const express = require('express');
const helmet = require('helmet');
const cors = require('cors');
const compression = require('compression');
const morgan = require('morgan');
require('express-async-errors'); // Handle async errors
const config = require('./config/config.json');
const { swaggerUi, swaggerSpec } = require('./config/swagger');

// Import configurations
const { initializeDatabase } = require('./config/database');
const { setupRelationships } = require('./models');
const { redisClient } = require('./config/redis');

// Import middleware
const { errorHandler, notFoundHandler } = require('./middleware/errorHandler');

// Import routes
const authRoutes = require('./routes/authRoutes');
const schoolRoutes = require('./routes/schoolRoutes');
const classRoutes = require('./routes/classRoutes');
const academicYearRoutes = require('./routes/academicYearRoutes');
const subjectRoutes = require('./routes/subjectRoutes');
const userRoutes = require('./routes/userRoutes');
const studentRoutes = require('./routes/studentRoutes');
const teacherRoutes = require('./routes/teacherRoutes');
const roomRoutes = require('./routes/roomRoutes');
const attendanceRoutes = require('./routes/attendanceRoutes');
const gradeRoutes = require('./routes/gradeRoutes');
const subscriptionRoutes = require('./routes/subscriptionRoutes');
const trainingRoutes = require('./routes/trainingRoutes');
const parentTaskRoutes = require('./routes/parentTaskRoutes');
const chapterRoutes = require('./routes/chapterRoutes');
const gameRoutes = require('./routes/gameRoutes');
const lessonRoutes = require('./routes/lessonRoutes');
const chapterLessonRoutes = require('./routes/chapterLessonRoutes');
const vocabRoutes = require('./routes/vocabRoutes');
const grammarRoutes = require('./routes/grammarRoutes');
const storyRoutes = require('./routes/storyRoutes');
const learningContentRoutes = require('./routes/learningContentRoutes');

/**
 * Initialize Express Application
 */
const app = express();

/**
 * Security Middleware
 */
app.use(helmet({
  contentSecurityPolicy: {
    directives: {
      defaultSrc: ["'self'"],
      scriptSrc: ["'self'", "'unsafe-inline'"], // Allow inline scripts for Swagger UI
      styleSrc: ["'self'", "'unsafe-inline'"], // Allow inline styles for Swagger UI
      imgSrc: ["'self'", "data:", "https:", "validator.swagger.io"], // Allow Swagger validator
      connectSrc: ["'self'"],
      fontSrc: ["'self'"],
      objectSrc: ["'none'"],
      mediaSrc: ["'self'"],
      frameSrc: ["'none'"],
    },
  },
}));
app.use(cors({
  origin: config.cors.origin,
  credentials: true,
}));

/**
 * Body Parsing Middleware
 */
app.use(express.json({ limit: '10mb' }));
app.use(express.urlencoded({ extended: true, limit: '10mb' }));

/**
 * Static Files Middleware
 */
app.use(express.static('public'));

/**
 * Compression Middleware
 */
app.use(compression());

/**
 * Logging Middleware
 */
if (config.server.env === 'development') {
  app.use(morgan('dev'));
} else {
  app.use(morgan('combined'));
}

/**
 * Health Check Endpoint
 */
app.get('/health', async (req, res) => {
  try {
    // Check database connection
    await require('./config/database').testConnection();
    
    // Check Redis connection
    await redisClient.ping();
    
    res.json({
      success: true,
      status: 'healthy',
      timestamp: new Date().toISOString(),
      uptime: process.uptime(),
      environment: config.server.env,
      services: {
        database: 'connected',
        redis: 'connected',
      },
    });
  } catch (error) {
    res.status(503).json({
      success: false,
      status: 'unhealthy',
      error: error.message,
    });
  }
});

