AMMWithdraw.cpp

#include <xrpl/tx/transactors/dex/AMMWithdraw.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/Number.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/core/ServiceRegistry.h>
#include <xrpl/ledger/Sandbox.h>
#include <xrpl/ledger/helpers/AMMHelpers.h>
#include <xrpl/ledger/helpers/MPTokenHelpers.h>
#include <xrpl/ledger/helpers/RippleStateHelpers.h>
#include <xrpl/ledger/helpers/TokenHelpers.h>
#include <xrpl/protocol/AMMCore.h>
#include <xrpl/protocol/AccountID.h>
#include <xrpl/protocol/Asset.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/IOUAmount.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Issue.h>
#include <xrpl/protocol/Keylet.h>
#include <xrpl/protocol/MPTIssue.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STAmount.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/STTx.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/TxFlags.h>
#include <xrpl/protocol/XRPAmount.h>
#include <xrpl/tx/Transactor.h>
 
#include <algorithm>
#include <bit>
#include <cstdint>
#include <exception>
#include <optional>
#include <tuple>
#include <utility>
 
namespace xrpl {
 
bool
AMMWithdraw::checkExtraFeatures(PreflightContext const& ctx)
{
    if (!ammEnabled(ctx.rules))
        return false;
 
    auto const amount = ctx.tx[~sfAmount];
    auto const amount2 = ctx.tx[~sfAmount2];
 
    return ctx.rules.enabled(featureMPTokensV2) ||
        (!ctx.tx[sfAsset].holds<MPTIssue>() && !ctx.tx[sfAsset2].holds<MPTIssue>() &&
         !(amount && amount->holds<MPTIssue>()) && !(amount2 && amount2->holds<MPTIssue>()));
}
 
std::uint32_t
AMMWithdraw::getFlagsMask(PreflightContext const& ctx)
{
    return tfAMMWithdrawMask;
}
 
NotTEC
AMMWithdraw::preflight(PreflightContext const& ctx)
{
    auto const flags = ctx.tx.getFlags();
 
    auto const amount = ctx.tx[~sfAmount];
    auto const amount2 = ctx.tx[~sfAmount2];
    auto const ePrice = ctx.tx[~sfEPrice];
    auto const lpTokens = ctx.tx[~sfLPTokenIn];
    // Valid combinations are:
    //   LPTokens
    //   tfWithdrawAll
    //   Amount
    //   tfOneAssetWithdrawAll & Amount
    //   Amount and Amount2
    //   Amount and LPTokens
    //   Amount and EPrice
    if (std::popcount(flags & tfWithdrawSubTx) != 1)
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid flags.";
        return temMALFORMED;
    }
    if (ctx.tx.isFlag(tfLPToken))
    {
        if (!lpTokens || amount || amount2 || ePrice)
            return temMALFORMED;
    }
    else if (ctx.tx.isFlag(tfWithdrawAll))
    {
        if (lpTokens || amount || amount2 || ePrice)
            return temMALFORMED;
    }
    else if (ctx.tx.isFlag(tfOneAssetWithdrawAll) || ctx.tx.isFlag(tfSingleAsset))
    {
        if (!amount || lpTokens || amount2 || ePrice)
            return temMALFORMED;
    }
    else if (ctx.tx.isFlag(tfTwoAsset))
    {
        if (!amount || !amount2 || lpTokens || ePrice)
            return temMALFORMED;
    }
    else if (ctx.tx.isFlag(tfOneAssetLPToken))
    {
        if (!amount || !lpTokens || amount2 || ePrice)
            return temMALFORMED;
    }
    else if (ctx.tx.isFlag(tfLimitLPToken))
    {
        if (!amount || !ePrice || lpTokens || amount2)
            return temMALFORMED;
    }
 
    auto const asset = ctx.tx[sfAsset];
    auto const asset2 = ctx.tx[sfAsset2];
    if (auto const res = invalidAMMAssetPair(asset, asset2))
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: Invalid asset pair.";
        return res;
    }
 
    if (amount && amount2 && amount->asset() == amount2->asset())
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid tokens, same issue." << amount->asset() << " "
                            << amount2->asset();
        return temBAD_AMM_TOKENS;
    }
 
    if (lpTokens && *lpTokens <= beast::kZero)
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid tokens.";
        return temBAD_AMM_TOKENS;
    }
 
    if (amount)
    {
        if (auto const res = invalidAMMAmount(
                *amount,
                std::make_optional(std::make_pair(asset, asset2)),
                ((flags & (tfOneAssetWithdrawAll | tfOneAssetLPToken)) != 0u) || ePrice))
        {
            JLOG(ctx.j.debug()) << "AMM Withdraw: invalid Asset1Out";
            return res;
        }
    }
 
    if (amount2)
    {
        if (auto const res =
                invalidAMMAmount(*amount2, std::make_optional(std::make_pair(asset, asset2))))
        {
            JLOG(ctx.j.debug()) << "AMM Withdraw: invalid Asset2OutAmount";
            return res;
        }
    }
 
    if (ePrice)
    {
        if (auto const res = invalidAMMAmount(*ePrice))
        {
            JLOG(ctx.j.debug()) << "AMM Withdraw: invalid EPrice";
            return res;
        }
    }
 
    return tesSUCCESS;
}
 
static std::optional<STAmount>
tokensWithdraw(
    STAmount const& lpTokens,
    std::optional<STAmount> const& tokensIn,
    std::uint32_t flags)
{
    if ((flags & (tfWithdrawAll | tfOneAssetWithdrawAll)) != 0u)
        return lpTokens;
    return tokensIn;
}
 
