/**
 * This module implements the reference expansion as imeplemented by
 * commercetools.
 *
 * See https://docs.commercetools.com/api/general-concepts#reference-expansion
 *
 * TODO: implement support for multi-dimensional array
 */
type ExpandResult = {
	element: string;
	index?: string | number;
	rest?: string;
};

export const parseExpandClause = (clause: string): ExpandResult => {
	const result: ExpandResult = {
		element: clause,
		index: undefined,
		rest: undefined,
	};

	const pos = clause.indexOf(".");
	if (pos > 0) {
		result.element = clause.substring(0, pos);
		result.rest = clause.substring(pos + 1);
	}

	const match = result.element.match(/\[([^\]+])]/);
	if (match) {
		result.index = match[1] === "*" ? "*" : Number.parseInt(match[1], 10);
		result.element = result.element.substring(0, match.index);
	}
	return result;
};