keeper.go

package keeper

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"path/filepath"

	wasmvm "github.com/CosmWasm/wasmvm"
	wasmvmtypes "github.com/CosmWasm/wasmvm/types"
	"github.com/cosmos/cosmos-sdk/codec"
	"github.com/cosmos/cosmos-sdk/store/prefix"
	sdk "github.com/cosmos/cosmos-sdk/types"
	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
	authkeeper "github.com/cosmos/cosmos-sdk/x/auth/keeper"
	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
	distributionkeeper "github.com/cosmos/cosmos-sdk/x/distribution/keeper"
	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
	stakingkeeper "github.com/cosmos/cosmos-sdk/x/staking/keeper"
	"github.com/konstellation/kn-sdk/x/wasm/internal/types"
	"github.com/tendermint/tendermint/crypto"
	"github.com/tendermint/tendermint/libs/log"
)

// GasMultiplier is how many cosmwasm gas points = 1 sdk gas point
// SDK reference costs can be found here: https://github.com/cosmos/cosmos-sdk/blob/02c6c9fafd58da88550ab4d7d494724a477c8a68/store/types/gas.go#L153-L164
// A write at ~3000 gas and ~200us = 10 gas per us (microsecond) cpu/io
// Rough timing have 88k gas at 90us, which is equal to 1k sdk gas... (one read)
//
// Please not that all gas prices returned to the wasmer engine should have this multiplied
const GasMultiplier uint64 = 100

// MaxGas for a contract is 10 billion wasmer gas (enforced in rust to prevent overflow)
// The limit for v0.9.3 is defined here: https://github.com/CosmWasm/cosmwasm/blob/v0.9.3/packages/vm/src/backends/singlepass.rs#L15-L23
// (this will be increased in future releases)
const MaxGas = 10_000_000_000

// InstanceCost is how much SDK gas we charge each time we load a WASM instance.
// Creating a new instance is costly, and this helps put a recursion limit to contracts calling contracts.
const InstanceCost uint64 = 40_000

// CompileCost is how much SDK gas we charge *per byte* for compiling WASM code.
const CompileCost uint64 = 2

// contractMemoryLimit is the memory limit of each contract execution (in MiB)
// constant value so all nodes run with the same limit.
const contractMemoryLimit = 32

// Keeper will have a reference to Wasmer with it's own data directory.
type Keeper struct {
	storeKey      sdk.StoreKey
	cdc           codec.Marshaler
	accountKeeper authkeeper.AccountKeeper
	bankKeeper    bankkeeper.Keeper

	wasmer       types.WasmerEngine
	queryPlugins QueryPlugins
	messenger    MessageHandler
	// queryGasLimit is the max wasmvm gas that can be spent on executing a query with a contract
	queryGasLimit uint64
	authZPolicy   AuthorizationPolicy
	paramSpace    paramtypes.Subspace
}

// NewKeeper creates a new contract Keeper instance
// If customEncoders is non-nil, we can use this to override some of the message handler, especially custom
func NewKeeper(
	cdc codec.Marshaler,
	storeKey sdk.StoreKey,
	paramSpace paramtypes.Subspace,
	accountKeeper authkeeper.AccountKeeper,
	bankKeeper bankkeeper.Keeper,
	stakingKeeper stakingkeeper.Keeper,
	distKeeper distributionkeeper.Keeper,
	router sdk.Router,
	homeDir string,
	wasmConfig types.WasmConfig,
	supportedFeatures string,
	customEncoders *MessageEncoders,
	customPlugins *QueryPlugins,
) Keeper {
	wasmer, err := wasmvm.NewVM(filepath.Join(homeDir, "wasm"), supportedFeatures, contractMemoryLimit, wasmConfig.ContractDebugMode, wasmConfig.MemoryCacheSize)
	if err != nil {
		panic(err)
	}

