Detect and convert file charsets

charset-tools.js

const exec = require('child_process').exec;
const fs = require('fs');

const iconv = (from, to, encoding, isFallback) => {
  return new Promise((resolve, reject) => {
    exec(`iconv -f ${encoding.trim()} -t utf-8 ${from} > ${to}`, (err) => {
      if (err && !isFallback) {
        return resolve(iconv(from, to, 'ISO_8859-1', true));
      }
      
      if (err) return reject(err);

      resolve();
    });
  });
};

const detect = (file) => {
  return new Promise((resolve, reject) => {
    if (!fs.existsSync(file)) {
      reject(new Error(`file ${file} not found`)) ;
    }
    exec(`uchardet ${file}`, (err, encoding) => {
      if (err) reject(err);
      resolve(encoding.trim());
    });
  });
};

const convert = (from, to) => {
  return new Promise((resolve, reject) => {
    detect(from).then((encoding) => {
      resolve(iconv(from, to, encoding));
    }).catch(reject);
  });
};

module.exports = {
  convert,
  detect,
  iconv
};