const ethers = require("ethers");

const { bigInt } = require("snarkjs");
const { eddsa, babyJub, mimc7 } = require("circomlib");

const f = async () => {
  const privateKey =
    "0x0123456789012345678901234567890123456789012345678901234567890123";

  const wallet = new ethers.Wallet(privateKey);

  // Message hash
  const messageHash = ethers.utils.id("Hello world");
  const messageHashBytes = ethers.utils.arrayify(messageHash);

  // Ethereum Signature
  const flatSig = await wallet.signMessage(messageHashBytes);
  const splittedSig = ethers.utils.splitSignature(flatSig);

  // Formatting signature
  const r = bigInt(splittedSig.r).mod(babyJub.subOrder);
  const s = bigInt(splittedSig.s);
  const A = babyJub.mulPointEscalar(babyJub.Base8, s.shr(3));
  const R8 = babyJub.mulPointEscalar(babyJub.Base8, r);
  const hm = mimc7.multiHash([R8[0], R8[1], A[0], A[1], bigInt(messageHash)]);
  const S = r.add(hm.mul(s)).mod(babyJub.subOrder);

  const signature = {
    R8,
    S
  };

  const publicKey = babyJub.unpackPoint(
    Buffer.from(wallet.signingKey.publicKey, "hex")
  );

  console.log(
    eddsa.verify(Buffer.from(messageHash, "hex"), signature, publicKey)
  );
};

f();