/**
 * API Info Endpoint
 */
app.get('/api', (req, res) => {
  res.json({
    success: true,
    name: 'Sena School Management API',
    version: '1.0.0',
    description: 'API for managing 200 schools with Redis caching and BullMQ job processing',
    endpoints: {
      auth: '/api/auth',
      schools: '/api/schools',
      classes: '/api/classes',
      academicYears: '/api/academic-years',
      subjects: '/api/subjects',
      users: '/api/users',
      students: '/api/students',
      teachers: '/api/teachers',
      rooms: '/api/rooms',
      attendance: '/api/attendance',
      grades: '/api/grades',
      subscriptions: '/api/subscriptions',
      training: '/api/training',
      parentTasks: '/api/parent-tasks',
      chapters: '/api/chapters',
      lessons: '/api/lessons',
      games: '/api/games',
      vocab: '/api/vocab',
    },
    documentation: '/api-docs',
  });
});

/**
 * Swagger API Documentation
 */
app.use('/api-docs', swaggerUi.serve);
app.get('/api-docs', swaggerUi.setup(swaggerSpec, {
  customCss: '.swagger-ui .topbar { display: none }',
  customSiteTitle: 'SENA API Documentation',
  customfavIcon: '/favicon.ico',
  swaggerOptions: {
    persistAuthorization: true,
    displayRequestDuration: true,
    filter: true,
    syntaxHighlight: {
      theme: 'monokai',
    },
  },
}));

/**
 * Swagger JSON endpoint
 */
app.get('/api-docs.json', (req, res) => {
  res.setHeader('Content-Type', 'application/json');
  res.send(swaggerSpec);
});

/**
 * API Routes
 */
app.use('/api/auth', authRoutes);
app.use('/api/schools', schoolRoutes);
app.use('/api/classes', classRoutes);
app.use('/api/academic-years', academicYearRoutes);
app.use('/api/subjects', subjectRoutes);
app.use('/api/users', userRoutes);
app.use('/api/students', studentRoutes);
app.use('/api/teachers', teacherRoutes);
app.use('/api/rooms', roomRoutes);
app.use('/api/attendance', attendanceRoutes);
app.use('/api/grades', gradeRoutes);
app.use('/api/subscriptions', subscriptionRoutes);
app.use('/api/training', trainingRoutes);
app.use('/api/parent-tasks', parentTaskRoutes);
app.use('/api/chapters', chapterRoutes);
app.use('/api/chapters', chapterLessonRoutes); // Nested route: /api/chapters/:id/lessons
app.use('/api/games', gameRoutes);
app.use('/api/lessons', lessonRoutes);
app.use('/api/vocab', vocabRoutes);
app.use('/api/grammar', grammarRoutes);
app.use('/api/stories', storyRoutes);
app.use('/api/learning-content', learningContentRoutes);

/**
 * Queue Status Endpoint
 */
app.get('/api/queues/status', async (req, res) => {
  try {
    const { getQueueMetrics, QueueNames } = require('./config/bullmq');
    
    const metrics = await Promise.all(
      Object.values(QueueNames).map(queueName => getQueueMetrics(queueName))
    );
    
    res.json({
      success: true,
      data: metrics,
    });
  } catch (error) {
    res.status(500).json({
      success: false,
      error: error.message,
    });
  }
});

/**
 * Cache Stats Endpoint
 */
app.get('/api/cache/stats', async (req, res) => {
  try {
    const info = await redisClient.info('stats');
    const dbSize = await redisClient.dbsize();
    
    res.json({
      success: true,
      data: {
        dbSize,
        stats: info,
      },
    });
  } catch (error) {
    res.status(500).json({
      success: false,
      error: error.message,
    });
  }
});

/**
 * 404 Handler
 */
app.use(notFoundHandler);

/**
 * Global Error Handler
 */
app.use(errorHandler);

/**
 * Initialize Application
 */
const initializeApp = async () => {
  try {
    // Initialize database connection
    await initializeDatabase();
    
    // Setup model relationships
    setupRelationships();
    
    console.log('✅ Application initialized successfully');
  } catch (error) {
    console.error('❌ Application initialization failed:', error.message);
    throw error;
  }
};

module.exports = { app, initializeApp };