const getFileExtension = (filename: string) => {
  return filename.split('.').pop();
};
const getFileType = (extension: string) => {
  switch (extension) {
    case 'js':
      return 'text/javascript';
    case 'css':
      return 'text/css';
    case 'html':
      return 'text/html';
    case 'json':
      return 'application/json';
    case 'png':
      return 'image/png';
    case 'jpg':
      return 'image/jpeg';
    case 'jpeg':
      return 'image/jpeg';
    case 'gif':
      return 'image/gif';
    case 'svg':
      return 'image/svg+xml';
    case 'webp':
      return 'image/webp';
    case 'ico':
      return 'image/x-icon';
    default:
      return 'text/plain';
  }
};
const checkIsBase64 = (content: string) => {
  return content.startsWith('data:');
};
/**
 * 获取文件的目录和文件名
 * @param filename 文件名
 * @returns 目录和文件名
 */
export const getDirectoryAndName = (filename: string) => {
  if (!filename) {
    return null;
  }
  if (filename.startsWith('.')) {
    return null;
  } else {
    filename = filename.replace(/^\/+/, ''); // Remove all leading slashes
  }
  const hasDirectory = filename.includes('/');
  if (!hasDirectory) {
    return { directory: '', name: filename };
  }
  const parts = filename.split('/');
  const name = parts.pop()!; // Get the last part as the file name
  const directory = parts.join('/'); // Join the remaining parts as the directory
  return { directory, name };
};
/**
 * 把字符串转为文件流，并返回文件流，根据filename的扩展名，自动设置文件类型.
 * 当不是文本类型，自动需要把base64的字符串转为blob
 * @param content 字符串
 * @param filename 文件名
 * @returns 文件流
 */
export const toFile = (content: string, filename: string) => {
  // 如果文件名是 a/d/a.js 格式的，则需要把d作为目录，a.js作为文件名
  const directoryAndName = getDirectoryAndName(filename);
  if (!directoryAndName) {
    throw new Error('Invalid filename');
  }
  const { name } = directoryAndName;
  const extension = getFileExtension(name);
  if (!extension) {
    throw new Error('Invalid filename');
  }
  const isBase64 = checkIsBase64(content);
  const type = getFileType(extension);

  if (isBase64) {
    // Decode base64 string
    const base64Data = content.split(',')[1]; // Remove the data URL prefix
    const byteCharacters = atob(base64Data);
    const byteNumbers = new Array(byteCharacters.length);
    for (let i = 0; i < byteCharacters.length; i++) {
      byteNumbers[i] = byteCharacters.charCodeAt(i);
    }
    const byteArray = new Uint8Array(byteNumbers);
    const blob = new Blob([byteArray], { type });
    return new File([blob], filename, { type });
  } else {
    const blob = new Blob([content], { type });
    return new File([blob], filename, { type });
  }
};

/**
 * 把字符串转为文本文件
 * @param content 字符串
 * @param filename 文件名
 * @returns 文件流
 */
export const toTextFile = (content: string = 'keep directory exist', filename: string = 'keep.txt') => {
  const file = toFile(content, filename);
  return file;
};