Writing to Snapchain

import {
  ID_GATEWAY_ADDRESS,
  idGatewayABI,
  KEY_GATEWAY_ADDRESS,
  keyGatewayABI,
  ID_REGISTRY_ADDRESS,
  idRegistryABI,
  FarcasterNetwork,
} from '@farcaster/hub-web';
import { zeroAddress } from 'viem';
import { optimism } from 'viem/chains';
import { generatePrivateKey, privateKeyToAccount, toAccount } from "viem/accounts";

/**
 * Populate the following constants with your own values
 */
const CUSTODY_PRIVATE_KEY = '<REQUIRED>'; // A private key corresponding with any ETH address.
const OP_PROVIDER_URL = '<REQUIRED>'; // Alchemy or Infura url
const RECOVERY_ADDRESS = zeroAddress; // Optional, using the default value means the account will not be recoverable later if the mnemonic is lost
const SIGNER_PRIVATE_KEY: Hex = zeroAddress; // Optional, using the default means a new signer will be created each time

// Note: crackle is the Farcaster team's mainnet node, which is password protected to prevent abuse. Use a 3rd party node
// provider like https://neynar.com/ Or, run your own mainnet node and broadcast to it permissionlessly.
const HUB_URL = 'crackle.farcaster.xyz:3383'; // URL + Port of the node
const HUB_USERNAME = ''; // Username for auth, leave blank if not using TLS
const HUB_PASS = ''; // Password for auth, leave blank if not using TLS
const USE_SSL = false; // set to true if talking to a node that uses SSL (3rd party hosted nodes or nodes that require auth)
const FC_NETWORK = FarcasterNetwork.MAINNET; // Network of the node

const CHAIN = optimism;

const IdGateway = {
  abi: idGatewayABI,
  address: ID_GATEWAY_ADDRESS,
  chain: CHAIN,
};
const IdContract = {
  abi: idRegistryABI,
  address: ID_REGISTRY_ADDRESS,
  chain: CHAIN,
};
const KeyContract = {
  abi: keyGatewayABI,
  address: KEY_GATEWAY_ADDRESS,
  chain: CHAIN,
};

const getOrRegisterFid = async (): Promise<number> => {
  const balance = await getBalance(walletClient, { address: account.address });
  const existingFid = (await readContract(walletClient, {
    ...IdContract,
    functionName: "idOf",
    args: [account.address],
  })) as bigint;

  console.log(`Using address: ${account.address} with balance: ${balance}`);

  if (balance === 0n && existingFid === 0n) {
    throw new Error("No existing Fid and no funds to register an fid");
  }

  if (existingFid > 0n) {
    return parseInt(existingFid.toString());
  }

  const price = await readContract(walletClient, {
    ...IdGateway,
    functionName: "price",
  });

  if (balance < price) {
    throw new Error(`Insufficient balance to rent storage, required: ${price}, balance: ${balance}`);
  }

  const { request: registerRequest } = await simulateContract(walletClient, {
    ...IdGateway,
    functionName: "register",
    args: [RECOVERY_ADDRESS],
    value: price,
  });
  const registerTxHash = await writeContract(walletClient, registerRequest);
  const registerTxReceipt = await waitForTransactionReceipt(walletClient, { hash: registerTxHash });

  if (registerTxReceipt.logs[0]) {
    // Now extract the FID from the logs
    const registerLog = decodeEventLog({
      abi: idRegistryABI,
      data: registerTxReceipt.logs[0].data,
      topics: registerTxReceipt.logs[0].topics,
    });

    const fid = parseInt(registerLog.args["id"]);
    return fid;
  } else {
    throw new Error("Did not receive logs for registered fid");
  }
};

const fid = await getOrRegisterFid();

const getOrRegisterSigner = async (fid: number) => {
  if (SIGNER_PRIVATE_KEY !== zeroAddress) {
    // If a private key is provided, we assume the signer is already in the key registry
    const privateKeyBytes = fromHex(SIGNER_PRIVATE_KEY, "bytes");
    const publicKeyBytes = ed25519.getPublicKey(privateKeyBytes);
    return privateKeyBytes;
  }

  const privateKey = ed25519.utils.randomPrivateKey();
  const publicKey = toHex(ed25519.getPublicKey(privateKey));

