//! This example shows how to implement a node with a custom EVM

#![cfg_attr(not(test), warn(unused_crate_dependencies))]

use alloy_genesis::Genesis;
use reth::{
    builder::{components::ExecutorBuilder, BuilderContext, NodeBuilder},
    primitives::{
        address,
        revm_primitives::{Env, PrecompileResult},
        Bytes,
    },
    revm::{
        handler::register::EvmHandler,
        inspector_handle_register,
        precompile::{Precompile, PrecompileOutput, PrecompileSpecId},
        ContextPrecompiles, Database, Evm, EvmBuilder, GetInspector,
    },
    tasks::TaskManager,
};
use reth_chainspec::{Chain, ChainSpec, Head};
use reth_evm_ethereum::EthEvmConfig;
use reth_node_api::{ConfigureEvm, ConfigureEvmEnv, FullNodeTypes};
use reth_node_core::{args::RpcServerArgs, node_config::NodeConfig};
use reth_node_ethereum::{
    node::{EthereumAddOns, EthereumPayloadBuilder},
    EthExecutorProvider, EthereumNode,
};
use reth_primitives::{
    revm_primitives::{AnalysisKind, CfgEnvWithHandlerCfg, TxEnv},
    Address, Header, TransactionSigned, U256,
};
use reth_tracing::{RethTracer, Tracer};
use std::sync::Arc;

/// Custom EVM configuration
#[derive(Debug, Clone, Copy, Default)]
#[non_exhaustive]
pub struct MyEvmConfig;

impl MyEvmConfig {
    /// Sets the precompiles to the EVM handler
    ///
    /// This will be invoked when the EVM is created via [ConfigureEvm::evm] or
    /// [ConfigureEvm::evm_with_inspector]
    ///
    /// This will use the default mainnet precompiles and add additional precompiles.
    pub fn set_precompiles<EXT, DB>(handler: &mut EvmHandler<EXT, DB>)
    where
        DB: Database,
    {
        // first we need the evm spec id, which determines the precompiles
        let spec_id = handler.cfg.spec_id;

        // install the precompiles
        handler.pre_execution.load_precompiles = Arc::new(move || {
            let mut precompiles = ContextPrecompiles::new(PrecompileSpecId::from_spec_id(spec_id));
            precompiles.extend([(
                address!("0000000000000000000000000000000000000999"),
                Precompile::Env(Self::my_precompile).into(),
            )]);
            precompiles
        });
    }

    /// A custom precompile that does nothing
    fn my_precompile(_data: &Bytes, _gas: u64, _env: &Env) -> PrecompileResult {
        Ok(PrecompileOutput::new(0, Bytes::new()))
    }
}

impl ConfigureEvmEnv for MyEvmConfig {
    fn fill_cfg_env(
        &self,
        cfg_env: &mut CfgEnvWithHandlerCfg,
        chain_spec: &ChainSpec,
        header: &Header,
        total_difficulty: U256,
    ) {
        let spec_id = reth_evm_ethereum::revm_spec(
            chain_spec,
            &Head {
                number: header.number,
                timestamp: header.timestamp,
                difficulty: header.difficulty,
                total_difficulty,
                hash: Default::default(),
            },
        );

        cfg_env.chain_id = chain_spec.chain().id();
        cfg_env.perf_analyse_created_bytecodes = AnalysisKind::Analyse;

        cfg_env.handler_cfg.spec_id = spec_id;
    }

    fn fill_tx_env(&self, tx_env: &mut TxEnv, transaction: &TransactionSigned, sender: Address) {
        EthEvmConfig::default().fill_tx_env(tx_env, transaction, sender)
    }

    fn fill_tx_env_system_contract_call(
        &self,
        env: &mut Env,
        caller: Address,
        contract: Address,
        data: Bytes,
    ) {
        EthEvmConfig::default().fill_tx_env_system_contract_call(env, caller, contract, data)
    }
}

impl ConfigureEvm for MyEvmConfig {
    type DefaultExternalContext<'a> = ();

    fn evm<DB: Database>(&self, db: DB) -> Evm<'_, Self::DefaultExternalContext<'_>, DB> {
        EvmBuilder::default()
            .with_db(db)
            // add additional precompiles
            .append_handler_register(MyEvmConfig::set_precompiles)
            .build()
    }

    fn evm_with_inspector<DB, I>(&self, db: DB, inspector: I) -> Evm<'_, I, DB>
    where
        DB: Database,
        I: GetInspector<DB>,
    {
        EvmBuilder::default()
            .with_db(db)
            .with_external_context(inspector)
            // add additional precompiles
            .append_handler_register(MyEvmConfig::set_precompiles)
            .append_handler_register(inspector_handle_register)
            .build()
    }

    fn default_external_context<'a>(&self) -> Self::DefaultExternalContext<'a> {}
}

/// Builds a regular ethereum block executor that uses the custom EVM.
#[derive(Debug, Default, Clone, Copy)]
#[non_exhaustive]
pub struct MyExecutorBuilder;

impl<Node> ExecutorBuilder<Node> for MyExecutorBuilder
where
    Node: FullNodeTypes,
{
    type EVM = MyEvmConfig;
    type Executor = EthExecutorProvider<Self::EVM>;

    async fn build_evm(
        self,
        ctx: &BuilderContext<Node>,
    ) -> eyre::Result<(Self::EVM, Self::Executor)> {
        Ok((
            MyEvmConfig::default(),
            EthExecutorProvider::new(ctx.chain_spec(), MyEvmConfig::default()),
        ))
    }
}

#[tokio::main]
async fn main() -> eyre::Result<()> {
    let _guard = RethTracer::new().init()?;

    let tasks = TaskManager::current();

    // create a custom chain spec
    let spec = ChainSpec::builder()
        .chain(Chain::mainnet())
        .genesis(Genesis::default())
        .london_activated()
        .paris_activated()
        .shanghai_activated()
        .cancun_activated()
        .build();

    let node_config =
        NodeConfig::test().with_rpc(RpcServerArgs::default().with_http()).with_chain(spec);

    let handle = NodeBuilder::new(node_config)
        .testing_node(tasks.executor())
        // configure the node with regular ethereum types
        .with_types::<EthereumNode>()
        // use default ethereum components but with our executor
        .with_components(
            EthereumNode::components()
                .executor(MyExecutorBuilder::default())
                .payload(EthereumPayloadBuilder::new(MyEvmConfig::default())),
        )
        .with_add_ons::<EthereumAddOns>()
        .launch()
        .await
        .unwrap();

    println!("Node started");

    handle.node_exit_future.await
}