/**
 * CSRF Protection Usage Example
 * Demonstrates how to use the CSRF protection system
 */

import { CSRFManager } from './csrf-manager';
import type { CSRFConfig, CSRFRequest } from './types';

// Example configuration
const config: CSRFConfig = {
  secret: 'your-secret-key-here-should-be-random-and-secure',
  tokenExpiry: 60 * 60 * 1000, // 1 hour
  cookieName: '__csrf-token',
  headerName: 'X-CSRF-Token',
  fieldName: '_csrf',
  secureCookie: true,
  httpOnlyCookie: true,
  sameSite: 'strict'
};

// Initialize CSRF manager
const csrfManager = new CSRFManager(config);

// Example 1: Session-based CSRF protection
function sessionBasedExample() {
  console.log('=== Session-based CSRF Protection ===');

  const sessionId = 'user-session-12345';

  // Generate a token for the session
  const token = csrfManager.generateToken(sessionId);
  console.log('Generated token:', token.value);

  // Generate HTML form field
  const formField = csrfManager.generateFormField(sessionId);
  console.log('Form field HTML:', formField);

  // Validate the token
  const validationResult = csrfManager.validateToken(token.value, sessionId);
  console.log('Token validation:', validationResult);

  // Simulate a request with the token
  const request: CSRFRequest = {
    headers: { 'X-CSRF-Token': token.value },
    sessionId
  };

  const requestValidation = csrfManager.validateRequest(request);
  console.log('Request validation:', requestValidation);
}

// Example 2: Double-submit cookie pattern
function doubleSubmitExample() {
  console.log('\n=== Double-Submit Cookie Pattern ===');

  const sessionId = 'user-session-67890';

  // Set up double-submit protection
  const response = csrfManager.setupDoubleSubmitProtection(sessionId);
  console.log('Response headers:', response.headers);
  console.log('Response cookies:', response.cookies);

  // Simulate a request with matching tokens
  const request: CSRFRequest = {
    headers: { 'X-CSRF-Token': response.headers['X-CSRF-Token'] || '' },
    cookies: { '__csrf-token': response.cookies[0]?.value || '' }
  };

  const validationResult = csrfManager.validateRequest(request);
  console.log('Double-submit validation:', validationResult);
}

// Example 3: Client-side integration
function clientSideExample() {
  console.log('\n=== Client-side Integration ===');

  // Generate client-side script
  const clientScript = csrfManager.generateClientScript('user-session-12345');
  console.log('Client script length:', clientScript.length, 'characters');
  console.log('Script includes form injection:', clientScript.includes('injectFormTokens'));
  console.log('Script includes AJAX interceptor:', clientScript.includes('setupAjaxInterceptor'));
}

// Example 4: Express.js middleware example
function expressMiddlewareExample() {
  console.log('\n=== Express.js Middleware Example ===');

  // This would be used in an Express.js application
  const csrfMiddleware = (req: any, res: any, next: any) => {
    // Skip CSRF protection for GET requests
    if (req.method === 'GET') {
      return next();
    }

    // Extract session ID (from session middleware)
    const sessionId = req.session?.id || req.sessionID;

    if (!sessionId) {
      return res.status(403).json({ error: 'Session required' });
    }

    // Create request object
    const csrfRequest: CSRFRequest = {
      headers: req.headers,
      body: req.body,
      cookies: req.cookies,
      sessionId
    };

    // Validate CSRF protection
    const validation = csrfManager.validateRequest(csrfRequest);

    if (!validation.valid) {
      return res.status(403).json({
        error: 'CSRF validation failed',
        message: validation.error
      });
    }

    next();
  };

  console.log('Express middleware created');
  console.log('Usage: app.use(csrfMiddleware)');
}

// Example 5: Statistics and monitoring
function statisticsExample() {
  console.log('\n=== Statistics and Monitoring ===');

  // Generate some tokens for different sessions
  csrfManager.generateToken('session-1');
  csrfManager.generateToken('session-1');
  csrfManager.generateToken('session-2');

  const stats = csrfManager.getStats();
  console.log('CSRF Statistics:', stats);

  const config = csrfManager.getConfig();
  console.log('CSRF Configuration:', {
    tokenExpiry: config.tokenExpiry,
    cookieName: config.cookieName,
    headerName: config.headerName,
    fieldName: config.fieldName
  });
}

// Run examples
if (require.main === module) {
  sessionBasedExample();
  doubleSubmitExample();
  clientSideExample();
  expressMiddlewareExample();
  statisticsExample();

  // Clean up
  csrfManager.destroy();
}

export {
    clientSideExample, doubleSubmitExample, expressMiddlewareExample, sessionBasedExample, statisticsExample
};