# Ch 1: Constants and Utilities

In this chapter, you will learn about defining constants and utility functions which we will frequently use throughout the project. *Estimated time: \~10 minutes*

First, navigate to the root of the directory/monorepo and run `bun install` to install all the dependencies.

Now, navigate to make a `lib` folder inside `packages/cli` with the files `constants.ts` and `utils.ts` and navigate to it:

```
mkdir -p packages/cli/lib
touch packages/cli/lib/constants.ts packages/cli/lib/utils.ts
cd packages/cli/lib
```

`constants.ts` will contain the constants we use throughout the project while `utils.ts` will contain the necessary utility functions.

Add the following to `constants.ts`:

```typescript
import { join } from "path";

const CONTRACT_NAME = "ClownBeatdown";
const CONTRACT_DIR = join(__dirname, "../../contracts");

export { CONTRACT_NAME, CONTRACT_DIR };
```

This file centralizes key project constants:

* `CONTRACT_NAME`: The ClownBeatdown contract name.
* `CONTRACT_DIR`: Path to the contracts directory.

Now, add the following to `utils.ts`:

```typescript
import fs from "fs";
import { type ShieldedWalletClient, getShieldedContract } from "seismic-viem";
import { Abi, Address } from "viem";

async function getShieldedContractWithCheck(
  walletClient: ShieldedWalletClient,
  abi: Abi,
  address: Address,
) {
  const contract = getShieldedContract({
    abi: abi,
    address: address,
    client: walletClient,
  });

  const code = await walletClient.getCode({
    address: address,
  });
  if (!code) {
    throw new Error("Please deploy contract before running this script.");
  }

  return contract;
}

function readContractAddress(broadcastFile: string): `0x${string}` {
  const broadcast = JSON.parse(fs.readFileSync(broadcastFile, "utf8"));
  if (!broadcast.transactions?.[0]?.contractAddress) {
    throw new Error("Invalid broadcast file format");
  }
  return broadcast.transactions[0].contractAddress;
}

function readContractABI(abiFile: string): Abi {
  const abi = JSON.parse(fs.readFileSync(abiFile, "utf8"));
  if (!abi.abi) {
    throw new Error("Invalid ABI file format");
  }
  return abi.abi;
}

export { getShieldedContractWithCheck, readContractAddress, readContractABI };
```

This file contains utility functions to interact with your ClownBeatdown contract:

* `getShieldedContractWithCheck`: Ensures the contract is deployed and returns a shielded contract instance.
* `readContractAddress`: Reads the deployed contract's address from a broadcast file.
* `readContractABI`: Parses the contract's ABI from an ABI file for use in interactions.