// 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 keeper

import (
	"math/big"

	errorsmod "cosmossdk.io/errors"
	"github.com/cosmos/cosmos-sdk/codec"
	"github.com/cosmos/cosmos-sdk/store/prefix"
	storetypes "github.com/cosmos/cosmos-sdk/store/types"
	sdk "github.com/cosmos/cosmos-sdk/types"
	paramstypes "github.com/cosmos/cosmos-sdk/x/params/types"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core"
	ethtypes "github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/params"
	"github.com/tendermint/tendermint/libs/log"

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

// Keeper grants access to the EVM module state and implements the go-ethereum StateDB interface.
type Keeper struct {
	// Protobuf codec
	cdc codec.BinaryCodec
	// Store key required for the EVM Prefix KVStore. It is required by:
	// - storing account's Storage State
	// - storing account's Code
	// - storing transaction Logs
	// - storing Bloom filters by block height. Needed for the Web3 API.
	storeKey storetypes.StoreKey

	// key to access the transient store, which is reset on every block during Commit
	transientKey storetypes.StoreKey

	// the address capable of executing a MsgUpdateParams message. Typically, this should be the x/gov module account.
	authority sdk.AccAddress
	// access to account state
	accountKeeper types.AccountKeeper
	// update balance and accounting operations with coins
	bankKeeper types.BankKeeper
	// access historical headers for EVM state transition execution
	stakingKeeper types.StakingKeeper
	// fetch EIP1559 base fee and parameters
	feeMarketKeeper types.FeeMarketKeeper

	// chain ID number obtained from the context's chain id
	eip155ChainID *big.Int

	// Tracer used to collect execution traces from the EVM transaction execution
	tracer string

	// EVM Hooks for tx post-processing
	hooks types.EvmHooks

	// custom stateless precompiled smart contracts
	customPrecompiles evm.PrecompiledContracts

	// evm constructor function
	evmConstructor evm.Constructor
	// Legacy subspace
	ss paramstypes.Subspace
}

// NewKeeper generates new evm module keeper
func NewKeeper(
	cdc codec.BinaryCodec,
	storeKey, transientKey storetypes.StoreKey,
	authority sdk.AccAddress,
	ak types.AccountKeeper,
	bankKeeper types.BankKeeper,
	sk types.StakingKeeper,
	fmk types.FeeMarketKeeper,
	customPrecompiles evm.PrecompiledContracts,
	evmConstructor evm.Constructor,
	tracer string,
	ss paramstypes.Subspace,
) *Keeper {
	// ensure evm module account is set
	if addr := ak.GetModuleAddress(types.ModuleName); addr == nil {
		panic("the EVM module account has not been set")
	}

	// ensure the authority account is correct
	if err := sdk.VerifyAddressFormat(authority); err != nil {
		panic(err)
	}

	// NOTE: we pass in the parameter space to the CommitStateDB in order to use custom denominations for the EVM operations
	return &Keeper{
		cdc:               cdc,
		authority:         authority,
		accountKeeper:     ak,
		bankKeeper:        bankKeeper,
		stakingKeeper:     sk,
		feeMarketKeeper:   fmk,
		storeKey:          storeKey,
		transientKey:      transientKey,
		customPrecompiles: customPrecompiles,
		evmConstructor:    evmConstructor,
		tracer:            tracer,
		ss:                ss,
	}
}

// Logger returns a module-specific logger.
func (k Keeper) Logger(ctx sdk.Context) log.Logger {
	return ctx.Logger().With("module", types.ModuleName)
}

// WithChainID sets the chain id to the local variable in the keeper
func (k *Keeper) WithChainID(ctx sdk.Context) {
	chainID, err := ethermint.ParseChainID(ctx.ChainID())
	if err != nil {
		panic(err)
	}

	if k.eip155ChainID != nil && k.eip155ChainID.Cmp(chainID) != 0 {
		panic("chain id already set")
	}

	k.eip155ChainID = chainID
}

// ChainID returns the EIP155 chain ID for the EVM context
func (k Keeper) ChainID() *big.Int {
	return k.eip155ChainID
}

// ----------------------------------------------------------------------------
// Block Bloom
// Required by Web3 API.
// ----------------------------------------------------------------------------

// EmitBlockBloomEvent emit block bloom events
func (k Keeper) EmitBlockBloomEvent(ctx sdk.Context, bloom ethtypes.Bloom) {
	ctx.EventManager().EmitEvent(
		sdk.NewEvent(
			types.EventTypeBlockBloom,
			sdk.NewAttribute(types.AttributeKeyEthereumBloom, string(bloom.Bytes())),
		),
	)
}

