main-async-pattern.js

const path = require('path');
const fs = require('fs');
const crypto = require('crypto');
const { promisify } = require('util');

const readdirAsync = promisify(fs.readdir);
const statAsync = promisify(fs.stat);
const imageSizeAsync = promisify(imageSize);

const asyncForEach = async (array, callback) => {
  for (let index = 0; index < array.length; index += 1) {
    await callback(array[index], index, array);
  }
};

async function getFiles(dir) {
  const subdirs = await readdirAsync(dir);
  const files = await Promise.all(
    subdirs.map(async subdir => {
      const res = path.resolve(dir, subdir);
      return (await statAsync(res)).isDirectory() ? getFiles(res) : res;
    })
  );
  return files.reduce((a, f) => a.concat(f), []);
}

const main = async () => {
  const BASE_URL = 'http://static.fastcampus.co.kr/assets';
  const baseDir = path.resolve(__dirname, '../html/assets');

  try {
    let insertCount = 0;
    let updateCount = 0;
    const files = await getFiles(baseDir);
  
    await asyncForEach(files, async (file, index) => {
      const code = file.substring(baseDir.length + 1);
      const mimeType = mime.lookup(code) || 'application/octet-stream';
      if (/^image\//.test(mimeType)) {
        const dim = await imageSizeAsync(file);
        imageWidth = dim.width;
        imageHeight = dim.height;
      }
      const existing = await Asset.selectByCode(code);
      if (existing) {
        updateCount += 1;
        await Asset.updateById(existing.id, Object.assign(existing, asset));
      } else {
        insertCount += 1;
        await Asset.insert({
          type: 'ASSET',
          state: 'NORMAL',
        });
      }
    });
  } catch (e) {
    error('failed to upsert assets', e);
  }
};

main().catch(err => {
  error(err);
});