const TYPE_LABELS = {
  "application/pdf": "PDF",
  "application/msword": "Word",
  "application/vnd.openxmlformats-officedocument.wordprocessingml.document": "Word",
  "application/vnd.ms-excel": "Excel",
  "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet": "Excel",
  "application/vnd.ms-powerpoint": "PowerPoint",
  "application/vnd.openxmlformats-officedocument.presentationml.presentation": "PowerPoint",
  "application/zip": "ZIP",
  "application/json": "JSON",
  "text/plain": "Text",
  "text/csv": "CSV",
  "image/jpeg": "JPEG",
  "image/jpg": "JPEG",
  "image/png": "PNG",
  "image/gif": "GIF",
  "image/webp": "WebP",
  "image/svg+xml": "SVG",
};

export function formatFileSize(bytes) {
  const size = Number(bytes);
  if (!Number.isFinite(size) || size <= 0) return "";
  if (size < 1024) return `${size} B`;
  if (size < 1024 * 1024) return `${Math.round(size / 1024)} KB`;
  if (size < 1024 * 1024 * 1024) return `${(size / (1024 * 1024)).toFixed(1)} MB`;
  return `${(size / (1024 * 1024 * 1024)).toFixed(1)} GB`;
}

export function fileTypeLabel(type, filename = "") {
  const mime = String(type || "").toLowerCase();
  if (TYPE_LABELS[mime]) return TYPE_LABELS[mime];
  if (mime.startsWith("image/")) return mime.slice(6).toUpperCase();
  if (mime.startsWith("video/")) return "Video";
  if (mime.startsWith("audio/")) return "Audio";
  const ext = String(filename).split(".").pop();
  if (ext && ext !== filename && ext.length <= 5) return ext.toUpperCase();
  return "File";
}

export function fileMetaLine(type, size, filename = "") {
  return [fileTypeLabel(type, filename), formatFileSize(size)].filter(Boolean).join(" · ");
}