Funding methods

import {
  createPublicClient, erc20Abi, http, toHex,
  type Address, type WalletClient,
} from 'viem';
import { base } from 'viem/chains';

const USDC = '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913';
const publicClient = createPublicClient({ chain: base, transport: http() });

export async function fundWithErc3009(
  walletClient: WalletClient,
  owner: Address,
  deposit: { vaultAddress: Address; amount: string; deadline: number },
): Promise<unknown> {
  try {
    if (await walletClient.getChainId() !== base.id) {
      throw new Error('Connect the wallet to Base mainnet');
    }
    const now = Math.floor(Date.now() / 1000);
    const validBefore = Math.min(deposit.deadline, now + 3600);
    if (validBefore <= now + 60) {
      throw new Error('Request a fresh deposit quote before signing');
    }
    const name = await publicClient.readContract({
      address: USDC, abi: erc20Abi, functionName: 'name',
    });
    const nonce = toHex(crypto.getRandomValues(new Uint8Array(32)));
    const authorization = {
      from: owner,
      to: deposit.vaultAddress,
      value: deposit.amount,
      validAfter: '0',
      validBefore: String(validBefore),
      nonce,
    };
    const signature = await walletClient.signTypedData({
      account: owner,
      domain: { name, version: '2', chainId: base.id, verifyingContract: USDC },
      types: {
        TransferWithAuthorization: [
          { name: 'from', type: 'address' },
          { name: 'to', type: 'address' },
          { name: 'value', type: 'uint256' },
          { name: 'validAfter', type: 'uint256' },
          { name: 'validBefore', type: 'uint256' },
          { name: 'nonce', type: 'bytes32' },
        ],
      },
      primaryType: 'TransferWithAuthorization',
      message: {
        ...authorization,
        value: BigInt(authorization.value),
        validAfter: 0n,
        validBefore: BigInt(validBefore),
      },
    });
    if (Math.floor(Date.now() / 1000) >= validBefore - 60) {
      throw new Error('Authorization is too close to expiry; do not submit it');
    }
    const payload = {
      chainId: base.id,
      target: { depositAddress: deposit.vaultAddress },
      authorization,
      signature,
    };
    // Persist this exact payload securely before sending, so an uncertain
    // response can be retried without collecting a second authorization.
    const response = await fetch(
      'https://api.eco.com/v1/circle-gateway/deposit-addresses/submit/erc-3009',
      {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload),
        signal: AbortSignal.timeout(30_000),
      },
    );
    const text = await response.text();
    if (!response.ok) throw new Error(`HTTP ${response.status}: ${text}`);
    return JSON.parse(text);
  } catch (error) {
    throw new Error('ERC-3009 deposit submission failed; inspect any existing job before signing again', {
      cause: error,
    });
  }
}