import * as fs from 'fs';

import * as json from '@discoveryjs/json-ext';

import { getLogger } from './loggers';

const logger = getLogger('json');

const writeFile = (path: fs.PathLike, obj: object) => new Promise<boolean>((resolve, reject) => {
  const renameSync = (oldPath: fs.PathLike, newPath: fs.PathLike) => {
    try {
      fs.renameSync(oldPath, newPath);
      return newPath;
    } catch (err) {
      reject(err);
    }
  }
  let backupPath: fs.PathLike;
  if (fs.statSync(path).size > 0) {
    backupPath = renameSync(path, `${path}.bak`);
  }
  json.stringifyStream(obj)
    .on('error', err => { logger.error(err); if (fs.existsSync(backupPath)) renameSync(backupPath, path); resolve(false); })
    .pipe(fs.createWriteStream(path))
    .on('error', err => { reject(err); })
    .on('finish', () => { if (fs.existsSync(backupPath)) fs.unlinkSync(`${path}.bak`); resolve(true); });
});

const readFile = (path: fs.PathLike) => new Promise<any>((resolve, reject) => {
  json.parseChunked(
    fs.createReadStream(path)
      .on('error', err => { reject(err); })
  ).then(resolve);
});

export {writeFile, readFile};