fork_ref_transact.rs

use alloy_sol_types::sol;
use alloy_sol_types::SolCall;
use ethers_providers::{Http, Provider};
use revm::{
    db::{CacheDB, EmptyDB, EthersDB},
    primitives::{address, ExecutionResult, Output, TransactTo, U256},
    Database, Evm,
};
use std::sync::Arc;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // create ethers client and wrap it in Arc<M>
    let client = Provider::<Http>::try_from(
        "https://mainnet.infura.io/v3/c60b0bb42f8a4c6481ecd229eddaca27",
    )?;
    let client = Arc::new(client);

    // ----------------------------------------------------------- //
    //             Storage slots of UniV2Pair contract             //
    // =========================================================== //
    // storage[5] = factory: address                               //
    // storage[6] = token0: address                                //
    // storage[7] = token1: address                                //
    // storage[8] = (res0, res1, ts): (uint112, uint112, uint32)   //
    // storage[9] = price0CumulativeLast: uint256                  //
    // storage[10] = price1CumulativeLast: uint256                 //
    // storage[11] = kLast: uint256                                //
    // =========================================================== //

    // choose slot of storage that you would like to transact with
    let slot = U256::from(8);

    // ETH/USDT pair on Uniswap V2
    let pool_address = address!("0d4a11d5EEaaC28EC3F61d100daF4d40471f1852");

    // generate abi for the calldata from the human readable interface
    sol! {
        function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    }

    // encode abi into Bytes
    let encoded = getReservesCall::new(()).abi_encode();

    // initialize new EthersDB
    let mut ethersdb = EthersDB::new(Arc::clone(&client), None).unwrap();

    // query basic properties of an account incl bytecode
    let acc_info = ethersdb.basic(pool_address).unwrap().unwrap();

    // query value of storage slot at account address
    let value = ethersdb.storage(pool_address, slot).unwrap();

    // initialise empty in-memory-db
    let mut cache_db = CacheDB::new(EmptyDB::default());

    // insert basic account info which was generated via Web3DB with the corresponding address
    cache_db.insert_account_info(pool_address, acc_info);

    // insert our pre-loaded storage slot to the corresponding contract key (address) in the DB
    cache_db
        .insert_account_storage(pool_address, slot, value)
        .unwrap();

    // initialise an empty (default) EVM
    let mut evm = Evm::builder()
        .with_db(cache_db)
        .modify_tx_env(|tx| {
            // fill in missing bits of env struct
            // change that to whatever caller you want to be
            tx.caller = address!("0000000000000000000000000000000000000000");
            // account you want to transact with
            tx.transact_to = TransactTo::Call(pool_address);
            // calldata formed via abigen
            tx.data = encoded.into();
            // transaction value in wei
            tx.value = U256::from(0);
        })
        .build();

    // execute transaction without writing to the DB
    let ref_tx = evm.transact().unwrap();
    // select ExecutionResult struct
    let result = ref_tx.result;

    // unpack output call enum into raw bytes
    let value = match result {
        ExecutionResult::Success {
            output: Output::Call(value),
            ..
        } => value,
        result => panic!("Execution failed: {result:?}"),
    };

    // decode bytes to reserves + ts via alloy's abi decode
    let return_vals = getReservesCall::abi_decode_returns(&value, true)?;

    // Print emulated getReserves() call output
    println!("Reserve0: {:#?}", return_vals.reserve0);
    println!("Reserve1: {:#?}", return_vals.reserve1);
    println!("Timestamp: {:#?}", return_vals.blockTimestampLast);

    Ok(())
}