footer-leading-blank.ts

import toLines from "@commitlint/to-lines";
import message from "@commitlint/message";
import { SyncRule } from "@commitlint/types";

export const footerLeadingBlank: SyncRule = (parsed, when = "always") => {
	// Flunk if no footer is found
	if (!parsed.footer) {
		return [true];
	}

	const negated = when === "never";
	const rawLines = toLines(parsed.raw);
	const footerLines = toLines(parsed.footer);
	const footerOffset = rawLines.indexOf(footerLines[0]);
	const [leading] = rawLines.slice(footerOffset - 1);

	// Check if the first line of footer is empty
	const succeeds = leading === "";

	return [
		negated ? !succeeds : succeeds,
		message([
			"footer",
			negated ? "may not" : "must",
			"have leading blank line",
		]),
	];
};