import express from 'express';
import cors from 'cors';
import path from 'path';
import { fileURLToPath } from 'url';
import dotenv from 'dotenv';
import { StripeService } from './services/stripe.service.js';
import { AIService } from './services/ai.service.js';
import { WorkflowService } from './services/workflow.service.js';
import paymentRoutes from './routes/payment.js';
import authRoutes, { verifyToken } from './routes/auth.js';
import orderRoutes from './routes/order.js';
import adminRoutes from './routes/admin.js';
import knowledgeRoutes from './routes/knowledge.js';
import projectRoutes from './routes/project.js';
import workflowRoutes from './routes/workflow.js';
import userRoutes from './routes/user.js';
import apikeyRoutes from './routes/apikey.js';
import externalRoutes from './routes/external.js';
import concurrencyRoutes from './routes/concurrency.js';
import debugRoutes from './routes/debug.js';
import { setupWorkers } from './lib/queue.js';
import { ConcurrencyService } from './services/concurrency.service.js';
import { initDB, getDB } from './lib/db.js';
import { initPG } from './lib/pg.js';
import crypto from 'crypto';
import { aiCircuitBreaker } from './lib/circuit-breaker.js';
import { SystemService } from './lib/system.js';
import { initSocket } from './lib/socket.js';
import http from 'http';
import { rateLimit } from 'express-rate-limit';
import { QuotaService } from './services/quota.service.js';

dotenv.config();

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
const port = Number(process.env.PORT) || 7860;

const startServer = async () => {
  try {
    console.log('[系统] 正在启动服务...');
    
    // 1. 初始化数据库
    await initDB();
    const db = await getDB();
    
    try {
      await initPG();
    } catch (e) {
      console.warn('[Database] PostgreSQL 初始化跳过 (非致命):', e);
    }

    // 2. Stripe Webhook
    app.post('/api/payment/webhook', express.raw({ type: 'application/json' }), async (req, res) => {
      const sig = req.headers['stripe-signature'] as string;
      try {
        await StripeService.handleWebhook(sig, req.body);
        res.json({ received: true });
      } catch (err: any) {
        res.status(400).send(`Webhook 错误: ${err.message}`);
      }
    });

    // 3. 全局限流
    const apiLimiter = rateLimit({
      windowMs: 15 * 60 * 1000,
      max: 2000,
      message: { error: { message: "请求过于频繁，请稍后再试", type: "rate_limit_error", code: "429" } },
      standardHeaders: true,
      legacyHeaders: false,
    });

    app.use(express.json());
    app.use(cors());
    app.use('/api/', apiLimiter);

    // 4. 审计日志
    app.use((req, _res, next) => {
      if (!req.url.includes('/api/debug/queue-status')) {
        console.log(`[${new Date().toISOString()}] ${req.method} ${req.url}`);
      }
      next();
    });

    // 5. 业务路由
    app.use('/api/auth', authRoutes);
    app.use('/api/payment', paymentRoutes);
    app.use('/api/order', orderRoutes);
    app.use('/api/admin', adminRoutes);
    app.use('/api/knowledge', knowledgeRoutes);
    app.use('/api/project', projectRoutes);
    app.use('/api/workflow', workflowRoutes);
    app.use('/api/user', userRoutes);
    app.use('/api/apikey', apikeyRoutes);
    app.use('/api/v1', externalRoutes);
    app.use('/api/concurrency', concurrencyRoutes);
    app.use('/api/debug', debugRoutes);

    // --- AI 业务核心接口 ---
    app.post('/api/ai/chat', verifyToken, async (req: any, res) => {
      const { query, sessionId: incomingSessionId, knowledgeBaseId, model } = req.body;
      const userId = req.user.userId;

      if (!QuotaService.checkAndConsume(userId)) {
        return res.status(402).json({ error: { message: "配额不足", type: "insufficient_quota", code: "402" } });
      }

      let sessionId = incomingSessionId || crypto.randomUUID();
      if (!incomingSessionId) {
        db.prepare('INSERT INTO chat_sessions (id, user_id, title, knowledge_base_id) VALUES (?, ?, ?, ?)')
          .run(sessionId, userId, query.slice(0, 20) + (query.length > 20 ? '...' : ''), knowledgeBaseId || null);
      }

      try {
        const { stream, sources } = await aiCircuitBreaker.execute(async () => {
          return await AIService.chatWithKnowledge(userId, query, knowledgeBaseId, model);
        });
        
        res.setHeader('Content-Type', 'text/event-stream');
        res.setHeader('Cache-Control', 'no-cache');
        res.setHeader('Connection', 'keep-alive');
        res.write(`data: ${JSON.stringify({ sessionId, sources })}\n\n`);