TER
AMMWithdraw::preclaim(PreclaimContext const& ctx)
{
    auto const accountID = ctx.tx[sfAccount];
 
    auto const ammSle = ctx.view.read(keylet::amm(ctx.tx[sfAsset], ctx.tx[sfAsset2]));
    if (!ammSle)
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: Invalid asset pair.";
        return terNO_AMM;
    }
 
    auto const amount = ctx.tx[~sfAmount];
    auto const amount2 = ctx.tx[~sfAmount2];
 
    auto const expected = ammHolds(
        ctx.view,
        *ammSle,
        amount ? amount->asset() : std::optional<Asset>{},
        amount2 ? amount2->asset() : std::optional<Asset>{},
        FreezeHandling::IgnoreFreeze,
        AuthHandling::IgnoreAuth,
        ctx.j);
    if (!expected)
        return expected.error();
    auto const [amountBalance, amount2Balance, lptAMMBalance] = *expected;
    if (lptAMMBalance == beast::kZero)
        return tecAMM_EMPTY;
    if (amountBalance <= beast::kZero || amount2Balance <= beast::kZero ||
        lptAMMBalance < beast::kZero)
    {
        // LCOV_EXCL_START
        JLOG(ctx.j.debug()) << "AMM Withdraw: reserves or tokens balance is zero.";
        return tecINTERNAL;
        // LCOV_EXCL_STOP
    }
 
    auto const ammAccountID = ammSle->getAccountID(sfAccount);
 
    auto checkAmount = [&](std::optional<STAmount> const& amount, auto const& balance) -> TER {
        if (amount)
        {
            if (amount > balance)
            {
                JLOG(ctx.j.debug())
                    << "AMM Withdraw: withdrawing more than the balance, " << *amount;
                return tecAMM_BALANCE;
            }
            // WeakAuth - MPToken is created if it doesn't exist.
            if (auto const ter =
                    requireAuth(ctx.view, amount->asset(), accountID, AuthType::WeakAuth))
            {
                JLOG(ctx.j.debug())
                    << "AMM Withdraw: account is not authorized, " << amount->asset();
                return ter;
            }
            if (ctx.view.rules().enabled(fixCleanup3_3_0))
            {
                if (auto const ret = checkWithdrawFreeze(
                        ctx.view, ammAccountID, accountID, accountID, amount->asset()))
                {
                    JLOG(ctx.j.debug()) << "AMM Withdraw: frozen, " << to_string(accountID) << " "
                                        << to_string(amount->asset());
                    return ret;
                }
            }
            else
            {
                // AMM account or currency frozen
                if (auto const ter = checkFrozen(ctx.view, ammAccountID, amount->asset());
                    !isTesSuccess(ter))
                {
                    JLOG(ctx.j.debug())
                        << "AMM Withdraw: AMM account or currency is frozen or locked, "
                        << to_string(accountID);
                    return ter;
                }
                // Account frozen
                if (auto const ter = checkIndividualFrozen(ctx.view, accountID, amount->asset());
                    !isTesSuccess(ter))
                {
                    JLOG(ctx.j.debug())
                        << "AMM Withdraw: account is frozen or locked, " << to_string(accountID)
                        << " " << to_string(amount->asset());
                    return ter;
                }
            }
        }
        return tesSUCCESS;
    };
 
    if (auto const ter = checkAmount(amount, amountBalance))
        return ter;
 
    if (auto const ter = checkAmount(amount2, amount2Balance))
        return ter;
 
    auto const lpTokens = ammLPHolds(ctx.view, *ammSle, ctx.tx[sfAccount], ctx.j);
    auto const lpTokensWithdraw = tokensWithdraw(lpTokens, ctx.tx[~sfLPTokenIn], ctx.tx.getFlags());
 
    if (lpTokens <= beast::kZero)
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: tokens balance is zero.";
        return tecAMM_BALANCE;
    }
 
    if (lpTokensWithdraw && lpTokensWithdraw->asset() != lpTokens.asset())
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid LPTokens.";
        return temBAD_AMM_TOKENS;
    }
 
    if (lpTokensWithdraw && *lpTokensWithdraw > lpTokens)
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid tokens.";
        return tecAMM_INVALID_TOKENS;
    }
 
    if (auto const ePrice = ctx.tx[~sfEPrice]; ePrice && ePrice->asset() != lpTokens.asset())
    {
        JLOG(ctx.j.debug()) << "AMM Withdraw: invalid EPrice.";
        return temBAD_AMM_TOKENS;
    }
 
    if ((ctx.tx.getFlags() & (tfLPToken | tfWithdrawAll)) != 0u)
    {
        if (auto const ter = checkAmount(amountBalance, amountBalance))
            return ter;
        if (auto const ter = checkAmount(amount2Balance, amount2Balance))
            return ter;
    }
 
