// auth-context.tsx
import React, { createContext, useContext, useEffect, useState } from 'react';

interface AuthContextType {
  user: User | null;
  token: string | null;
  refreshToken: string | null;
  login: (username: string, password: string) => Promise<void>;
  logout: () => Promise<void>;
  refreshSession: () => Promise<void>;
  isAuthenticated: boolean;
}

export const AuthContext = createContext<AuthContextType | undefined>(undefined);

export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [user, setUser] = useState<User | null>(null);
  const [token, setToken] = useState<string | null>(null);
  const [refreshToken, setRefreshToken] = useState<string | null>(null);

  // Auto-refresh token before expiry
  useEffect(() => {
    if (!token || !refreshToken) return;

    const tokenData = parseJWT(token);
    const expiryTime = tokenData.exp * 1000;
    const refreshTime = expiryTime - 5 * 60 * 1000; // 5 minutes before expiry
    
    const timeout = setTimeout(() => {
      refreshSession();
    }, refreshTime - Date.now());

    return () => clearTimeout(timeout);
  }, [token, refreshToken]);

  const login = async (username: string, password: string) => {
    const response = await fetch('/api/auth/login', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ username, password })
    });

    if (!response.ok) {
      const error = await response.json();
      throw new Error(error.message || 'Login failed');
    }

    const data = await response.json();
    setUser(data.user);
    setToken(data.access_token);
    setRefreshToken(data.refresh_token);
    
    localStorage.setItem('access_token', data.access_token);
    localStorage.setItem('refresh_token', data.refresh_token);
  };

  const refreshSession = async () => {
    if (!refreshToken) {
      throw new Error('No refresh token available');
    }

    try {
      const response = await fetch('/api/auth/refresh', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ refresh_token: refreshToken })
      });

      if (!response.ok) {
        throw new Error('Session refresh failed');
      }

      const data = await response.json();
      setToken(data.access_token);
      setRefreshToken(data.refresh_token);
      
      localStorage.setItem('access_token', data.access_token);
      localStorage.setItem('refresh_token', data.refresh_token);
    } catch (error) {
      // Refresh failed, redirect to login
      logout();
      window.location.href = '/login';
    }
  };

  const logout = async () => {
    if (token) {
      await fetch('/api/auth/logout', {
        method: 'POST',
        headers: { 'Authorization': `Bearer ${token}` }
      });
    }

    setUser(null);
    setToken(null);
    setRefreshToken(null);
    
    localStorage.removeItem('access_token');
    localStorage.removeItem('refresh_token');
    
    window.location.href = '/login';
  };

  return (
    <AuthContext.Provider value={{
      user,
      token,
      refreshToken,
      login,
      logout,
      refreshSession,
      isAuthenticated: !!token
    }}>
      {children}
    </AuthContext.Provider>
  );
}