export const PDF_FILE_ACCEPT = ".pdf,application/pdf";

export function isPdfFile(file: File) {
  return file.type === "application/pdf" || file.name.toLowerCase().endsWith(".pdf");
}

export function splitPdfFiles(files: File[] | FileList | null | undefined) {
  const source = Array.from(files ?? []);
  return {
    accepted: source.filter(isPdfFile),
    rejected: source.filter((file) => !isPdfFile(file)),
  };
}

export function rejectedPdfMessage(rejected: File[]) {
  if (!rejected.length) {
    return "";
  }
  const names = rejected.slice(0, 3).map((file) => file.name || "未命名文件").join("、");
  const suffix = rejected.length > 3 ? `等 ${rejected.length} 个文件` : "";
  return `发票上传仅支持 PDF，已忽略 ${names}${suffix}。`;
}