    return tesSUCCESS;
}
 
FreezeHandling
AMMWithdraw::issuerFreezeHandling() const
{
    // When the withdrawer is the issuer of a pool asset, the issuer can
    // always receive their own token — even when the pool is frozen.
    // Use IgnoreFreeze so ammHolds returns real balances instead of zero.
    if (!ctx_.view().rules().enabled(fixCleanup3_3_0))
        return FreezeHandling::ZeroIfFrozen;
 
    auto const asset1 = Asset{ctx_.tx[sfAsset]};
    auto const asset2 = Asset{ctx_.tx[sfAsset2]};
    if (!asset1.native() && accountID_ == asset1.getIssuer())
        return FreezeHandling::IgnoreFreeze;
    if (!asset2.native() && accountID_ == asset2.getIssuer())
        return FreezeHandling::IgnoreFreeze;
 
    return FreezeHandling::ZeroIfFrozen;
}
 
std::pair<TER, bool>
AMMWithdraw::applyGuts(Sandbox& sb)
{
    auto const amount = ctx_.tx[~sfAmount];
    auto const amount2 = ctx_.tx[~sfAmount2];
    auto const ePrice = ctx_.tx[~sfEPrice];
    auto ammSle = sb.peek(keylet::amm(ctx_.tx[sfAsset], ctx_.tx[sfAsset2]));
    if (!ammSle)
        return {tecINTERNAL, false};  // LCOV_EXCL_LINE
    auto const ammAccountID = (*ammSle)[sfAccount];
    auto const accountSle = sb.read(keylet::account(ammAccountID));
    if (!accountSle)
        return {tecINTERNAL, false};  // LCOV_EXCL_LINE
    auto const lpTokens = ammLPHolds(ctx_.view(), *ammSle, ctx_.tx[sfAccount], ctx_.journal);
    auto const lpTokensWithdraw =
        tokensWithdraw(lpTokens, ctx_.tx[~sfLPTokenIn], ctx_.tx.getFlags());
 
    // Due to rounding, the LPTokenBalance of the last LP
    // might not match the LP's trustline balance
    if (sb.rules().enabled(fixAMMv1_1))
    {
        if (auto const res = verifyAndAdjustLPTokenBalance(sb, lpTokens, ammSle, accountID_); !res)
            return {res.error(), false};
    }
 
    auto const tfee = getTradingFee(ctx_.view(), *ammSle, accountID_);
 
    auto const freezeHandling = issuerFreezeHandling();
 
    auto const expected = ammHolds(
        sb,
        *ammSle,
        amount ? amount->asset() : std::optional<Asset>{},
        amount2 ? amount2->asset() : std::optional<Asset>{},
        freezeHandling,
        AuthHandling::ZeroIfUnauthorized,
        ctx_.journal);
    if (!expected)
        return {expected.error(), false};
    auto const [amountBalance, amount2Balance, lptAMMBalance] = *expected;
    auto const subTxType = ctx_.tx.getFlags() & tfWithdrawSubTx;
 
    auto const [result, newLPTokenBalance] = [&,
                                              &amountBalance = amountBalance,
                                              &amount2Balance = amount2Balance,
                                              &lptAMMBalance =
                                                  lptAMMBalance]() -> std::pair<TER, STAmount> {
        if (subTxType & tfTwoAsset)
        {
            return equalWithdrawLimit(
                sb,
                *ammSle,
                ammAccountID,
                amountBalance,
                amount2Balance,
                lptAMMBalance,
                *amount,
                *amount2,
                tfee);
        }
        if (subTxType & tfOneAssetLPToken || subTxType & tfOneAssetWithdrawAll)
        {
            return singleWithdrawTokens(
                sb,
                *ammSle,
                ammAccountID,
                amountBalance,
                lptAMMBalance,
                *amount,
                *lpTokensWithdraw,
                tfee);
        }
        if (subTxType & tfLimitLPToken)
        {
            return singleWithdrawEPrice(
                sb, *ammSle, ammAccountID, amountBalance, lptAMMBalance, *amount, *ePrice, tfee);
        }
        if (subTxType & tfSingleAsset)
        {
            return singleWithdraw(
                sb, *ammSle, ammAccountID, amountBalance, lptAMMBalance, *amount, tfee);
        }
        if (subTxType & tfLPToken || subTxType & tfWithdrawAll)
        {
            return equalWithdrawTokens(
                sb,
                *ammSle,
                ammAccountID,
                amountBalance,
                amount2Balance,
                lptAMMBalance,
                lpTokens,
                *lpTokensWithdraw,
                tfee);
        }
        // should not happen.
        // LCOV_EXCL_START
        JLOG(j_.error()) << "AMM Withdraw: invalid options.";
        return std::make_pair(tecINTERNAL, STAmount{});
        // LCOV_EXCL_STOP
    }();
 
    if (!isTesSuccess(result))
        return {result, false};
 
    if (sb.rules().enabled(fixCleanup3_3_0) && sb.rules().enabled(fixAMMv1_3))
    {
        if (auto const ter = checkAMMPrecisionLoss(
                sb, ammAccountID, ctx_.tx[sfAsset], ctx_.tx[sfAsset2], newLPTokenBalance, j_);
            !isTesSuccess(ter))
        {
            return {ter, false};
        }
    }
 
    auto const res = deleteAMMAccountIfEmpty(
        sb, ammSle, newLPTokenBalance, ctx_.tx[sfAsset], ctx_.tx[sfAsset2], j_);
    // LCOV_EXCL_START
    if (!res.second)
        return {res.first, false};
    // LCOV_EXCL_STOP
 
