View.cpp

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.
 
    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#include <xrpld/app/misc/CredentialHelpers.h>
#include <xrpld/ledger/ReadView.h>
#include <xrpld/ledger/View.h>
 
#include <xrpl/basics/Expected.h>
#include <xrpl/basics/Log.h>
#include <xrpl/basics/chrono.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/LedgerFormats.h>
#include <xrpl/protocol/MPTIssue.h>
#include <xrpl/protocol/Protocol.h>
#include <xrpl/protocol/Quality.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/TxFlags.h>
#include <xrpl/protocol/digest.h>
#include <xrpl/protocol/st.h>
 
#include <type_traits>
#include <variant>
 
namespace ripple {
 
namespace detail {
 
template <
    class V,
    class N,
    class = std::enable_if_t<
        std::is_same_v<std::remove_cv_t<N>, SLE> &&
        std::is_base_of_v<ReadView, V>>>
bool
internalDirNext(
    V& view,
    uint256 const& root,
    std::shared_ptr<N>& page,
    unsigned int& index,
    uint256& entry)
{
    auto const& svIndexes = page->getFieldV256(sfIndexes);
    XRPL_ASSERT(
        index <= svIndexes.size(),
        "ripple::detail::internalDirNext : index inside range");
 
    if (index >= svIndexes.size())
    {
        auto const next = page->getFieldU64(sfIndexNext);
 
        if (!next)
        {
            entry.zero();
            return false;
        }
 
        if constexpr (std::is_const_v<N>)
            page = view.read(keylet::page(root, next));
        else
            page = view.peek(keylet::page(root, next));
 
        XRPL_ASSERT(page, "ripple::detail::internalDirNext : non-null root");
 
        if (!page)
            return false;
 
        index = 0;
 
        return internalDirNext(view, root, page, index, entry);
    }
 
    entry = svIndexes[index++];
    return true;
}
 
template <
    class V,
    class N,
    class = std::enable_if_t<
        std::is_same_v<std::remove_cv_t<N>, SLE> &&
        std::is_base_of_v<ReadView, V>>>
bool
internalDirFirst(
    V& view,
    uint256 const& root,
    std::shared_ptr<N>& page,
    unsigned int& index,
    uint256& entry)
{
    if constexpr (std::is_const_v<N>)
        page = view.read(keylet::page(root));
    else
        page = view.peek(keylet::page(root));
 
    if (!page)
        return false;
 
    index = 0;
 
    return internalDirNext(view, root, page, index, entry);
}
 
}  // namespace detail
 
bool
dirFirst(
    ApplyView& view,
    uint256 const& root,
    std::shared_ptr<SLE>& page,
    unsigned int& index,
    uint256& entry)
{
    return detail::internalDirFirst(view, root, page, index, entry);
}
 
bool
dirNext(
    ApplyView& view,
    uint256 const& root,
    std::shared_ptr<SLE>& page,
    unsigned int& index,
    uint256& entry)
{
    return detail::internalDirNext(view, root, page, index, entry);
}
 
bool
cdirFirst(
    ReadView const& view,
    uint256 const& root,
    std::shared_ptr<SLE const>& page,
    unsigned int& index,
    uint256& entry)
{
    return detail::internalDirFirst(view, root, page, index, entry);
}
 
bool
cdirNext(
    ReadView const& view,
    uint256 const& root,
    std::shared_ptr<SLE const>& page,
    unsigned int& index,
    uint256& entry)
{
    return detail::internalDirNext(view, root, page, index, entry);
}
 
//------------------------------------------------------------------------------
//
// Observers
//
//------------------------------------------------------------------------------
 
bool
hasExpired(ReadView const& view, std::optional<std::uint32_t> const& exp)
{
    using d = NetClock::duration;
    using tp = NetClock::time_point;
 
    return exp && (view.parentCloseTime() >= tp{d{*exp}});
}
 
bool
isGlobalFrozen(ReadView const& view, AccountID const& issuer)
{
    if (isXRP(issuer))
        return false;
    if (auto const sle = view.read(keylet::account(issuer)))
        return sle->isFlag(lsfGlobalFreeze);
    return false;
}
 
bool
isGlobalFrozen(ReadView const& view, MPTIssue const& mptIssue)
{
    if (auto const sle = view.read(keylet::mptIssuance(mptIssue.getMptID())))
        return sle->isFlag(lsfMPTLocked);
    return false;
}
 
bool
isGlobalFrozen(ReadView const& view, Asset const& asset)
{
    return std::visit(
        [&]<ValidIssueType TIss>(TIss const& issue) {
            if constexpr (std::is_same_v<TIss, Issue>)
                return isGlobalFrozen(view, issue.getIssuer());
            else
                return isGlobalFrozen(view, issue);
        },
        asset.value());
}
 
bool
isIndividualFrozen(
    ReadView const& view,
    AccountID const& account,
    Currency const& currency,
    AccountID const& issuer)
{
    if (isXRP(currency))
        return false;
    if (issuer != account)
    {
        // Check if the issuer froze the line
        auto const sle = view.read(keylet::line(account, issuer, currency));
        if (sle &&
            sle->isFlag((issuer > account) ? lsfHighFreeze : lsfLowFreeze))
            return true;
    }
    return false;
}
 
bool
isIndividualFrozen(
    ReadView const& view,
    AccountID const& account,
    MPTIssue const& mptIssue)
{
    if (auto const sle =
            view.read(keylet::mptoken(mptIssue.getMptID(), account)))
        return sle->isFlag(lsfMPTLocked);
    return false;
}
 
// Can the specified account spend the specified currency issued by
// the specified issuer or does the freeze flag prohibit it?
bool
isFrozen(
    ReadView const& view,
    AccountID const& account,
    Currency const& currency,
    AccountID const& issuer)
{
    if (isXRP(currency))
        return false;
    auto sle = view.read(keylet::account(issuer));
    if (sle && sle->isFlag(lsfGlobalFreeze))
        return true;
    if (issuer != account)
    {
        // Check if the issuer froze the line
        sle = view.read(keylet::line(account, issuer, currency));
        if (sle &&
            sle->isFlag((issuer > account) ? lsfHighFreeze : lsfLowFreeze))
            return true;
    }
    return false;
}
 
bool
isFrozen(
    ReadView const& view,
    AccountID const& account,
    MPTIssue const& mptIssue,
    int depth)
{
    return isGlobalFrozen(view, mptIssue) ||
        isIndividualFrozen(view, account, mptIssue) ||
        isVaultPseudoAccountFrozen(view, account, mptIssue, depth);
}
 
[[nodiscard]] bool
isAnyFrozen(
    ReadView const& view,
    std::initializer_list<AccountID> const& accounts,
    MPTIssue const& mptIssue,
    int depth)
{
    if (isGlobalFrozen(view, mptIssue))
        return true;
 
    for (auto const& account : accounts)
    {
        if (isIndividualFrozen(view, account, mptIssue))
            return true;
    }
 
    for (auto const& account : accounts)
    {
        if (isVaultPseudoAccountFrozen(view, account, mptIssue, depth))
            return true;
    }
 
    return false;
}
 
bool
isVaultPseudoAccountFrozen(
    ReadView const& view,
    AccountID const& account,
    MPTIssue const& mptShare,
    int depth)
{
    if (!view.rules().enabled(featureSingleAssetVault))
        return false;
 
    if (depth >= maxAssetCheckDepth)
        return true;  // LCOV_EXCL_LINE
 
    auto const mptIssuance =
        view.read(keylet::mptIssuance(mptShare.getMptID()));
    if (mptIssuance == nullptr)
        return false;  // zero MPToken won't block deletion of MPTokenIssuance
 
    auto const issuer = mptIssuance->getAccountID(sfIssuer);
    auto const mptIssuer = view.read(keylet::account(issuer));
    if (mptIssuer == nullptr)
    {  // LCOV_EXCL_START
        UNREACHABLE("ripple::isVaultPseudoAccountFrozen : null MPToken issuer");
        return false;
    }  // LCOV_EXCL_STOP
 
    if (!mptIssuer->isFieldPresent(sfVaultID))
        return false;  // not a Vault pseudo-account, common case
 
    auto const vault =
        view.read(keylet::vault(mptIssuer->getFieldH256(sfVaultID)));
    if (vault == nullptr)
    {  // LCOV_EXCL_START
        UNREACHABLE("ripple::isVaultPseudoAccountFrozen : null vault");
        return false;
    }  // LCOV_EXCL_STOP
 
    return isAnyFrozen(view, {issuer, account}, vault->at(sfAsset), depth + 1);
}
 
bool
isDeepFrozen(
    ReadView const& view,
    AccountID const& account,
    Currency const& currency,
    AccountID const& issuer)
{
    if (isXRP(currency))
    {
        return false;
    }
 
    if (issuer == account)
    {
        return false;
    }
 
    auto const sle = view.read(keylet::line(account, issuer, currency));
    if (!sle)
    {
        return false;
    }
 
    return sle->isFlag(lsfHighDeepFreeze) || sle->isFlag(lsfLowDeepFreeze);
}
 
bool
isLPTokenFrozen(
    ReadView const& view,
    AccountID const& account,
    Issue const& asset,
    Issue const& asset2)
{
    return isFrozen(view, account, asset.currency, asset.account) ||
        isFrozen(view, account, asset2.currency, asset2.account);
}
 
STAmount
accountHolds(
    ReadView const& view,
    AccountID const& account,
    Currency const& currency,
    AccountID const& issuer,
    FreezeHandling zeroIfFrozen,
    beast::Journal j)
{
    STAmount amount;
    if (isXRP(currency))
    {
        return {xrpLiquid(view, account, 0, j)};
    }
 
    // IOU: Return balance on trust line modulo freeze
    auto const sle = view.read(keylet::line(account, issuer, currency));
    auto const allowBalance = [&]() {
        if (!sle)
        {
            return false;
        }
 
        if (zeroIfFrozen == fhZERO_IF_FROZEN)
        {
            if (isFrozen(view, account, currency, issuer) ||
                isDeepFrozen(view, account, currency, issuer))
            {
                return false;
            }
 
            // when fixFrozenLPTokenTransfer is enabled, if currency is lptoken,
            // we need to check if the associated assets have been frozen
            if (view.rules().enabled(fixFrozenLPTokenTransfer))
            {
                auto const sleIssuer = view.read(keylet::account(issuer));
                if (!sleIssuer)
                {
                    return false;  // LCOV_EXCL_LINE
                }
                else if (sleIssuer->isFieldPresent(sfAMMID))
                {
                    auto const sleAmm =
                        view.read(keylet::amm((*sleIssuer)[sfAMMID]));
 
                    if (!sleAmm ||
                        isLPTokenFrozen(
                            view,
                            account,
                            (*sleAmm)[sfAsset].get<Issue>(),
                            (*sleAmm)[sfAsset2].get<Issue>()))
                    {
                        return false;
                    }
                }
            }
        }
 
        return true;
    }();
 
    if (allowBalance)
    {
        amount = sle->getFieldAmount(sfBalance);
        if (account > issuer)
        {
            // Put balance in account terms.
            amount.negate();
        }
        amount.setIssuer(issuer);
    }
    else
    {
        amount.clear(Issue{currency, issuer});
    }
 
    JLOG(j.trace()) << "accountHolds:"
                    << " account=" << to_string(account)
                    << " amount=" << amount.getFullText();
 
    return view.balanceHook(account, issuer, amount);
}
 
STAmount
accountHolds(
    ReadView const& view,
    AccountID const& account,
    Issue const& issue,
    FreezeHandling zeroIfFrozen,
    beast::Journal j)
{
    return accountHolds(
        view, account, issue.currency, issue.account, zeroIfFrozen, j);
}
 
