var el = document.getElementById("hash");
var hashHexValue = "";
var crypto = window.crypto || window.msCrypto;
var fieldNonce = document.getElementById("textNonce");
const difficulty = 3;

if (!crypto.subtle) { alert("Cryptography API not Supported") };

async function rollHash() {
  var promise = await crypto.subtle.digest({name: "SHA-256"}, str2ab(document.getElementById("textImages").value + fieldNonce.value));
  hashHexValue = ab2hex(promise);
  if (hashHexValue.substring(0, difficulty) == Array(difficulty + 1).join("0")) {
    lastSuccessfulNonce = "LSN: " + hashHexValue + ", " + fieldNonce.value;
    document.getElementById("lsn").textContent = lastSuccessfulNonce;
    var el = document.getElementById("textImages");
    el.value += "\r\n" + lastSuccessfulNonce;
    el.scrollTop = el.scrollHeight;
  }
}

function ab2hex(buffer) { // buffer is an ArrayBuffer
  return Array.prototype.map.call(new Uint8Array(buffer), x => ('00' + x.toString(16)).slice(-2)).join('');
}

function ab2binary(buffer) { // buffer is an ArrayBuffer
  return Array.prototype.map.call(new Uint8Array(buffer), x => ('00000000' + x.toString(2)).slice(-8)).join('');
}

function ab2str(buf) {
  return String.fromCharCode.apply(null, new Uint16Array(buf));
}

function str2ab(str) {
  var buf = new ArrayBuffer(str.length*2); // 2 bytes for each char
  var bufView = new Uint16Array(buf);
  for (var i=0, strLen=str.length; i < strLen; i++) {
    bufView[i] = str.charCodeAt(i);
  }
  return buf;
}

var buttonCompleteHash = document.getElementById("btnCompleteHash");

textImages.onpaste = function (event) {
  rollHash();
  fieldNonce.value = -1;
  document.getElementById("hash").textContent = hashHexValue;
}

buttonCompleteHash.onclick = function () {
  if (document.getElementById("btnCompleteHash").value === "⇥") {
    document.getElementById("btnCompleteHash").value = "◼";
    intervalHundredths = window.setInterval (function () {
      fieldNonce.value = parseInt(fieldNonce.value) + 1;
      rollHash();
    }, 0.01);
    intervalTenths = window.setInterval (function () {
      document.getElementById("hash").textContent = hashHexValue;
    }, 10);      
  } else {
    document.getElementById("btnCompleteHash").value = "⇥";
    clearInterval(intervalHundredths);
    clearInterval(intervalTenths);
  }
};

function myCheck() {
  // Get the checkbox
  var checkBox = document.getElementById("myCheck1");
  // Get the output text
  var text = document.getElementById("text");

  // If the checkbox is checked, display the output text
  if (checkBox.checked == true){
    text.style.display = "inline-block";
  } else {
    text.style.display = "none";
  }
}