    JLOG(ctx_.journal.trace()) << "AMM Withdraw: tokens " << to_string(newLPTokenBalance.iou())
                               << " " << to_string(lpTokens.iou()) << " "
                               << to_string(lptAMMBalance.iou());
 
    return {tesSUCCESS, true};
}
 
TER
AMMWithdraw::doApply()
{
    // This is the ledger view that we work against. Transactions are applied
    // as we go on processing transactions.
    Sandbox sb(&ctx_.view());
 
    auto const result = applyGuts(sb);
    if (result.second)
        sb.apply(ctx_.rawView());
 
    return result.first;
}
 
std::pair<TER, STAmount>
AMMWithdraw::withdraw(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& amountWithdraw,
    std::optional<STAmount> const& amount2Withdraw,
    STAmount const& lpTokensAMMBalance,
    STAmount const& lpTokensWithdraw,
    std::uint16_t tfee)
{
    TER ter;
    STAmount newLPTokenBalance;
    std::tie(ter, newLPTokenBalance, std::ignore, std::ignore) = withdraw(
        view,
        ammSle,
        ammAccount,
        accountID_,
        amountBalance,
        amountWithdraw,
        amount2Withdraw,
        lpTokensAMMBalance,
        lpTokensWithdraw,
        tfee,
        issuerFreezeHandling(),
        AuthHandling::ZeroIfUnauthorized,
        isWithdrawAll(ctx_.tx),
        preFeeBalance_,
        j_);
    return {ter, newLPTokenBalance};
}
 
std::tuple<TER, STAmount, STAmount, std::optional<STAmount>>
AMMWithdraw::withdraw(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    AccountID const& account,
    STAmount const& amountBalance,
    STAmount const& amountWithdraw,
    std::optional<STAmount> const& amount2Withdraw,
    STAmount const& lpTokensAMMBalance,
    STAmount const& lpTokensWithdraw,
    std::uint16_t tfee,
    FreezeHandling freezeHandling,
    AuthHandling authHandling,
    WithdrawAll withdrawAll,
    XRPAmount const& priorBalance,
    beast::Journal const& journal)
{
    auto const lpTokens = ammLPHolds(view, ammSle, account, journal);
    auto const expected = ammHolds(
        view, ammSle, amountWithdraw.asset(), std::nullopt, freezeHandling, authHandling, journal);
    // LCOV_EXCL_START
    if (!expected)
        return {expected.error(), STAmount{}, STAmount{}, STAmount{}};
    // LCOV_EXCL_STOP
    auto const [curBalance, curBalance2, _] = *expected;
    (void)_;
 
    auto const [amountWithdrawActual, amount2WithdrawActual, lpTokensWithdrawActual] =
        [&]() -> std::tuple<STAmount, std::optional<STAmount>, STAmount> {
        if (withdrawAll == WithdrawAll::No)
        {
            return adjustAmountsByLPTokens(
                amountBalance,
                amountWithdraw,
                amount2Withdraw,
                lpTokensAMMBalance,
                lpTokensWithdraw,
                tfee,
                IsDeposit::No);
        }
        return std::make_tuple(amountWithdraw, amount2Withdraw, lpTokensWithdraw);
    }();
 
    if (lpTokensWithdrawActual <= beast::kZero || lpTokensWithdrawActual > lpTokens)
    {
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw, invalid LP tokens: "
                              << lpTokensWithdrawActual << " " << lpTokens << " "
                              << lpTokensAMMBalance;
        return {tecAMM_INVALID_TOKENS, STAmount{}, STAmount{}, STAmount{}};
    }
 
    // Should not happen since the only LP on last withdraw
    // has the balance set to the lp token trustline balance.
    if (view.rules().enabled(fixAMMv1_1) && lpTokensWithdrawActual > lpTokensAMMBalance)
    {
        // LCOV_EXCL_START
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw, unexpected LP tokens: "
                              << lpTokensWithdrawActual << " " << lpTokens << " "
                              << lpTokensAMMBalance;
        return {tecINTERNAL, STAmount{}, STAmount{}, STAmount{}};
        // LCOV_EXCL_STOP
    }
 
    // Withdrawing one side of the pool
    if ((amountWithdrawActual == curBalance && amount2WithdrawActual != curBalance2) ||
        (amount2WithdrawActual == curBalance2 && amountWithdrawActual != curBalance))
    {
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw one side of the pool "
                              << " curBalance: " << curBalance << " " << amountWithdrawActual
                              << " lpTokensBalance: " << lpTokensWithdraw << " lptBalance "
                              << lpTokensAMMBalance;
        return {tecAMM_BALANCE, STAmount{}, STAmount{}, STAmount{}};
    }
 
