// promisify(f, true) to get array of results
function promisify(f, manyArgs = false) {
  return function (...args) {
    return new Promise((resolve, reject) => {
      function callback(err, ...results) { // our custom callback for f
        if (err) {
          reject(err);
        } else {
          // resolve with all callback results if manyArgs is specified
          resolve(manyArgs ? results : results[0]);
        }
      }

      args.push(callback);

      f.call(this, ...args);
    });
  };
}

// usage:
f = promisify(f, true);
f(...).then(arrayOfResults => ..., err => ...);

const powerset = arr =>
  arr.reduce((a, v) => a.concat(a.map(r => r.concat(v))), [[]]);
  
powerset([1, 2]); // [[], [1], [2], [1, 2]]

const dragAndDropDiv = editor.container;

dragAndDropDiv.addEventListener('dragover', function(e) {
    e.stopPropagation();
    e.preventDefault();
    e.dataTransfer.dropEffect = 'copy';
});
dragAndDropDiv.addEventListener("drop",function(e){
    // Prevent default behavior (Prevent file from being opened)
    e.stopPropagation();
    e.preventDefault();
    const files = e.dataTransfer.items; // Array of all files

    console.assert(files.length >= 1);

    if (files[0].kind === 'file') {
        var file = e.dataTransfer.items[0].getAsFile();
        const fileSize = file.size;
        const fileName = file.name;
        const fileMimeType = file.type;

        reader = new FileReader();

        reader.onloadend = function(){
            editor.setValue(reader.result);
        }

        reader.readAsText(file);
    }else{
        //Maybe handle if text is dropped
        console.log(files[0].kind);
    }
});

const countSubstrings = (str, searchValue) => {
  let count = 0,
    i = 0;
  while (true) {
    const r = str.indexOf(searchValue, i);
    if (r !== -1) [count, i] = [count + 1, r + 1];
    else return count;
  }
};

countSubstrings('tiktok tok tok tik tok tik', 'tik'); // 3
countSubstrings('tutut tut tut', 'tut'); // 4

const celsiusToFahrenheit = (celsius) => celsius * 9/5 + 32;
const fahrenheitToCelsius = (fahrenheit) => (fahrenheit - 32) * 5/9;
// Examples
celsiusToFahrenheit(15);    // 59
celsiusToFahrenheit(0);     // 32
celsiusToFahrenheit(-20);   // -4
fahrenheitToCelsius(59);    // 15
fahrenheitToCelsius(32);    // 0

const hammingDistance = (num1, num2) =>
  ((num1 ^ num2).toString(2).match(/1/g) || '').length;
  
hammingDistance(2, 3); // 1