function asciiToUint8Array(str) {
  var chars = [];
  for (var i = 0; i < str.length; ++i) {
    chars.push(str.charCodeAt(i));
  }
  return new Uint8Array(chars);
}

function convertStringToArrayBufferView(str) {
  var bytes = new Uint8Array(str.length);
  for (var iii = 0; iii < str.length; iii++) {
    bytes[iii] = str.charCodeAt(iii);
  }
  return bytes;
}

function buf2hex ( buffer ) {
  return Array.prototype.map.call(new Uint8Array(buffer), x => ('00' + x.toString(16)).slice(-2)).join('');
}

function log_text(s) {
  var d = document.createElement("div");
  d.innerHTML = s;
  document.getElementById('log').appendChild(d);
}

function debug() {
  window.hwcrypto.debug().then(function(response) {log_text("Debug: " + response);});
}

function sign() {

  alert("sign()");

  // Clear log
  document.getElementById('log').innerHTML = '';
  // Timestamp
  log_text("sign() clicked on " + new Date().toUTCString());

  // Select hash
  var hashtype = "SHA-256";

  // Set backend if asked
  var backend = "autodetect";

  // get language
  var lang = "en";
  if (!window.hwcrypto.use(backend)) {
    log_text("Selecting backend failed.");
  }

  var hash = $("#hashvalue").val();
  log_text("Signing " + hashtype + ": " + hash);

  // debug
  window.hwcrypto.debug().then(function(response) {
    log_text("Debug: " + response);
  }, function(err) {
    log_text("debug() failed: " + err);
    return;
  });

  // Sign
  window.hwcrypto.getCertificate({lang: lang}).then(function(response) {
    var cert = response;
    log_text("Using certificate:\n" + hexToPem(response.hex));
    window.hwcrypto.sign(cert, {type: hashtype, hex: hash}, {lang: lang}).then(
      function(response) {
        log_text("Generated signature:\n" + response.hex.match(/.{1,64}/g).join("\n"));
      },
      function(err) { log_text("sign() failed: " + err); }
    );
  },
    function(err) { log_text("getCertificate() failed: " + err); }
  );
}