	// set KeyTable if it has not already been set
	if !paramSpace.HasKeyTable() {
		paramSpace = paramSpace.WithKeyTable(types.ParamKeyTable())
	}

	keeper := Keeper{
		storeKey:      storeKey,
		cdc:           cdc,
		wasmer:        wasmer,
		accountKeeper: accountKeeper,
		bankKeeper:    bankKeeper,
		messenger:     NewMessageHandler(router, customEncoders),
		queryGasLimit: wasmConfig.SmartQueryGasLimit,
		authZPolicy:   DefaultAuthorizationPolicy{},
		paramSpace:    paramSpace,
	}
	keeper.queryPlugins = DefaultQueryPlugins(bankKeeper, stakingKeeper, distKeeper, &keeper).Merge(customPlugins)
	return keeper
}

func (k Keeper) getUploadAccessConfig(ctx sdk.Context) types.AccessConfig {
	var a types.AccessConfig
	k.paramSpace.Get(ctx, types.ParamStoreKeyUploadAccess, &a)
	return a
}

func (k Keeper) getInstantiateAccessConfig(ctx sdk.Context) types.AccessType {
	var a types.AccessType
	k.paramSpace.Get(ctx, types.ParamStoreKeyInstantiateAccess, &a)
	return a
}

func (k Keeper) GetMaxWasmCodeSize(ctx sdk.Context) uint64 {
	var a uint64
	k.paramSpace.Get(ctx, types.ParamStoreKeyMaxWasmCodeSize, &a)
	return a
}

// GetParams returns the total set of wasm parameters.
func (k Keeper) GetParams(ctx sdk.Context) types.Params {
	var params types.Params
	k.paramSpace.GetParamSet(ctx, &params)
	return params
}

func (k Keeper) setParams(ctx sdk.Context, ps types.Params) {
	k.paramSpace.SetParamSet(ctx, &ps)
}

// Create uploads and compiles a WASM contract, returning a short identifier for the contract
func (k Keeper) Create(ctx sdk.Context, creator sdk.AccAddress, wasmCode []byte, source string, builder string, instantiateAccess *types.AccessConfig) (codeID uint64, err error) {
	return k.create(ctx, creator, wasmCode, source, builder, instantiateAccess, k.authZPolicy)
}

func (k Keeper) create(ctx sdk.Context, creator sdk.AccAddress, wasmCode []byte, source string, builder string, instantiateAccess *types.AccessConfig, authZ AuthorizationPolicy) (codeID uint64, err error) {
	if !authZ.CanCreateCode(k.getUploadAccessConfig(ctx), creator) {
		return 0, sdkerrors.Wrap(sdkerrors.ErrUnauthorized, "can not create code")
	}
	wasmCode, err = uncompress(wasmCode, k.GetMaxWasmCodeSize(ctx))
	if err != nil {
		return 0, sdkerrors.Wrap(types.ErrCreateFailed, err.Error())
	}
	ctx.GasMeter().ConsumeGas(CompileCost*uint64(len(wasmCode)), "Compiling WASM Bytecode")

	codeHash, err := k.wasmer.Create(wasmCode)
	if err != nil {
		// return 0, sdkerrors.Wrap(err, "cosmwasm create")
		return 0, sdkerrors.Wrap(types.ErrCreateFailed, err.Error())
	}
	store := ctx.KVStore(k.storeKey)
	codeID = k.autoIncrementID(ctx, types.KeyLastCodeID)
	if instantiateAccess == nil {
		defaultAccessConfig := k.getInstantiateAccessConfig(ctx).With(creator)
		instantiateAccess = &defaultAccessConfig
	}
	codeInfo := types.NewCodeInfo(codeHash, creator, source, builder, *instantiateAccess)
	// 0x01 | codeID (uint64) -> ContractInfo
	store.Set(types.GetCodeKey(codeID), k.cdc.MustMarshalBinaryBare(&codeInfo))

