$extract_manipulated_string.ts

/**
 * 🧰 *type util*
 *
 * Extract the manipulated string from any of the intrinsic string manipulation types:
 *
 * - `Uppercase`
 * - `Lowercase`
 * - `Capitalize`
 * - `Uncapitalize`
 */
export type $ExtractManipulatedString<T extends string> = [T, unknown] extends [unknown, T]
	? T
	: $ExtractManipulatedString._UpperOrElse<
			T,
			$ExtractManipulatedString._LowerOrElse<
				T,
				$ExtractManipulatedString._CapOrElse<T, $ExtractManipulatedString._UncapOrElse<T, T>>
			>
		>

export namespace $ExtractManipulatedString {
	export type _UpperOrElse<N, Else> = N extends Uppercase<infer Y>
		? string extends Y
			? Uppercase<any> extends N
				? Y
				: N
			: $ExtractManipulatedString<Y>
		: Else
	export type _LowerOrElse<N, Else> = N extends Lowercase<infer Y>
		? string extends Y
			? Lowercase<any> extends N
				? Y
				: N
			: $ExtractManipulatedString<Y>
		: Else
	export type _CapOrElse<N, Else> = N extends Capitalize<infer Y>
		? string extends Y
			? Capitalize<any> extends N
				? Y
				: N
			: $ExtractManipulatedString<Y>
		: Else
	export type _UncapOrElse<N, Else> = N extends Uncapitalize<infer Y>
		? string extends Y
			? Uncapitalize<any> extends N
				? Y
				: N
			: $ExtractManipulatedString<Y>
		: Else
}