import express, { Request, Response, NextFunction } from 'express';
import dotenv from 'dotenv';
import cookieParser from 'cookie-parser';

import passport from './src/routes/passport';
import { logger } from './src/services/logger';

// Import routers
import authRouter from './src/routes/auth';
import publicRouter from './src/routes/public';
import userRouter from './src/routes/user';
import adminRouter from './src/routes/admin';
import aiRouter from './src/routes/ai';

// Load environment variables from a .env file at the root of your project
dotenv.config();

const app = express();

// --- Core Middleware ---
app.use(express.json()); // Middleware to parse JSON request bodies
app.use(cookieParser()); // Middleware to parse cookies
app.use(passport.initialize()); // Initialize Passport
 
// --- Logging Middleware ---

const getDurationInMilliseconds = (start: [number, number]): number => {
    const NS_PER_SEC = 1e9;
    const NS_TO_MS = 1e6;
    const diff = process.hrtime(start);
    return (diff[0] * NS_PER_SEC + diff[1]) / NS_TO_MS;
};

const requestLogger = (req: Request, res: Response, next: NextFunction) => {
    const start = process.hrtime();
    const { method, originalUrl } = req;

    res.on('finish', () => {
        const user = req.user as { id?: string } | undefined;
        const durationInMilliseconds = getDurationInMilliseconds(start);
        const { statusCode } = res;
        const userIdentifier = user?.id ? ` (User: ${user.id})` : '';

        const logMessage = `${method} ${originalUrl} ${statusCode} ${durationInMilliseconds.toFixed(2)}ms${userIdentifier}`;

        if (statusCode >= 500) logger.error(logMessage);
        else if (statusCode >= 400) logger.warn(logMessage);
        else logger.info(logMessage);
    });

    next();
};

app.use(requestLogger); // Use the logging middleware for all requests

// --- Security Warning ---
if ((process.env.JWT_SECRET || 'your_super_secret_jwt_key_change_this') === 'your_super_secret_jwt_key_change_this') {
    logger.warn('Security Warning: JWT_SECRET is using a default, insecure value. Please set a strong secret in your .env file.');
}

// --- API Routes ---

app.use('/api', publicRouter);
app.use('/api/auth', authRouter);
app.use('/api', userRouter); // Contains protected user routes
app.use('/api/admin', adminRouter);
app.use('/api/ai', aiRouter);

// --- Error Handling and Server Startup ---

// Basic error handling middleware
app.use((err: Error, req: Request, res: Response, next: NextFunction) => {
  logger.error('Unhandled application error:', { error: err.stack });
  // The 'next' parameter is required for Express to identify this as an error-handling middleware.
  // We log it here to satisfy the 'no-unused-vars' lint rule, as it's not called in this terminal handler.
  logger.info('Terminal error handler invoked. The "next" function is part of the required signature.', { next: String(next) });
  if (!res.headersSent) {
    res.status(500).json({ message: 'Something broke!' });
  }
});

const PORT = process.env.PORT || 3001;
app.listen(PORT, () => {
  logger.info(`Authentication server started on port ${PORT}`);
});