export type OfficeFileKind = "docx" | "xlsx" | "pptx" | "eml" | "mail";

const mimeTypes: Record<OfficeFileKind, string> = {
  docx: "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
  xlsx: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
  pptx: "application/vnd.openxmlformats-officedocument.presentationml.presentation",
  eml: "message/rfc822",
  mail: "application/octet-stream"
};

export function isDesktopOfficeBridgeAvailable() {
  return Boolean(window.qoffice?.isDesktop && window.qoffice.openOfficeFile && window.qoffice.saveOfficeFile);
}

export async function openDesktopOfficeFile(kind: OfficeFileKind): Promise<File | null> {
  const result = await window.qoffice?.openOfficeFile?.(kind);
  if (!result || result.canceled) {
    return null;
  }

  if (!result.base64Data) {
    throw new Error("Desktop-оболочка QOffice не вернула данные файла.");
  }

  return new File([base64ToBytes(result.base64Data)], result.fileName ?? `qoffice.${kind}`, {
    type: mimeTypes[kind]
  });
}

export async function saveDesktopOfficeFile(kind: OfficeFileKind, defaultFileName: string, blob: Blob) {
  const bridge = window.qoffice;
  if (!bridge?.saveOfficeFile) {
    throw new Error("Desktop-оболочка QOffice недоступна.");
  }

  const base64Data = bytesToBase64(new Uint8Array(await blob.arrayBuffer()));
  return bridge.saveOfficeFile(kind, defaultFileName, base64Data);
}

export function bytesToBase64(bytes: Uint8Array) {
  let binary = "";
  const chunkSize = 0x8000;
  for (let index = 0; index < bytes.length; index += chunkSize) {
    binary += String.fromCharCode(...bytes.slice(index, index + chunkSize));
  }
  return btoa(binary);
}

export function base64ToBytes(base64Data: string) {
  const binary = atob(base64Data);
  const bytes = new Uint8Array(binary.length);
  for (let index = 0; index < binary.length; index += 1) {
    bytes[index] = binary.charCodeAt(index);
  }
  return bytes;
}