const INLINE_MEDIA_PATTERN = /!\[([^\]]*)\]\(swt-attachment:\/\/(\d+)\)/g;

export const shangwutongInlineMediaIndexes = contentAttributes => {
  const indexes = contentAttributes?.swt?.inline_media;
  if (!Array.isArray(indexes)) return new Set();

  return new Set(
    indexes.map(Number).filter(index => Number.isInteger(index) && index >= 0)
  );
};

const attachmentURL = attachment => attachment?.dataUrl ?? attachment?.data_url;

const resolveAttachmentURL = dataUrl => {
  if (!dataUrl) return '';

  try {
    return new URL(
      dataUrl,
      typeof window === 'undefined'
        ? 'http://localhost'
        : window.location.origin
    ).href;
  } catch {
    return dataUrl;
  }
};

export const formatShangwutongInlineContent = (
  content,
  attachments,
  contentAttributes
) => {
  const indexes = shangwutongInlineMediaIndexes(contentAttributes);
  if (!indexes.size) return content || '';

  const renderedIndexes = new Set();
  const formattedContent = (content || '').replace(
    INLINE_MEDIA_PATTERN,
    (match, alt, rawIndex) => {
      const index = Number(rawIndex);
      if (!indexes.has(index)) return match;
      renderedIndexes.add(index);

      const dataUrl = resolveAttachmentURL(attachmentURL(attachments?.[index]));
      if (!dataUrl) return alt || '商务通表情';

      return `![${alt || '商务通表情'}](<${dataUrl}>)`;
    }
  );

  const missingImages = [...indexes]
    .filter(index => !renderedIndexes.has(index))
    .map(index => {
      const dataUrl = resolveAttachmentURL(attachmentURL(attachments?.[index]));
      return dataUrl ? `![商务通表情](<${dataUrl}>)` : '商务通表情';
    });

  if (!missingImages.length) return formattedContent;
  return [formattedContent, missingImages.join('')].filter(Boolean).join('\n');
};