STAmount
accountHolds(
    ReadView const& view,
    AccountID const& account,
    MPTIssue const& mptIssue,
    FreezeHandling zeroIfFrozen,
    AuthHandling zeroIfUnauthorized,
    beast::Journal j)
{
    STAmount amount;
 
    auto const sleMpt =
        view.read(keylet::mptoken(mptIssue.getMptID(), account));
 
    if (!sleMpt)
        amount.clear(mptIssue);
    else if (
        zeroIfFrozen == fhZERO_IF_FROZEN && isFrozen(view, account, mptIssue))
        amount.clear(mptIssue);
    else
    {
        amount = STAmount{mptIssue, sleMpt->getFieldU64(sfMPTAmount)};
 
        // Only if auth check is needed, as it needs to do an additional read
        // operation. Note featureSingleAssetVault will affect error codes.
        if (zeroIfUnauthorized == ahZERO_IF_UNAUTHORIZED &&
            view.rules().enabled(featureSingleAssetVault))
        {
            if (auto const err =
                    requireAuth(view, mptIssue, account, AuthType::StrongAuth);
                !isTesSuccess(err))
                amount.clear(mptIssue);
        }
        else if (zeroIfUnauthorized == ahZERO_IF_UNAUTHORIZED)
        {
            auto const sleIssuance =
                view.read(keylet::mptIssuance(mptIssue.getMptID()));
 
            // if auth is enabled on the issuance and mpt is not authorized,
            // clear amount
            if (sleIssuance && sleIssuance->isFlag(lsfMPTRequireAuth) &&
                !sleMpt->isFlag(lsfMPTAuthorized))
                amount.clear(mptIssue);
        }
    }
 
    return amount;
}
 
[[nodiscard]] STAmount
accountHolds(
    ReadView const& view,
    AccountID const& account,
    Asset const& asset,
    FreezeHandling zeroIfFrozen,
    AuthHandling zeroIfUnauthorized,
    beast::Journal j)
{
    return std::visit(
        [&](auto const& value) {
            if constexpr (std::is_same_v<
                              std::remove_cvref_t<decltype(value)>,
                              Issue>)
            {
                return accountHolds(view, account, value, zeroIfFrozen, j);
            }
            return accountHolds(
                view, account, value, zeroIfFrozen, zeroIfUnauthorized, j);
        },
        asset.value());
}
 
STAmount
accountFunds(
    ReadView const& view,
    AccountID const& id,
    STAmount const& saDefault,
    FreezeHandling freezeHandling,
    beast::Journal j)
{
    if (!saDefault.native() && saDefault.getIssuer() == id)
        return saDefault;
 
    return accountHolds(
        view,
        id,
        saDefault.getCurrency(),
        saDefault.getIssuer(),
        freezeHandling,
        j);
}
 
// Prevent ownerCount from wrapping under error conditions.
//
// adjustment allows the ownerCount to be adjusted up or down in multiple steps.
// If id != std::nullopt, then do error reporting.
//
// Returns adjusted owner count.
static std::uint32_t
confineOwnerCount(
    std::uint32_t current,
    std::int32_t adjustment,
    std::optional<AccountID> const& id = std::nullopt,
    beast::Journal j = beast::Journal{beast::Journal::getNullSink()})
{
    std::uint32_t adjusted{current + adjustment};
    if (adjustment > 0)
    {
        // Overflow is well defined on unsigned
        if (adjusted < current)
        {
            if (id)
            {
                JLOG(j.fatal())
                    << "Account " << *id << " owner count exceeds max!";
            }
            adjusted = std::numeric_limits<std::uint32_t>::max();
        }
    }
    else
    {
        // Underflow is well defined on unsigned
        if (adjusted > current)
        {
            if (id)
            {
                JLOG(j.fatal())
                    << "Account " << *id << " owner count set below 0!";
            }
            adjusted = 0;
            XRPL_ASSERT(!id, "ripple::confineOwnerCount : id is not set");
        }
    }
    return adjusted;
}
 
XRPAmount
xrpLiquid(
    ReadView const& view,
    AccountID const& id,
    std::int32_t ownerCountAdj,
    beast::Journal j)
{
    auto const sle = view.read(keylet::account(id));
    if (sle == nullptr)
        return beast::zero;
 
    // Return balance minus reserve
    std::uint32_t const ownerCount = confineOwnerCount(
        view.ownerCountHook(id, sle->getFieldU32(sfOwnerCount)), ownerCountAdj);
 
    // AMMs have no reserve requirement
    auto const reserve = sle->isFieldPresent(sfAMMID)
        ? XRPAmount{0}
        : view.fees().accountReserve(ownerCount);
 
    auto const fullBalance = sle->getFieldAmount(sfBalance);
 
    auto const balance = view.balanceHook(id, xrpAccount(), fullBalance);
 
    STAmount const amount =
        (balance < reserve) ? STAmount{0} : balance - reserve;
 
    JLOG(j.trace()) << "accountHolds:"
                    << " account=" << to_string(id)
                    << " amount=" << amount.getFullText()
                    << " fullBalance=" << fullBalance.getFullText()
                    << " balance=" << balance.getFullText()
                    << " reserve=" << reserve << " ownerCount=" << ownerCount
                    << " ownerCountAdj=" << ownerCountAdj;
 
    return amount.xrp();
}
 
void
forEachItem(
    ReadView const& view,
    Keylet const& root,
    std::function<void(std::shared_ptr<SLE const> const&)> const& f)
{
    XRPL_ASSERT(
        root.type == ltDIR_NODE, "ripple::forEachItem : valid root type");
 
    if (root.type != ltDIR_NODE)
        return;
 
    auto pos = root;
 
    while (true)
    {
        auto sle = view.read(pos);
        if (!sle)
            return;
        for (auto const& key : sle->getFieldV256(sfIndexes))
            f(view.read(keylet::child(key)));
        auto const next = sle->getFieldU64(sfIndexNext);
        if (!next)
            return;
        pos = keylet::page(root, next);
    }
}
 
bool
forEachItemAfter(
    ReadView const& view,
    Keylet const& root,
    uint256 const& after,
    std::uint64_t const hint,
    unsigned int limit,
    std::function<bool(std::shared_ptr<SLE const> const&)> const& f)
{
    XRPL_ASSERT(
        root.type == ltDIR_NODE, "ripple::forEachItemAfter : valid root type");
 
    if (root.type != ltDIR_NODE)
        return false;
 
    auto currentIndex = root;
 
    // If startAfter is not zero try jumping to that page using the hint
    if (after.isNonZero())
    {
        auto const hintIndex = keylet::page(root, hint);
 
        if (auto hintDir = view.read(hintIndex))
        {
            for (auto const& key : hintDir->getFieldV256(sfIndexes))
            {
                if (key == after)
                {
                    // We found the hint, we can start here
                    currentIndex = hintIndex;
                    break;
                }
            }
        }
 
        bool found = false;
        for (;;)
        {
            auto const ownerDir = view.read(currentIndex);
            if (!ownerDir)
                return found;
            for (auto const& key : ownerDir->getFieldV256(sfIndexes))
            {
                if (!found)
                {
                    if (key == after)
                        found = true;
                }
                else if (f(view.read(keylet::child(key))) && limit-- <= 1)
                {
                    return found;
                }
            }
 
            auto const uNodeNext = ownerDir->getFieldU64(sfIndexNext);
            if (uNodeNext == 0)
                return found;
            currentIndex = keylet::page(root, uNodeNext);
        }
    }
    else
    {
        for (;;)
        {
            auto const ownerDir = view.read(currentIndex);
            if (!ownerDir)
                return true;
            for (auto const& key : ownerDir->getFieldV256(sfIndexes))
                if (f(view.read(keylet::child(key))) && limit-- <= 1)
                    return true;
            auto const uNodeNext = ownerDir->getFieldU64(sfIndexNext);
            if (uNodeNext == 0)
                return true;
            currentIndex = keylet::page(root, uNodeNext);
        }
    }
}
 
Rate
transferRate(ReadView const& view, AccountID const& issuer)
{
    auto const sle = view.read(keylet::account(issuer));
 
    if (sle && sle->isFieldPresent(sfTransferRate))
        return Rate{sle->getFieldU32(sfTransferRate)};
 
    return parityRate;
}
 
Rate
transferRate(ReadView const& view, MPTID const& issuanceID)
{
    // fee is 0-50,000 (0-50%), rate is 1,000,000,000-2,000,000,000
    // For example, if transfer fee is 50% then 10,000 * 50,000 = 500,000
    // which represents 50% of 1,000,000,000
    if (auto const sle = view.read(keylet::mptIssuance(issuanceID));
        sle && sle->isFieldPresent(sfTransferFee))
        return Rate{1'000'000'000u + 10'000 * sle->getFieldU16(sfTransferFee)};
 
    return parityRate;
}
 
Rate
transferRate(ReadView const& view, STAmount const& amount)
{
    return std::visit(
        [&]<ValidIssueType TIss>(TIss const& issue) {
            if constexpr (std::is_same_v<TIss, Issue>)
                return transferRate(view, issue.getIssuer());
            else
                return transferRate(view, issue.getMptID());
        },
        amount.asset().value());
}
 
bool
areCompatible(
    ReadView const& validLedger,
    ReadView const& testLedger,
    beast::Journal::Stream& s,
    char const* reason)
{
    bool ret = true;
 
    if (validLedger.info().seq < testLedger.info().seq)
    {
        // valid -> ... -> test
        auto hash = hashOfSeq(
            testLedger,
            validLedger.info().seq,
            beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != validLedger.info().hash))
        {
            JLOG(s) << reason << " incompatible with valid ledger";
 
            JLOG(s) << "Hash(VSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if (validLedger.info().seq > testLedger.info().seq)
    {
        // test -> ... -> valid
        auto hash = hashOfSeq(
            validLedger,
            testLedger.info().seq,
            beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != testLedger.info().hash))
        {
            JLOG(s) << reason << " incompatible preceding ledger";
 
            JLOG(s) << "Hash(NSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if (
        (validLedger.info().seq == testLedger.info().seq) &&
        (validLedger.info().hash != testLedger.info().hash))
    {
        // Same sequence number, different hash
        JLOG(s) << reason << " incompatible ledger";
 
        ret = false;
    }
 
    if (!ret)
    {
        JLOG(s) << "Val: " << validLedger.info().seq << " "
                << to_string(validLedger.info().hash);
 
        JLOG(s) << "New: " << testLedger.info().seq << " "
                << to_string(testLedger.info().hash);
    }
 
    return ret;
}
 
bool
areCompatible(
    uint256 const& validHash,
    LedgerIndex validIndex,
    ReadView const& testLedger,
    beast::Journal::Stream& s,
    char const* reason)
{
    bool ret = true;
 
    if (testLedger.info().seq > validIndex)
    {
        // Ledger we are testing follows last valid ledger
        auto hash = hashOfSeq(
            testLedger,
            validIndex,
            beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != validHash))
        {
            JLOG(s) << reason << " incompatible following ledger";
            JLOG(s) << "Hash(VSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if (
        (validIndex == testLedger.info().seq) &&
        (testLedger.info().hash != validHash))
    {
        JLOG(s) << reason << " incompatible ledger";
 
        ret = false;
    }
 
    if (!ret)
    {
        JLOG(s) << "Val: " << validIndex << " " << to_string(validHash);
 
