src/context/AuthContext.tsx

"use client";

import * as React from "react";
import { useRouter } from "next/navigation";

interface User {
  email: string;
  fullName: string;
  isPremium: boolean;
}

interface AuthContextType {
  user: User | null;
  token: string | null; // Exposed directly for API Client (File #38)
  isLoading: boolean;
  logout: () => void;
  refreshAuth: () => void;
}

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

/**
 * Global Auth Provider
 * Centralizes JWT management and reactive token state.
 */
export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [user, setUser] = React.useState<User | null>(null);
  const [token, setToken] = React.useState<string | null>(null);
  const [isLoading, setIsLoading] = React.useState(true);
  const router = useRouter();

  // 1. Memoized Token Decoder
  const decodeToken = React.useCallback((jwt: string): User | null => {
    try {
      const payload = JSON.parse(window.atob(jwt.split(".")[1]));
      return {
        email: payload.sub,
        fullName: payload.full_name || payload.sub.split('@')[0],
        isPremium: payload.is_premium === true,
      };
    } catch {
      return null;
    }
  }, []);

  // 2. The "Sync" Engine
  const refreshAuth = React.useCallback(() => {
    // Only run in browser
    if (typeof window === "undefined") return;

    const storedToken = localStorage.getItem("token");

    if (storedToken) {
      const decodedUser = decodeToken(storedToken);
      if (decodedUser) {
        setUser(decodedUser);
        setToken(storedToken);
      } else {
        // Token is malformed - clear everything
        localStorage.removeItem("token");
        setUser(null);
        setToken(null);
      }
    } else {
      setUser(null);
      setToken(null);
    }
    setIsLoading(false);
  }, [decodeToken]);

  // Initial Sync
  React.useEffect(() => {
    refreshAuth();
  }, [refreshAuth]);

  // 3. Centralized Logout
  const logout = React.useCallback(() => {
    localStorage.removeItem("token");
    setToken(null);
    setUser(null);
    router.push("/login");
  }, [router]);

  // 4. Provider Value
  const value = React.useMemo(() => ({
    user,
    token,
    isLoading,
    logout,
    refreshAuth
  }), [user, token, isLoading, logout, refreshAuth]);

  return (
    <AuthContext.Provider value={value}>
      {children}
    </AuthContext.Provider>
  );
}

export function useAuth() {
  const context = React.useContext(AuthContext);
  if (context === undefined) {
    throw new Error("useAuth must be used within an AuthProvider");
  }
  return context;
}