// GetAuthority returns the x/evm module authority address
func (k Keeper) GetAuthority() sdk.AccAddress {
	return k.authority
}

// GetBlockBloomTransient returns bloom bytes for the current block height
func (k Keeper) GetBlockBloomTransient(ctx sdk.Context) *big.Int {
	store := prefix.NewStore(ctx.TransientStore(k.transientKey), types.KeyPrefixTransientBloom)
	heightBz := sdk.Uint64ToBigEndian(uint64(ctx.BlockHeight()))
	bz := store.Get(heightBz)
	if len(bz) == 0 {
		return big.NewInt(0)
	}

	return new(big.Int).SetBytes(bz)
}

// SetBlockBloomTransient sets the given bloom bytes to the transient store. This value is reset on
// every block.
func (k Keeper) SetBlockBloomTransient(ctx sdk.Context, bloom *big.Int) {
	store := prefix.NewStore(ctx.TransientStore(k.transientKey), types.KeyPrefixTransientBloom)
	heightBz := sdk.Uint64ToBigEndian(uint64(ctx.BlockHeight()))
	store.Set(heightBz, bloom.Bytes())
}

// ----------------------------------------------------------------------------
// Tx
// ----------------------------------------------------------------------------

// SetTxIndexTransient set the index of processing transaction
func (k Keeper) SetTxIndexTransient(ctx sdk.Context, index uint64) {
	store := ctx.TransientStore(k.transientKey)
	store.Set(types.KeyPrefixTransientTxIndex, sdk.Uint64ToBigEndian(index))
}

// GetTxIndexTransient returns EVM transaction index on the current block.
func (k Keeper) GetTxIndexTransient(ctx sdk.Context) uint64 {
	store := ctx.TransientStore(k.transientKey)
	bz := store.Get(types.KeyPrefixTransientTxIndex)
	if len(bz) == 0 {
		return 0
	}

	return sdk.BigEndianToUint64(bz)
}

// ----------------------------------------------------------------------------
// Log
// ----------------------------------------------------------------------------

// GetLogSizeTransient returns EVM log index on the current block.
func (k Keeper) GetLogSizeTransient(ctx sdk.Context) uint64 {
	store := ctx.TransientStore(k.transientKey)
	bz := store.Get(types.KeyPrefixTransientLogSize)
	if len(bz) == 0 {
		return 0
	}

	return sdk.BigEndianToUint64(bz)
}

// SetLogSizeTransient fetches the current EVM log index from the transient store, increases its
// value by one and then sets the new index back to the transient store.
func (k Keeper) SetLogSizeTransient(ctx sdk.Context, logSize uint64) {
	store := ctx.TransientStore(k.transientKey)
	store.Set(types.KeyPrefixTransientLogSize, sdk.Uint64ToBigEndian(logSize))
}

// ----------------------------------------------------------------------------
// Storage
// ----------------------------------------------------------------------------

// GetAccountStorage return state storage associated with an account
func (k Keeper) GetAccountStorage(ctx sdk.Context, address common.Address) types.Storage {
	storage := types.Storage{}

	k.ForEachStorage(ctx, address, func(key, value common.Hash) bool {
		storage = append(storage, types.NewState(key, value))
		return true
	})

	return storage
}

// ----------------------------------------------------------------------------
// Account
// ----------------------------------------------------------------------------

// SetHooks sets the hooks for the EVM module
// It should be called only once during initialization, it panic if called more than once.
func (k *Keeper) SetHooks(eh types.EvmHooks) *Keeper {
	if k.hooks != nil {
		panic("cannot set evm hooks twice")
	}

	k.hooks = eh
	return k
}

// PostTxProcessing delegate the call to the hooks. If no hook has been registered, this function returns with a `nil` error
func (k *Keeper) PostTxProcessing(ctx sdk.Context, msg core.Message, receipt *ethtypes.Receipt) error {
	if k.hooks == nil {
		return nil
	}
	return k.hooks.PostTxProcessing(ctx, msg, receipt)
}

// Tracer return a default vm.Tracer based on current keeper state
func (k Keeper) Tracer(ctx sdk.Context, msg core.Message, ethCfg *params.ChainConfig) vm.EVMLogger {
	return types.NewTracer(k.tracer, msg, ethCfg, ctx.BlockHeight())
}