        JLOG(s) << "New: " << testLedger.info().seq << " "
                << to_string(testLedger.info().hash);
    }
 
    return ret;
}
 
bool
dirIsEmpty(ReadView const& view, Keylet const& k)
{
    auto const sleNode = view.read(k);
    if (!sleNode)
        return true;
    if (!sleNode->getFieldV256(sfIndexes).empty())
        return false;
    // The first page of a directory may legitimately be empty even if there
    // are other pages (the first page is the anchor page) so check to see if
    // there is another page. If there is, the directory isn't empty.
    return sleNode->getFieldU64(sfIndexNext) == 0;
}
 
std::set<uint256>
getEnabledAmendments(ReadView const& view)
{
    std::set<uint256> amendments;
 
    if (auto const sle = view.read(keylet::amendments()))
    {
        if (sle->isFieldPresent(sfAmendments))
        {
            auto const& v = sle->getFieldV256(sfAmendments);
            amendments.insert(v.begin(), v.end());
        }
    }
 
    return amendments;
}
 
majorityAmendments_t
getMajorityAmendments(ReadView const& view)
{
    majorityAmendments_t ret;
 
    if (auto const sle = view.read(keylet::amendments()))
    {
        if (sle->isFieldPresent(sfMajorities))
        {
            using tp = NetClock::time_point;
            using d = tp::duration;
 
            auto const majorities = sle->getFieldArray(sfMajorities);
 
            for (auto const& m : majorities)
                ret[m.getFieldH256(sfAmendment)] =
                    tp(d(m.getFieldU32(sfCloseTime)));
        }
    }
 
    return ret;
}
 
std::optional<uint256>
hashOfSeq(ReadView const& ledger, LedgerIndex seq, beast::Journal journal)
{
    // Easy cases...
    if (seq > ledger.seq())
    {
        JLOG(journal.warn())
            << "Can't get seq " << seq << " from " << ledger.seq() << " future";
        return std::nullopt;
    }
    if (seq == ledger.seq())
        return ledger.info().hash;
    if (seq == (ledger.seq() - 1))
        return ledger.info().parentHash;
 
    if (int diff = ledger.seq() - seq; diff <= 256)
    {
        // Within 256...
        auto const hashIndex = ledger.read(keylet::skip());
        if (hashIndex)
        {
            XRPL_ASSERT(
                hashIndex->getFieldU32(sfLastLedgerSequence) ==
                    (ledger.seq() - 1),
                "ripple::hashOfSeq : matching ledger sequence");
            STVector256 vec = hashIndex->getFieldV256(sfHashes);
            if (vec.size() >= diff)
                return vec[vec.size() - diff];
            JLOG(journal.warn())
                << "Ledger " << ledger.seq() << " missing hash for " << seq
                << " (" << vec.size() << "," << diff << ")";
        }
        else
        {
            JLOG(journal.warn())
                << "Ledger " << ledger.seq() << ":" << ledger.info().hash
                << " missing normal list";
        }
    }
 
    if ((seq & 0xff) != 0)
    {
        JLOG(journal.debug())
            << "Can't get seq " << seq << " from " << ledger.seq() << " past";
        return std::nullopt;
    }
 
    // in skiplist
    auto const hashIndex = ledger.read(keylet::skip(seq));
    if (hashIndex)
    {
        auto const lastSeq = hashIndex->getFieldU32(sfLastLedgerSequence);
        XRPL_ASSERT(lastSeq >= seq, "ripple::hashOfSeq : minimum last ledger");
        XRPL_ASSERT(
            (lastSeq & 0xff) == 0, "ripple::hashOfSeq : valid last ledger");
        auto const diff = (lastSeq - seq) >> 8;
        STVector256 vec = hashIndex->getFieldV256(sfHashes);
        if (vec.size() > diff)
            return vec[vec.size() - diff - 1];
    }
    JLOG(journal.warn()) << "Can't get seq " << seq << " from " << ledger.seq()
                         << " error";
    return std::nullopt;
}
 
//------------------------------------------------------------------------------
//
// Modifiers
//
//------------------------------------------------------------------------------
 
void
adjustOwnerCount(
    ApplyView& view,
    std::shared_ptr<SLE> const& sle,
    std::int32_t amount,
    beast::Journal j)
{
    if (!sle)
        return;
    XRPL_ASSERT(amount, "ripple::adjustOwnerCount : nonzero amount input");
    std::uint32_t const current{sle->getFieldU32(sfOwnerCount)};
    AccountID const id = (*sle)[sfAccount];
    std::uint32_t const adjusted = confineOwnerCount(current, amount, id, j);
    view.adjustOwnerCountHook(id, current, adjusted);
    sle->setFieldU32(sfOwnerCount, adjusted);
    view.update(sle);
}
 
std::function<void(SLE::ref)>
describeOwnerDir(AccountID const& account)
{
    return [&account](std::shared_ptr<SLE> const& sle) {
        (*sle)[sfOwner] = account;
    };
}
 
TER
dirLink(ApplyView& view, AccountID const& owner, std::shared_ptr<SLE>& object)
{
    auto const page = view.dirInsert(
        keylet::ownerDir(owner), object->key(), describeOwnerDir(owner));
    if (!page)
        return tecDIR_FULL;  // LCOV_EXCL_LINE
    object->setFieldU64(sfOwnerNode, *page);
    return tesSUCCESS;
}
 
AccountID
pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey)
{
    // This number must not be changed without an amendment
    constexpr std::uint16_t maxAccountAttempts = 256;
    for (std::uint16_t i = 0; i < maxAccountAttempts; ++i)
    {
        ripesha_hasher rsh;
        auto const hash = sha512Half(i, view.info().parentHash, pseudoOwnerKey);
        rsh(hash.data(), hash.size());
        AccountID const ret{static_cast<ripesha_hasher::result_type>(rsh)};
        if (!view.read(keylet::account(ret)))
            return ret;
    }
    return beast::zero;
}
 
// Note, the list of the pseudo-account designator fields below MUST be
// maintained but it does NOT need to be amendment-gated, since a
// non-active amendment will not set any field, by definition. Specific
// properties of a pseudo-account are NOT checked here, that's what
// InvariantCheck is for.
static std::array<SField const*, 2> const pseudoAccountOwnerFields = {
    &sfAMMID,    //
    &sfVaultID,  //
};
 
Expected<std::shared_ptr<SLE>, TER>
createPseudoAccount(
    ApplyView& view,
    uint256 const& pseudoOwnerKey,
    SField const& ownerField)
{
    XRPL_ASSERT(
        std::count_if(
            pseudoAccountOwnerFields.begin(),
            pseudoAccountOwnerFields.end(),
            [&ownerField](SField const* sf) -> bool {
                return *sf == ownerField;
            }) == 1,
        "ripple::createPseudoAccount : valid owner field");
 
    auto const accountId = pseudoAccountAddress(view, pseudoOwnerKey);
    if (accountId == beast::zero)
        return Unexpected(tecDUPLICATE);
 
    // Create pseudo-account.
    auto account = std::make_shared<SLE>(keylet::account(accountId));
    account->setAccountID(sfAccount, accountId);
    account->setFieldAmount(sfBalance, STAmount{});
 
    // Pseudo-accounts can't submit transactions, so set the sequence number
    // to 0 to make them easier to spot and verify, and add an extra level
    // of protection.
    std::uint32_t const seqno =                        //
        view.rules().enabled(featureSingleAssetVault)  //
        ? 0                                            //
        : view.seq();
    account->setFieldU32(sfSequence, seqno);
    // Ignore reserves requirement, disable the master key, allow default
    // rippling, and enable deposit authorization to prevent payments into
    // pseudo-account.
    account->setFieldU32(
        sfFlags, lsfDisableMaster | lsfDefaultRipple | lsfDepositAuth);
    // Link the pseudo-account with its owner object.
    account->setFieldH256(ownerField, pseudoOwnerKey);
 
    view.insert(account);
 
    return account;
}
 
[[nodiscard]] bool
isPseudoAccount(std::shared_ptr<SLE const> sleAcct)
{
    // Intentionally use defensive coding here because it's cheap and makes the
    // semantics of true return value clean.
    return sleAcct && sleAcct->getType() == ltACCOUNT_ROOT &&
        std::count_if(
            pseudoAccountOwnerFields.begin(),
            pseudoAccountOwnerFields.end(),
            [&sleAcct](SField const* sf) -> bool {
                return sleAcct->isFieldPresent(*sf);
            }) > 0;
}
 
[[nodiscard]] TER
addEmptyHolding(
    ApplyView& view,
    AccountID const& accountID,
    XRPAmount priorBalance,
    Issue const& issue,
    beast::Journal journal)
{
    // Every account can hold XRP.
    if (issue.native())
        return tesSUCCESS;
 
    auto const& issuerId = issue.getIssuer();
    auto const& currency = issue.currency;
    if (isGlobalFrozen(view, issuerId))
        return tecFROZEN;  // LCOV_EXCL_LINE
 
    auto const& srcId = issuerId;
    auto const& dstId = accountID;
    auto const high = srcId > dstId;
    auto const index = keylet::line(srcId, dstId, currency);
    auto const sleSrc = view.peek(keylet::account(srcId));
    auto const sleDst = view.peek(keylet::account(dstId));
    if (!sleDst || !sleSrc)
        return tefINTERNAL;  // LCOV_EXCL_LINE
    if (!sleSrc->isFlag(lsfDefaultRipple))
        return tecINTERNAL;  // LCOV_EXCL_LINE
    // If the line already exists, don't create it again.
    if (view.read(index))
        return tecDUPLICATE;
    return trustCreate(
        view,
        high,
        srcId,
        dstId,
        index.key,
        sleDst,
        /*auth=*/false,
        /*noRipple=*/true,
        /*freeze=*/false,
        /*deepFreeze*/ false,
        /*balance=*/STAmount{Issue{currency, noAccount()}},
        /*limit=*/STAmount{Issue{currency, dstId}},
        /*qualityIn=*/0,
        /*qualityOut=*/0,
        journal);
}
 
[[nodiscard]] TER
addEmptyHolding(
    ApplyView& view,
    AccountID const& accountID,
    XRPAmount priorBalance,
    MPTIssue const& mptIssue,
    beast::Journal journal)
{
    auto const& mptID = mptIssue.getMptID();
    auto const mpt = view.peek(keylet::mptIssuance(mptID));
    if (!mpt)
        return tefINTERNAL;  // LCOV_EXCL_LINE
    if (mpt->isFlag(lsfMPTLocked))
        return tefINTERNAL;  // LCOV_EXCL_LINE
    if (view.peek(keylet::mptoken(mptID, accountID)))
        return tecDUPLICATE;
 
    return authorizeMPToken(view, priorBalance, mptID, accountID, journal);
}
 
[[nodiscard]] TER
authorizeMPToken(
    ApplyView& view,
    XRPAmount const& priorBalance,
    MPTID const& mptIssuanceID,
    AccountID const& account,
    beast::Journal journal,
    std::uint32_t flags,
    std::optional<AccountID> holderID)
{
    auto const sleAcct = view.peek(keylet::account(account));
    if (!sleAcct)
        return tecINTERNAL;
 
    // If the account that submitted the tx is a holder
    // Note: `account_` is holder's account
    //       `holderID` is NOT used
    if (!holderID)
    {
        // When a holder wants to unauthorize/delete a MPT, the ledger must
        //      - delete mptokenKey from owner directory
        //      - delete the MPToken
        if (flags & tfMPTUnauthorize)
        {
            auto const mptokenKey = keylet::mptoken(mptIssuanceID, account);
            auto const sleMpt = view.peek(mptokenKey);
            if (!sleMpt || (*sleMpt)[sfMPTAmount] != 0)
                return tecINTERNAL;  // LCOV_EXCL_LINE
 
            if (!view.dirRemove(
                    keylet::ownerDir(account),
                    (*sleMpt)[sfOwnerNode],
                    sleMpt->key(),
                    false))
                return tecINTERNAL;  // LCOV_EXCL_LINE
 
            adjustOwnerCount(view, sleAcct, -1, journal);
 
            view.erase(sleMpt);
            return tesSUCCESS;
        }
 
        // A potential holder wants to authorize/hold a mpt, the ledger must:
        //      - add the new mptokenKey to the owner directory
        //      - create the MPToken object for the holder
 
        // The reserve that is required to create the MPToken. Note
        // that although the reserve increases with every item
        // an account owns, in the case of MPTokens we only
        // *enforce* a reserve if the user owns more than two
        // items. This is similar to the reserve requirements of trust lines.
        std::uint32_t const uOwnerCount = sleAcct->getFieldU32(sfOwnerCount);
        XRPAmount const reserveCreate(
            (uOwnerCount < 2) ? XRPAmount(beast::zero)
                              : view.fees().accountReserve(uOwnerCount + 1));
 
        if (priorBalance < reserveCreate)
            return tecINSUFFICIENT_RESERVE;
 
        auto const mptokenKey = keylet::mptoken(mptIssuanceID, account);
        auto mptoken = std::make_shared<SLE>(mptokenKey);
        if (auto ter = dirLink(view, account, mptoken))
            return ter;  // LCOV_EXCL_LINE
 
