const fs = require('fs');
const path = require('path');
const translate = require('google-translate-api');

const non_english_regex = new RegExp('[^\u0000-\u007F]+');

const translateKey = 'YOUR_API_KEY_HERE';
const googleTranslate = require('google-translate')(translateKey);

/* Helper functions */

/* from comment from TifPun located @ https://gist.github.com/kethinov/6658166 */
function walkSync(dir, filelist) {
  var files = fs.readdirSync(dir);
  filelist = filelist || [];

  files.forEach(function(file) {
    if (fs.statSync(path.join(dir, file)).isDirectory()) {
      filelist = walkSync(path.join(dir, file), filelist);
    } else {
      filelist.push(path.join(dir, file));
    }
  });

  return filelist;
};

function translatePath(dir) {
  var results = walkSync(dir);
  var promises = [];

  if (results) {
    for(var i = 0; i < results.length; i++) {
      const file = results[i];
      const parsedFile = path.parse(file);

      if (non_english_regex.test(parsedFile.name) && parsedFile.name.indexOf('%') == -1) {

        var promise = new Promise(function(resolve, reject) {
          googleTranslate.translate(parsedFile.name, 'en', function(err, translation) {
            if (err) {
              reject(err);
            }

            var newName = path.join(parsedFile.dir, translation.translatedText + parsedFile.ext);
            fs.rename(file, newName, function(error) {
              if (error) {
                reject(err);
              }

              console.log('renamed file: ' + file + ', to ' + newName);
              resolve();
            });

          });
        });

        promises.push(promise);

      }
    }
  } else {
    console.log("no files");
  }

  return promises;
}


/* Main function */

function main() {
  if (process.argv.length != 3) {
    console.log('usage: node translate.js [path to translate]');
  } else {
    console.log("checking path: " + process.argv[2]);

    Promise.all(translatePath(process.argv[2])).then(function() {
      console.log("translation complete!");
    });
  }
}

main();