        let assistantResponse = '';
        for await (const chunk of stream) {
          const content = chunk.choices[0]?.delta?.content || '';
          if (content) {
            assistantResponse += content;
            res.write(`data: ${JSON.stringify({ content })}\n\n`);
          }
        }

        const userEmbedding = await AIService.getEmbedding(query);
        db.prepare('INSERT INTO chat_messages (id, session_id, role, content, embedding) VALUES (?, ?, ?, ?, ?)')
          .run(crypto.randomUUID(), sessionId, 'user', query, JSON.stringify(userEmbedding));
        db.prepare('INSERT INTO chat_messages (id, session_id, role, content) VALUES (?, ?, ?, ?)')
          .run(crypto.randomUUID(), sessionId, 'assistant', assistantResponse);

        if (!incomingSessionId) {
          AIService.generateTitle(query, assistantResponse).then(smartTitle => {
            db.prepare('UPDATE chat_sessions SET title = ? WHERE id = ?').run(smartTitle, sessionId);
          }).catch(err => console.error('[AI] 标题生成失败:', err));
        }

        SystemService.logAudit(userId, 'CHAT', 'SUCCESS', { sessionId });
        res.end();
      } catch (err: any) {
        console.error('[AI] 对话出错:', err.message);
        res.status(err.message.includes('[熔断]') ? 503 : 500).json({ error: err.message });
      }
    });

    app.get('/api/ai/messages/:sessionId', verifyToken, (req: any, res) => {
      const { sessionId } = req.params;
      const messages = db.prepare('SELECT * FROM chat_messages WHERE session_id = ? ORDER BY created_at ASC').all(sessionId);
      res.json({ success: true, messages });
    });

    app.get('/api/ai/sessions', verifyToken, (req: any, res) => {
      const userId = req.user.userId;
      const sessions = db.prepare('SELECT * FROM chat_sessions WHERE user_id = ? ORDER BY created_at DESC').all(userId);
      res.json({ success: true, sessions });
    });

    app.delete('/api/ai/sessions/:sessionId', verifyToken, (req: any, res) => {
      const { sessionId } = req.params;
      const userId = req.user.userId;
      const session = db.prepare('SELECT id FROM chat_sessions WHERE id = ? AND user_id = ?').get(sessionId, userId);
      if (!session) return res.status(403).json({ success: false, error: '权限不足' });
      db.prepare('DELETE FROM chat_messages WHERE session_id = ?').run(sessionId);
      db.prepare('DELETE FROM chat_sessions WHERE id = ?').run(sessionId);
      res.json({ success: true });
    });

    app.patch('/api/ai/sessions/:sessionId', verifyToken, (req: any, res) => {
      const { sessionId } = req.params;
      const { title } = req.body;
      const userId = req.user.userId;
      const result = db.prepare('UPDATE chat_sessions SET title = ? WHERE id = ? AND user_id = ?').run(title, sessionId, userId);
      res.json({ success: result.changes > 0 });
    });

    app.get('/api/system/stats', verifyToken, (_req, res) => {
      res.json({ success: true, circuitBreaker: aiCircuitBreaker.getStatus(), serverTime: new Date().toISOString() });
    });

    // 6. 队列工作
    setupWorkers(
      async (data) => WorkflowService.execute(data.workflow, data.input, data.userId),
      async (data) => AIService.processDocument(data)
    );

    // 7. 静态文件
    const isProd = process.env.NODE_ENV === 'production';
    const distPath = isProd ? path.resolve(__dirname, '../../') : path.resolve(__dirname, '../dist');
    app.use(express.static(distPath));
    app.get('*', (req, res) => {
      if (req.path.startsWith('/api/')) return res.status(404).json({ error: 'API Not Found' });
      res.sendFile(path.join(distPath, 'index.html'));
    });

    // 8. 启动
    const httpServer = http.createServer(app);
    initSocket(httpServer);

    const server = httpServer.listen(port, '0.0.0.0', async () => {
      await ConcurrencyService.loadData();
      console.log(`[服务器] 全栈后端运行在: http://0.0.0.0:${port}`);
    });

    // 9. 优雅退出
    const shutdown = async (signal: string) => {
      console.log(`\n[${signal}] 正在存档...`);
      await ConcurrencyService.saveSnapshot();
      server.close(() => process.exit(0));
    };
    process.on('SIGTERM', () => shutdown('SIGTERM'));
    process.on('SIGINT', () => shutdown('SIGINT'));

  } catch (err) {
    console.error('[系统] 启动失败:', err);
    process.exit(1);
  }
};

startServer();

export default app;