/* eslint-disable class-methods-use-this */
import { platform } from '@launchdarkly/js-server-sdk-common';
import * as fs from 'fs';

const fsPromises = fs.promises;

export default class NodeFilesystem implements platform.Filesystem {
  async getFileTimestamp(path: string): Promise<number> {
    const stat = await fsPromises.stat(path);
    return stat.mtimeMs;
  }

  async readFile(path: string): Promise<string> {
    return fsPromises.readFile(path, 'utf8');
  }

  watch(
    path: string,
    callback: (eventType: string, filename: string) => void
  ): platform.WatchHandle {
    return fs.watch(path, { persistent: false }, (eventType) => {
      callback(eventType, path);
    });
  }
}