Various improvements (#6)

* nit(web3js): adds `setFeeCurrency()` todo

* refactor(viem): adds ERC20 transfer and refactors code

* docs(CONTRIBUTING): adds a basic development guide

* nit(README): linting

* nit(viem): transaction message

* chore(constants): refactor constants into separate file

* docs(README): fix header

* docs(README): adds URLs

.nvmrc

@@ -0,0 +1 @@
+18.17.1

CONTRIBUTING.md

@@ -0,0 +1,45 @@
+# Contributing
+
+## Basic guide
+
+This guide is intended to help you get started with contributing. By following these steps,
+you will understand the development process and workflow.
+
+### Cloning the repository
+
+To start contributing to the project, clone it to your local machine using git:
+
+```sh
+$ git clone https://github.com/celo-org/feecurrency.git
+```
+
+Navigate to the project's root directory:
+
+```sh
+$ cd developer-tooling
+```
+
+### Installing Node.js
+
+We use [Node.js](https://nodejs.org/en/) to run the project locally.
+You need to install the **Node.js version** specified in [.nvmrc](./.nvmrc). To do so, run:
+
+```sh
+$ nvm install
+$ nvm use
+```
+
+### Installing dependencies
+
+Once in the project's root directory, run the following command to install the project's 
+dependencies:
+
+```sh
+$ yarn install
+```
+
+After installing the dependencies, the project is ready to be run. 
+
+```sh
+$ yarn ts-node <scrip-name>
+```

README.md

@@ -1,51 +1,52 @@
 # Fee Currencies on Celo
 
-> [!TIP]
-> Code examples for [docs.celo.org > Paying for Gas in Tokens](https://docs.celo.org/protocol/transaction/erc20-transaction-fees#alfajores-testnet). Visit that page for more information.
+> [!TIP] Code examples for
+> [docs.celo.org > Paying for Gas in Tokens](https://docs.celo.org/protocol/transaction/erc20-transaction-fees#alfajores-testnet).
+> Visit that page for more information.
 
-Fee currency transactions are unique to Celo. Fee currency transactions are made using a 
-custom transaction type described here: `celo-org/txtypes` (TODO(Arthur): link repo). Visit that repository for an explainer 
-and more context on the lower-level implementation of fee currency transactions.
+Fee currency transactions are unique to Celo. Fee currency transactions are made using a custom
+transaction type described here: [`celo-org/txtypes`](https://github.com/celo-org/txtypes). Visit
+that repository for an explainer and more context on the lower-level implementation of fee currency
+transactions.
 
-This repo provides as a higher-level explainer on making fee currency transactions with popular 
+This repo provides as a higher-level explainer on making fee currency transactions with popular
 JS/TS client libraries.
 
 ## Usage
 
 ### `viem` (Recommended ✅)
 
-We recommend you build with `viem`, if you are starting from scratch. 
-See demo in [`viem.ts`](/viem.ts).
+We recommend you build with `viem`, if you are starting from scratch. See demo in
+[`viem.ts`](/viem.ts).
 
-## RPC client (Experts-only 🟠)
+### Raw transaction (Experts-only 🟠)
 
-We don't recommend constructing fee currency transactions without client libraries, if you are 
-not an expert.
+We don't recommend constructing fee currency transactions without client libraries, if you are not
+an expert.
 
 That's because constructing fee currency transactions without client libraries requires a thorough
-understanding of cryptographic signatures, transaction serialization, and typed transaction 
+understanding of cryptographic signatures, transaction serialization, and typed transaction
 envelopes.
 
-But, if you would really like to construct fee currency transactions this way, you 
-can learn more about the transaction arguments and format here: `celo-org/txtypes`.
+But, if you would really like to construct fee currency transactions this way, you can learn more
+about the transaction arguments and format here: `celo-org/txtypes`.
 
 ### `web3js` + `@celo/connect` (Discouraged ❌)
 
 We don't recommend you build with `web3js` and `@celo/connect`, if you are starting from scratch.
 
-That's because `@celo/connect` only supports `[email protected]`, and not the latest version 
+That's because `@celo/connect` only supports `[email protected]`, and not the latest version
 `[email protected]`.
 
-Instead, we recommend you build with `viem`. But, for completeness, we included a demo in 
+Instead, we recommend you build with `viem`. But, for completeness, we included a demo in
 [`web3.ts`](/web3.ts) so you can see usage patterns.
 
 ### `@celo/contractkit` (Discouraged ❌)
 
 We don't recommend you build with `@celo/contractkit`, if you are starting from scratch.
 
-That's because `@celo/contractkit` is a library for developers who want to 
-interact with core contracts (TODO(Arthur): link docs.celo.org) like `Governance.sol` or 
-`Election.sol`. 
+That's because `@celo/contractkit` is a library for developers who want to interact with
+[core contracts](https://docs.celo.org/contract-addresses) like `Governance.sol` or `Election.sol`.
 
