catch(e => console.warn('[DB] addMessage failed:', e.message));
      return res.json({
        success: true,
        data: {
          content: fastGreetingReply,
        },
      });
    }

    const knowledgeReply = await tryKnowledgeReply(sessionId, session, message);
    if (knowledgeReply) {
      session.handoffSummaryUsed = true;
      db.addMessage(sessionId, 'assistant', knowledgeReply.content, 'chat_bot', 'search_knowledge', knowledgeReply.meta).catch(e => console.warn('[DB] addMessage failed:', e.message));
      return res.json({
        success: true,
        data: {
          content: knowledgeReply.content,
        },
      });
    }

    // 首次对话时注入语音历史作为上下文，之后 Coze 自动管理会话历史
    const extraMessages = !session.conversationId ? buildInitialContextMessages(session) : [];

    const result = await cozeChatService.chat(
      session.userId,
      message,
      session.conversationId,
      extraMessages
    );
    const normalizedContent = normalizeAssistantText(result.content);

    // 保存 Coze 返回的 conversationId
    session.conversationId = result.conversationId;
    session.handoffSummaryUsed = true;

    console.log(`[Chat] Assistant(${sessionId}): ${normalizedContent?.substring(0, 100)}`);

    // 写入数据库：AI 回复
    if (normalizedContent) {
      db.addMessage(sessionId, 'assistant', normalizedContent, 'chat_bot').catch(e => console.warn('[DB] addMessage failed:', e.message));
    }

    res.json({
      success: true,
      data: {
        content: normalizedContent,
      },
    });
  } catch (error) {
    console.error('[Chat] Send failed:', error.message);
    res.status(500).json({ success: false, error: error.message });
  }
});

/**
 * GET /api/chat/history/:sessionId
 * 获取会话状态
 */
router.get('/history/:sessionId', (req, res) => {
  const session = chatSessions.get(req.params.sessionId);
  if (!session) {
    return res.json({ success: true, data: [] });
  }

  res.json({
    success: true,
    data: {
      conversationId: session.conversationId,
      fromVoice: session.fromVoice,
    },
  });
});

/**
 * POST /api/chat/send-stream
 * 流式发送文字消息（SSE），逐字输出 Coze 智能体回复
 */
router.post('/send-stream', async (req, res) => {
  const { sessionId, message } = req.body;

  if (!sessionId || !message) {
    return res.status(400).json({ success: false, error: 'sessionId and message are required' });
  }

  let session = chatSessions.get(sessionId);
  if (!session) {
    session = await buildChatSessionState(sessionId, []);
    chatSessions.set(sessionId, session);
  }
  session.lastActiveAt = Date.now();

  console.log(`[Chat][SSE] User(${sessionId}): ${message}`);

  // 写入数据库：用户消息
  db.addMessage(sessionId, 'user', message, 'chat_user').catch(e => console.warn('[DB] addMessage failed:', e.message));

  // 设置 SSE 响应头
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');
  res.setHeader('X-Accel-Buffering', 'no');
  res.flushHeaders();

  const fastGreetingReply = buildFastGreetingReply(message);
  if (fastGreetingReply) {
    db.addMessage(sessionId, 'assistant', fastGreetingReply, 'chat_bot').catch(e => console.warn('[DB] addMessage failed:', e.message));
    res.write(`data: ${JSON.stringify({ type: 'done', content: fastGreetingReply })}\n\n`);
    return res.end();
  }

  try {
    const knowledgeReply = await tryKnowledgeReply(sessionId, session, message);
    if (knowledgeReply) {
      session.handoffSummaryUsed = true;
      db.addMessage(sessionId, 'assistant', knowledgeReply.content, 'chat_bot', 'search_knowledge', knowledgeReply.meta).catch(e => console.warn('[DB] addMessage failed:', e.message));
      res.write(`data: ${JSON.stringify({ type: 'done', content: knowledgeReply.content })}\n\n`);
      return res.end();
    }
    // 首次对话时注入语音历史作为上下文
    const extraMessages = !session.conversationId ? buildInitialContextMessages(session) : [];

    const result = await cozeChatService.chatStream(
      session.userId,
      message,
      session.conversationId,
      extraMessages,
      {
        onChunk: (text) => {
          res.write(`data: ${JSON.stringify({ type: 'chunk', content: text })}\n\n`);
        },
        onDone: () => {},
      }
    );
    const normalizedContent = normalizeAssistantText(result.content);

    // 保存 Coze 返回的 conversationId
    session.conversationId = result.conversationId;
    session.handoffSummaryUsed = true;
    console.log(`[Chat][SSE] Assistant(${sessionId}): ${normalizedContent?.substring(0, 100)}`);

    // 写入数据库：AI 回复
    if (normalizedContent) {
      db.addMessage(sessionId, 'assistant', normalizedContent, 'chat_bot').catch(e => console.warn('[DB] addMessage failed:', e.message));
    }

    res.write(`data: ${JSON.stringify({ type: 'done', content: normalizedContent })}\n\n`);
    res.end();
  } catch (error) {
    console.error('[Chat][SSE] Stream failed:', error.message);
    res.write(`data: ${JSON.stringify({ type: 'error', error: error.message })}\n\n`);
    res.end();
  }
});

/**
 * DELETE /api/chat/:sessionId
 * 删除对话会话
 */
router.delete('/:sessionId', (req, res) => {
  chatSessions.delete(req.params.sessionId);
  res.json({ success: true });
});

// 定时清理过期会话（30 分钟无活动）
setInterval(() => {
  const now = Date.now();
  const TTL = 30 * 60 * 1000;
  for (const [id, session] of chatSessions) {
    if (now - (session.lastActiveAt || session.createdAt) > TTL) {
      chatSessions.delete(id);
      console.log(`[Chat] Session expired and cleaned: ${id}`);
    }
  }
}, 5 * 60 * 1000);

module.exports = router;