        (*mptoken)[sfAccount] = account;
        (*mptoken)[sfMPTokenIssuanceID] = mptIssuanceID;
        (*mptoken)[sfFlags] = 0;
        view.insert(mptoken);
 
        // Update owner count.
        adjustOwnerCount(view, sleAcct, 1, journal);
 
        return tesSUCCESS;
    }
 
    auto const sleMptIssuance = view.read(keylet::mptIssuance(mptIssuanceID));
    if (!sleMptIssuance)
        return tecINTERNAL;
 
    // If the account that submitted this tx is the issuer of the MPT
    // Note: `account_` is issuer's account
    //       `holderID` is holder's account
    if (account != (*sleMptIssuance)[sfIssuer])
        return tecINTERNAL;
 
    auto const sleMpt = view.peek(keylet::mptoken(mptIssuanceID, *holderID));
    if (!sleMpt)
        return tecINTERNAL;
 
    std::uint32_t const flagsIn = sleMpt->getFieldU32(sfFlags);
    std::uint32_t flagsOut = flagsIn;
 
    // Issuer wants to unauthorize the holder, unset lsfMPTAuthorized on
    // their MPToken
    if (flags & tfMPTUnauthorize)
        flagsOut &= ~lsfMPTAuthorized;
    // Issuer wants to authorize a holder, set lsfMPTAuthorized on their
    // MPToken
    else
        flagsOut |= lsfMPTAuthorized;
 
    if (flagsIn != flagsOut)
        sleMpt->setFieldU32(sfFlags, flagsOut);
 
    view.update(sleMpt);
    return tesSUCCESS;
}
 
TER
trustCreate(
    ApplyView& view,
    bool const bSrcHigh,
    AccountID const& uSrcAccountID,
    AccountID const& uDstAccountID,
    uint256 const& uIndex,      // --> ripple state entry
    SLE::ref sleAccount,        // --> the account being set.
    bool const bAuth,           // --> authorize account.
    bool const bNoRipple,       // --> others cannot ripple through
    bool const bFreeze,         // --> funds cannot leave
    bool bDeepFreeze,           // --> can neither receive nor send funds
    STAmount const& saBalance,  // --> balance of account being set.
                                // Issuer should be noAccount()
    STAmount const& saLimit,    // --> limit for account being set.
                                // Issuer should be the account being set.
    std::uint32_t uQualityIn,
    std::uint32_t uQualityOut,
    beast::Journal j)
{
    JLOG(j.trace()) << "trustCreate: " << to_string(uSrcAccountID) << ", "
                    << to_string(uDstAccountID) << ", "
                    << saBalance.getFullText();
 
    auto const& uLowAccountID = !bSrcHigh ? uSrcAccountID : uDstAccountID;
    auto const& uHighAccountID = bSrcHigh ? uSrcAccountID : uDstAccountID;
 
    auto const sleRippleState = std::make_shared<SLE>(ltRIPPLE_STATE, uIndex);
    view.insert(sleRippleState);
 
    auto lowNode = view.dirInsert(
        keylet::ownerDir(uLowAccountID),
        sleRippleState->key(),
        describeOwnerDir(uLowAccountID));
 
    if (!lowNode)
        return tecDIR_FULL;
 
    auto highNode = view.dirInsert(
        keylet::ownerDir(uHighAccountID),
        sleRippleState->key(),
        describeOwnerDir(uHighAccountID));
 
    if (!highNode)
        return tecDIR_FULL;
 
    bool const bSetDst = saLimit.getIssuer() == uDstAccountID;
    bool const bSetHigh = bSrcHigh ^ bSetDst;
 
    XRPL_ASSERT(sleAccount, "ripple::trustCreate : non-null SLE");
    if (!sleAccount)
        return tefINTERNAL;
 
    XRPL_ASSERT(
        sleAccount->getAccountID(sfAccount) ==
            (bSetHigh ? uHighAccountID : uLowAccountID),
        "ripple::trustCreate : matching account ID");
    auto const slePeer =
        view.peek(keylet::account(bSetHigh ? uLowAccountID : uHighAccountID));
    if (!slePeer)
        return tecNO_TARGET;
 
    // Remember deletion hints.
    sleRippleState->setFieldU64(sfLowNode, *lowNode);
    sleRippleState->setFieldU64(sfHighNode, *highNode);
 
    sleRippleState->setFieldAmount(
        bSetHigh ? sfHighLimit : sfLowLimit, saLimit);
    sleRippleState->setFieldAmount(
        bSetHigh ? sfLowLimit : sfHighLimit,
        STAmount(Issue{
            saBalance.getCurrency(), bSetDst ? uSrcAccountID : uDstAccountID}));
 
    if (uQualityIn)
        sleRippleState->setFieldU32(
            bSetHigh ? sfHighQualityIn : sfLowQualityIn, uQualityIn);
 
    if (uQualityOut)
        sleRippleState->setFieldU32(
            bSetHigh ? sfHighQualityOut : sfLowQualityOut, uQualityOut);
 
    std::uint32_t uFlags = bSetHigh ? lsfHighReserve : lsfLowReserve;
 
    if (bAuth)
    {
        uFlags |= (bSetHigh ? lsfHighAuth : lsfLowAuth);
    }
    if (bNoRipple)
    {
        uFlags |= (bSetHigh ? lsfHighNoRipple : lsfLowNoRipple);
    }
    if (bFreeze)
    {
        uFlags |= (bSetHigh ? lsfHighFreeze : lsfLowFreeze);
    }
    if (bDeepFreeze)
    {
        uFlags |= (bSetHigh ? lsfHighDeepFreeze : lsfLowDeepFreeze);
    }
 
    if ((slePeer->getFlags() & lsfDefaultRipple) == 0)
    {
        // The other side's default is no rippling
        uFlags |= (bSetHigh ? lsfLowNoRipple : lsfHighNoRipple);
    }
 
    sleRippleState->setFieldU32(sfFlags, uFlags);
    adjustOwnerCount(view, sleAccount, 1, j);
 
    // ONLY: Create ripple balance.
    sleRippleState->setFieldAmount(
        sfBalance, bSetHigh ? -saBalance : saBalance);
 
    view.creditHook(
        uSrcAccountID, uDstAccountID, saBalance, saBalance.zeroed());
 
    return tesSUCCESS;
}
 
[[nodiscard]] TER
removeEmptyHolding(
    ApplyView& view,
    AccountID const& accountID,
    Issue const& issue,
    beast::Journal journal)
{
    if (issue.native())
    {
        auto const sle = view.read(keylet::account(accountID));
        if (!sle)
            return tecINTERNAL;
        auto const balance = sle->getFieldAmount(sfBalance);
        if (balance.xrp() != 0)
            return tecHAS_OBLIGATIONS;
        return tesSUCCESS;
    }
 
    // `asset` is an IOU.
    auto const line = view.peek(keylet::line(accountID, issue));
    if (!line)
        return tecOBJECT_NOT_FOUND;
    if (line->at(sfBalance)->iou() != beast::zero)
        return tecHAS_OBLIGATIONS;
 
    // Adjust the owner count(s)
    if (line->isFlag(lsfLowReserve))
    {
        // Clear reserve for low account.
        auto sleLowAccount =
            view.peek(keylet::account(line->at(sfLowLimit)->getIssuer()));
        if (!sleLowAccount)
            return tecINTERNAL;
        adjustOwnerCount(view, sleLowAccount, -1, journal);
        // It's not really necessary to clear the reserve flag, since the line
        // is about to be deleted, but this will make the metadata reflect an
        // accurate state at the time of deletion.
        line->clearFlag(lsfLowReserve);
    }
 
    if (line->isFlag(lsfHighReserve))
    {
        // Clear reserve for high account.
        auto sleHighAccount =
            view.peek(keylet::account(line->at(sfHighLimit)->getIssuer()));
        if (!sleHighAccount)
            return tecINTERNAL;
        adjustOwnerCount(view, sleHighAccount, -1, journal);
        // It's not really necessary to clear the reserve flag, since the line
        // is about to be deleted, but this will make the metadata reflect an
        // accurate state at the time of deletion.
        line->clearFlag(lsfHighReserve);
    }
 
    return trustDelete(
        view,
        line,
        line->at(sfLowLimit)->getIssuer(),
        line->at(sfHighLimit)->getIssuer(),
        journal);
}
 
[[nodiscard]] TER
removeEmptyHolding(
    ApplyView& view,
    AccountID const& accountID,
    MPTIssue const& mptIssue,
    beast::Journal journal)
{
    auto const& mptID = mptIssue.getMptID();
    auto const mptoken = view.peek(keylet::mptoken(mptID, accountID));
    if (!mptoken)
        return tecOBJECT_NOT_FOUND;
    if (mptoken->at(sfMPTAmount) != 0)
        return tecHAS_OBLIGATIONS;
 
    return authorizeMPToken(
        view,
        {},  // priorBalance
        mptID,
        accountID,
        journal,
        tfMPTUnauthorize  // flags
    );
}
 
TER
trustDelete(
    ApplyView& view,
    std::shared_ptr<SLE> const& sleRippleState,
    AccountID const& uLowAccountID,
    AccountID const& uHighAccountID,
    beast::Journal j)
{
    // Detect legacy dirs.
    std::uint64_t uLowNode = sleRippleState->getFieldU64(sfLowNode);
    std::uint64_t uHighNode = sleRippleState->getFieldU64(sfHighNode);
 
    JLOG(j.trace()) << "trustDelete: Deleting ripple line: low";
 
    if (!view.dirRemove(
            keylet::ownerDir(uLowAccountID),
            uLowNode,
            sleRippleState->key(),
            false))
    {
        return tefBAD_LEDGER;
    }
 
    JLOG(j.trace()) << "trustDelete: Deleting ripple line: high";
 
    if (!view.dirRemove(
            keylet::ownerDir(uHighAccountID),
            uHighNode,
            sleRippleState->key(),
            false))
    {
        return tefBAD_LEDGER;
    }
 
    JLOG(j.trace()) << "trustDelete: Deleting ripple line: state";
    view.erase(sleRippleState);
 
    return tesSUCCESS;
}
 
TER
offerDelete(ApplyView& view, std::shared_ptr<SLE> const& sle, beast::Journal j)
{
    if (!sle)
        return tesSUCCESS;
    auto offerIndex = sle->key();
    auto owner = sle->getAccountID(sfAccount);
 
    // Detect legacy directories.
    uint256 uDirectory = sle->getFieldH256(sfBookDirectory);
 
    if (!view.dirRemove(
            keylet::ownerDir(owner),
            sle->getFieldU64(sfOwnerNode),
            offerIndex,
            false))
    {
        return tefBAD_LEDGER;
    }
 
    if (!view.dirRemove(
            keylet::page(uDirectory),
            sle->getFieldU64(sfBookNode),
            offerIndex,
            false))
    {
        return tefBAD_LEDGER;
    }
 
    if (sle->isFieldPresent(sfAdditionalBooks))
    {
        XRPL_ASSERT(
            sle->isFlag(lsfHybrid) && sle->isFieldPresent(sfDomainID),
            "ripple::offerDelete : should be a hybrid domain offer");
 
        auto const& additionalBookDirs = sle->getFieldArray(sfAdditionalBooks);
 
        for (auto const& bookDir : additionalBookDirs)
        {
            auto const& dirIndex = bookDir.getFieldH256(sfBookDirectory);
            auto const& dirNode = bookDir.getFieldU64(sfBookNode);
 
            if (!view.dirRemove(
                    keylet::page(dirIndex), dirNode, offerIndex, false))
            {
                return tefBAD_LEDGER;  // LCOV_EXCL_LINE
            }
        }
    }
 
    adjustOwnerCount(view, view.peek(keylet::account(owner)), -1, j);
 
    view.erase(sle);
 
    return tesSUCCESS;
}
 
// Direct send w/o fees:
// - Redeeming IOUs and/or sending sender's own IOUs.
// - Create trust line if needed.
// --> bCheckIssuer : normally require issuer to be involved.
static TER
rippleCreditIOU(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    bool bCheckIssuer,
    beast::Journal j)
{
    AccountID const& issuer = saAmount.getIssuer();
    Currency const& currency = saAmount.getCurrency();
 