	return codeID, nil
}

func (k Keeper) importCode(ctx sdk.Context, codeID uint64, codeInfo types.CodeInfo, wasmCode []byte) error {
	wasmCode, err := uncompress(wasmCode, k.GetMaxWasmCodeSize(ctx))
	if err != nil {
		return sdkerrors.Wrap(types.ErrCreateFailed, err.Error())
	}
	newCodeHash, err := k.wasmer.Create(wasmCode)
	if err != nil {
		return sdkerrors.Wrap(types.ErrCreateFailed, err.Error())
	}
	if !bytes.Equal(codeInfo.CodeHash, newCodeHash) {
		return sdkerrors.Wrap(types.ErrInvalid, "code hashes not same")
	}

	store := ctx.KVStore(k.storeKey)
	key := types.GetCodeKey(codeID)
	if store.Has(key) {
		return sdkerrors.Wrapf(types.ErrDuplicate, "duplicate code: %d", codeID)
	}
	// 0x01 | codeID (uint64) -> ContractInfo
	store.Set(key, k.cdc.MustMarshalBinaryBare(&codeInfo))
	return nil
}

// Instantiate creates an instance of a WASM contract
func (k Keeper) Instantiate(ctx sdk.Context, codeID uint64, creator, admin sdk.AccAddress, initMsg []byte, label string, deposit sdk.Coins) (sdk.AccAddress, error) {
	return k.instantiate(ctx, codeID, creator, admin, initMsg, label, deposit, k.authZPolicy)
}

func (k Keeper) instantiate(ctx sdk.Context, codeID uint64, creator, admin sdk.AccAddress, initMsg []byte, label string, deposit sdk.Coins, authZ AuthorizationPolicy) (sdk.AccAddress, error) {
	ctx.GasMeter().ConsumeGas(InstanceCost, "Loading CosmWasm module: init")

	// create contract address
	contractAddress := k.generateContractAddress(ctx, codeID)
	existingAcct := k.accountKeeper.GetAccount(ctx, contractAddress)
	if existingAcct != nil {
		return nil, sdkerrors.Wrap(types.ErrAccountExists, existingAcct.GetAddress().String())
	}

	// deposit initial contract funds
	if !deposit.IsZero() {
		if k.bankKeeper.BlockedAddr(creator) {
			return nil, sdkerrors.Wrap(sdkerrors.ErrInvalidAddress, "blocked address can not be used")
		}
		sdkerr := k.bankKeeper.SendCoins(ctx, creator, contractAddress, deposit)
		if sdkerr != nil {
			return nil, sdkerr
		}
	} else {
		// create an empty account (so we don't have issues later)
		// TODO: can we remove this?
		contractAccount := k.accountKeeper.NewAccountWithAddress(ctx, contractAddress)
		k.accountKeeper.SetAccount(ctx, contractAccount)
	}

	// get contact info
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(types.GetCodeKey(codeID))
	if bz == nil {
		return nil, sdkerrors.Wrap(types.ErrNotFound, "code")
	}
	var codeInfo types.CodeInfo
	k.cdc.MustUnmarshalBinaryBare(bz, &codeInfo)

	if !authZ.CanInstantiateContract(codeInfo.InstantiateConfig, creator) {
		return nil, sdkerrors.Wrap(sdkerrors.ErrUnauthorized, "can not instantiate")
	}

	// prepare params for contract instantiate call
	env := types.NewEnv(ctx, contractAddress)
	info := types.NewInfo(creator, deposit)

	// create prefixed data store
	// 0x03 | contractAddress (sdk.AccAddress)
	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)

	// prepare querier
	querier := QueryHandler{
		Ctx:     ctx,
		Plugins: k.queryPlugins,
	}

	// instantiate wasm contract
	gas := gasForContract(ctx)
	res, gasUsed, err := k.wasmer.Instantiate(codeInfo.CodeHash, env, info, initMsg, prefixStore, cosmwasmAPI, querier, gasMeter(ctx), gas)
	consumeGas(ctx, gasUsed)
	if err != nil {
		return contractAddress, sdkerrors.Wrap(types.ErrInstantiateFailed, err.Error())
	}

