type DeepReadonly<T> =
  T extends ((...args: any[]) => any) ? T : // Preserve functions as is
  T extends object ? { readonly [P in keyof T]: DeepReadonly<T[P]> } :
  T;

// Example Usage:
interface Address {
  street: string;
  city: string;
}

interface UserProfile {
  name: string;
  age: number;
  address: Address;
  hobbies: string[];
  options: {
    notifications: boolean;
    theme: 'dark' | 'light';
  };
  logActivity: (message: string) => void;
}

type ImmutableUserProfile = DeepReadonly<UserProfile>;

const userProfile: ImmutableUserProfile = {
  name: 'John Doe',
  age: 30,
  address: {
    street: '123 Main St',
    city: 'Anytown',
  },
  hobbies: ['reading', 'coding'],
  options: {
    notifications: true,
    theme: 'dark',
  },
  logActivity: (msg: string) => console.log(msg),
};

// userProfile.name = 'Jane Doe'; // Error: Cannot assign to 'name' because it is a read-only property.
// userProfile.address.city = 'Otherville'; // Error: Cannot assign to 'city' because it is a read-only property.
// userProfile.hobbies.push('gaming'); // Error: Property 'push' does not exist on type 'readonly string[]'.

// Functions are preserved and can still be called:
userProfile.logActivity('User viewed profile'); // No error