/**
 * Parse List-Unsubscribe URLs from raw email headers.
 *
 * Handles RFC 2822 header folding (continuation lines) and extracts
 * all angle-bracket-delimited URIs from the List-Unsubscribe header.
 */
export function parseListUnsubscribe(rawHeaders: string): string[] | null {
	// Unfold continuation lines (RFC 2822: CRLF followed by whitespace)
	const unfolded = rawHeaders.replace(/\r?\n[ \t]+/g, " ");
	const match = unfolded.match(/^List-Unsubscribe:\s*(.+)$/im);
	if (!match) return null;
	const urls = [...match[1].matchAll(/<([^>]+)>/g)].map((m) => m[1]);
	return urls.length > 0 ? urls : null;
}