// DOM primitives ported from static/mnw.js.

/**
 * Escape all five HTML-special characters. Safe for both element-content and
 * attribute interpolation. Ported from mnw.js:19 (the Run 20 single escaper);
 * the one canonical escaper — feature code must not ship its own.
 */
export function escapeHtml(s: unknown): string {
  return String(s)
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

/** Attribute-context alias — identical five-char escape (escapeHtml is already
 *  attribute-safe); named separately so call sites read intentfully. */
export const escapeAttr = escapeHtml;

/** Resolve `data-target` (space-separated element ids) to the elements that
 *  currently exist. Ported from mnw.js:725. */
export function targets(el: Element): HTMLElement[] {
  const raw = el.getAttribute('data-target');
  if (!raw) return [];
  return raw
    .split(/\s+/)
    .filter(Boolean)
    .map((id) => document.getElementById(id))
    .filter((e): e is HTMLElement => e !== null);
}

/** `document.getElementById` guarded against null/empty ids. */
export function byId(id: string | null | undefined): HTMLElement | null {
  return id ? document.getElementById(id) : null;
}