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// Copyright 2019-2022 PureStake Inc.
// This file is part Utils package, originally developed by PureStake

// Utils is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Utils is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Utils.  If not, see <http://www.gnu.org/licenses/>.

//! Utils related to Substrate features:
//! - Substrate call dispatch.
//! - Substrate DB read and write costs

use crate::{revert, EvmResult};
use core::marker::PhantomData;
use frame_support::{
    dispatch::{Dispatchable, GetDispatchInfo, PostDispatchInfo},
    traits::Get,
    weights::Weight,
};
use pallet_3vm_evm::GasWeightMapping;
use pallet_3vm_evm_primitives::{ExitError, PrecompileFailure, PrecompileHandle};

/// Helper functions requiring a Substrate runtime.
/// This runtime must of course implement `pallet_3vm_evm::Config`.
#[derive(Clone, Copy, Debug)]
pub struct RuntimeHelper<Runtime>(PhantomData<Runtime>);

/*
impl<Runtime> RuntimeHelper<Runtime>
    where
        Runtime: pallet_3vm_evm::Config,
        Runtime::RuntimeCall: Dispatchable<PostInfo = PostDispatchInfo> + GetDispatchInfo,
{
    /// Try to dispatch a Substrate call.
    /// Return an error if there are not enough gas, or if the call fails.
    /// If successful returns the used gas using the Runtime GasWeightMapping.
    pub fn try_dispatch<RuntimeCall>(
        handle: &mut impl PrecompileHandle,
        origin: <Runtime::RuntimeCall as Dispatchable>::RuntimeOrigin,
        call: RuntimeCall,
    ) -> EvmResult<()>
        where
            Runtime::RuntimeCall: From<RuntimeCall>,
    {
        let call = Runtime::RuntimeCall::from(call);
        let dispatch_info = call.get_dispatch_info();

        // Make sure there is enough gas.
        let remaining_gas = handle.remaining_gas();
        let required_gas = Runtime::GasWeightMapping::weight_to_gas(dispatch_info.weight);
        if required_gas > remaining_gas {
            return Err(PrecompileFailure::Error {
                exit_status: ExitError::OutOfGas,
            });
        }

        // Dispatch call.
        // It may be possible to not record gas cost if the call returns Pays::No.
        // However while Substrate handle checking weight while not making the sender pay for it,
        // the EVM doesn't. It seems this safer to always record the costs to avoid unmetered
        // computations.
        let used_weight = call
            .dispatch(origin)
            .map_err(|e| revert(alloc::format!("Dispatched call failed with error: {:?}", e)))?
            .actual_weight;

        let used_gas = Runtime::GasWeightMapping::weight_to_gas(used_weight.unwrap_or(dispatch_info.weight));

        handle.record_cost(used_gas)?;

        Ok(())
    }
}
*/

impl<Runtime> RuntimeHelper<Runtime>
where
    Runtime: pallet_3vm_evm::Config + frame_system::Config,
{
    /// Cost of a Substrate DB write in gas.
    pub fn db_write_gas_cost() -> u64 {
        <Runtime as pallet_3vm_evm::Config>::GasWeightMapping::weight_to_gas(
            <Runtime as frame_system::Config>::DbWeight::get().writes(1),
        )
    }

    /// Cost of a Substrate DB read in gas.
    pub fn db_read_gas_cost() -> u64 {
        <Runtime as pallet_3vm_evm::Config>::GasWeightMapping::weight_to_gas(
            <Runtime as frame_system::Config>::DbWeight::get().reads(1),
        )
    }
}