/**
 * Convert markdown content into a plaintext string suitable for TTS.
 * Strips code blocks, images, and excess whitespace.
 */
export function markdownToPlainText(markdown: string): string {
  if (!markdown) return '';

  let text = markdown;

  // Remove fenced code blocks
  text = text.replace(/```[\s\S]*?```/g, '');
  // Remove inline code
  text = text.replace(/`([^`]*)`/g, '$1');
  // Remove images: ![alt](url)
  text = text.replace(/!\[[^\]]*\]\([^)]+\)/g, '');
  // Replace markdown links with link text
  text = text.replace(/\[([^\]]+)\]\([^)]+\)/g, '$1');
  // Strip emphasis markers (**bold**, __bold__, *italics*, _italics_)
  text = text.replace(/(\*\*|__)(.*?)\1/g, '$2');
  text = text.replace(/(\*|_)(.*?)\1/g, '$2');
  // Remove stray asterisks/underscores that might remain
  text = text.replace(/[*_]+/g, '');
  // Replace headings with emphasized text
  text = text.replace(/^(#{1,6})\s*(.*)$/gm, '$2');
  // Replace list markers with dash
  text = text.replace(/^\s*[-*+]\s+/gm, '- ');
  // Normalize whitespace
  text = text.replace(/\s+\n/g, '\n').replace(/\n{3,}/g, '\n\n');

  return text.trim();
}