-Instead, we recommend you build with `viem`. But, for completeness, we included a demo in 
+Instead, we recommend you build with `viem`. But, for completeness, we included a demo in
 [`contractkit.ts`](/contractkit.ts) so you can see usage patterns.

constants.ts

@@ -0,0 +1,12 @@
+import "dotenv/config";
+
+export const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF"; // arbitrary address
+export const cUSD_CONTRACT_ADDRESS = "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1"; // ERC20
+export const USDC_CONTRACT_ADDRESS = "0x780c1551C2Be3ea3B1f8b1E4CeDc9C3CE40da24E"; // ERC20
+export const USDC_ADAPTER_ADDRESS = "0xDB93874fE111F5a87Acc11Ff09Ee9450Ac6509AE"; // Adapter
+export const PRIVATE_KEY = process.env.PRIVATE_KEY;
+if (!PRIVATE_KEY) {
+    throw new Error(
+        "PRIVATE_KEY is not set in .env file. Please set PRIVATE_KEY in .env file."
+    );
+}

contractkit.ts

@@ -1,19 +1,11 @@
 import { newKit } from "@celo/contractkit";
-import "dotenv/config";
-
-/**
- * Constants
- */
-const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF"; // arbitrary address
-const cUSD_CONTRACT_ADDRESS = "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1"; // ERC20
-const USDC_CONTRACT_ADDRESS = "0x780c1551C2Be3ea3B1f8b1E4CeDc9C3CE40da24E"; // ERC20
-const USDC_ADAPTER_ADDRESS = "0xDB93874fE111F5a87Acc11Ff09Ee9450Ac6509AE"; // Adapter
-const PRIVATE_KEY = process.env.PRIVATE_KEY;
-if (!PRIVATE_KEY) {
-    throw new Error(
-        "PRIVATE_KEY is not set in .env file. Please set PRIVATE_KEY=<your_private_key> in .env file."
-    );
-}
+import {
+    PRIVATE_KEY,
+    RECIPIENT,
+    cUSD_CONTRACT_ADDRESS,
+    USDC_CONTRACT_ADDRESS,
+    USDC_ADAPTER_ADDRESS,
+} from "./constants";
 
 /**
  * Boilerplate to create a ContractKit instance and ContractKit-compatible wallet
@@ -48,7 +40,7 @@ async function erc20Transfer() {
         feeCurrency: cUSD_CONTRACT_ADDRESS,
     });
 
-    console.log(transactionReceipt);
+    console.log(`Done! Transaction hash: ${transactionReceipt.transactionHash}`);
 }
 
 erc20Transfer().catch((err) => {

viem.ts

@@ -1,49 +1,64 @@
-import { createPublicClient, createWalletClient, http, parseEther, parseGwei } from "viem";
+import {
+    createPublicClient,
+    createWalletClient,
+    http,
+    getContract,
+    erc20Abi,
+    parseUnits,
+    formatUnits,
+} from "viem";
 import { privateKeyToAccount } from "viem/accounts";
 import { celoAlfajores } from "viem/chains";
-import "dotenv/config"; // use to read private key from environment variable
-
-const PRIVATE_KEY = process.env.PRIVATE_KEY;
-if (!PRIVATE_KEY) {
-    throw new Error(
-        "PRIVATE_KEY is not set in .env file. Please set PRIVATE_KEY=<your_private_key> in .env file."
-    );
-}
-const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF"; // arbitrary address
+import {
+    PRIVATE_KEY,
+    RECIPIENT,
+    cUSD_CONTRACT_ADDRESS,
+    USDC_CONTRACT_ADDRESS,
+    USDC_ADAPTER_ADDRESS,
+} from "./constants";
 
 /**
- * Boilerplate to create a viem client
+ * Boilerplate to create a viem client and viem-compatible wallet
  */
-const account = privateKeyToAccount(`0x${PRIVATE_KEY}`);
-const publicClient = createPublicClient({
+const read = createPublicClient({
     chain: celoAlfajores,
     transport: http(),
 });
-const walletClient = createWalletClient({
+const write = createWalletClient({
     chain: celoAlfajores, // Celo testnet
     transport: http(),
 });
+const sender = privateKeyToAccount(`0x${PRIVATE_KEY}`);
 
