/**
 * Returns the input source object with the defaults applied
 *
 * @example
 * ```js
 * type Example = {
 * 	optional?: boolean;
 * 	required: boolean;
 * }
 * const input: Example = { required: true };
 * const output = defaults(input, { optional: false });
 * // => { required: true, optional: false }
 * ```
 */
export const defaults = <T extends object>(
	obj: T,
	def: Required<
		Pick<
			T,
			Exclude<
				keyof T,
				Exclude<{ [K in keyof T]: T[K] extends Exclude<T[keyof T], undefined> ? K : never }[keyof T], undefined>
			>
		>
	>,
): Required<T> => {
	const input = Object.fromEntries(Object.entries(obj).filter(([_key, value]) => value !== undefined));

	return {
		...def,
		...input,
	} as Required<T>;
};