	// emit all events from this contract itself
	events := types.ParseEvents(res.Attributes, contractAddress)
	ctx.EventManager().EmitEvents(events)

	// persist instance first
	createdAt := types.NewAbsoluteTxPosition(ctx)
	contractInfo := types.NewContractInfo(codeID, creator, admin, label, createdAt)
	k.storeContractInfo(ctx, contractAddress, &contractInfo)
	k.appendToContractHistory(ctx, contractAddress, contractInfo.InitialHistory(initMsg))

	// then dispatch so that contract could be called back
	err = k.dispatchMessages(ctx, contractAddress, res.Messages)
	if err != nil {
		return nil, err
	}

	return contractAddress, nil
}

// Execute executes the contract instance
func (k Keeper) Execute(ctx sdk.Context, contractAddress sdk.AccAddress, caller sdk.AccAddress, msg []byte, coins sdk.Coins) (*sdk.Result, error) {
	ctx.GasMeter().ConsumeGas(InstanceCost, "Loading CosmWasm module: execute")

	codeInfo, prefixStore, err := k.contractInstance(ctx, contractAddress)
	if err != nil {
		return nil, err
	}

	// add more funds
	if !coins.IsZero() {
		if k.bankKeeper.BlockedAddr(caller) {
			return nil, sdkerrors.Wrap(sdkerrors.ErrInvalidAddress, "blocked address can not be used")
		}

		sdkerr := k.bankKeeper.SendCoins(ctx, caller, contractAddress, coins)
		if sdkerr != nil {
			return nil, sdkerr
		}
	}

	env := types.NewEnv(ctx, contractAddress)
	info := types.NewInfo(caller, coins)

	// prepare querier
	querier := QueryHandler{
		Ctx:     ctx,
		Plugins: k.queryPlugins,
	}

	gas := gasForContract(ctx)
	res, gasUsed, execErr := k.wasmer.Execute(codeInfo.CodeHash, env, info, msg, prefixStore, cosmwasmAPI, querier, gasMeter(ctx), gas)
	consumeGas(ctx, gasUsed)
	if execErr != nil {
		return nil, sdkerrors.Wrap(types.ErrExecuteFailed, execErr.Error())
	}

	// emit all events from this contract itself
	events := types.ParseEvents(res.Attributes, contractAddress)
	ctx.EventManager().EmitEvents(events)

	err = k.dispatchMessages(ctx, contractAddress, res.Messages)
	if err != nil {
		return nil, err
	}

	return &sdk.Result{
		Data: res.Data,
	}, nil
}

// Migrate allows to upgrade a contract to a new code with data migration.
func (k Keeper) Migrate(ctx sdk.Context, contractAddress sdk.AccAddress, caller sdk.AccAddress, newCodeID uint64, msg []byte) (*sdk.Result, error) {
	return k.migrate(ctx, contractAddress, caller, newCodeID, msg, k.authZPolicy)
}

func (k Keeper) migrate(ctx sdk.Context, contractAddress sdk.AccAddress, caller sdk.AccAddress, newCodeID uint64, msg []byte, authZ AuthorizationPolicy) (*sdk.Result, error) {
	ctx.GasMeter().ConsumeGas(InstanceCost, "Loading CosmWasm module: migrate")

	contractInfo := k.GetContractInfo(ctx, contractAddress)
	if contractInfo == nil {
		return nil, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "unknown contract")
	}
	if !authZ.CanModifyContract(contractInfo.AdminAddr(), caller) {
		return nil, sdkerrors.Wrap(sdkerrors.ErrUnauthorized, "can not migrate")
	}

	newCodeInfo := k.GetCodeInfo(ctx, newCodeID)
	if newCodeInfo == nil {
		return nil, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "unknown code")
	}

	var noDeposit sdk.Coins
	env := types.NewEnv(ctx, contractAddress)
	info := types.NewInfo(caller, noDeposit)

