/**
 * Helper utility functions for QueryBuilder.
 */
export class QueryBuilderUtils {
	/**
	 * Checks if given value is a string representation of alias property,
	 * e.g. "post.category" or "post.id".
	 */
	static isAliasProperty(str: any): str is string {
		// alias property must be a string and must have a dot separator
		if (typeof str !== 'string' || str.indexOf('.') === -1) return false;

		// extra alias and its property relation
		const [aliasName, propertyName] = str.split('.'); // todo: what about relations in embedded?
		if (!aliasName || !propertyName) return false;

		// alias and property must be represented in a special format
		// const aliasNameRegexp = /^[a-zA-Z0-9_-]+$/;
		// if (!aliasNameRegexp.test(aliasName) || !aliasNameRegexp.test(propertyName))
		//     return false;
		// make sure string is not a subquery
		if (str.indexOf('(') !== -1 || str.indexOf(')') !== -1) return false;

		return true;
	}
}