utils.go

// Copyright Tharsis Labs Ltd.(Evmos)
// SPDX-License-Identifier:ENCL-1.0(https://github.com/evmos/evmos/blob/main/LICENSE)

package ibc

import (
	"strings"

	errorsmod "cosmossdk.io/errors"
	"cosmossdk.io/math"
	sdk "github.com/cosmos/cosmos-sdk/types"
	errortypes "github.com/cosmos/cosmos-sdk/types/errors"

	transfertypes "github.com/cosmos/ibc-go/v7/modules/apps/transfer/types"
	channeltypes "github.com/cosmos/ibc-go/v7/modules/core/04-channel/types"
	transferkeeper "github.com/evmos/evmos/v16/x/ibc/transfer/keeper"

	"github.com/evmos/evmos/v16/utils"
)

// GetTransferSenderRecipient returns the sender and recipient sdk.AccAddresses
// from an ICS20 FungibleTokenPacketData as well as the original sender bech32
// address from the packet data. This function fails if:
//   - the packet data is not FungibleTokenPacketData
//   - sender address is invalid
//   - recipient address is invalid
func GetTransferSenderRecipient(packet channeltypes.Packet) (
	sender, recipient sdk.AccAddress,
	senderBech32, recipientBech32 string,
	err error,
) {
	// unmarshal packet data to obtain the sender and recipient
	var data transfertypes.FungibleTokenPacketData
	if err := transfertypes.ModuleCdc.UnmarshalJSON(packet.GetData(), &data); err != nil {
		return nil, nil, "", "", errorsmod.Wrapf(errortypes.ErrUnknownRequest, "cannot unmarshal ICS-20 transfer packet data")
	}

	// validate the sender bech32 address from the counterparty chain
	// and change the bech32 human readable prefix (HRP) of the sender to `evmos`
	sender, err = utils.GetEvmosAddressFromBech32(data.Sender)
	if err != nil {
		return nil, nil, "", "", errorsmod.Wrap(err, "invalid sender")
	}

	// validate the recipient bech32 address from the counterparty chain
	// and change the bech32 human readable prefix (HRP) of the recipient to `evmos`
	recipient, err = utils.GetEvmosAddressFromBech32(data.Receiver)
	if err != nil {
		return nil, nil, "", "", errorsmod.Wrap(err, "invalid recipient")
	}

	return sender, recipient, data.Sender, data.Receiver, nil
}

// GetTransferAmount returns the amount from an ICS20 FungibleTokenPacketData as a string.
func GetTransferAmount(packet channeltypes.Packet) (string, error) {
	// unmarshal packet data to obtain the sender and recipient
	var data transfertypes.FungibleTokenPacketData
	if err := transfertypes.ModuleCdc.UnmarshalJSON(packet.GetData(), &data); err != nil {
		return "", errorsmod.Wrapf(errortypes.ErrUnknownRequest, "cannot unmarshal ICS-20 transfer packet data")
	}

	if data.Amount == "" {
		return "", errorsmod.Wrapf(errortypes.ErrInvalidCoins, "empty amount")
	}

	if _, ok := math.NewIntFromString(data.Amount); !ok {
		return "", errorsmod.Wrapf(errortypes.ErrInvalidCoins, "invalid amount")
	}

	return data.Amount, nil
}

// GetReceivedCoin returns the transferred coin from an ICS20 FungibleTokenPacketData
// as seen from the destination chain.
// If the receiving chain is the source chain of the tokens, it removes the prefix
// path added by source (i.e sender) chain to the denom. Otherwise, it adds the
// prefix path from the destination chain to the denom.
func GetReceivedCoin(srcPort, srcChannel, dstPort, dstChannel, rawDenom, rawAmt string) sdk.Coin {
	// NOTE: Denom and amount are already validated
	amount, _ := math.NewIntFromString(rawAmt)

	if transfertypes.ReceiverChainIsSource(srcPort, srcChannel, rawDenom) {
		// remove prefix added by sender chain
		voucherPrefix := transfertypes.GetDenomPrefix(srcPort, srcChannel)
		unprefixedDenom := rawDenom[len(voucherPrefix):]

		// coin denomination used in sending from the escrow address
		denom := unprefixedDenom

		// The denomination used to send the coins is either the native denom or the hash of the path
		// if the denomination is not native.
		denomTrace := transfertypes.ParseDenomTrace(unprefixedDenom)
		if denomTrace.Path != "" {
			denom = denomTrace.IBCDenom()
		}

		return sdk.Coin{
			Denom:  denom,
			Amount: amount,
		}
	}

	// since SendPacket did not prefix the denomination, we must prefix denomination here
	sourcePrefix := transfertypes.GetDenomPrefix(dstPort, dstChannel)
	// NOTE: sourcePrefix contains the trailing "/"
	prefixedDenom := sourcePrefix + rawDenom

	// construct the denomination trace from the full raw denomination
	denomTrace := transfertypes.ParseDenomTrace(prefixedDenom)
	voucherDenom := denomTrace.IBCDenom()

	return sdk.Coin{
		Denom:  voucherDenom,
		Amount: amount,
	}
}

// GetSentCoin returns the sent coin from an ICS20 FungibleTokenPacketData.
func GetSentCoin(rawDenom, rawAmt string) sdk.Coin {
	// NOTE: Denom and amount are already validated
	amount, _ := math.NewIntFromString(rawAmt)
	trace := transfertypes.ParseDenomTrace(rawDenom)

	return sdk.Coin{
		Denom:  trace.IBCDenom(),
		Amount: amount,
	}
}

// GetDenomTrace returns the denomination trace from the corresponding IBC denomination. If the
// denomination is not an IBC voucher or the trace is not found, it returns an error.
func GetDenomTrace(
	transferKeeper transferkeeper.Keeper,
	ctx sdk.Context,
	denom string,
) (transfertypes.DenomTrace, error) {
	if !strings.HasPrefix(denom, "ibc/") {
		return transfertypes.DenomTrace{}, errorsmod.Wrapf(ErrNoIBCVoucherDenom, denom)
	}

	hash, err := transfertypes.ParseHexHash(denom[4:])
	if err != nil {
		return transfertypes.DenomTrace{}, err
	}

	denomTrace, found := transferKeeper.GetDenomTrace(ctx, hash)
	if !found {
		return transfertypes.DenomTrace{}, ErrDenomTraceNotFound
	}

	return denomTrace, nil
}

// DeriveDecimalsFromDenom returns the number of decimals of an IBC coin
// depending on the prefix of the base denomination
func DeriveDecimalsFromDenom(baseDenom string) (uint8, error) {
	var decimals uint8
	if len(baseDenom) == 0 {
		return decimals, errorsmod.Wrapf(ErrInvalidBaseDenom, "Base denom cannot be an empty string")
	}

	switch baseDenom[0] {
	case 'u': // micro (u) -> 6 decimals
		decimals = 6
	case 'a': // atto (a) -> 18 decimals
		decimals = 18
	default:
		return decimals, errorsmod.Wrapf(
			ErrInvalidBaseDenom,
			"Should be either micro ('u[...]') or atto ('a[...]'); got: %q",
			baseDenom,
		)
	}
	return decimals, nil
}