	// prepare querier
	querier := QueryHandler{
		Ctx:     ctx,
		Plugins: k.queryPlugins,
	}

	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
	gas := gasForContract(ctx)
	res, gasUsed, err := k.wasmer.Migrate(newCodeInfo.CodeHash, env, info, msg, &prefixStore, cosmwasmAPI, &querier, gasMeter(ctx), gas)
	consumeGas(ctx, gasUsed)
	if err != nil {
		return nil, sdkerrors.Wrap(types.ErrMigrationFailed, err.Error())
	}

	// emit all events from this contract migration itself
	events := types.ParseEvents(res.Attributes, contractAddress)
	ctx.EventManager().EmitEvents(events)

	// delete old secondary index entry
	k.deleteContractSecondIndex(ctx, contractAddress, contractInfo)
	// persist migration updates
	historyEntry := contractInfo.AddMigration(ctx, newCodeID, msg)
	k.appendToContractHistory(ctx, contractAddress, historyEntry)
	k.storeContractInfo(ctx, contractAddress, contractInfo)

	// then dispatch
	if err := k.dispatchMessages(ctx, contractAddress, res.Messages); err != nil {
		return nil, sdkerrors.Wrap(err, "dispatch")
	}

	return &sdk.Result{
		Data: res.Data,
	}, nil
}

func (k Keeper) deleteContractSecondIndex(ctx sdk.Context, contractAddress sdk.AccAddress, contractInfo *types.ContractInfo) {
	ctx.KVStore(k.storeKey).Delete(types.GetContractByCreatedSecondaryIndexKey(contractAddress, contractInfo))
}

// UpdateContractAdmin sets the admin value on the ContractInfo. It must be a valid address (use ClearContractAdmin to remove it)
func (k Keeper) UpdateContractAdmin(ctx sdk.Context, contractAddress sdk.AccAddress, caller sdk.AccAddress, newAdmin sdk.AccAddress) error {
	return k.setContractAdmin(ctx, contractAddress, caller, newAdmin, k.authZPolicy)
}

// ClearContractAdmin sets the admin value on the ContractInfo to nil, to disable further migrations/ updates.
func (k Keeper) ClearContractAdmin(ctx sdk.Context, contractAddress sdk.AccAddress, caller sdk.AccAddress) error {
	return k.setContractAdmin(ctx, contractAddress, caller, nil, k.authZPolicy)
}

func (k Keeper) setContractAdmin(ctx sdk.Context, contractAddress, caller, newAdmin sdk.AccAddress, authZ AuthorizationPolicy) error {
	contractInfo := k.GetContractInfo(ctx, contractAddress)
	if contractInfo == nil {
		return sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "unknown contract")
	}
	if !authZ.CanModifyContract(contractInfo.AdminAddr(), caller) {
		return sdkerrors.Wrap(sdkerrors.ErrUnauthorized, "can not modify contract")
	}
	contractInfo.Admin = newAdmin.String()
	k.storeContractInfo(ctx, contractAddress, contractInfo)
	return nil
}

func (k Keeper) appendToContractHistory(ctx sdk.Context, contractAddr sdk.AccAddress, newEntries ...types.ContractCodeHistoryEntry) {
	store := ctx.KVStore(k.storeKey)
	// find last element position
	var pos uint64
	prefixStore := prefix.NewStore(store, types.GetContractCodeHistoryElementPrefix(contractAddr))
	if iter := prefixStore.ReverseIterator(nil, nil); iter.Valid() {
		pos = sdk.BigEndianToUint64(iter.Value())
	}
	// then store with incrementing position
	for _, e := range newEntries {
		pos++
		key := types.GetContractCodeHistoryElementKey(contractAddr, pos)
		store.Set(key, k.cdc.MustMarshalBinaryBare(&e))
	}
}

func (k Keeper) GetContractHistory(ctx sdk.Context, contractAddr sdk.AccAddress) []types.ContractCodeHistoryEntry {
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), types.GetContractCodeHistoryElementPrefix(contractAddr))
	r := make([]types.ContractCodeHistoryEntry, 0)
	iter := prefixStore.Iterator(nil, nil)
	for ; iter.Valid(); iter.Next() {
		var e types.ContractCodeHistoryEntry
		k.cdc.MustUnmarshalBinaryBare(iter.Value(), &e)
		r = append(r, e)
	}
	return r
}

