const EXT_MIME: Record<string, string> = {
  pdf: 'application/pdf',
  png: 'image/png',
  jpg: 'image/jpeg',
  jpeg: 'image/jpeg',
  gif: 'image/gif',
  webp: 'image/webp',
  bmp: 'image/bmp',
  svg: 'image/svg+xml',
  mp4: 'video/mp4',
  mov: 'video/quicktime',
  avi: 'video/x-msvideo',
  webm: 'video/webm',
  mkv: 'video/x-matroska',
  m4v: 'video/x-m4v',
  wmv: 'video/x-ms-wmv',
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  xls: 'application/vnd.ms-excel',
  csv: 'text/csv',
  docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
  doc: 'application/msword',
  pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
  ppt: 'application/vnd.ms-powerpoint',
  hwp: 'application/x-hwp',
  hwpx: 'application/hwp+zip',
  txt: 'text/plain',
};

/** multer가 application/octet-stream 으로 저장할 때 확장자로 보정 */
export function resolveFileMime(originalName: string, stored?: string | null): string {
  const ext = originalName.split('.').pop()?.toLowerCase() ?? '';
  const fromExt = ext ? EXT_MIME[ext] : undefined;

  if (!stored || stored === 'application/octet-stream' || stored === 'application/x-msdownload') {
    return fromExt ?? stored ?? 'application/octet-stream';
  }

  if (fromExt && stored.startsWith('application/') && stored.includes('octet')) {
    return fromExt;
  }

  return stored;
}

export function isInlinePreviewMime(mime: string): boolean {
  return (
    mime.startsWith('image/') ||
    mime.startsWith('video/') ||
    mime.startsWith('text/') ||
    mime === 'application/pdf' ||
    mime.includes('spreadsheet') ||
    mime.includes('excel') ||
    mime.includes('wordprocessingml') ||
    mime.includes('presentationml') ||
    mime === 'application/msword' ||
    mime === 'application/vnd.ms-powerpoint' ||
    mime === 'application/x-hwp' ||
    mime === 'application/hwp+zip'
  );
}