    // May happen if withdrawing an amount close to one side of the pool
    if (lpTokensWithdrawActual == lpTokensAMMBalance &&
        (amountWithdrawActual != curBalance || amount2WithdrawActual != curBalance2))
    {
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw all tokens "
                              << " curBalance: " << curBalance << " " << amountWithdrawActual
                              << " curBalance2: " << amount2WithdrawActual.value_or(STAmount{0})
                              << " lpTokensBalance: " << lpTokensWithdraw << " lptBalance "
                              << lpTokensAMMBalance;
        return {tecAMM_BALANCE, STAmount{}, STAmount{}, STAmount{}};
    }
 
    // Withdrawing more than the pool's balance
    if (amountWithdrawActual > curBalance || amount2WithdrawActual > curBalance2)
    {
        JLOG(journal.debug()) << "AMM Withdraw: withdrawing more than the pool's balance "
                              << " curBalance: " << curBalance << " " << amountWithdrawActual
                              << " curBalance2: " << curBalance2 << " "
                              << (amount2WithdrawActual ? *amount2WithdrawActual : STAmount{})
                              << " lpTokensBalance: " << lpTokensWithdraw << " lptBalance "
                              << lpTokensAMMBalance;
        return {tecAMM_BALANCE, STAmount{}, STAmount{}, STAmount{}};
    }
 
    // Updated pool state must be valid - either all balances are zero
    // or all balances are non-zero.
    if (view.rules().enabled(featureMPTokensV2))
    {
        bool const newBalanceZero = (curBalance - amountWithdrawActual) == beast::kZero;
        bool const newBalance2Zero =
            (curBalance2 - amount2WithdrawActual.value_or(curBalance2.asset())) == beast::kZero;
        bool const newLPTokensZero = (lpTokensAMMBalance - lpTokensWithdrawActual) == beast::kZero;
        // newBalance2Zero can be zero if that side of the pool is frozen.
        // ignore newBalance2Zero if one-sided withdrawal.
        bool const valid = [&]() {
            if (!amount2WithdrawActual)
                return newBalanceZero == newLPTokensZero;
            return newBalanceZero == newBalance2Zero && newBalance2Zero == newLPTokensZero;
        }();
        if (!valid)
        {
            JLOG(journal.debug()) << "AMM Withdraw: some balances are zero"
                                  << " curBalance: " << curBalance << " " << amountWithdrawActual
                                  << " curBalance2: " << curBalance2 << " "
                                  << (amount2WithdrawActual ? *amount2WithdrawActual : STAmount{})
                                  << " lpTokensBalance: " << lpTokensWithdraw << " lptBalance "
                                  << lpTokensAMMBalance;
            return {tecAMM_BALANCE, STAmount{}, STAmount{}, STAmount{}};
        }
    }
 
    // Check the reserve in case a trustline or MPT has to be created
    bool const enabledFixAmMv12 = view.rules().enabled(fixAMMv1_2);
    // If seated after a call to sufficientReserve() then MPToken must be
    // authorized
    std::optional<Keylet> mptokenKey;
    auto sufficientReserve = [&](Asset const& asset) -> TER {
        mptokenKey = std::nullopt;
        if (!enabledFixAmMv12 || isXRP(asset))
            return tesSUCCESS;
        bool const isIssue = asset.holds<Issue>();
        bool const assetNotExists = [&] {
            if (isIssue)
                return !view.exists(keylet::trustLine(account, asset.get<Issue>()));
            auto const issuanceKey = keylet::mptokenIssuance(asset.get<MPTIssue>());
            mptokenKey = keylet::mptoken(issuanceKey.key, account);
            if (!view.exists(*mptokenKey))
                return true;
            mptokenKey = std::nullopt;
            return false;
        }();
        if (assetNotExists)
        {
            auto sleAccount = view.peek(keylet::account(account));
            if (!sleAccount)
                return tecINTERNAL;  // LCOV_EXCL_LINE
            STAmount const balance = (*sleAccount)[sfBalance];
            std::uint32_t const ownerCount = sleAccount->at(sfOwnerCount);
 
            // See also TrustSet::doApply() and MPTokenAuthorize::authorize()
            XRPAmount const reserve(
                (ownerCount < 2) ? XRPAmount(beast::kZero)
                                 : view.fees().accountReserve(ownerCount + 1));
 
            auto const balanceAdj = isIssue ? std::max(priorBalance, balance.xrp()) : priorBalance;
            if (balanceAdj < reserve)
                return tecINSUFFICIENT_RESERVE;
        }
        return tesSUCCESS;
    };
 
    // Create MPToken if it doesn't exist
    auto createMPToken = [&](Asset const& asset) -> TER {
        // If mptoken is seated then must authorize
        if (mptokenKey && account != asset.getIssuer())
        {
            auto const& mptIssue = asset.get<MPTIssue>();
            if (auto const err = requireAuth(view, mptIssue, account, AuthType::WeakAuth);
                !isTesSuccess(err))
                return err;
 
            if (auto const err = checkCreateMPT(view, mptIssue, account, journal);
                !isTesSuccess(err))
            {
                return err;
            }
        }
        return tesSUCCESS;
    };
 
    if (auto const err = sufficientReserve(amountWithdrawActual.asset()))
        return {err, STAmount{}, STAmount{}, STAmount{}};
 
    if (auto const res = createMPToken(amountWithdrawActual.asset()); !isTesSuccess(res))
        return {res, STAmount{}, STAmount{}, STAmount{}};
 
