const csv = require('csv-parser')
const fs = require('fs')

class CsvReader {
  static readFile(filename, handler) {
    let res = [];
    return new Promise((resolve, reject) => {
      fs.createReadStream(filename)
        .pipe(csv())
        .on('data', (data) => res.push(handler(data)))
        .on('end', () => {
          resolve(res)
        }).on('error', (err)=> {
          reject(err);
        });
    });
  }
}
module.exports = CsvReader;