const jwt = require('jsonwebtoken');
import { Request, Response, NextFunction } from 'express';
import { OAuth2Client } from 'google-auth-library';
import dataService from './unifiedDataService';

// Simplified authentication service - removes excessive logging and complexity
class AuthService {
  private jwtSecret: string;
  private jwtExpiry: string = '24h';
  private googleClient: OAuth2Client;

  constructor() {
    // Auto-generate a secure JWT secret if not provided
    if (process.env.JWT_SECRET) {
      this.jwtSecret = process.env.JWT_SECRET;
      console.log('Using JWT_SECRET from environment');
    } else {
      // Generate a cryptographically secure random secret
      const crypto = require('crypto');
      this.jwtSecret = crypto.randomBytes(64).toString('hex');
      console.log('Generated new JWT_SECRET (this will change on restart)');
      console.log('To persist sessions across restarts, set JWT_SECRET in .env');
    }
    
    // Initialize Google OAuth client
    this.googleClient = new OAuth2Client(process.env.GOOGLE_CLIENT_ID);
  }

  // Generate JWT token
  generateToken(user: any): string {
    const payload = { id: user.id, email: user.email, role: user.role };
    return jwt.sign(payload, this.jwtSecret, { expiresIn: this.jwtExpiry }) as string;
  }

  // Verify Google ID token from frontend
  async verifyGoogleToken(credential: string): Promise<{ user: any; token: string }> {
    try {
      // Verify the token with Google
      const ticket = await this.googleClient.verifyIdToken({
        idToken: credential,
        audience: process.env.GOOGLE_CLIENT_ID,
      });
      
      const payload = ticket.getPayload();
      if (!payload || !payload.email) {
        throw new Error('Invalid token payload');
      }

      // Find or create user
      let user = await dataService.getUserByEmail(payload.email);
      
      if (!user) {
        // Auto-create user with coordinator role
        user = await dataService.createUser({
          email: payload.email,
          name: payload.name || payload.email,
          role: 'coordinator',
          googleId: payload.sub
        });
      }

      // Generate our JWT
      const token = this.generateToken(user);
      
      return { user, token };
    } catch (error) {
      console.error('Token verification error:', error);
      throw new Error('Failed to verify Google token');
    }
  }

  // Verify JWT token
  verifyToken(token: string): any {
    try {
      return jwt.verify(token, this.jwtSecret);
    } catch (error) {
      return null;
    }
  }

  // Middleware to check authentication
  requireAuth = async (req: Request & { user?: any }, res: Response, next: NextFunction) => {
    const token = req.headers.authorization?.replace('Bearer ', '');
    
    if (!token) {
      return res.status(401).json({ error: 'Authentication required' });
    }

    const decoded = this.verifyToken(token);
    if (!decoded) {
      return res.status(401).json({ error: 'Invalid or expired token' });
    }

    // Get fresh user data
    const user = await dataService.getUserById(decoded.id);
    if (!user) {
      return res.status(401).json({ error: 'User not found' });
    }

    req.user = user;
    next();
  };

  // Middleware to check role
  requireRole = (roles: string[]) => {
    return (req: Request & { user?: any }, res: Response, next: NextFunction) => {
      if (!req.user) {
        return res.status(401).json({ error: 'Authentication required' });
      }

      if (!roles.includes(req.user.role)) {
        return res.status(403).json({ error: 'Insufficient permissions' });
      }

      next();
    };
  };

  // Google OAuth helpers
  getGoogleAuthUrl(): string {
    if (!process.env.GOOGLE_CLIENT_ID || !process.env.GOOGLE_REDIRECT_URI) {
      throw new Error('Google OAuth not configured. Please set GOOGLE_CLIENT_ID and GOOGLE_REDIRECT_URI in .env file');
    }
    
    const params = new URLSearchParams({
      client_id: process.env.GOOGLE_CLIENT_ID,
      redirect_uri: process.env.GOOGLE_REDIRECT_URI,
      response_type: 'code',
      scope: 'email profile',
      access_type: 'offline',
      prompt: 'consent'
    });

    return `https://accounts.google.com/o/oauth2/v2/auth?${params}`;
  }

  async exchangeGoogleCode(code: string): Promise<any> {
    const response = await fetch('https://oauth2.googleapis.com/token', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        code,
        client_id: process.env.GOOGLE_CLIENT_ID,
        client_secret: process.env.GOOGLE_CLIENT_SECRET,
        redirect_uri: process.env.GOOGLE_REDIRECT_URI,
        grant_type: 'authorization_code'
      })
    });

    if (!response.ok) {
      throw new Error('Failed to exchange authorization code');
    }

    return response.json();
  }

  async getGoogleUserInfo(accessToken: string): Promise<any> {
    const response = await fetch('https://www.googleapis.com/oauth2/v2/userinfo', {
      headers: { Authorization: `Bearer ${accessToken}` }
    });

    if (!response.ok) {
      throw new Error('Failed to get user info');
    }

    return response.json();
  }

  // Simplified login/signup
  async handleGoogleAuth(code: string): Promise<{ user: any; token: string }> {
    // Exchange code for tokens
    const tokens = await this.exchangeGoogleCode(code);
    
    // Get user info
    const googleUser = await this.getGoogleUserInfo(tokens.access_token);
    
    // Find or create user
    let user = await dataService.getUserByEmail(googleUser.email);
    
    if (!user) {
      // Auto-create user with coordinator role
      user = await dataService.createUser({
        email: googleUser.email,
        name: googleUser.name,
        role: 'coordinator',
        googleId: googleUser.id
      });
    }

    // Generate JWT
    const token = this.generateToken(user);
    
    return { user, token };
  }
}

export default new AuthService();