    // Make sure issuer is involved.
    XRPL_ASSERT(
        !bCheckIssuer || uSenderID == issuer || uReceiverID == issuer,
        "ripple::rippleCreditIOU : matching issuer or don't care");
    (void)issuer;
 
    // Disallow sending to self.
    XRPL_ASSERT(
        uSenderID != uReceiverID,
        "ripple::rippleCreditIOU : sender is not receiver");
 
    bool const bSenderHigh = uSenderID > uReceiverID;
    auto const index = keylet::line(uSenderID, uReceiverID, currency);
 
    XRPL_ASSERT(
        !isXRP(uSenderID) && uSenderID != noAccount(),
        "ripple::rippleCreditIOU : sender is not XRP");
    XRPL_ASSERT(
        !isXRP(uReceiverID) && uReceiverID != noAccount(),
        "ripple::rippleCreditIOU : receiver is not XRP");
 
    // If the line exists, modify it accordingly.
    if (auto const sleRippleState = view.peek(index))
    {
        STAmount saBalance = sleRippleState->getFieldAmount(sfBalance);
 
        if (bSenderHigh)
            saBalance.negate();  // Put balance in sender terms.
 
        view.creditHook(uSenderID, uReceiverID, saAmount, saBalance);
 
        STAmount const saBefore = saBalance;
 
        saBalance -= saAmount;
 
        JLOG(j.trace()) << "rippleCreditIOU: " << to_string(uSenderID) << " -> "
                        << to_string(uReceiverID)
                        << " : before=" << saBefore.getFullText()
                        << " amount=" << saAmount.getFullText()
                        << " after=" << saBalance.getFullText();
 
        std::uint32_t const uFlags(sleRippleState->getFieldU32(sfFlags));
        bool bDelete = false;
 
        // FIXME This NEEDS to be cleaned up and simplified. It's impossible
        //       for anyone to understand.
        if (saBefore > beast::zero
            // Sender balance was positive.
            && saBalance <= beast::zero
            // Sender is zero or negative.
            && (uFlags & (!bSenderHigh ? lsfLowReserve : lsfHighReserve))
            // Sender reserve is set.
            &&
            static_cast<bool>(
                uFlags & (!bSenderHigh ? lsfLowNoRipple : lsfHighNoRipple)) !=
                static_cast<bool>(
                    view.read(keylet::account(uSenderID))->getFlags() &
                    lsfDefaultRipple) &&
            !(uFlags & (!bSenderHigh ? lsfLowFreeze : lsfHighFreeze)) &&
            !sleRippleState->getFieldAmount(
                !bSenderHigh ? sfLowLimit : sfHighLimit)
            // Sender trust limit is 0.
            && !sleRippleState->getFieldU32(
                   !bSenderHigh ? sfLowQualityIn : sfHighQualityIn)
            // Sender quality in is 0.
            && !sleRippleState->getFieldU32(
                   !bSenderHigh ? sfLowQualityOut : sfHighQualityOut))
        // Sender quality out is 0.
        {
            // Clear the reserve of the sender, possibly delete the line!
            adjustOwnerCount(
                view, view.peek(keylet::account(uSenderID)), -1, j);
 
            // Clear reserve flag.
            sleRippleState->setFieldU32(
                sfFlags,
                uFlags & (!bSenderHigh ? ~lsfLowReserve : ~lsfHighReserve));
 
            // Balance is zero, receiver reserve is clear.
            bDelete = !saBalance  // Balance is zero.
                && !(uFlags & (bSenderHigh ? lsfLowReserve : lsfHighReserve));
            // Receiver reserve is clear.
        }
 
        if (bSenderHigh)
            saBalance.negate();
 
        // Want to reflect balance to zero even if we are deleting line.
        sleRippleState->setFieldAmount(sfBalance, saBalance);
        // ONLY: Adjust ripple balance.
 
        if (bDelete)
        {
            return trustDelete(
                view,
                sleRippleState,
                bSenderHigh ? uReceiverID : uSenderID,
                !bSenderHigh ? uReceiverID : uSenderID,
                j);
        }
 
        view.update(sleRippleState);
        return tesSUCCESS;
    }
 
    STAmount const saReceiverLimit(Issue{currency, uReceiverID});
    STAmount saBalance{saAmount};
 
    saBalance.setIssuer(noAccount());
 
    JLOG(j.debug()) << "rippleCreditIOU: "
                       "create line: "
                    << to_string(uSenderID) << " -> " << to_string(uReceiverID)
                    << " : " << saAmount.getFullText();
 
    auto const sleAccount = view.peek(keylet::account(uReceiverID));
    if (!sleAccount)
        return tefINTERNAL;
 
    bool const noRipple = (sleAccount->getFlags() & lsfDefaultRipple) == 0;
 
    return trustCreate(
        view,
        bSenderHigh,
        uSenderID,
        uReceiverID,
        index.key,
        sleAccount,
        false,
        noRipple,
        false,
        false,
        saBalance,
        saReceiverLimit,
        0,
        0,
        j);
}
 
// Send regardless of limits.
// --> saAmount: Amount/currency/issuer to deliver to receiver.
// <-- saActual: Amount actually cost.  Sender pays fees.
static TER
rippleSendIOU(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    STAmount& saActual,
    beast::Journal j,
    WaiveTransferFee waiveFee)
{
    auto const issuer = saAmount.getIssuer();
 
    XRPL_ASSERT(
        !isXRP(uSenderID) && !isXRP(uReceiverID),
        "ripple::rippleSendIOU : neither sender nor receiver is XRP");
    XRPL_ASSERT(
        uSenderID != uReceiverID,
        "ripple::rippleSendIOU : sender is not receiver");
 
    if (uSenderID == issuer || uReceiverID == issuer || issuer == noAccount())
    {
        // Direct send: redeeming IOUs and/or sending own IOUs.
        auto const ter =
            rippleCreditIOU(view, uSenderID, uReceiverID, saAmount, false, j);
        if (view.rules().enabled(featureDeletableAccounts) && ter != tesSUCCESS)
            return ter;
        saActual = saAmount;
        return tesSUCCESS;
    }
 
    // Sending 3rd party IOUs: transit.
 
    // Calculate the amount to transfer accounting
    // for any transfer fees if the fee is not waived:
    saActual = (waiveFee == WaiveTransferFee::Yes)
        ? saAmount
        : multiply(saAmount, transferRate(view, issuer));
 
    JLOG(j.debug()) << "rippleSendIOU> " << to_string(uSenderID) << " - > "
                    << to_string(uReceiverID)
                    << " : deliver=" << saAmount.getFullText()
                    << " cost=" << saActual.getFullText();
 
    TER terResult =
        rippleCreditIOU(view, issuer, uReceiverID, saAmount, true, j);
 
    if (tesSUCCESS == terResult)
        terResult = rippleCreditIOU(view, uSenderID, issuer, saActual, true, j);
 
    return terResult;
}
 
static TER
accountSendIOU(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    beast::Journal j,
    WaiveTransferFee waiveFee)
{
    if (view.rules().enabled(fixAMMv1_1))
    {
        if (saAmount < beast::zero || saAmount.holds<MPTIssue>())
        {
            return tecINTERNAL;
        }
    }
    else
    {
        XRPL_ASSERT(
            saAmount >= beast::zero && !saAmount.holds<MPTIssue>(),
            "ripple::accountSendIOU : minimum amount and not MPT");
    }
 
    /* If we aren't sending anything or if the sender is the same as the
     * receiver then we don't need to do anything.
     */
    if (!saAmount || (uSenderID == uReceiverID))
        return tesSUCCESS;
 
    if (!saAmount.native())
    {
        STAmount saActual;
 
        JLOG(j.trace()) << "accountSendIOU: " << to_string(uSenderID) << " -> "
                        << to_string(uReceiverID) << " : "
                        << saAmount.getFullText();
 
        return rippleSendIOU(
            view, uSenderID, uReceiverID, saAmount, saActual, j, waiveFee);
    }
 
    /* XRP send which does not check reserve and can do pure adjustment.
     * Note that sender or receiver may be null and this not a mistake; this
     * setup is used during pathfinding and it is carefully controlled to
     * ensure that transfers are balanced.
     */
    TER terResult(tesSUCCESS);
 
    SLE::pointer sender = uSenderID != beast::zero
        ? view.peek(keylet::account(uSenderID))
        : SLE::pointer();
    SLE::pointer receiver = uReceiverID != beast::zero
        ? view.peek(keylet::account(uReceiverID))
        : SLE::pointer();
 
    if (auto stream = j.trace())
    {
        std::string sender_bal("-");
        std::string receiver_bal("-");
 
        if (sender)
            sender_bal = sender->getFieldAmount(sfBalance).getFullText();
 
        if (receiver)
            receiver_bal = receiver->getFieldAmount(sfBalance).getFullText();
 
        stream << "accountSendIOU> " << to_string(uSenderID) << " ("
               << sender_bal << ") -> " << to_string(uReceiverID) << " ("
               << receiver_bal << ") : " << saAmount.getFullText();
    }
 
    if (sender)
    {
        if (sender->getFieldAmount(sfBalance) < saAmount)
        {
            // VFALCO Its laborious to have to mutate the
            //        TER based on params everywhere
            terResult = view.open() ? TER{telFAILED_PROCESSING}
                                    : TER{tecFAILED_PROCESSING};
        }
        else
        {
            auto const sndBal = sender->getFieldAmount(sfBalance);
            view.creditHook(uSenderID, xrpAccount(), saAmount, sndBal);
 
            // Decrement XRP balance.
            sender->setFieldAmount(sfBalance, sndBal - saAmount);
            view.update(sender);
        }
    }
 
    if (tesSUCCESS == terResult && receiver)
    {
        // Increment XRP balance.
        auto const rcvBal = receiver->getFieldAmount(sfBalance);
        receiver->setFieldAmount(sfBalance, rcvBal + saAmount);
        view.creditHook(xrpAccount(), uReceiverID, saAmount, -rcvBal);
 
        view.update(receiver);
    }
 
    if (auto stream = j.trace())
    {
        std::string sender_bal("-");
        std::string receiver_bal("-");
 
        if (sender)
            sender_bal = sender->getFieldAmount(sfBalance).getFullText();
 
        if (receiver)
            receiver_bal = receiver->getFieldAmount(sfBalance).getFullText();
 
        stream << "accountSendIOU< " << to_string(uSenderID) << " ("
               << sender_bal << ") -> " << to_string(uReceiverID) << " ("
               << receiver_bal << ") : " << saAmount.getFullText();
    }
 
    return terResult;
}
 
static TER
rippleCreditMPT(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    beast::Journal j)
{
    // Do not check MPT authorization here - it must have been checked earlier
    auto const mptID = keylet::mptIssuance(saAmount.get<MPTIssue>().getMptID());
    auto const issuer = saAmount.getIssuer();
    auto sleIssuance = view.peek(mptID);
    if (!sleIssuance)
        return tecOBJECT_NOT_FOUND;
    if (uSenderID == issuer)
    {
        (*sleIssuance)[sfOutstandingAmount] += saAmount.mpt().value();
        view.update(sleIssuance);
    }
    else
    {
        auto const mptokenID = keylet::mptoken(mptID.key, uSenderID);
        if (auto sle = view.peek(mptokenID))
        {
            auto const amt = sle->getFieldU64(sfMPTAmount);
            auto const pay = saAmount.mpt().value();
            if (amt < pay)
                return tecINSUFFICIENT_FUNDS;
            (*sle)[sfMPTAmount] = amt - pay;
            view.update(sle);
        }
        else
            return tecNO_AUTH;
    }
 
    if (uReceiverID == issuer)
    {
        auto const outstanding = sleIssuance->getFieldU64(sfOutstandingAmount);
        auto const redeem = saAmount.mpt().value();
        if (outstanding >= redeem)
        {
            sleIssuance->setFieldU64(sfOutstandingAmount, outstanding - redeem);
            view.update(sleIssuance);
        }
        else
            return tecINTERNAL;
    }
    else
    {
        auto const mptokenID = keylet::mptoken(mptID.key, uReceiverID);
        if (auto sle = view.peek(mptokenID))
        {
            (*sle)[sfMPTAmount] += saAmount.mpt().value();
            view.update(sle);
        }
        else
            return tecNO_AUTH;
    }
 
    return tesSUCCESS;
}
 
static TER
rippleSendMPT(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    STAmount& saActual,
    beast::Journal j,
    WaiveTransferFee waiveFee)
{
    XRPL_ASSERT(
        uSenderID != uReceiverID,
        "ripple::rippleSendMPT : sender is not receiver");
 
