/**
 * Strip CommonMark backslash-escapes from a string. A backslash followed by
 * any ASCII punctuation character collapses to that character; backslash
 * followed by anything else (or end-of-string) is preserved.
 *
 * Why we need this: the article-content pipeline runs HTML through Turndown
 * to produce markdown source, and Turndown defensively escapes characters
 * that would otherwise have markdown meaning (`\_`, `\-`, `\[`, `\.` …).
 * Our TUI markdown renderer should *display* markdown, not show its source,
 * so the escapes have to be removed before rendering.
 *
 * Spec: https://spec.commonmark.org/0.30/#backslash-escapes
 */

// CommonMark ASCII-punctuation set. Kept as a literal-character class so the
// regex engine doesn't have to interpret it.
const ESCAPABLE = /\\([!"#$%&'()*+,\-./:;<=>?@[\]^_`{|}~\\])/g;

export function unescapeMarkdownPunctuation(input: string): string {
  if (!input.includes('\\')) return input;
  return input.replace(ESCAPABLE, '$1');
}