Example for estimateFees()

import { encodePacked, parseEther, http, createWalletClient, publicActions, formatEther } from 'viem'
import { optimism } from 'viem/chains'
import { privateKeyToAccount } from 'viem/accounts'
import { estimateFeesAbi, lzDepositAbi } from './abis'
const account = privateKeyToAccount('0x...')
 
const client = createWalletClient({
  account,
  chain: optimism,
  transport: http(),
}).extend(publicActions)
 
const lzIds = [110, 175] // Arbitrum and Arbitrum Nova LayerZero chain IDs
 
// Estimate
const createAdapterParams = (gasLimit: bigint, nativeAmount: bigint, to: string) => {
  return encodePacked(['uint16', 'uint256', 'uint256', 'address'], [2, gasLimit, nativeAmount, to as `0x${string}`])
}
 
// Prepare parameters for Arbitrum and Optimism
const arbitrumParamsEstimate = createAdapterParams(
  BigInt(30_000),
  parseEther('0.000002'),
  '0x0000000000000000000000000000000000000000',
)
const arbitrumNovaParamsEstimate = createAdapterParams(
  BigInt(30_000),
  parseEther('0.000002'),
  '0x0000000000000000000000000000000000000000',
)
 
// Prepare the final object to send to the estimateFees() function
const adapterParamsEstimate = [arbitrumParamsEstimate, arbitrumNovaParamsEstimate]
 
async function estimateFees(lzIds: number[], adapterParamsEstimate: `0x${string}`[]): Promise<bigint> {
  const fees = (await client.readContract({
    address: '0xbf94ed69281709958c8f60bc15cd1bb6badcd4a4',
    abi: estimateFeesAbi,
    functionName: 'estimateFees',
    args: [lzIds, adapterParamsEstimate],
  })) as bigint[]
 
  // Aggregate the fees together to use in the `deposit()` function
  const lzFees = fees.reduce((p, c) => p + c, BigInt(0))
 
  return lzFees
}