    // Safe to get MPT since rippleSendMPT is only called by accountSendMPT
    auto const issuer = saAmount.getIssuer();
 
    auto const sle =
        view.read(keylet::mptIssuance(saAmount.get<MPTIssue>().getMptID()));
    if (!sle)
        return tecOBJECT_NOT_FOUND;
 
    if (uSenderID == issuer || uReceiverID == issuer)
    {
        // if sender is issuer, check that the new OutstandingAmount will not
        // exceed MaximumAmount
        if (uSenderID == issuer)
        {
            auto const sendAmount = saAmount.mpt().value();
            auto const maximumAmount =
                sle->at(~sfMaximumAmount).value_or(maxMPTokenAmount);
            if (sendAmount > maximumAmount ||
                sle->getFieldU64(sfOutstandingAmount) >
                    maximumAmount - sendAmount)
                return tecPATH_DRY;
        }
 
        // Direct send: redeeming MPTs and/or sending own MPTs.
        auto const ter =
            rippleCreditMPT(view, uSenderID, uReceiverID, saAmount, j);
        if (ter != tesSUCCESS)
            return ter;
        saActual = saAmount;
        return tesSUCCESS;
    }
 
    // Sending 3rd party MPTs: transit.
    saActual = (waiveFee == WaiveTransferFee::Yes)
        ? saAmount
        : multiply(
              saAmount,
              transferRate(view, saAmount.get<MPTIssue>().getMptID()));
 
    JLOG(j.debug()) << "rippleSendMPT> " << to_string(uSenderID) << " - > "
                    << to_string(uReceiverID)
                    << " : deliver=" << saAmount.getFullText()
                    << " cost=" << saActual.getFullText();
 
    if (auto const terResult =
            rippleCreditMPT(view, issuer, uReceiverID, saAmount, j);
        terResult != tesSUCCESS)
        return terResult;
 
    return rippleCreditMPT(view, uSenderID, issuer, saActual, j);
}
 
static TER
accountSendMPT(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    beast::Journal j,
    WaiveTransferFee waiveFee)
{
    XRPL_ASSERT(
        saAmount >= beast::zero && saAmount.holds<MPTIssue>(),
        "ripple::accountSendMPT : minimum amount and MPT");
 
    /* If we aren't sending anything or if the sender is the same as the
     * receiver then we don't need to do anything.
     */
    if (!saAmount || (uSenderID == uReceiverID))
        return tesSUCCESS;
 
    STAmount saActual{saAmount.asset()};
 
    return rippleSendMPT(
        view, uSenderID, uReceiverID, saAmount, saActual, j, waiveFee);
}
 
TER
accountSend(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    beast::Journal j,
    WaiveTransferFee waiveFee)
{
    return std::visit(
        [&]<ValidIssueType TIss>(TIss const& issue) {
            if constexpr (std::is_same_v<TIss, Issue>)
                return accountSendIOU(
                    view, uSenderID, uReceiverID, saAmount, j, waiveFee);
            else
                return accountSendMPT(
                    view, uSenderID, uReceiverID, saAmount, j, waiveFee);
        },
        saAmount.asset().value());
}
 
static bool
updateTrustLine(
    ApplyView& view,
    SLE::pointer state,
    bool bSenderHigh,
    AccountID const& sender,
    STAmount const& before,
    STAmount const& after,
    beast::Journal j)
{
    if (!state)
        return false;
    std::uint32_t const flags(state->getFieldU32(sfFlags));
 
    auto sle = view.peek(keylet::account(sender));
    if (!sle)
        return false;
 
    // YYY Could skip this if rippling in reverse.
    if (before > beast::zero
        // Sender balance was positive.
        && after <= beast::zero
        // Sender is zero or negative.
        && (flags & (!bSenderHigh ? lsfLowReserve : lsfHighReserve))
        // Sender reserve is set.
        && static_cast<bool>(
               flags & (!bSenderHigh ? lsfLowNoRipple : lsfHighNoRipple)) !=
            static_cast<bool>(sle->getFlags() & lsfDefaultRipple) &&
        !(flags & (!bSenderHigh ? lsfLowFreeze : lsfHighFreeze)) &&
        !state->getFieldAmount(!bSenderHigh ? sfLowLimit : sfHighLimit)
        // Sender trust limit is 0.
        && !state->getFieldU32(!bSenderHigh ? sfLowQualityIn : sfHighQualityIn)
        // Sender quality in is 0.
        &&
        !state->getFieldU32(!bSenderHigh ? sfLowQualityOut : sfHighQualityOut))
    // Sender quality out is 0.
    {
        // VFALCO Where is the line being deleted?
        // Clear the reserve of the sender, possibly delete the line!
        adjustOwnerCount(view, sle, -1, j);
 
        // Clear reserve flag.
        state->setFieldU32(
            sfFlags, flags & (!bSenderHigh ? ~lsfLowReserve : ~lsfHighReserve));
 
        // Balance is zero, receiver reserve is clear.
        if (!after  // Balance is zero.
            && !(flags & (bSenderHigh ? lsfLowReserve : lsfHighReserve)))
            return true;
    }
    return false;
}
 
TER
issueIOU(
    ApplyView& view,
    AccountID const& account,
    STAmount const& amount,
    Issue const& issue,
    beast::Journal j)
{
    XRPL_ASSERT(
        !isXRP(account) && !isXRP(issue.account),
        "ripple::issueIOU : neither account nor issuer is XRP");
 
    // Consistency check
    XRPL_ASSERT(issue == amount.issue(), "ripple::issueIOU : matching issue");
 
    // Can't send to self!
    XRPL_ASSERT(
        issue.account != account, "ripple::issueIOU : not issuer account");
 
    JLOG(j.trace()) << "issueIOU: " << to_string(account) << ": "
                    << amount.getFullText();
 
    bool bSenderHigh = issue.account > account;
 
    auto const index = keylet::line(issue.account, account, issue.currency);
 
    if (auto state = view.peek(index))
    {
        STAmount final_balance = state->getFieldAmount(sfBalance);
 
        if (bSenderHigh)
            final_balance.negate();  // Put balance in sender terms.
 
        STAmount const start_balance = final_balance;
 
        final_balance -= amount;
 
        auto const must_delete = updateTrustLine(
            view,
            state,
            bSenderHigh,
            issue.account,
            start_balance,
            final_balance,
            j);
 
        view.creditHook(issue.account, account, amount, start_balance);
 
        if (bSenderHigh)
            final_balance.negate();
 
        // Adjust the balance on the trust line if necessary. We do this even if
        // we are going to delete the line to reflect the correct balance at the
        // time of deletion.
        state->setFieldAmount(sfBalance, final_balance);
        if (must_delete)
            return trustDelete(
                view,
                state,
                bSenderHigh ? account : issue.account,
                bSenderHigh ? issue.account : account,
                j);
 
        view.update(state);
 
        return tesSUCCESS;
    }
 
    // NIKB TODO: The limit uses the receiver's account as the issuer and
    // this is unnecessarily inefficient as copying which could be avoided
    // is now required. Consider available options.
    STAmount const limit(Issue{issue.currency, account});
    STAmount final_balance = amount;
 
    final_balance.setIssuer(noAccount());
 
    auto const receiverAccount = view.peek(keylet::account(account));
    if (!receiverAccount)
        return tefINTERNAL;
 
    bool noRipple = (receiverAccount->getFlags() & lsfDefaultRipple) == 0;
 
    return trustCreate(
        view,
        bSenderHigh,
        issue.account,
        account,
        index.key,
        receiverAccount,
        false,
        noRipple,
        false,
        false,
        final_balance,
        limit,
        0,
        0,
        j);
}
 
TER
redeemIOU(
    ApplyView& view,
    AccountID const& account,
    STAmount const& amount,
    Issue const& issue,
    beast::Journal j)
{
    XRPL_ASSERT(
        !isXRP(account) && !isXRP(issue.account),
        "ripple::redeemIOU : neither account nor issuer is XRP");
 
    // Consistency check
    XRPL_ASSERT(issue == amount.issue(), "ripple::redeemIOU : matching issue");
 
    // Can't send to self!
    XRPL_ASSERT(
        issue.account != account, "ripple::redeemIOU : not issuer account");
 
    JLOG(j.trace()) << "redeemIOU: " << to_string(account) << ": "
                    << amount.getFullText();
 
    bool bSenderHigh = account > issue.account;
 
    if (auto state =
            view.peek(keylet::line(account, issue.account, issue.currency)))
    {
        STAmount final_balance = state->getFieldAmount(sfBalance);
 
        if (bSenderHigh)
            final_balance.negate();  // Put balance in sender terms.
 
        STAmount const start_balance = final_balance;
 
        final_balance -= amount;
 
        auto const must_delete = updateTrustLine(
            view, state, bSenderHigh, account, start_balance, final_balance, j);
 
        view.creditHook(account, issue.account, amount, start_balance);
 
        if (bSenderHigh)
            final_balance.negate();
 
        // Adjust the balance on the trust line if necessary. We do this even if
        // we are going to delete the line to reflect the correct balance at the
        // time of deletion.
        state->setFieldAmount(sfBalance, final_balance);
 
        if (must_delete)
        {
            return trustDelete(
                view,
                state,
                bSenderHigh ? issue.account : account,
                bSenderHigh ? account : issue.account,
                j);
        }
 
        view.update(state);
        return tesSUCCESS;
    }
 
    // In order to hold an IOU, a trust line *MUST* exist to track the
    // balance. If it doesn't, then something is very wrong. Don't try
    // to continue.
    JLOG(j.fatal()) << "redeemIOU: " << to_string(account)
                    << " attempts to redeem " << amount.getFullText()
                    << " but no trust line exists!";
 
    return tefINTERNAL;
}
 
TER
transferXRP(
    ApplyView& view,
    AccountID const& from,
    AccountID const& to,
    STAmount const& amount,
    beast::Journal j)
{
    XRPL_ASSERT(
        from != beast::zero, "ripple::transferXRP : nonzero from account");
    XRPL_ASSERT(to != beast::zero, "ripple::transferXRP : nonzero to account");
    XRPL_ASSERT(from != to, "ripple::transferXRP : sender is not receiver");
    XRPL_ASSERT(amount.native(), "ripple::transferXRP : amount is XRP");
 
    SLE::pointer const sender = view.peek(keylet::account(from));
    SLE::pointer const receiver = view.peek(keylet::account(to));
    if (!sender || !receiver)
        return tefINTERNAL;
 
    JLOG(j.trace()) << "transferXRP: " << to_string(from) << " -> "
                    << to_string(to) << ") : " << amount.getFullText();
 
    if (sender->getFieldAmount(sfBalance) < amount)
    {
        // VFALCO Its unfortunate we have to keep
        //        mutating these TER everywhere
        // FIXME: this logic should be moved to callers maybe?
        return view.open() ? TER{telFAILED_PROCESSING}
                           : TER{tecFAILED_PROCESSING};
    }
 
