self/app/utils/snarkjs.ts

// utils from snarkjs. If snarkjs is updated and this breaks, might move this to lambda function
function unstringifyBigInts(o: any): any {
  if (typeof o == "string" && /^[0-9]+$/.test(o)) {
      return BigInt(o);
  } else if (typeof o == "string" && /^0x[0-9a-fA-F]+$/.test(o)) {
      return BigInt(o);
  } else if (Array.isArray(o)) {
      return o.map(unstringifyBigInts);
  } else if (typeof o == "object") {
      if (o === null) return null;
      const res: any = {};
      const keys = Object.keys(o);
      keys.forEach((k) => {
          res[k] = unstringifyBigInts(o[k]);
      });
      return res;
  } else {
      return o;
  }
}

function p256(n: any) {
  let nstr = n.toString(16);
  while (nstr.length < 64) nstr = "0"+nstr;
  nstr = `"0x${nstr}"`;
  return nstr;
}

export default function groth16ExportSolidityCallData(_proof: any, _pub: any) {
  const proof = unstringifyBigInts(_proof);
  const pub = unstringifyBigInts(_pub);

  let inputs = "";
  for (let i=0; i<pub.length; i++) {
      if (inputs != "") inputs = inputs + ",";
      inputs = inputs + p256(pub[i]);
  }

  const S =`[${p256(proof.a[0])}, ${p256(proof.a[1])}],` +
    `[[${p256(proof.b[0][1])}, ${p256(proof.b[0][0])}],[${p256(proof.b[1][1])}, ${p256(proof.b[1][0])}]],` +
    `[${p256(proof.c[0])}, ${p256(proof.c[1])}],` +
    `[${inputs}]`;

  return S;
}