/**
 * @description Creates a new type by taking type T and overwriting properties that exist in U with U's types.
 *              Properties in U that are not in T are also included.
 * @template T The base type.
 * @template U The type whose properties will override T's and be added.
 */
type Overwrite<T, U> = Omit<T, keyof U> & U;

// --- Usage Example ---
interface BaseSettings {
  theme: 'light' | 'dark';
  fontSize: number;
  notifications: boolean;
  language: string;
}

interface UserSettings {
  theme: 'dark'; // Overwrites 'theme' from BaseSettings
  notifications: 'email' | 'sms'; // Overwrites 'notifications'
  analytics: boolean; // New property, not in BaseSettings
}

type FinalSettings = Overwrite<BaseSettings, UserSettings>;
/* Expected:
{
  fontSize: number;
  language: string;
  theme: 'dark'; // Overwritten
  notifications: 'email' | 'sms'; // Overwritten
  analytics: boolean; // Added
}
*/

const settings: FinalSettings = {
  fontSize: 16,
  language: 'en-US',
  theme: 'dark', // Must be 'dark'
  notifications: 'email', // Must be 'email' or 'sms'
  analytics: true,
};

// This would cause a type error because 'theme' must be 'dark'
// const invalidSettings: FinalSettings = {
//   fontSize: 16,
//   language: 'en-US',
//   theme: 'light',
//   notifications: 'email',
//   analytics: true,
// };