// QuerySmart queries the smart contract itself.
func (k Keeper) QuerySmart(ctx sdk.Context, contractAddr sdk.AccAddress, req []byte) ([]byte, error) {
	ctx.GasMeter().ConsumeGas(InstanceCost, "Loading CosmWasm module: query")

	codeInfo, prefixStore, err := k.contractInstance(ctx, contractAddr)
	if err != nil {
		return nil, err
	}
	// prepare querier
	querier := QueryHandler{
		Ctx:     ctx,
		Plugins: k.queryPlugins,
	}

	env := types.NewEnv(ctx, contractAddr)
	queryResult, gasUsed, qErr := k.wasmer.Query(codeInfo.CodeHash, env, req, prefixStore, cosmwasmAPI, querier, gasMeter(ctx), gasForContract(ctx))
	consumeGas(ctx, gasUsed)
	if qErr != nil {
		return nil, sdkerrors.Wrap(types.ErrQueryFailed, qErr.Error())
	}
	return queryResult, nil
}

// QueryRaw returns the contract's state for give key. Returns `nil` when key is `nil`.
func (k Keeper) QueryRaw(ctx sdk.Context, contractAddress sdk.AccAddress, key []byte) []byte {
	if key == nil {
		return nil
	}
	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
	return prefixStore.Get(key)
}

func (k Keeper) contractInstance(ctx sdk.Context, contractAddress sdk.AccAddress) (types.CodeInfo, prefix.Store, error) {
	store := ctx.KVStore(k.storeKey)

	contractBz := store.Get(types.GetContractAddressKey(contractAddress))
	if contractBz == nil {
		return types.CodeInfo{}, prefix.Store{}, sdkerrors.Wrap(types.ErrNotFound, "contract")
	}
	var contract types.ContractInfo
	k.cdc.MustUnmarshalBinaryBare(contractBz, &contract)

	contractInfoBz := store.Get(types.GetCodeKey(contract.CodeID))
	if contractInfoBz == nil {
		return types.CodeInfo{}, prefix.Store{}, sdkerrors.Wrap(types.ErrNotFound, "contract info")
	}
	var codeInfo types.CodeInfo
	k.cdc.MustUnmarshalBinaryBare(contractInfoBz, &codeInfo)
	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
	return codeInfo, prefixStore, nil
}

func (k Keeper) GetContractInfo(ctx sdk.Context, contractAddress sdk.AccAddress) *types.ContractInfo {
	store := ctx.KVStore(k.storeKey)
	var contract types.ContractInfo
	contractBz := store.Get(types.GetContractAddressKey(contractAddress))
	if contractBz == nil {
		return nil
	}
	k.cdc.MustUnmarshalBinaryBare(contractBz, &contract)
	return &contract
}

func (k Keeper) containsContractInfo(ctx sdk.Context, contractAddress sdk.AccAddress) bool {
	store := ctx.KVStore(k.storeKey)
	return store.Has(types.GetContractAddressKey(contractAddress))
}

func (k Keeper) storeContractInfo(ctx sdk.Context, contractAddress sdk.AccAddress, contract *types.ContractInfo) {
	store := ctx.KVStore(k.storeKey)
	store.Set(types.GetContractAddressKey(contractAddress), k.cdc.MustMarshalBinaryBare(contract))
	store.Set(types.GetContractByCreatedSecondaryIndexKey(contractAddress, contract), []byte{})
}

