import lodash from "https://esm.sh/lodash";

const createHmacString = (privateKey, message) => {
    const key = CryptoJS.enc.Utf8.parse(privateKey);
    const hmac = CryptoJS.HmacSHA256(message, key);
    return CryptoJS.enc.Hex.stringify(hmac);
}

function* byteGenerator({
  serverSeed,
  clientSeed,
  nonce,
  cursor,
}: {
  serverSeed: string;
  clientSeed: string;
  nonce: number;
  cursor: number;
}) {
  let currentRound = Math.floor(cursor / 32);
  let currentRoundCursor = cursor;
  currentRoundCursor -= currentRound * 32;

  while (true) {
    const message = `${clientSeed}:${nonce}:${currentRound}`;
    const hmacHex = createHmacString(serverSeed, message);
    const buffer = CryptoJS.enc.Hex.parse(hmacHex);

    while (currentRoundCursor < 32) {
      yield Number(buffer.words[Math.floor(currentRoundCursor / 4)] >> (8 * (3 - (currentRoundCursor % 4))) & 0xff);
      currentRoundCursor += 1;
    }
    currentRoundCursor = 0;
    currentRound += 1;
  }
}

function generateFloats({
  serverSeed,
  clientSeed,
  nonce,
  cursor,
  count,
}: {
  serverSeed: string;
  clientSeed: string;
  nonce: number;
  cursor: number;
  count: number;
}): number[] {
  const generator = byteGenerator({ serverSeed, clientSeed, nonce, cursor });
  const bytes = [];
  while (bytes.length < count * 4) {
    const nextValue = generator.next().value;
    if (typeof nextValue === "number") {
      bytes.push(nextValue);
    } else {
      throw new Error("Generator did not yield a number");
    }
  }

  return lodash.chunk(bytes, 4).map((bytesChunk) => {
    return bytesChunk.reduce((result, value, i) => {
      const divider = 256 ** (i + 1);
      const partialResult = value / divider;
      return result + partialResult;
    }, 0);
  });
}

document.getElementById('verify').onclick = () => {
  const serverSeed = document.getElementById('serverSeed').value
  const nonce = document.getElementById('nonce').value
  const clientSeed = document.getElementById('clientSeed').value

  if (!serverSeed) return error('Server seed is required')
  if (!nonce) return error('Server hash is required')
  if (!clientSeed) return error('Client seed is required')

  const floats = generateFloats({ serverSeed, clientSeed, nonce, cursor: 0, count: 1 });
  const rng = Math.floor(floats[0] * 38);
  const outcome = rng - 1;
  result.innerHTML = `<div class="text-center">
  

      <div class="text-gray-300">
          Result number: ${outcome}
        </div>
     
  </div>`
}