    // Withdraw amountWithdraw
    auto res = accountSend(
        view, ammAccount, account, amountWithdrawActual, journal, WaiveTransferFee::Yes);
    if (!isTesSuccess(res))
    {
        // LCOV_EXCL_START
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw " << amountWithdrawActual;
        return {res, STAmount{}, STAmount{}, STAmount{}};
        // LCOV_EXCL_STOP
    }
 
    // Withdraw amount2Withdraw
    if (amount2WithdrawActual)
    {
        if (auto const err = sufficientReserve(amount2WithdrawActual->asset()); !isTesSuccess(err))
            return {err, STAmount{}, STAmount{}, STAmount{}};
 
        if (auto const res = createMPToken(amount2WithdrawActual->asset()); !isTesSuccess(res))
            return {res, STAmount{}, STAmount{}, STAmount{}};
 
        res = accountSend(
            view, ammAccount, account, *amount2WithdrawActual, journal, WaiveTransferFee::Yes);
        if (!isTesSuccess(res))
        {
            // LCOV_EXCL_START
            JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw " << *amount2WithdrawActual;
            return {res, STAmount{}, STAmount{}, STAmount{}};
            // LCOV_EXCL_STOP
        }
    }
 
    // Withdraw LP tokens
    res = redeemIOU(
        view, account, lpTokensWithdrawActual, lpTokensWithdrawActual.get<Issue>(), journal);
    if (!isTesSuccess(res))
    {
        // LCOV_EXCL_START
        JLOG(journal.debug()) << "AMM Withdraw: failed to withdraw LPTokens";
        return {res, STAmount{}, STAmount{}, STAmount{}};
        // LCOV_EXCL_STOP
    }
 
    return std::make_tuple(
        tesSUCCESS,
        lpTokensAMMBalance - lpTokensWithdrawActual,
        amountWithdrawActual,
        amount2WithdrawActual);
}
 
static STAmount
adjustLPTokensIn(
    Rules const& rules,
    STAmount const& lptAMMBalance,
    STAmount const& lpTokensWithdraw,
    WithdrawAll withdrawAll)
{
    if (!rules.enabled(fixAMMv1_3) || withdrawAll == WithdrawAll::Yes)
        return lpTokensWithdraw;
    return adjustLPTokens(lptAMMBalance, lpTokensWithdraw, IsDeposit::No);
}

std::pair<TER, STAmount>
AMMWithdraw::equalWithdrawTokens(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& amount2Balance,
    STAmount const& lptAMMBalance,
    STAmount const& lpTokens,
    STAmount const& lpTokensWithdraw,
    std::uint16_t tfee)
{
    TER ter;
    STAmount newLPTokenBalance;
    std::tie(ter, newLPTokenBalance, std::ignore, std::ignore) = equalWithdrawTokens(
        view,
        ammSle,
        accountID_,
        ammAccount,
        amountBalance,
        amount2Balance,
        lptAMMBalance,
        lpTokens,
        lpTokensWithdraw,
        tfee,
        issuerFreezeHandling(),
        AuthHandling::ZeroIfUnauthorized,
        isWithdrawAll(ctx_.tx),
        preFeeBalance_,
        ctx_.journal);
    return {ter, newLPTokenBalance};
}
 
std::pair<TER, bool>
AMMWithdraw::deleteAMMAccountIfEmpty(
    Sandbox& sb,
    SLE::pointer const ammSle,
    STAmount const& lpTokenBalance,
    Asset const& asset1,
    Asset const& asset2,
    beast::Journal const& journal)
{
    TER ter;
    bool updateBalance = true;
    if (lpTokenBalance == beast::kZero)
    {
        ter = deleteAMMAccount(sb, asset1, asset2, journal);
        if (!isTesSuccess(ter) && ter != tecINCOMPLETE)
            return {ter, false};  // LCOV_EXCL_LINE
 
        updateBalance = (ter == tecINCOMPLETE);
    }
 
    if (updateBalance)
    {
        ammSle->setFieldAmount(sfLPTokenBalance, lpTokenBalance);
        sb.update(ammSle);
    }
 
    return {ter, true};
}

std::tuple<TER, STAmount, STAmount, std::optional<STAmount>>
AMMWithdraw::equalWithdrawTokens(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const account,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& amount2Balance,
    STAmount const& lptAMMBalance,
    STAmount const& lpTokens,
    STAmount const& lpTokensWithdraw,
    std::uint16_t tfee,
    FreezeHandling freezeHandling,
    AuthHandling authHandling,
    WithdrawAll withdrawAll,
    XRPAmount const& priorBalance,
    beast::Journal const& journal)
{
    try
    {
        // Withdrawing all tokens in the pool
        if (lpTokensWithdraw == lptAMMBalance)
        {
            return withdraw(
                view,
                ammSle,
                ammAccount,
                account,
                amountBalance,
                amountBalance,
                amount2Balance,
                lptAMMBalance,
                lpTokensWithdraw,
                tfee,
                freezeHandling,
                authHandling,
                WithdrawAll::Yes,
                priorBalance,
                journal);
        }
 