func (k Keeper) IterateContractInfo(ctx sdk.Context, cb func(sdk.AccAddress, types.ContractInfo) bool) {
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), types.ContractKeyPrefix)
	iter := prefixStore.Iterator(nil, nil)
	for ; iter.Valid(); iter.Next() {
		var contract types.ContractInfo
		k.cdc.MustUnmarshalBinaryBare(iter.Value(), &contract)
		// cb returns true to stop early
		if cb(iter.Key(), contract) {
			break
		}
	}
}

func (k Keeper) GetContractState(ctx sdk.Context, contractAddress sdk.AccAddress) sdk.Iterator {
	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
	return prefixStore.Iterator(nil, nil)
}

func (k Keeper) importContractState(ctx sdk.Context, contractAddress sdk.AccAddress, models []types.Model) error {
	prefixStoreKey := types.GetContractStorePrefix(contractAddress)
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), prefixStoreKey)
	for _, model := range models {
		if model.Value == nil {
			model.Value = []byte{}
		}
		if prefixStore.Has(model.Key) {
			return sdkerrors.Wrapf(types.ErrDuplicate, "duplicate key: %x", model.Key)
		}
		prefixStore.Set(model.Key, model.Value)
	}
	return nil
}

func (k Keeper) GetCodeInfo(ctx sdk.Context, codeID uint64) *types.CodeInfo {
	store := ctx.KVStore(k.storeKey)
	var codeInfo types.CodeInfo
	codeInfoBz := store.Get(types.GetCodeKey(codeID))
	if codeInfoBz == nil {
		return nil
	}
	k.cdc.MustUnmarshalBinaryBare(codeInfoBz, &codeInfo)
	return &codeInfo
}

func (k Keeper) containsCodeInfo(ctx sdk.Context, codeID uint64) bool {
	store := ctx.KVStore(k.storeKey)
	return store.Has(types.GetCodeKey(codeID))
}

func (k Keeper) IterateCodeInfos(ctx sdk.Context, cb func(uint64, types.CodeInfo) bool) {
	prefixStore := prefix.NewStore(ctx.KVStore(k.storeKey), types.CodeKeyPrefix)
	iter := prefixStore.Iterator(nil, nil)
	for ; iter.Valid(); iter.Next() {
		var c types.CodeInfo
		k.cdc.MustUnmarshalBinaryBare(iter.Value(), &c)
		// cb returns true to stop early
		if cb(binary.BigEndian.Uint64(iter.Key()), c) {
			return
		}
	}
}

func (k Keeper) GetByteCode(ctx sdk.Context, codeID uint64) ([]byte, error) {
	store := ctx.KVStore(k.storeKey)
	var codeInfo types.CodeInfo
	codeInfoBz := store.Get(types.GetCodeKey(codeID))
	if codeInfoBz == nil {
		return nil, nil
	}
	k.cdc.MustUnmarshalBinaryBare(codeInfoBz, &codeInfo)
	return k.wasmer.GetCode(codeInfo.CodeHash)
}

func (k Keeper) dispatchMessages(ctx sdk.Context, contractAddr sdk.AccAddress, msgs []wasmvmtypes.CosmosMsg) error {
	for _, msg := range msgs {
		if err := k.messenger.Dispatch(ctx, contractAddr, msg); err != nil {
			return err
		}
	}
	return nil
}

func gasForContract(ctx sdk.Context) uint64 {
	meter := ctx.GasMeter()
	if meter.IsOutOfGas() {
		return 0
	}
	remaining := (meter.Limit() - meter.GasConsumedToLimit()) * GasMultiplier
	if remaining > MaxGas {
		return MaxGas
	}
	return remaining
}

func consumeGas(ctx sdk.Context, gas uint64) {
	consumed := gas / GasMultiplier
	ctx.GasMeter().ConsumeGas(consumed, "wasm contract")
	// throw OutOfGas error if we ran out (got exactly to zero due to better limit enforcing)
	if ctx.GasMeter().IsOutOfGas() {
		panic(sdk.ErrorOutOfGas{"Wasmer function execution"})
	}
}