-async function nativeTransfer() {
-    console.log(`Initiating fee currency transaction...`);
-    const transactionHash = await walletClient.sendTransaction({
-        account, // Sender
-        to: RECIPIENT, // recipient
-        // TODO: Adjust the amount to send based on the token's decimals (USDC has 6 decimals)
-        value: parseEther("0.01"), // 0.01 CELO
-        feeCurrency: "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1", // cUSD fee currency
-        // gas: // TODO: implement gas estimation
-        maxFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
-        maxPriorityFeePerGas: parseGwei("10"), // Special field for dynamic fee transaction type (EIP-1559)
-    });
+/**
+ *  Set up ERC20 contract
+ */
+const contract = getContract({
+    address: cUSD_CONTRACT_ADDRESS,
+    abi: erc20Abi,
+    client: { public: read, wallet: write },
+});
 
-    const transactionReceipt = await publicClient.waitForTransactionReceipt({
-        hash: await transactionHash,
-    });
+/**
+ * Makes a transaction to transfer ERC20 tokens using a fee currency
+ */
+async function erc20Transfer() {
+    console.log(`Initiating fee currency transaction...`);
+
+    const [symbol, decimals, tokenBalance] = await Promise.all([
+        contract.read.symbol(),
+        contract.read.decimals(),
+        contract.read.balanceOf([sender.address]),
+    ]);
+    console.log(`${symbol} balance of ${sender.address}: ${formatUnits(tokenBalance, decimals)}`);
 
-    console.log(transactionReceipt);
+    const transactionHash = await contract.write.transfer(
+        [RECIPIENT, parseUnits("0.01", decimals)],
+        { account: sender, feeCurrency: cUSD_CONTRACT_ADDRESS }
+    );
+    console.log(`Done! Transaction hash: ${transactionHash}`);
 }
 
-nativeTransfer().catch((err) => {
+erc20Transfer().catch((err) => {
     console.error("An error occurred:", err);
 });

web3.ts

@@ -1,23 +1,16 @@
 import Web3 from "web3";
-import { Connection } from "@celo/connect";
-import { LocalWallet } from "@celo/wallet-local"
+import { CeloTxReceipt, Connection } from "@celo/connect";
+import { LocalWallet } from "@celo/wallet-local";
 import "dotenv/config";
-import { AbiItem } from 'web3-utils';
+import { AbiItem } from "web3-utils";
 import { ERC20ABI } from "./erc20Abi";
-
-/**
- * Constants
- */
-const RECIPIENT = "0x22579CA45eE22E2E16dDF72D955D6cf4c767B0eF"; // arbitrary address
-const cUSD_CONTRACT_ADDRESS = "0x874069Fa1Eb16D44d622F2e0Ca25eeA172369bC1"; // ERC20
-const USDC_CONTRACT_ADDRESS = "0x780c1551C2Be3ea3B1f8b1E4CeDc9C3CE40da24E"; // ERC20
-const USDC_ADAPTER_ADDRESS = "0xDB93874fE111F5a87Acc11Ff09Ee9450Ac6509AE"; // Adapter
-const PRIVATE_KEY = process.env.PRIVATE_KEY;
-if (!PRIVATE_KEY) {
-    throw new Error(
-        "PRIVATE_KEY is not set in .env file. Please set PRIVATE_KEY=<your_private_key> in .env file."
-    );
-}
+import {
+    PRIVATE_KEY,
+    RECIPIENT,
+    cUSD_CONTRACT_ADDRESS,
+    USDC_CONTRACT_ADDRESS,
+    USDC_ADAPTER_ADDRESS,
+} from "./constants";
 
 /**
  * Boilerplate to create a web3js client and web3js-compatible wallet
@@ -32,9 +25,9 @@ const connection = new Connection(web3, celoWallet);
  */
 const contract = new web3.eth.Contract(ERC20ABI as AbiItem[], cUSD_CONTRACT_ADDRESS);
 
-/** 
+/**
  * Makes a transaction to transfer ERC20 tokens using a fee currency
-*/
+ */
 async function erc20Transfer() {
     console.log(`Initiating fee currency transaction...`);
 
@@ -47,19 +40,21 @@ async function erc20Transfer() {
     // Get the sender's address
     const sender = celoWallet.getAccounts()[0];
 
-    const transactionReceipt = await connection
+    const transactionReceipt = (await connection
         .sendTransaction({
             from: sender,
             to: cUSD_CONTRACT_ADDRESS,
             feeCurrency: cUSD_CONTRACT_ADDRESS,
             data: transactionObject.encodeABI(),
         })
         .then((tx) => tx.waitReceipt())
-        .catch((err) => console.error(err));
-    
-    console.log(transactionReceipt);
+        .catch((err) => console.error(err))) as CeloTxReceipt;
+
+    console.log(`Done! Transaction hash: ${transactionReceipt.transactionHash}`);
 }
 
+// TODO(Arthur): Add example using `setFeeCurrency()`
+
 // Initiate the transfer
 erc20Transfer().catch((err) => {
     console.error("An error occurred:", err);