var s = "e"
var max_it = 1000
var special_chars = 10
var digit_chars = 6
var cap_chars = 4

function hex2a(hexx) {
    var hex = hexx.toString();//force conversion
    var str = '';
    for (var i = 0; i < hex.length; i += 2){
      str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
    }
    return str;
}

function sha256(str, it) {
  if (it > max_it){
    throw new Error("can't find a match to satisfy regex");
  }
  console.log("iteration: ",it)
  // We transform the string into an arraybuffer.
  var buffer = new TextEncoder("utf-8").encode(str);
  return crypto.subtle.digest("SHA-256", buffer).then(function (hash) {
    var t = hex(hash)
    if (!reg.test(t) && it < max_it){
        console.log("failed requirements",t)
      var new_it = it + 1
      return sha256(t,new_it)
    } else if(it >= max_it){
        console.log("HORROR")
        return false
    }
    else{
      return [t,it]
    }

  });
}

var reg_string = '(?=(.*(\`|\~|\!|\@|\#|\$|\%|\^|\*|\(|\|\-)){'+special_chars+'})(?=(.*\d){'+digit_chars+'})(?=.*[a-z])(?=(.*[A-Z]){'+cap_chars+'}).{14,14}'

var reg = new RegExp(reg_string)
console.log("regexp",reg)

function hex(buffer) {
  var hexCodes = [];
  var view = new DataView(buffer);
  for (var i = 0; i < view.byteLength; i += 4) {
    // Using getUint32 reduces the number of iterations needed (we process 4 bytes each time)
    var value = view.getUint32(i)
    // toString(16) will give the hex representation of the number without padding
    var stringValue = value.toString(8)

    // We use concatenation and slice for padding
    //var padding = '00000000'
    var padding = ''
    var paddedValue = (padding + hex2a(stringValue)).slice(-padding.length)
    hexCodes.push(paddedValue);
  }

  // Join all the hex strings into one
  return hexCodes.join("");
}
console.log("Input 'e' should take 454 iterations to satisfy 10 special, 6 digits, and 4 caps");
sha256(s,1).then(function(digest) {
  console.log(digest);
  console.log("test",reg.test(digest))
});