        auto const tokensAdj =
            adjustLPTokensIn(view.rules(), lptAMMBalance, lpTokensWithdraw, withdrawAll);
        if (view.rules().enabled(fixAMMv1_3) && tokensAdj == beast::kZero)
            return {tecAMM_INVALID_TOKENS, STAmount{}, STAmount{}, std::nullopt};
        // the adjusted tokens are factored in
        auto const frac = divide(tokensAdj, lptAMMBalance, noIssue());
        auto const amountWithdraw =
            getRoundedAsset(view.rules(), amountBalance, frac, IsDeposit::No);
        auto const amount2Withdraw =
            getRoundedAsset(view.rules(), amount2Balance, frac, IsDeposit::No);
        // LP is making equal withdrawal by tokens but the requested amount
        // of LP tokens is likely too small and results in one-sided pool
        // withdrawal due to round off. Fail so the user withdraws
        // more tokens.
        if (amountWithdraw == beast::kZero || amount2Withdraw == beast::kZero)
            return {tecAMM_FAILED, STAmount{}, STAmount{}, STAmount{}};
 
        return withdraw(
            view,
            ammSle,
            ammAccount,
            account,
            amountBalance,
            amountWithdraw,
            amount2Withdraw,
            lptAMMBalance,
            tokensAdj,
            tfee,
            freezeHandling,
            authHandling,
            withdrawAll,
            priorBalance,
            journal);
    }
    // LCOV_EXCL_START
    catch (std::exception const& e)
    {
        JLOG(journal.error()) << "AMMWithdraw::equalWithdrawTokens exception " << e.what();
    }
    return {tecINTERNAL, STAmount{}, STAmount{}, STAmount{}};
    // LCOV_EXCL_STOP
}

std::pair<TER, STAmount>
AMMWithdraw::equalWithdrawLimit(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& amount2Balance,
    STAmount const& lptAMMBalance,
    STAmount const& amount,
    STAmount const& amount2,
    std::uint16_t tfee)
{
    auto frac = Number{amount} / amountBalance;
    auto tokensAdj = getRoundedLPTokens(view.rules(), lptAMMBalance, frac, IsDeposit::No);
    if (view.rules().enabled(fixAMMv1_3) && tokensAdj == beast::kZero)
        return {tecAMM_INVALID_TOKENS, STAmount{}};
    // factor in the adjusted tokens
    frac = adjustFracByTokens(view.rules(), lptAMMBalance, tokensAdj, frac);
    auto const amount2Withdraw = getRoundedAsset(view.rules(), amount2Balance, frac, IsDeposit::No);
    if (amount2Withdraw <= amount2)
    {
        return withdraw(
            view,
            ammSle,
            ammAccount,
            amountBalance,
            amount,
            amount2Withdraw,
            lptAMMBalance,
            tokensAdj,
            tfee);
    }
 
    frac = Number{amount2} / amount2Balance;
    auto amountWithdraw = getRoundedAsset(view.rules(), amountBalance, frac, IsDeposit::No);
    tokensAdj = getRoundedLPTokens(view.rules(), lptAMMBalance, frac, IsDeposit::No);
    if (view.rules().enabled(fixAMMv1_3) && tokensAdj == beast::kZero)
        return {tecAMM_INVALID_TOKENS, STAmount{}};  // LCOV_EXCL_LINE
    // factor in the adjusted tokens
    frac = adjustFracByTokens(view.rules(), lptAMMBalance, tokensAdj, frac);
    amountWithdraw = getRoundedAsset(view.rules(), amountBalance, frac, IsDeposit::No);
    if (!view.rules().enabled(fixAMMv1_3))
    {
        // LCOV_EXCL_START
        XRPL_ASSERT(
            amountWithdraw <= amount,
            "xrpl::AMMWithdraw::equalWithdrawLimit : maximum amountWithdraw");
        // LCOV_EXCL_STOP
    }
    else if (amountWithdraw > amount)
    {
        return {tecAMM_FAILED, STAmount{}};  // LCOV_EXCL_LINE
    }
    return withdraw(
        view,
        ammSle,
        ammAccount,
        amountBalance,
        amountWithdraw,
        amount2,
        lptAMMBalance,
        tokensAdj,
        tfee);
}

std::pair<TER, STAmount>
AMMWithdraw::singleWithdraw(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& lptAMMBalance,
    STAmount const& amount,
    std::uint16_t tfee)
{
    auto const tokens = adjustLPTokensIn(
        view.rules(),
        lptAMMBalance,
        lpTokensIn(amountBalance, amount, lptAMMBalance, tfee),
        isWithdrawAll(ctx_.tx));
    if (tokens == beast::kZero)
    {
        if (!view.rules().enabled(fixAMMv1_3))
        {
            return {tecAMM_FAILED, STAmount{}};  // LCOV_EXCL_LINE
        }
 