// GetAccountWithoutBalance load nonce and codehash without balance,
// more efficient in cases where balance is not needed.
func (k *Keeper) GetAccountWithoutBalance(ctx sdk.Context, addr common.Address) *statedb.Account {
	cosmosAddr := sdk.AccAddress(addr.Bytes())
	acct := k.accountKeeper.GetAccount(ctx, cosmosAddr)
	if acct == nil {
		return nil
	}

	codeHash := types.EmptyCodeHash
	ethAcct, ok := acct.(ethermint.EthAccountI)
	if ok {
		codeHash = ethAcct.GetCodeHash().Bytes()
	}

	return &statedb.Account{
		Nonce:    acct.GetSequence(),
		CodeHash: codeHash,
	}
}

// GetAccountOrEmpty returns empty account if not exist, returns error if it's not `EthAccount`
func (k *Keeper) GetAccountOrEmpty(ctx sdk.Context, addr common.Address) statedb.Account {
	acct := k.GetAccount(ctx, addr)
	if acct != nil {
		return *acct
	}

	// empty account
	return statedb.Account{
		Balance:  new(big.Int),
		CodeHash: types.EmptyCodeHash,
	}
}

// GetNonce returns the sequence number of an account, returns 0 if not exists.
func (k *Keeper) GetNonce(ctx sdk.Context, addr common.Address) uint64 {
	cosmosAddr := sdk.AccAddress(addr.Bytes())
	acct := k.accountKeeper.GetAccount(ctx, cosmosAddr)
	if acct == nil {
		return 0
	}

	return acct.GetSequence()
}

// GetBalance load account's balance of gas token
func (k *Keeper) GetBalance(ctx sdk.Context, addr common.Address) *big.Int {
	cosmosAddr := sdk.AccAddress(addr.Bytes())
	evmDenom := k.GetEVMDenom(ctx)
	// if node is pruned, params is empty. Return invalid value
	if evmDenom == "" {
		return big.NewInt(-1)
	}
	coin := k.bankKeeper.GetBalance(ctx, cosmosAddr, evmDenom)
	return coin.Amount.BigInt()
}

// GetBaseFee returns current base fee, return values:
// - `nil`: london hardfork not enabled.
// - `0`: london hardfork enabled but feemarket is not enabled.
// - `n`: both london hardfork and feemarket are enabled.
func (k Keeper) GetBaseFee(ctx sdk.Context, ethCfg *params.ChainConfig) *big.Int {
	return k.getBaseFee(ctx, types.IsLondon(ethCfg, ctx.BlockHeight()))
}

func (k Keeper) getBaseFee(ctx sdk.Context, london bool) *big.Int {
	if !london {
		return nil
	}
	baseFee := k.feeMarketKeeper.GetBaseFee(ctx)
	if baseFee == nil {
		// return 0 if feemarket not enabled.
		baseFee = big.NewInt(0)
	}
	return baseFee
}

// GetMinGasMultiplier returns the MinGasMultiplier param from the fee market module
func (k Keeper) GetMinGasMultiplier(ctx sdk.Context) sdk.Dec {
	fmkParmas := k.feeMarketKeeper.GetParams(ctx)
	if fmkParmas.MinGasMultiplier.IsNil() {
		// in case we are executing eth_call on a legacy block, returns a zero value.
		return sdk.ZeroDec()
	}
	return fmkParmas.MinGasMultiplier
}

// ResetTransientGasUsed reset gas used to prepare for execution of current cosmos tx, called in ante handler.
func (k Keeper) ResetTransientGasUsed(ctx sdk.Context) {
	store := ctx.TransientStore(k.transientKey)
	store.Delete(types.KeyPrefixTransientGasUsed)
}

// GetTransientGasUsed returns the gas used by current cosmos tx.
func (k Keeper) GetTransientGasUsed(ctx sdk.Context) uint64 {
	store := ctx.TransientStore(k.transientKey)
	bz := store.Get(types.KeyPrefixTransientGasUsed)
	if len(bz) == 0 {
		return 0
	}
	return sdk.BigEndianToUint64(bz)
}

// SetTransientGasUsed sets the gas used by current cosmos tx.
func (k Keeper) SetTransientGasUsed(ctx sdk.Context, gasUsed uint64) {
	store := ctx.TransientStore(k.transientKey)
	bz := sdk.Uint64ToBigEndian(gasUsed)
	store.Set(types.KeyPrefixTransientGasUsed, bz)
}

// AddTransientGasUsed accumulate gas used by each eth msgs included in current cosmos tx.
func (k Keeper) AddTransientGasUsed(ctx sdk.Context, gasUsed uint64) (uint64, error) {
	result := k.GetTransientGasUsed(ctx) + gasUsed
	if result < gasUsed {
		return 0, errorsmod.Wrap(types.ErrGasOverflow, "transient gas used")
	}
	k.SetTransientGasUsed(ctx, result)
	return result, nil
}