    // Decrement XRP balance.
    sender->setFieldAmount(
        sfBalance, sender->getFieldAmount(sfBalance) - amount);
    view.update(sender);
 
    receiver->setFieldAmount(
        sfBalance, receiver->getFieldAmount(sfBalance) + amount);
    view.update(receiver);
 
    return tesSUCCESS;
}
 
TER
requireAuth(
    ReadView const& view,
    Issue const& issue,
    AccountID const& account,
    AuthType authType)
{
    if (isXRP(issue) || issue.account == account)
        return tesSUCCESS;
 
    auto const trustLine =
        view.read(keylet::line(account, issue.account, issue.currency));
    // If account has no line, and this is a strong check, fail
    if (!trustLine && authType == AuthType::StrongAuth)
        return tecNO_LINE;
 
    // If this is a weak or legacy check, or if the account has a line, fail if
    // auth is required and not set on the line
    if (auto const issuerAccount = view.read(keylet::account(issue.account));
        issuerAccount && (*issuerAccount)[sfFlags] & lsfRequireAuth)
    {
        if (trustLine)
            return ((*trustLine)[sfFlags] &
                    ((account > issue.account) ? lsfLowAuth : lsfHighAuth))
                ? tesSUCCESS
                : TER{tecNO_AUTH};
        return TER{tecNO_LINE};
    }
 
    return tesSUCCESS;
}
 
TER
requireAuth(
    ReadView const& view,
    MPTIssue const& mptIssue,
    AccountID const& account,
    AuthType authType,
    int depth)
{
    auto const mptID = keylet::mptIssuance(mptIssue.getMptID());
    auto const sleIssuance = view.read(mptID);
    if (!sleIssuance)
        return tecOBJECT_NOT_FOUND;
 
    auto const mptIssuer = sleIssuance->getAccountID(sfIssuer);
 
    // issuer is always "authorized"
    if (mptIssuer == account)  // Issuer won't have MPToken
        return tesSUCCESS;
 
    if (view.rules().enabled(featureSingleAssetVault))
    {
        if (depth >= maxAssetCheckDepth)
            return tecINTERNAL;  // LCOV_EXCL_LINE
 
        // requireAuth is recursive if the issuer is a vault pseudo-account
        auto const sleIssuer = view.read(keylet::account(mptIssuer));
        if (!sleIssuer)
            return tefINTERNAL;  // LCOV_EXCL_LINE
 
        if (sleIssuer->isFieldPresent(sfVaultID))
        {
            auto const sleVault =
                view.read(keylet::vault(sleIssuer->getFieldH256(sfVaultID)));
            if (!sleVault)
                return tefINTERNAL;  // LCOV_EXCL_LINE
 
            auto const asset = sleVault->at(sfAsset);
            if (auto const err = std::visit(
                    [&]<ValidIssueType TIss>(TIss const& issue) {
                        if constexpr (std::is_same_v<TIss, Issue>)
                            return requireAuth(view, issue, account, authType);
                        else
                            return requireAuth(
                                view, issue, account, authType, depth + 1);
                    },
                    asset.value());
                !isTesSuccess(err))
                return err;
        }
    }
 
    auto const mptokenID = keylet::mptoken(mptID.key, account);
    auto const sleToken = view.read(mptokenID);
 
    // if account has no MPToken, fail
    if (!sleToken &&
        (authType == AuthType::StrongAuth || authType == AuthType::Legacy))
        return tecNO_AUTH;
 
    // Note, this check is not amendment-gated because DomainID will be always
    // empty **unless** writing to it has been enabled by an amendment
    auto const maybeDomainID = sleIssuance->at(~sfDomainID);
    if (maybeDomainID)
    {
        XRPL_ASSERT(
            sleIssuance->getFieldU32(sfFlags) & lsfMPTRequireAuth,
            "ripple::requireAuth : issuance requires authorization");
        // ter = tefINTERNAL | tecOBJECT_NOT_FOUND | tecNO_AUTH | tecEXPIRED
        if (auto const ter =
                credentials::validDomain(view, *maybeDomainID, account);
            isTesSuccess(ter))
            return ter;  // Note: sleToken might be null
        else if (!sleToken)
            return ter;
        // We ignore error from validDomain if we found sleToken, as it could
        // belong to someone who is explicitly authorized e.g. a vault owner.
    }
 
    // mptoken must be authorized if issuance enabled requireAuth
    if (sleIssuance->isFlag(lsfMPTRequireAuth) &&
        (!sleToken || !sleToken->isFlag(lsfMPTAuthorized)))
        return tecNO_AUTH;
 
    return tesSUCCESS;  // Note: sleToken might be null
}
 
[[nodiscard]] TER
enforceMPTokenAuthorization(
    ApplyView& view,
    MPTID const& mptIssuanceID,
    AccountID const& account,
    XRPAmount const& priorBalance,  // for MPToken authorization
    beast::Journal j)
{
    auto const sleIssuance = view.read(keylet::mptIssuance(mptIssuanceID));
    if (!sleIssuance)
        return tefINTERNAL;  // LCOV_EXCL_LINE
 
    XRPL_ASSERT(
        sleIssuance->isFlag(lsfMPTRequireAuth),
        "ripple::enforceMPTokenAuthorization : authorization required");
 
    if (account == sleIssuance->at(sfIssuer))
        return tefINTERNAL;  // LCOV_EXCL_LINE
 
    auto const keylet = keylet::mptoken(mptIssuanceID, account);
    auto const sleToken = view.read(keylet);  //  NOTE: might be null
    auto const maybeDomainID = sleIssuance->at(~sfDomainID);
    bool expired = false;
    bool const authorizedByDomain = [&]() -> bool {
        // NOTE: defensive here, shuld be checked in preclaim
        if (!maybeDomainID.has_value())
            return false;  // LCOV_EXCL_LINE
 
        auto const ter = verifyValidDomain(view, account, *maybeDomainID, j);
        if (isTesSuccess(ter))
            return true;
        if (ter == tecEXPIRED)
            expired = true;
        return false;
    }();
 
    if (!authorizedByDomain && sleToken == nullptr)
    {
        // Could not find MPToken and won't create one, could be either of:
        //
        // 1. Field sfDomainID not set in MPTokenIssuance or
        // 2. Account has no matching and accepted credentials or
        // 3. Account has all expired credentials (deleted in verifyValidDomain)
        //
        // Either way, return tecNO_AUTH and there is nothing else to do
        return expired ? tecEXPIRED : tecNO_AUTH;
    }
    else if (!authorizedByDomain && maybeDomainID.has_value())
    {
        // Found an MPToken but the account is not authorized and we expect
        // it to have been authorized by the domain. This could be because the
        // credentials used to create the MPToken have expired or been deleted.
        return expired ? tecEXPIRED : tecNO_AUTH;
    }
    else if (!authorizedByDomain)
    {
        // We found an MPToken, but sfDomainID is not set, so this is a classic
        // MPToken which requires authorization by the token issuer.
        XRPL_ASSERT(
            sleToken != nullptr && !maybeDomainID.has_value(),
            "ripple::enforceMPTokenAuthorization : found MPToken");
        if (sleToken->isFlag(lsfMPTAuthorized))
            return tesSUCCESS;
 
        return tecNO_AUTH;
    }
    else if (authorizedByDomain && sleToken != nullptr)
    {
        // Found an MPToken, authorized by the domain. Ignore authorization flag
        // lsfMPTAuthorized because it is meaningless. Return tesSUCCESS
        XRPL_ASSERT(
            maybeDomainID.has_value(),
            "ripple::enforceMPTokenAuthorization : found MPToken for domain");
        return tesSUCCESS;
    }
    else if (authorizedByDomain)
    {
        // Could not find MPToken but there should be one because we are
        // authorized by domain. Proceed to create it, then return tesSUCCESS
        XRPL_ASSERT(
            maybeDomainID.has_value() && sleToken == nullptr,
            "ripple::enforceMPTokenAuthorization : new MPToken for domain");
        if (auto const err = authorizeMPToken(
                view,
                priorBalance,   // priorBalance
                mptIssuanceID,  // mptIssuanceID
                account,        // account
                j);
            !isTesSuccess(err))
            return err;
 
        return tesSUCCESS;
    }
 
    // LCOV_EXCL_START
    UNREACHABLE(
        "ripple::enforceMPTokenAuthorization : condition list is incomplete");
    return tefINTERNAL;
}  // LCOV_EXCL_STOP
 
TER
canTransfer(
    ReadView const& view,
    MPTIssue const& mptIssue,
    AccountID const& from,
    AccountID const& to)
{
    auto const mptID = keylet::mptIssuance(mptIssue.getMptID());
    auto const sleIssuance = view.read(mptID);
    if (!sleIssuance)
        return tecOBJECT_NOT_FOUND;
 
    if (!(sleIssuance->getFieldU32(sfFlags) & lsfMPTCanTransfer))
    {
        if (from != (*sleIssuance)[sfIssuer] && to != (*sleIssuance)[sfIssuer])
            return TER{tecNO_AUTH};
    }
    return tesSUCCESS;
}
 
TER
cleanupOnAccountDelete(
    ApplyView& view,
    Keylet const& ownerDirKeylet,
    EntryDeleter const& deleter,
    beast::Journal j,
    std::optional<uint16_t> maxNodesToDelete)
{
    // Delete all the entries in the account directory.
    std::shared_ptr<SLE> sleDirNode{};
    unsigned int uDirEntry{0};
    uint256 dirEntry{beast::zero};
    std::uint32_t deleted = 0;
 
    if (view.exists(ownerDirKeylet) &&
        dirFirst(view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry))
    {
        do
        {
            if (maxNodesToDelete && ++deleted > *maxNodesToDelete)
                return tecINCOMPLETE;
 
            // Choose the right way to delete each directory node.
            auto sleItem = view.peek(keylet::child(dirEntry));
            if (!sleItem)
            {
                // Directory node has an invalid index.  Bail out.
                JLOG(j.fatal())
                    << "DeleteAccount: Directory node in ledger " << view.seq()
                    << " has index to object that is missing: "
                    << to_string(dirEntry);
                return tefBAD_LEDGER;
            }
 
            LedgerEntryType const nodeType{safe_cast<LedgerEntryType>(
                sleItem->getFieldU16(sfLedgerEntryType))};
 
            // Deleter handles the details of specific account-owned object
            // deletion
            auto const [ter, skipEntry] = deleter(nodeType, dirEntry, sleItem);
            if (ter != tesSUCCESS)
                return ter;
 
            // dirFirst() and dirNext() are like iterators with exposed
            // internal state.  We'll take advantage of that exposed state
            // to solve a common C++ problem: iterator invalidation while
            // deleting elements from a container.
            //
            // We have just deleted one directory entry, which means our
            // "iterator state" is invalid.
            //
            //  1. During the process of getting an entry from the
            //     directory uDirEntry was incremented from 'it' to 'it'+1.
            //
            //  2. We then deleted the entry at index 'it', which means the
            //     entry that was at 'it'+1 has now moved to 'it'.
            //
            //  3. So we verify that uDirEntry is indeed 'it'+1.  Then we jam it
            //     back to 'it' to "un-invalidate" the iterator.
            XRPL_ASSERT(
                uDirEntry >= 1,
                "ripple::cleanupOnAccountDelete : minimum dir entries");
            if (uDirEntry == 0)
            {
                JLOG(j.error())
                    << "DeleteAccount iterator re-validation failed.";
                return tefBAD_LEDGER;
            }
            if (skipEntry == SkipEntry::No)
                uDirEntry--;
 
        } while (
            dirNext(view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry));
    }
 
    return tesSUCCESS;
}
 
TER
deleteAMMTrustLine(
    ApplyView& view,
    std::shared_ptr<SLE> sleState,
    std::optional<AccountID> const& ammAccountID,
    beast::Journal j)
{
    if (!sleState || sleState->getType() != ltRIPPLE_STATE)
        return tecINTERNAL;
 
    auto const& [low, high] = std::minmax(
        sleState->getFieldAmount(sfLowLimit).getIssuer(),
        sleState->getFieldAmount(sfHighLimit).getIssuer());
    auto sleLow = view.peek(keylet::account(low));
    auto sleHigh = view.peek(keylet::account(high));
    if (!sleLow || !sleHigh)
        return tecINTERNAL;
    bool const ammLow = sleLow->isFieldPresent(sfAMMID);
    bool const ammHigh = sleHigh->isFieldPresent(sfAMMID);
 
