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Snippets of code that can be used to implement flows inside MiniPay
Make sure you are using Typescript v5 or above and Viem v2 or above.

​
Get the connected user’s address without any Library

// The code must run in a browser environment and not in node environment
if (window && window.ethereum) {
  // User has a injected wallet

  if (window.ethereum.isMiniPay) {
    // User is using Minipay

    // Requesting account addresses
    let accounts = await window.ethereum.request({
      method: "eth_requestAccounts",
      params: [],
    });

    // Injected wallets inject all available addresses,
    // to comply with API Minipay injects one address but in the form of array
    console.log(accounts[0]);
  }

  // User is not using MiniPay
}

// User does not have a injected wallet
To use the code snippets below, install the following packages: 
yarn add @celo/abis @celo/identity viem@1

​
Check cUSD Balance of an address

const { getContract, formatEther, createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");
const { stableTokenABI } = require("@celo/abis");

const STABLE_TOKEN_ADDRESS = "0x765DE816845861e75A25fCA122bb6898B8B1282a";

async function checkCUSDBalance(publicClient, address) {
  let StableTokenContract = getContract({
      abi: stableTokenABI,
      address: STABLE_TOKEN_ADDRESS,
      publicClient,
  });

  let balanceInBigNumber = await StableTokenContract.read.balanceOf([
      address,
  ]);

  let balanceInWei = balanceInBigNumber.toString();

  let balanceInEthers = formatEther(balanceInWei);

  return balanceInEthers;
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
}); // Mainnet

let balance = await checkCUSDBalance(publicClient, address); // In Ether unit

​
Check If a transaction succeeded

const { createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");

async function checkIfTransactionSucceeded(publicClient, transactionHash) {
  let receipt = await publicClient.getTransactionReceipt({
    hash: transactionHash,
  });

  return receipt.status === "success";
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
}); // Mainnet

let transactionStatus = await checkIfTransactionSucceeded(
  publicClient,
  transactionHash
);

​
Estimate Gas for a transaction (in Celo)

const { createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");

async function estimateGas(publicClient, transaction, feeCurrency = "") {
  return await publicClient.estimateGas({
    ...transaction,
    feeCurrency: feeCurrency ? feeCurrency : "",
  });
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

let gasLimit = await estimateGas(publicClient, {
  account: "0x8eb02597d85abc268bc4769e06a0d4cc603ab05f",
  to: "0x4f93fa058b03953c851efaa2e4fc5c34afdfab84",
  value: "0x1",
  data: "0x",
});

​
Estimate Gas for a transaction (in cUSD)

const { createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");

async function estimateGas(publicClient, transaction, feeCurrency = "") {
  return await publicClient.estimateGas({
    ...transaction,
    feeCurrency: feeCurrency ? feeCurrency : "",
  });
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

const STABLE_TOKEN_ADDRESS = "0x765DE816845861e75A25fCA122bb6898B8B1282a";

let gasLimit = await estimateGas(
  publicClient,
  {
    account: "0x8eb02597d85abc268bc4769e06a0d4cc603ab05f",
    to: "0x4f93fa058b03953c851efaa2e4fc5c34afdfab84",
    value: "0x1",
    data: "0x",
  },
  STABLE_TOKEN_ADDRESS
);

​
Estimate Gas Price for a transaction (in Celo)

const { createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");

async function estimateGasPrice(publicClient, feeCurrency = "") {
  return await publicClient.request({
    method: "eth_gasPrice",
    params: feeCurrency ? [feeCurrency] : [],
  });
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

let gasPrice = await estimateGasPrice(publicClient);

​
Estimate Gas Price for a transaction (in cUSD)

const { createPublicClient, http } = require("viem");
const { celo } = require("viem/chains");

async function estimateGasPrice(publicClient, feeCurrency = "") {
  return await publicClient.request({
    method: "eth_gasPrice",
    params: feeCurrency ? [feeCurrency] : [],
  });
}

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

const STABLE_TOKEN_ADDRESS = "0x765DE816845861e75A25fCA122bb6898B8B1282a";

let gasPrice = await estimateGasPrice(publicClient, STABLE_TOKEN_ADDRESS);

​
Calculate cUSD to be spent for transaction fees

const { createPublicClient, http, formatEther } = require("viem");
const { celo } = require("viem/chains");

const publicClient = createPublicClient({
  chain: celo,
  transport: http(),
});

const STABLE_TOKEN_ADDRESS = "0x765DE816845861e75A25fCA122bb6898B8B1282a";

// `estimateGas` implemented above
let gasLimit = await estimateGas(
  publicClient,
  {
      account: "0x8eb02597d85abc268bc4769e06a0d4cc603ab05f",
      to: "0x4f93fa058b03953c851efaa2e4fc5c34afdfab84",
      value: "0x1",
      data: "0x",
  },
  STABLE_TOKEN_ADDRESS
);

