// Advanced TypeScript Utility Types Examples

// 1. Partial - Make all properties optional
interface User {
  id: string;
  name: string;
  email: string;
}

type PartialUser = Partial<User>;
// Result: { id?: string; name?: string; email?: string }

// 2. Required - Make all properties required
type RequiredUser = Required<PartialUser>;
// Result: { id: string; name: string; email: string }

// 3. Pick - Select specific properties
type UserCredentials = Pick<User, 'email' | 'name'>;
// Result: { email: string; name: string }

// 4. Omit - Exclude specific properties
type UserWithoutId = Omit<User, 'id'>;
// Result: { name: string; email: string }

// 5. Custom Mapped Type - Make specific keys optional
type OptionalKeys<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;

type UserWithOptionalEmail = OptionalKeys<User, 'email'>;
// Result: { id: string; name: string; email?: string }

// 6. Readonly - Make all properties readonly
type ReadonlyUser = Readonly<User>;
// Properties cannot be reassigned

// 7. Record - Create object type with specific keys and values
type UserRoles = Record<'admin' | 'user' | 'guest', string[]>;
// Result: { admin: string[]; user: string[]; guest: string[] }

// 8. Advanced: Recursive Readonly
type DeepReadonly<T> = {
  readonly [P in keyof T]: T[P] extends object 
    ? DeepReadonly<T[P]> 
    : T[P];
};

interface NestedData {
  user: User;
  settings: { theme: string; notifications: boolean };
}

type ImmutableData = DeepReadonly<NestedData>;
// All nested properties are readonly!