/* Very simple worker which tries to find a nonce value to create a cryptonight-hash which 
 * is lower than the given target. */

importScripts('cn.js'); // imports the cn.js "glue" script generated by emscripten

// webassembly cryptonight is called here.
var cn = Module.cwrap('hash_cn', 'string', ['string', 'string']);

// A few helper (string) functions to help us working with the hex string
// which is used 

function zeroPad(num, places) {
  var zero = places - num.toString().length + 1;
  return Array(+(zero > 0 && zero)).join("0") + num;
}

function hex2int(s) {
  return parseInt(s.match(/[a-fA-F0-9]{2}/g).reverse().join(''), 16);
}

function int2hex(i) {
  return (zeroPad(i.toString(16), 8)).match(/[a-fA-F0-9]{2}/g).reverse().join('');
}

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

onmessage = function (e) {

  var jbthrt = e.data;
  var job = jbthrt.job;
  var thrt = jbthrt.throttle;

  var bsuccess = false;
  var hash = "";
  var hexnonce = 0;

  // calculate a cryptonight hash
  var calcHash = function () {

    if (job !== null) {

      var target = hex2int(job.target);
      var inonce = getRandomInt(0, 0xFFFFFFFF);
      hexnonce = int2hex(inonce);

      try {
        hash = cn(job.blob, hexnonce);
        var hashval = hex2int(hash.substring(56, 64));
        bsuccess = hashval < target;
      }
      catch (err) { console.log(err); }


    }
  };

  // submit a cryptonight hash
  var submit = function () {

    if (bsuccess) {
      var msg = {
        identifier: "solved",
        job_id: job.job_id,
        nonce: hexnonce,
        result: hash
      };
      postMessage(JSON.stringify(msg));
    } else {
      postMessage("nothing");
    }

  };

  if (thrt === 0) { calcHash(); submit(); }
  else {
    var t0 = performance.now();
    calcHash();
    var dt = performance.now() - t0;

    var sleept = Math.round(thrt / (100 - thrt + 10) * dt);
    setTimeout(submit, sleept);
  }

};