fs.ts

import { extendType, string } from '..';
import fs from 'fs';
import path from 'path';

/**
 * Resolves an existing path. Produces an error when path does not exist.
 * When provided a relative path, extends it using the current working directory.
 */
export const ExistingPath = extendType(string, {
  displayName: 'path',
  description: 'An existing path',
  async from(str) {
    const resolved = path.resolve(str);

    if (!fs.existsSync(resolved)) {
      throw new Error("Path doesn't exist");
    }

    return resolved;
  },
});

/**
 * Resolves to a directory if given one, and to a file's directory if file was given.
 * Fails when the directory or the given file does not exist.
 */
export const Directory = extendType(ExistingPath, {
  async from(resolved) {
    const stat = fs.statSync(resolved);

    if (stat.isDirectory()) {
      return resolved;
    }

    return path.dirname(resolved);
  },
  displayName: 'dir',
  description: 'A path to a directory or a file within a directory',
});

/**
 * Resolves to a path to an existing file
 */
export const File = extendType(ExistingPath, {
  async from(resolved) {
    const stat = fs.statSync(resolved);

    if (stat.isFile()) {
      return resolved;
    }

    throw new Error('Provided path is not a file');
  },
  displayName: 'file',
  description: 'A file in the file system',
});