import path from "path";
import * as dicomParser from "dicom-parser";
import fs from "fs";

/**
 * 定义一个异步函数来递归地查找.dcm文件
 * @param dir
 * @param fileList
 * @returns
 */
export const findDcmFiles = async (
  dir: string,
  fileList: string[] = []
): Promise<string[]> => {
  const files = await fs.promises.readdir(dir, { withFileTypes: true });
  await Promise.all(
    files.map(async (file) => {
      const filePath = path.join(dir, file.name);
      if (file.isDirectory()) {
        await findDcmFiles(filePath, fileList); // 递归调用以遍历子目录
      } else if (file.name.endsWith(".dcm")) {
        fileList.push(filePath); // 如果文件是.dcm文件，添加到列表中
      }
    })
  );
  return fileList;
};

/**
 * 获取单个dcm文件的metadata信息
 */
export const parseDICOMFile = async (filePath: string) => {
  try {
    const arrayBuffer = await fs.promises.readFile(filePath);
    const byteArray = new Uint8Array(arrayBuffer);
    const options = { TransferSyntaxUID: "1.2.840.10008.1.2" };
    const dataSet = dicomParser.parseDicom(byteArray, options);
    const StudyInstanceUID = dataSet.string("x0020000d");
    const SeriesInstanceUID = dataSet.string("x0020000e");
    const pixelDataElement = dataSet.elements.x7fe00010;
    const pixelData = new Uint16Array(
      dataSet.byteArray.buffer,
      pixelDataElement.dataOffset,
      pixelDataElement.length / 2
    );

    return {
      filePath,
      StudyInstanceUID,
      SeriesInstanceUID,
      pixelData,
    };
  } catch (error) {
    console.error(`Error parsing file ${filePath}:`, error);
  }
};

/**
 * 处理文件的函数，分批异步处理
 * @param filePaths
 * @param {number} batchSize 批次数
 * @returns
 */
export const processFilesInBatches = async (
  filePaths: string[],
  batchSize: number
) => {
  const results = [];
  for (let i = 0; i < filePaths.length; i += batchSize) {
    const batch = filePaths.slice(i, i + batchSize);
    const batchResults = await Promise.all(
      batch.map((filePath) => parseDICOMFile(filePath))
    );
    results.push(...batchResults);
  }
  return results;
};