brc20-prog 0.14.0

use std::collections::{HashMap, HashSet};

use alloy::primitives::{Address, Bytes};
use revm::context::{Block, Cfg, ContextTr};
use revm::handler::PrecompileProvider;
use revm::interpreter::{Gas, InputsImpl, InstructionResult, InterpreterResult};
use revm::precompile::{PrecompileSpecId, Precompiles};

use crate::engine::precompiles::{
    bip322_verify_precompile, btc_tx_details_precompile, get_locked_pkscript_precompile,
    last_sat_location_precompile,
};

lazy_static::lazy_static! {
    static ref BIP322_PRECOMPILE_ADDRESS: Address = "0x00000000000000000000000000000000000000fe".parse().expect("Invalid BIP322 precompile address");
    static ref BTC_TX_DETAILS_PRECOMPILE_ADDRESS: Address = "0x00000000000000000000000000000000000000fd".parse().expect("Invalid BTC transaction details precompile address");
    static ref LAST_SAT_LOCATION_PRECOMPILE_ADDRESS: Address = "0x00000000000000000000000000000000000000fc".parse().expect("Invalid last sat location precompile address");
    static ref GET_LOCKED_PK_SCRIPT_PRECOMPILE_ADDRESS: Address = "0x00000000000000000000000000000000000000fb".parse().expect("Invalid get locked pk script precompile address");
}

pub struct PrecompileCall {
    pub bytes: Bytes,
    pub gas_limit: u64,
    pub block_height: u64,
}

pub struct BRC20Precompiles {
    pub eth_precompiles: &'static Precompiles,
    pub custom_precompiles: HashMap<Address, fn(&PrecompileCall) -> InterpreterResult>,
    pub all_addresses: HashSet<Address>,
}

impl BRC20Precompiles {
    pub fn new(precompile_spec: PrecompileSpecId) -> Self {
        let eth_precompiles = Precompiles::new(precompile_spec);
        let mut all_addresses = eth_precompiles
            .addresses()
            .map(|x| x.clone())
            .collect::<HashSet<Address>>();
        all_addresses.insert(*BIP322_PRECOMPILE_ADDRESS);
        all_addresses.insert(*BTC_TX_DETAILS_PRECOMPILE_ADDRESS);
        all_addresses.insert(*LAST_SAT_LOCATION_PRECOMPILE_ADDRESS);
        all_addresses.insert(*GET_LOCKED_PK_SCRIPT_PRECOMPILE_ADDRESS);

        let mut custom_precompiles: HashMap<Address, fn(&PrecompileCall) -> InterpreterResult> =
            HashMap::new();
        custom_precompiles.insert(*BIP322_PRECOMPILE_ADDRESS, bip322_verify_precompile);
        custom_precompiles.insert(
            *BTC_TX_DETAILS_PRECOMPILE_ADDRESS,
            btc_tx_details_precompile,
        );
        custom_precompiles.insert(
            *LAST_SAT_LOCATION_PRECOMPILE_ADDRESS,
            last_sat_location_precompile,
        );
        custom_precompiles.insert(
            *GET_LOCKED_PK_SCRIPT_PRECOMPILE_ADDRESS,
            get_locked_pkscript_precompile,
        );

        Self {
            eth_precompiles,
            all_addresses,
            custom_precompiles,
        }
    }
}

impl<CTX: ContextTr> PrecompileProvider<CTX> for BRC20Precompiles {
    type Output = InterpreterResult;

    fn set_spec(&mut self, _: <CTX::Cfg as Cfg>::Spec) -> bool {
        // No-op
        true
    }

    fn run(
        &mut self,
        ctx: &mut CTX,
        address: &Address,
        inputs: &InputsImpl,
        _: bool,
        gas_limit: u64,
    ) -> Result<Option<Self::Output>, String> {
        if let Some(eth_precompile) = self.eth_precompiles.get(address) {
            match eth_precompile(&inputs.input, gas_limit) {
                Ok(output) => {
                    let mut gas = Gas::new(gas_limit);
                    if !gas.record_cost(output.gas_used) {
                        return Ok(Some(InterpreterResult::new(
                            InstructionResult::OutOfGas,
                            Bytes::new(),
                            gas,
                        )));
                    } else {
                        return Ok(Some(InterpreterResult::new(
                            InstructionResult::Stop,
                            output.bytes,
                            gas,
                        )));
                    }
                }
                Err(e) => return Err(e.to_string()),
            }
        } else if let Some(custom_precompile) = self.custom_precompiles.get(address) {
            return Ok(Some(custom_precompile(&PrecompileCall {
                bytes: inputs.input.clone(),
                gas_limit,
                block_height: ctx.block().number(),
            })));
        } else {
            return Ok(None);
        }
    }

    fn warm_addresses(&self) -> Box<impl Iterator<Item = Address>> {
        Box::new(self.all_addresses.iter().cloned())
    }

    fn contains(&self, address: &Address) -> bool {
        self.all_addresses.contains(address)
    }
}

/// Records a `gas` cost and fails the instruction if it would exceed the available gas.
pub fn use_gas(interpreter_result: &mut InterpreterResult, gas: u64) -> bool {
    if !interpreter_result.gas.record_cost(gas) {
        interpreter_result.result = revm::interpreter::InstructionResult::OutOfGas;
        return false;
    }
    true
}

/// Fails the instruction with a `PrecompileError` result.
pub fn precompile_error(
    mut interpreter_result: InterpreterResult,
    error: &'static str,
) -> InterpreterResult {
    interpreter_result.result = revm::interpreter::InstructionResult::PrecompileError;
    interpreter_result.output = Bytes::from_static(&error.as_bytes());
    interpreter_result
}

// Returns output for the instruction
pub fn precompile_output(
    mut interpreter_result: InterpreterResult,
    output: Vec<u8>,
) -> InterpreterResult {
    interpreter_result.result = revm::interpreter::InstructionResult::Stop;
    interpreter_result.output = output.into();
    interpreter_result
}

#[cfg(test)]
mod tests {
    use std::str::FromStr;

    use super::*;

    #[test]
    fn test_prague_spec_has_bls_precompiles() {
        // A sanity test to ensure that the Prague spec includes the BLS precompiles.
        let precompiles = BRC20Precompiles::new(PrecompileSpecId::PRAGUE);
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x000000000000000000000000000000000000000b").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x000000000000000000000000000000000000000c").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x000000000000000000000000000000000000000d").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x000000000000000000000000000000000000000e").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x000000000000000000000000000000000000000f").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x0000000000000000000000000000000000000010").unwrap()));
        assert!(precompiles
            .all_addresses
            .contains(&Address::from_str("0x0000000000000000000000000000000000000011").unwrap()));

        // Make sure it does not contain precompiles that are not part of the Prague spec
        assert!(!precompiles
            .all_addresses
            .contains(&Address::from_str("0x0000000000000000000000000000000000000012").unwrap()));
    }
}