useDirectorySync - syncs React Native directories (using react-native-fs) on appState change

useDirectorySync.ts

import { useState } from 'react';
import useAppState from 'react-native-appstate-hook';
import RNFS from 'react-native-fs';

async function copyDir(source: string, destination: string) {
  const fileChangeLog: string[] = [];

  await copyDirRecursive(source, destination, fileChangeLog);

  return fileChangeLog;
}

async function copyDirRecursive(source: string, destination: string, fileChangeLog: string[]) {
  const items = await RNFS.readDir(source);

  await RNFS.mkdir(destination);

  await items.forEach(async (item) => {
    if (item.isFile()) {
      const destinationFile = `${destination}/${item.name}`;

      const fileExists = await RNFS.exists(destinationFile);
      if (fileExists) {
        const sourceFileHash = await RNFS.hash(item.path, 'md5');
        const destinationFileHash = await RNFS.hash(destinationFile, 'md5');

        if (sourceFileHash === destinationFileHash) return;

        RNFS.unlink(destinationFile);

        return;
      }

      await RNFS.copyFile(item.path, destinationFile);

      fileChangeLog.push(destinationFile);
    } else {
      const sourceDir = `${source}/${item.name}`;
      const destinationDir = `${destination}/${item.name}`;

      await copyDirRecursive(sourceDir, destinationDir, fileChangeLog);
    }
  });
}

const useDirectorySync = (directorySource: string, directoryDestination: string) => {
  const [directoryPath, setDirectoryPath] = useState('');

  useAppState({
    onForeground: async () => {
      const filesChanged = await copyDir(directorySource, directoryDestination);
      if (filesChanged.length) console.info('FilesChanged', filesChanged);

      setDirectoryPath(directoryDestination);
    },
  });

  return directoryPath;
};

export default useDirectorySync;