// generates a contract address from codeID + instanceID
func (k Keeper) generateContractAddress(ctx sdk.Context, codeID uint64) sdk.AccAddress {
	instanceID := k.autoIncrementID(ctx, types.KeyLastInstanceID)
	return contractAddress(codeID, instanceID)
}

// contractAddress builds an sdk account address for a contract.
// Intentionally kept private as this is module internal logic.
func contractAddress(codeID, instanceID uint64) sdk.AccAddress {
	// NOTE: It is possible to get a duplicate address if either codeID or instanceID
	// overflow 32 bits. This is highly improbable, but something that could be refactored.
	contractID := codeID<<32 + instanceID
	return addrFromUint64(contractID)
}

// GetNextCodeID reads the next sequence id used for storing wasm code.
// Read only operation.
func (k Keeper) GetNextCodeID(ctx sdk.Context) uint64 {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(types.KeyLastCodeID)
	id := uint64(1)
	if bz != nil {
		id = binary.BigEndian.Uint64(bz)
	}
	return id
}

func (k Keeper) autoIncrementID(ctx sdk.Context, lastIDKey []byte) uint64 {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(lastIDKey)
	id := uint64(1)
	if bz != nil {
		id = binary.BigEndian.Uint64(bz)
	}
	bz = sdk.Uint64ToBigEndian(id + 1)
	store.Set(lastIDKey, bz)
	return id
}

// peekAutoIncrementID reads the current value without incrementing it.
func (k Keeper) peekAutoIncrementID(ctx sdk.Context, lastIDKey []byte) uint64 {
	store := ctx.KVStore(k.storeKey)
	bz := store.Get(lastIDKey)
	id := uint64(1)
	if bz != nil {
		id = binary.BigEndian.Uint64(bz)
	}
	return id
}

func (k Keeper) importAutoIncrementID(ctx sdk.Context, lastIDKey []byte, val uint64) error {
	store := ctx.KVStore(k.storeKey)
	if store.Has(lastIDKey) {
		return sdkerrors.Wrapf(types.ErrDuplicate, "autoincrement id: %s", string(lastIDKey))
	}
	bz := sdk.Uint64ToBigEndian(val)
	store.Set(lastIDKey, bz)
	return nil
}

func (k Keeper) importContract(ctx sdk.Context, contractAddr sdk.AccAddress, c *types.ContractInfo, state []types.Model) error {
	if !k.containsCodeInfo(ctx, c.CodeID) {
		return sdkerrors.Wrapf(types.ErrNotFound, "code id: %d", c.CodeID)
	}
	if k.containsContractInfo(ctx, contractAddr) {
		return sdkerrors.Wrapf(types.ErrDuplicate, "contract: %s", contractAddr)
	}

	historyEntry := c.ResetFromGenesis(ctx)
	k.appendToContractHistory(ctx, contractAddr, historyEntry)
	k.storeContractInfo(ctx, contractAddr, c)
	return k.importContractState(ctx, contractAddr, state)
}

func addrFromUint64(id uint64) sdk.AccAddress {
	addr := make([]byte, 20)
	addr[0] = 'C'
	binary.PutUvarint(addr[1:], id)
	return sdk.AccAddress(crypto.AddressHash(addr))
}

// MultipliedGasMeter wraps the GasMeter from context and multiplies all reads by out defined multiplier
type MultipiedGasMeter struct {
	originalMeter sdk.GasMeter
}

var _ wasmvm.GasMeter = MultipiedGasMeter{}

func (m MultipiedGasMeter) GasConsumed() sdk.Gas {
	return m.originalMeter.GasConsumed() * GasMultiplier
}

func gasMeter(ctx sdk.Context) MultipiedGasMeter {
	return MultipiedGasMeter{
		originalMeter: ctx.GasMeter(),
	}
}

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