World ID 4.0

mapping(uint256 => bool) internal oldNullifierHashes;
mapping(address => bool) public oldHasMinted;

function mint(){
  // Existing logic for checking World ID uniqueness
  if (hasMinted[msg.sender]) revert AlreadyMinted();
  if (nullifierHashes[nullifierHash]) revert DuplicateNullifier(nullifierHash);
}

mapping(uint256 => bool) internal nullifierHashes;
mapping(address => bool) public hasMinted;

// This function is used to verify a 4.0 proof
function mint({..., nullifier}){
  // Check old contracts and new mapping
  if (OldContract.hasMinted[msg.sender] || hasMinted[msg.sender]) revert AlreadyMinted();
  if (OldContract.oldNullifierHashes[nullifier] || nullifierHashes[nullifier]) revert DuplicateNullifier(nullifier);

  // Verify 4.0 Proof
  Verifier.verify(...)
}

// Needed to support v3 proofs during migration
function mintLegacy({..., nullifierHash}){
  // Check old contracts and new ones
  if (OldContract.hasMinted[msg.sender] || hasMinted[msg.sender]) revert AlreadyMinted();
  if (OldContract.oldNullifierHashes[nullifierHash] || nullifierHashes[nullifierHash]) revert DuplicateNullifier(nullifierHash);

  // Verify Legacy Proof
  WorldIDRouter.verify(...)
}

export async function createSession() {
  const rpContext = await fetch("/api/worldid/rp-context").then((r) => r.json());

  const request = await IDKit.createSession({
    app_id: APP_ID,
    rp_context: rpContext,
  }).constraints(any(CredentialRequest("proof_of_human")));

  // Web only: render this QR URL
  const qrUrl = request.connectorURI;

  const completion = await request.pollUntilCompletion({ timeout: 120000 });
  if (!completion.success) throw new Error(completion.error);

  const verify = await fetch("/api/worldid/verify", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(completion.result),
  }).then((r) => r.json());

  if (!verify.success) throw new Error("Verification failed");

  // IMPORTANT: Save this in order to prove future sessions for the same user
  return completion.result.session_id;
}

// sessionId should have been saved when you created the session
export async function proveSession(sessionId) {
  const rpContext = await fetch("/api/worldid/rp-context").then((r) => r.json());

  const request = await IDKit.proveSession(sessionId, {
    app_id: APP_ID,
    rp_context: rpContext,
  }).constraints(any(CredentialRequest("proof_of_human")));

  const completion = await request.pollUntilCompletion({ timeout: 120000 });
  if (!completion.success) throw new Error(completion.error);

  const verify = await fetch("/api/worldid/verify", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(completion.result),
  }).then((r) => r.json());

  if (!verify.success) throw new Error("Verification failed");

  return verify;
}