// `estimateGasPrice` implemented above
let gasPrice = await estimateGasPrice(publicClient, STABLE_TOKEN_ADDRESS);

let transactionFeesInCUSD = formatEther(gasLimit * hexToBigInt(gasPrice));

​
Resolve Minipay phone numbers to Addresses

Install the @celo/identity package: 
npm install @celo/identity

​
Step 1: Set up your issuer

The issuer is the account registering attestations. When a user requests attestation registration, verify they own the identifier (e.g., SMS verification for phone numbers). 
import { createClient } from "viem";
import { celoAlfajores } from "viem/chains";
import { privateKeyToAccount } from "viem/accounts";

// The issuer is the account that is registering the attestation
let ISSUER_PRIVATE_KEY = "YOUR_ISSUER_PRIVATE_KEY";

// Create Alfajores viem client with the issuer private key
const viemClient = createClient({
  account: privateKeyToAccount(ISSUER_PRIVATE_KEY),
  transport: http(),
  chain: celoAlfajores,
});

// Information provided by user, issuer should confirm they own the identifier
const userPlaintextIdentifier = "+12345678910";
const userAccountAddress = "0x000000000000000000000000000000000000user";

// Time at which issuer verified the user owns their identifier
const attestationVerifiedTime = Date.now();

​
Step 2: Check and top up ODIS quota

import { OdisUtils } from "@celo/identity";
import { AuthSigner } from "@celo/identity/lib/odis/query";

// authSigner provides information needed to authenticate with ODIS
const authSigner: AuthSigner = {
  authenticationMethod: OdisUtils.Query.AuthenticationMethod.WALLET_KEY,
  sign191: ({ message, account }) => viemClient.signMessage({ message, account }),
};

// serviceContext provides the ODIS endpoint and public key
const serviceContext = OdisUtils.Query.getServiceContext(
  OdisContextName.ALFAJORES
);

// Check existing quota on issuer account
const { remainingQuota } = await OdisUtils.Quota.getPnpQuotaStatus(
  issuerAddress,
  authSigner,
  serviceContext
);

// If needed, approve and send payment to OdisPayments to get quota for ODIS
if (remainingQuota < 1) {
  const stableTokenContract = await kit.contracts.getStableToken();
  const odisPaymentsContract = await kit.contracts.getOdisPayments();
  const ONE_CENT_CUSD_WEI = 10000000000000000;
  
  await stableTokenContract
    .increaseAllowance(odisPaymentsContract.address, ONE_CENT_CUSD_WEI)
    .sendAndWaitForReceipt();
    
  const odisPayment = await odisPaymentsContract
    .payInCUSD(issuerAddress, ONE_CENT_CUSD_WEI)
    .sendAndWaitForReceipt();
}

​
Step 3: Derive the obfuscated identifier

Get the obfuscated identifier from the plaintext identifier by querying ODIS: 
const { obfuscatedIdentifier } = await OdisUtils.Identifier.getObfuscatedIdentifier(
  userPlaintextIdentifier,
  OdisUtils.Identifier.IdentifierPrefix.PHONE_NUMBER,
  issuerAddress,
  authSigner,
  serviceContext
);

​
Step 4: Look up account addresses

Query the FederatedAttestations contract to look up account addresses owned by an identifier: 
const attestations = await federatedAttestationsContract.lookupAttestations(
  obfuscatedIdentifier,
  [issuerAddress] // Trusted issuers
);

console.log(attestations.accounts);

​
Request an ERC20 token transfer

import { createWalletClient, custom } from 'viem'
// import { celo } from 'viem/chains'
import { celoAlfajores } from 'viem/chains'
 
const client = createWalletClient({
  chain: celoAlfajores,
  // chain: celo,
  transport: custom(window.ethereum!)
})

const publicClient = createPublicClient({ 
  chain: celoAlfajores,
  // chain: celo,
  transport: http()
})

async function requestTransfer(tokenAddress, transferValue, tokenDecimals) {

  let hash = await client.sendTransaction({
    to: tokenAddress,
    // to: '0x765DE816845861e75A25fCA122bb6898B8B1282a' // cUSD (Mainnet)
    // to: '0xcebA9300f2b948710d2653dD7B07f33A8B32118C' // USDC (Mainnet)
    // to: '0x48065fbbe25f71c9282ddf5e1cd6d6a887483d5e' // USDT (Mainnet)
    data: encodeFunctionData({
      abi: stableTokenAbi, // Token ABI can be fetched from Explorer.
      functionName: "transfer",
      args: [
        receiverAddress,
        // Different tokens can have different decimals, cUSD (18), USDC (6)
        parseUnits(`${Number(transferValue)}`, tokenDecimals),
      ],
    }),
    // If the wallet is connected to a different network then you get an error.
    chain: celoAlfajores,
    // chain: celo,
  });

  const transaction = await publicClient.waitForTransactionReceipt({
    hash, // Transaction hash that can be used to search transaction on the explorer.
  });

  if (transaction.status === "success") {
    // Do something after transaction is successful.
  } else {
    // Do something after transaction has failed.
  }
}
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