  // To add a key, we need to sign the metadata with the fid of the app we're adding the key on behalf of
  // We'll use our own fid and custody address for simplicity. This can also be a separate App specific fid.
  const localAccount = toAccount(account);
  const eip712signer = new ViemLocalEip712Signer(localAccount);
  const metadata = await eip712signer.getSignedKeyRequestMetadata({
    requestFid: BigInt(fid),
    key: fromHex(publicKey, "bytes"),
    deadline: BigInt(Math.floor(Date.now() / 1000) + 60 * 60), // 1 hour from now
  });

  const metadataHex = toHex(metadata.unwrapOr(new Uint8Array()));

  const { request: signerAddRequest } = await simulateContract(walletClient, {
    ...KeyContract,
    functionName: "add",
    args: [1, publicKey, 1, metadataHex], // keyType, publicKey, metadataType, metadata
  });

  const signerAddTxHash = await writeContract(walletClient, signerAddRequest);
  await waitForTransactionReceipt(walletClient, { hash: signerAddTxHash });
  await new Promise((resolve) => setTimeout(resolve, 30000));
  return privateKey;
};


const signer = await getOrRegisterSigner(fid);

const registerFname = async (fid: number) => {
  try {
    // First check if this fid already has an fname
    const response = await axios.get(`https://fnames.farcaster.xyz/transfers/current?fid=${fid}`);
    const fname = response.data.transfer.username;
    return fname;
  } catch (e) {
    // No username, ignore and continue with registering
  }

  const fname = `fid-${fid}`;
  const timestamp = Math.floor(Date.now() / 1000);
  const localAccount = toAccount(account);
  const signer = new ViemLocalEip712Signer(localAccount as LocalAccount<string>);
  const userNameProofSignature = await signer.signUserNameProofClaim(
    makeUserNameProofClaim({
      name: fname,
      timestamp: timestamp,
      owner: account.address,
    }),
  );

  try {
    const response = await axios.post("https://fnames.farcaster.xyz/transfers", {
      name: fname, // Name to register
      from: 0, // Fid to transfer from (0 for a new registration)
      to: fid, // Fid to transfer to (0 to unregister)
      fid: fid, // Fid making the request (must match from or to)
      owner: account.address, // Custody address of fid making the request
      timestamp: timestamp, // Current timestamp in seconds
      signature: bytesToHex(userNameProofSignature._unsafeUnwrap()), // EIP-712 signature signed by the current custody address of the fid
    });
    return fname;
  } catch (e) {
    // @ts-ignore
    throw new Error(`Error registering fname: ${JSON.stringify(e.response.data)} (status: ${e.response.status})`);
  }
};

const fname = await registerFname(fid);

const submitMessage = async (resultPromise: HubAsyncResult<Message>) => {
  const result = await resultPromise;
  if (result.isErr()) {
    throw new Error(`Error creating message: ${result.error}`);
  }
  const messageSubmitResult = await hubClient.submitMessage(result.value, metadata);
  if (messageSubmitResult.isErr()) {
    throw new Error(`Error submitting message to node: ${messageSubmitResult.error}`);
  }
};

const signer = new NobleEd25519Signer(signerPrivateKey);
const dataOptions = {
  fid: fid,
  network: FC_NETWORK,
};
const userDataPfpBody = {
  type: UserDataType.USERNAME,
  value: fname,
};
await submitMessage(makeUserDataAdd(userDataPfpBody, dataOptions, signer));

await submitMessage(
  makeCastAdd(
    {
      text: "Hello World!",
      embeds: [],
      embedsDeprecated: [],
      mentions: [],
      mentionsPositions: [],
      type: CastType.CAST,
    },
    dataOptions,
    signer,
  )
);