//! Example of how to get the gas price in USD using the Chainlink ETH/USD feed.

use alloy::{

network::TransactionBuilder,

primitives::{address, utils::format_units, Address, Bytes, U256},

providers::{Provider, ProviderBuilder},

rpc::types::TransactionRequest,

sol,

sol_types::SolCall,

};

use eyre::Result;

use std::str::FromStr;

const ETH_USD_FEED: Address = address!("5f4eC3Df9cbd43714FE2740f5E3616155c5b8419");

const ETH_USD_FEED_DECIMALS: u8 = 8;

const ETH_DECIMALS: u32 = 18;

// Codegen from excerpt of Chainlink Aggregator interface.

// See: https://etherscan.io/address/0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419#code

sol!(

#[allow(missing_docs)]

function latestAnswer() external view returns (int256);

);

#[tokio::main]

async fn main() -> Result<()> {

// Spin up a forked Anvil node.

// Ensure `anvil` is available in $PATH.

let rpc_url = "https://eth.merkle.io";

let provider = ProviderBuilder::new().on_anvil_with_config(|anvil| anvil.fork(rpc_url));

// Create a call to get the latest answer from the Chainlink ETH/USD feed.

let call = latestAnswerCall {}.abi_encode();

let input = Bytes::from(call);

// Call the Chainlink ETH/USD feed contract.

let tx = TransactionRequest::default().with_to(ETH_USD_FEED).with_input(input);

let response = provider.call(&tx).await?;

let result = U256::from_str(&response.to_string())?;

// Get the gas price of the network.

let wei_per_gas = provider.get_gas_price().await?;

// Convert the gas price to Gwei and USD.

let gwei = format_units(wei_per_gas, "gwei")?.parse::<f64>()?;

let usd = get_usd_value(wei_per_gas, result)?;

println!("Gas price in Gwei: {gwei}");

println!("Gas price in USD: {usd}");

Ok(())

}

fn get_usd_value(amount: u128, price_usd: U256) -> Result<f64> {

let base = U256::from(10).pow(U256::from(ETH_DECIMALS));

let value = U256::from(amount) * price_usd / base;

let formatted = format_units(value, ETH_USD_FEED_DECIMALS)?.parse::<f64>()?;

Ok(formatted)

}