        return {tecAMM_INVALID_TOKENS, STAmount{}};
    }
    // factor in the adjusted tokens
    auto const [tokensAdj, amountWithdrawAdj] =
        adjustAssetOutByTokens(view.rules(), amountBalance, amount, lptAMMBalance, tokens, tfee);
    if (view.rules().enabled(fixAMMv1_3) && tokensAdj == beast::kZero)
        return {tecAMM_INVALID_TOKENS, STAmount{}};  // LCOV_EXCL_LINE
    return withdraw(
        view,
        ammSle,
        ammAccount,
        amountBalance,
        amountWithdrawAdj,
        std::nullopt,
        lptAMMBalance,
        tokensAdj,
        tfee);
}

std::pair<TER, STAmount>
AMMWithdraw::singleWithdrawTokens(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& lptAMMBalance,
    STAmount const& amount,
    STAmount const& lpTokensWithdraw,
    std::uint16_t tfee)
{
    auto const tokensAdj =
        adjustLPTokensIn(view.rules(), lptAMMBalance, lpTokensWithdraw, isWithdrawAll(ctx_.tx));
    if (view.rules().enabled(fixAMMv1_3) && tokensAdj == beast::kZero)
        return {tecAMM_INVALID_TOKENS, STAmount{}};
    // the adjusted tokens are factored in
    auto const amountWithdraw = ammAssetOut(amountBalance, lptAMMBalance, tokensAdj, tfee);
    if (amount == beast::kZero || amountWithdraw >= amount)
    {
        return withdraw(
            view,
            ammSle,
            ammAccount,
            amountBalance,
            amountWithdraw,
            std::nullopt,
            lptAMMBalance,
            tokensAdj,
            tfee);
    }
 
    return {tecAMM_FAILED, STAmount{}};
}

std::pair<TER, STAmount>
AMMWithdraw::singleWithdrawEPrice(
    Sandbox& view,
    SLE const& ammSle,
    AccountID const& ammAccount,
    STAmount const& amountBalance,
    STAmount const& lptAMMBalance,
    STAmount const& amount,
    STAmount const& ePrice,
    std::uint16_t tfee)
{
    // LPTokens is asset in => E = t / a and formula (8) is:
    // a = A*(t1**2 + t1*(f - 2))/(t1*f - 1)
    // substitute a as t/E =>
    // t/E = A*(t1**2 + t1*(f - 2))/(t1*f - 1), t1=t/T => t = t1*T
    // t1*T/E = A*((t/T)**2 + t*(f - 2)/T)/(t*f/T - 1) =>
    // T/E = A*(t1 + f-2)/(t1*f - 1) =>
    // T*(t1*f - 1) = A*E*(t1 + f - 2) =>
    // t1*T*f - T = t1*A*E + A*E*(f - 2) =>
    // t1*(T*f - A*E) = T + A*E*(f - 2) =>
    // t = T*(T + A*E*(f - 2))/(T*f - A*E)
    Number const ae = amountBalance * ePrice;
    auto const f = getFee(tfee);
    auto const denom = lptAMMBalance * f - ae;
    // fixCleanup3_3_0: guard against division by zero
    // when ePrice == lptAMMBalance*f/amountBalance
    if (view.rules().enabled(fixCleanup3_3_0) && denom == beast::kZero)
        return {tecAMM_FAILED, STAmount{}};
    auto tokNoRoundCb = [&] { return lptAMMBalance * (lptAMMBalance + ae * (f - 2)) / denom; };
    auto tokProdCb = [&] { return (lptAMMBalance + ae * (f - 2)) / denom; };
    auto const tokensAdj =
        getRoundedLPTokens(view.rules(), tokNoRoundCb, lptAMMBalance, tokProdCb, IsDeposit::No);
    if (tokensAdj <= beast::kZero)
    {
        if (!view.rules().enabled(fixAMMv1_3))
        {
            return {tecAMM_FAILED, STAmount{}};
        }
 
        return {tecAMM_INVALID_TOKENS, STAmount{}};
    }
    auto amtNoRoundCb = [&] { return tokensAdj / ePrice; };
    auto amtProdCb = [&] { return tokensAdj / ePrice; };
    // the adjusted tokens are factored in
    auto const amountWithdraw =
        getRoundedAsset(view.rules(), amtNoRoundCb, amount, amtProdCb, IsDeposit::No);
    if (amount == beast::kZero || amountWithdraw >= amount)
    {
        return withdraw(
            view,
            ammSle,
            ammAccount,
            amountBalance,
            amountWithdraw,
            std::nullopt,
            lptAMMBalance,
            tokensAdj,
            tfee);
    }
 
    return {tecAMM_FAILED, STAmount{}};
}
 
WithdrawAll
AMMWithdraw::isWithdrawAll(STTx const& tx)
{
    if ((tx[sfFlags] & (tfWithdrawAll | tfOneAssetWithdrawAll)) != 0u)
        return WithdrawAll::Yes;
    return WithdrawAll::No;
}
void
AMMWithdraw::visitInvariantEntry(bool, SLE::const_ref, SLE::const_ref)
{
    // No transaction-specific invariants yet (future work).
}
 
bool
AMMWithdraw::finalizeInvariants(STTx const&, TER, XRPAmount, ReadView const&, beast::Journal const&)
{
    // No transaction-specific invariants yet (future work).
    return true;
}
 
}  // namespace xrpl