// Copyright 2021 Evmos Foundation
// This file is part of Evmos' Ethermint library.
//
// The Ethermint library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The Ethermint library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the Ethermint library. If not, see https://github.com/evmos/ethermint/blob/main/LICENSE
package geth

import (
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/params"

	evm "github.com/evmos/ethermint/x/evm/vm"
)

var (
	_ evm.EVM         = (*EVM)(nil)
	_ evm.Constructor = NewEVM
)

// EVM is the wrapper for the go-ethereum EVM.
type EVM struct {
	*vm.EVM
}

// NewEVM defines the constructor function for the go-ethereum (geth) EVM. It uses
// the default precompiled contracts and the EVM concrete implementation from
// geth.
func NewEVM(
	blockCtx vm.BlockContext,
	txCtx vm.TxContext,
	stateDB vm.StateDB,
	chainConfig *params.ChainConfig,
	config vm.Config,
	_ evm.PrecompiledContracts, // unused
) evm.EVM {
	return &EVM{
		EVM: vm.NewEVM(blockCtx, txCtx, stateDB, chainConfig, config),
	}
}

// Context returns the EVM's Block Context
func (e EVM) Context() vm.BlockContext {
	return e.EVM.Context
}

// TxContext returns the EVM's Tx Context
func (e EVM) TxContext() vm.TxContext {
	return e.EVM.TxContext
}

// Config returns the configuration options for the EVM.
func (e EVM) Config() vm.Config {
	return e.EVM.Config
}

// Precompile returns the precompiled contract associated with the given address
// and the current chain configuration. If the contract cannot be found it returns
// nil.
func (e EVM) Precompile(addr common.Address) (p vm.PrecompiledContract, found bool) {
	precompiles := GetPrecompiles(e.ChainConfig(), e.EVM.Context.BlockNumber)
	p, found = precompiles[addr]
	return p, found
}

// ActivePrecompiles returns a list of all the active precompiled contract addresses
// for the current chain configuration.
func (EVM) ActivePrecompiles(rules params.Rules) []common.Address {
	return vm.ActivePrecompiles(rules)
}

// RunPrecompiledContract runs a stateless precompiled contract and ignores the address and
// value arguments. It uses the RunPrecompiledContract function from the geth vm package
func (EVM) RunPrecompiledContract(
	p evm.StatefulPrecompiledContract,
	_ common.Address, // address arg is unused
	input []byte,
	suppliedGas uint64,
	_ *big.Int, // 	value arg is unused
) (ret []byte, remainingGas uint64, err error) {
	return vm.RunPrecompiledContract(p, input, suppliedGas)
}