    // can't both be AMM
    if (ammLow && ammHigh)
        return tecINTERNAL;
 
    // at least one must be
    if (!ammLow && !ammHigh)
        return terNO_AMM;
 
    // one must be the target amm
    if (ammAccountID && (low != *ammAccountID && high != *ammAccountID))
        return terNO_AMM;
 
    if (auto const ter = trustDelete(view, sleState, low, high, j);
        ter != tesSUCCESS)
    {
        JLOG(j.error())
            << "deleteAMMTrustLine: failed to delete the trustline.";
        return ter;
    }
 
    auto const uFlags = !ammLow ? lsfLowReserve : lsfHighReserve;
    if (!(sleState->getFlags() & uFlags))
        return tecINTERNAL;
 
    adjustOwnerCount(view, !ammLow ? sleLow : sleHigh, -1, j);
 
    return tesSUCCESS;
}
 
TER
rippleCredit(
    ApplyView& view,
    AccountID const& uSenderID,
    AccountID const& uReceiverID,
    STAmount const& saAmount,
    bool bCheckIssuer,
    beast::Journal j)
{
    return std::visit(
        [&]<ValidIssueType TIss>(TIss const& issue) {
            if constexpr (std::is_same_v<TIss, Issue>)
            {
                return rippleCreditIOU(
                    view, uSenderID, uReceiverID, saAmount, bCheckIssuer, j);
            }
            else
            {
                XRPL_ASSERT(
                    !bCheckIssuer,
                    "ripple::rippleCredit : not checking issuer");
                return rippleCreditMPT(
                    view, uSenderID, uReceiverID, saAmount, j);
            }
        },
        saAmount.asset().value());
}
 
[[nodiscard]] STAmount
assetsToSharesDeposit(
    std::shared_ptr<SLE const> const& vault,
    std::shared_ptr<SLE const> const& issuance,
    STAmount const& assets)
{
    XRPL_ASSERT(
        assets.asset() == vault->at(sfAsset),
        "ripple::assetsToSharesDeposit : assets and vault match");
    Number assetTotal = vault->at(sfAssetsTotal);
    STAmount shares{vault->at(sfShareMPTID), static_cast<Number>(assets)};
    if (assetTotal == 0)
        return shares;
    Number shareTotal = issuance->at(sfOutstandingAmount);
    shares = shareTotal * (assets / assetTotal);
    return shares;
}
 
[[nodiscard]] STAmount
assetsToSharesWithdraw(
    std::shared_ptr<SLE const> const& vault,
    std::shared_ptr<SLE const> const& issuance,
    STAmount const& assets)
{
    XRPL_ASSERT(
        assets.asset() == vault->at(sfAsset),
        "ripple::assetsToSharesWithdraw : assets and vault match");
    Number assetTotal = vault->at(sfAssetsTotal);
    assetTotal -= vault->at(sfLossUnrealized);
    STAmount shares{vault->at(sfShareMPTID)};
    if (assetTotal == 0)
        return shares;
    Number shareTotal = issuance->at(sfOutstandingAmount);
    shares = shareTotal * (assets / assetTotal);
    return shares;
}
 
[[nodiscard]] STAmount
sharesToAssetsWithdraw(
    std::shared_ptr<SLE const> const& vault,
    std::shared_ptr<SLE const> const& issuance,
    STAmount const& shares)
{
    XRPL_ASSERT(
        shares.asset() == vault->at(sfShareMPTID),
        "ripple::sharesToAssetsWithdraw : shares and vault match");
    Number assetTotal = vault->at(sfAssetsTotal);
    assetTotal -= vault->at(sfLossUnrealized);
    STAmount assets{vault->at(sfAsset)};
    if (assetTotal == 0)
        return assets;
    Number shareTotal = issuance->at(sfOutstandingAmount);
    assets = assetTotal * (shares / shareTotal);
    return assets;
}
 
TER
rippleLockEscrowMPT(
    ApplyView& view,
    AccountID const& sender,
    STAmount const& amount,
    beast::Journal j)
{
    auto const mptIssue = amount.get<MPTIssue>();
    auto const mptID = keylet::mptIssuance(mptIssue.getMptID());
    auto sleIssuance = view.peek(mptID);
    if (!sleIssuance)
    {  // LCOV_EXCL_START
        JLOG(j.error()) << "rippleLockEscrowMPT: MPT issuance not found for "
                        << mptIssue.getMptID();
        return tecOBJECT_NOT_FOUND;
    }  // LCOV_EXCL_STOP
 
    if (amount.getIssuer() == sender)
    {  // LCOV_EXCL_START
        JLOG(j.error())
            << "rippleLockEscrowMPT: sender is the issuer, cannot lock MPTs.";
        return tecINTERNAL;
    }  // LCOV_EXCL_STOP
 
    // 1. Decrease the MPT Holder MPTAmount
    // 2. Increase the MPT Holder EscrowedAmount
    {
        auto const mptokenID = keylet::mptoken(mptID.key, sender);
        auto sle = view.peek(mptokenID);
        if (!sle)
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleLockEscrowMPT: MPToken not found for " << sender;
            return tecOBJECT_NOT_FOUND;
        }  // LCOV_EXCL_STOP
 
        auto const amt = sle->getFieldU64(sfMPTAmount);
        auto const pay = amount.mpt().value();
 
        // Underflow check for subtraction
        if (!canSubtract(STAmount(mptIssue, amt), STAmount(mptIssue, pay)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleLockEscrowMPT: insufficient MPTAmount for "
                << to_string(sender) << ": " << amt << " < " << pay;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        (*sle)[sfMPTAmount] = amt - pay;
 
        // Overflow check for addition
        uint64_t const locked = (*sle)[~sfLockedAmount].value_or(0);
 
        if (!canAdd(STAmount(mptIssue, locked), STAmount(mptIssue, pay)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleLockEscrowMPT: overflow on locked amount for "
                << to_string(sender) << ": " << locked << " + " << pay;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        if (sle->isFieldPresent(sfLockedAmount))
            (*sle)[sfLockedAmount] += pay;
        else
            sle->setFieldU64(sfLockedAmount, pay);
 
        view.update(sle);
    }
 
    // 1. Increase the Issuance EscrowedAmount
    // 2. DO NOT change the Issuance OutstandingAmount
    {
        uint64_t const issuanceEscrowed =
            (*sleIssuance)[~sfLockedAmount].value_or(0);
        auto const pay = amount.mpt().value();
 
        // Overflow check for addition
        if (!canAdd(
                STAmount(mptIssue, issuanceEscrowed), STAmount(mptIssue, pay)))
        {  // LCOV_EXCL_START
            JLOG(j.error()) << "rippleLockEscrowMPT: overflow on issuance "
                               "locked amount for "
                            << mptIssue.getMptID() << ": " << issuanceEscrowed
                            << " + " << pay;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        if (sleIssuance->isFieldPresent(sfLockedAmount))
            (*sleIssuance)[sfLockedAmount] += pay;
        else
            sleIssuance->setFieldU64(sfLockedAmount, pay);
 
        view.update(sleIssuance);
    }
    return tesSUCCESS;
}
 
TER
rippleUnlockEscrowMPT(
    ApplyView& view,
    AccountID const& sender,
    AccountID const& receiver,
    STAmount const& amount,
    beast::Journal j)
{
    auto const issuer = amount.getIssuer();
    auto const mptIssue = amount.get<MPTIssue>();
    auto const mptID = keylet::mptIssuance(mptIssue.getMptID());
    auto sleIssuance = view.peek(mptID);
    if (!sleIssuance)
    {  // LCOV_EXCL_START
        JLOG(j.error()) << "rippleUnlockEscrowMPT: MPT issuance not found for "
                        << mptIssue.getMptID();
        return tecOBJECT_NOT_FOUND;
    }  // LCOV_EXCL_STOP
 
    // Decrease the Issuance EscrowedAmount
    {
        if (!sleIssuance->isFieldPresent(sfLockedAmount))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: no locked amount in issuance for "
                << mptIssue.getMptID();
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        auto const locked = sleIssuance->getFieldU64(sfLockedAmount);
        auto const redeem = amount.mpt().value();
 
        // Underflow check for subtraction
        if (!canSubtract(
                STAmount(mptIssue, locked), STAmount(mptIssue, redeem)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: insufficient locked amount for "
                << mptIssue.getMptID() << ": " << locked << " < " << redeem;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        auto const newLocked = locked - redeem;
        if (newLocked == 0)
            sleIssuance->makeFieldAbsent(sfLockedAmount);
        else
            sleIssuance->setFieldU64(sfLockedAmount, newLocked);
        view.update(sleIssuance);
    }
 
    if (issuer != receiver)
    {
        // Increase the MPT Holder MPTAmount
        auto const mptokenID = keylet::mptoken(mptID.key, receiver);
        auto sle = view.peek(mptokenID);
        if (!sle)
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: MPToken not found for " << receiver;
            return tecOBJECT_NOT_FOUND;  // LCOV_EXCL_LINE
        }  // LCOV_EXCL_STOP
 
        auto current = sle->getFieldU64(sfMPTAmount);
        auto delta = amount.mpt().value();
 
        // Overflow check for addition
        if (!canAdd(STAmount(mptIssue, current), STAmount(mptIssue, delta)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: overflow on MPTAmount for "
                << to_string(receiver) << ": " << current << " + " << delta;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        (*sle)[sfMPTAmount] += delta;
        view.update(sle);
    }
    else
    {
        // Decrease the Issuance OutstandingAmount
        auto const outstanding = sleIssuance->getFieldU64(sfOutstandingAmount);
        auto const redeem = amount.mpt().value();
 
        // Underflow check for subtraction
        if (!canSubtract(
                STAmount(mptIssue, outstanding), STAmount(mptIssue, redeem)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: insufficient outstanding amount for "
                << mptIssue.getMptID() << ": " << outstanding << " < "
                << redeem;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        sleIssuance->setFieldU64(sfOutstandingAmount, outstanding - redeem);
        view.update(sleIssuance);
    }
 
    if (issuer == sender)
    {  // LCOV_EXCL_START
        JLOG(j.error()) << "rippleUnlockEscrowMPT: sender is the issuer, "
                           "cannot unlock MPTs.";
        return tecINTERNAL;
    }  // LCOV_EXCL_STOP
    else
    {
        // Decrease the MPT Holder EscrowedAmount
        auto const mptokenID = keylet::mptoken(mptID.key, sender);
        auto sle = view.peek(mptokenID);
        if (!sle)
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: MPToken not found for " << sender;
            return tecOBJECT_NOT_FOUND;
        }  // LCOV_EXCL_STOP
 
        if (!sle->isFieldPresent(sfLockedAmount))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: no locked amount in MPToken for "
                << to_string(sender);
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        auto const locked = sle->getFieldU64(sfLockedAmount);
        auto const delta = amount.mpt().value();
 
        // Underflow check for subtraction
        // LCOV_EXCL_START
        if (!canSubtract(STAmount(mptIssue, locked), STAmount(mptIssue, delta)))
        {  // LCOV_EXCL_START
            JLOG(j.error())
                << "rippleUnlockEscrowMPT: insufficient locked amount for "
                << to_string(sender) << ": " << locked << " < " << delta;
            return tecINTERNAL;
        }  // LCOV_EXCL_STOP
 
        auto const newLocked = locked - delta;
        if (newLocked == 0)
            sle->makeFieldAbsent(sfLockedAmount);
        else
            sle->setFieldU64(sfLockedAmount, newLocked);
        view.update(sle);
    }
    return tesSUCCESS;
}
 
bool
after(NetClock::time_point now, std::uint32_t mark)
{
    return now.time_since_epoch().count() > mark;
}
 
}  // namespace ripple