/** Decode common HTML entities (named + numeric) for plain-text display. */
function decodeHtmlEntities(text: string): string {
  return text
    .replace(/ /gi, ' ')
    .replace(/&/gi, '&')
    .replace(/&lt;/gi, '<')
    .replace(/&gt;/gi, '>')
    .replace(/&quot;/gi, '"')
    .replace(/&#39;|&apos;/gi, "'")
    .replace(/&sup2;/gi, '²')
    .replace(/&sup3;/gi, '³')
    .replace(/&eacute;/gi, 'é')
    .replace(/&Eacute;/gi, 'É')
    .replace(/&egrave;/gi, 'è')
    .replace(/&Egrave;/gi, 'È')
    .replace(/&agrave;/gi, 'à')
    .replace(/&Agrave;/gi, 'À')
    .replace(/&acirc;/gi, 'â')
    .replace(/&ocirc;/gi, 'ô')
    .replace(/&icirc;/gi, 'î')
    .replace(/&ucirc;/gi, 'û')
    .replace(/&ccedil;/gi, 'ç')
    .replace(/&Ccedil;/gi, 'Ç')
    .replace(/&euro;/gi, '€')
    .replace(/&mdash;/gi, '—')
    .replace(/&ndash;/gi, '–')
    .replace(/&hellip;/gi, '…')
    .replace(/&#(\d+);/g, (_, n) => {
      const code = Number(n);
      return Number.isFinite(code) ? String.fromCharCode(code) : _;
    })
    .replace(/&#x([0-9a-f]+);/gi, (_, h) => {
      const code = parseInt(h, 16);
      return Number.isFinite(code) ? String.fromCharCode(code) : _;
    });
}

/**
 * Convert HTML (or HTML-entity text) to readable plain text for React Native.
 * Safe to call on already-plain strings.
 */
export function htmlToPlainText(input: string | null | undefined): string {
  if (input == null) return '';
  let text = String(input);
  if (!text.trim()) return '';

  text = text
    .replace(/<\s*br\s*\/?\s*>/gi, '\n')
    .replace(/<\/\s*p\s*>/gi, '\n')
    .replace(/<\/\s*div\s*>/gi, '\n')
    .replace(/<\/\s*li\s*>/gi, '\n')
    .replace(/<\s*li[^>]*>/gi, '• ')
    .replace(/<[^>]+>/g, ' ');

  text = decodeHtmlEntities(text);
  return text.replace(/[ \t]+\n/g, '\n').replace(/\n{3,}/g, '\n\n').replace(/[ \t]{2,}/g, ' ').trim();
}

export function looksLikeHtml(input: string | null | undefined): boolean {
  if (!input) return false;
  return /<[a-z][\s\S]*>/i.test(input) || /&(nbsp|amp|lt|gt|quot|#\d+|#x[0-9a-f]+|[a-z]+);/i.test(input);
}