68 lines
2.1 KiB
Rust
68 lines
2.1 KiB
Rust
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use ethers::{prelude::*, utils::format_units};
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use std::{
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error::Error,
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ops::{Div, Mul},
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sync::Arc,
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};
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abigen!(
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AggregatorInterface,
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r#"[
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latestAnswer() public view virtual override returns (int256 answer)
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]"#,
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);
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const ETH_DECIMALS: u32 = 18;
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const USD_PRICE_DECIMALS: u32 = 8;
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const ETH_USD_FEED: &str = "0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419";
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const RPC_URI: &str = "https://mainnet.infura.io/v3/c60b0bb42f8a4c6481ecd229eddaca27";
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/// Retrieves the USD amount per gas unit, using a Chainlink price oracle.
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/// Function gets the amount of `wei` to be spent per gas unit then multiplies
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/// for the ETH USD value.
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#[tokio::main]
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async fn main() -> Result<(), Box<dyn Error>> {
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let client = get_client();
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let oracle = get_oracle(&client);
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let usd_per_eth: I256 = oracle.latest_answer().call().await?;
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let usd_per_eth: U256 = U256::from(usd_per_eth.as_u128());
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let wei_per_gas: U256 = client.get_gas_price().await?;
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// Gas stations use to report gas price in gwei units (1 gwei = 10^9 wei)
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let gwei: f64 = format_units(wei_per_gas, "gwei")?.parse::<f64>()?;
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// Let's convert the gas price to USD
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let usd_per_gas: f64 = usd_value(wei_per_gas, usd_per_eth)?;
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println!(
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r#"
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Gas price
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---------------
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{:>10.2} gwei
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{:>10.8} usd
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"#,
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gwei, usd_per_gas
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);
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Ok(())
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}
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/// `amount`: Number of wei per gas unit (18 decimals)
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/// `price_usd`: USD price per ETH (8 decimals)
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fn usd_value(amount: U256, price_usd: U256) -> Result<f64, Box<dyn Error>> {
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let base: U256 = U256::from(10).pow(ETH_DECIMALS.into());
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let value: U256 = amount.mul(price_usd).div(base);
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let f: String = format_units(value, USD_PRICE_DECIMALS)?;
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Ok(f.parse::<f64>()?)
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}
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fn get_client() -> Arc<Provider<Http>> {
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let provider: Provider<Http> = Provider::<Http>::try_from(RPC_URI).expect("Valid URL");
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Arc::new(provider)
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}
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fn get_oracle(client: &Arc<Provider<Http>>) -> AggregatorInterface<Provider<Http>> {
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let address: Address = ETH_USD_FEED.parse().expect("Valid address");
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AggregatorInterface::new(address, Arc::clone(client))
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}
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