Offer.h

#pragma once
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/contract.h>
#include <xrpl/ledger/View.h>
#include <xrpl/protocol/Quality.h>
#include <xrpl/protocol/Rules.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STLedgerEntry.h>
 
#include <stdexcept>
 
namespace xrpl {
 
template <class TIn, class TOut>
class TOfferBase
{
protected:
    Issue issIn_;
    Issue issOut_;
};
 
template <>
class TOfferBase<STAmount, STAmount>
{
public:
    explicit TOfferBase() = default;
};
 
template <class TIn = STAmount, class TOut = STAmount>
class TOffer : private TOfferBase<TIn, TOut>
{
private:
    SLE::pointer m_entry;
    Quality m_quality;
    AccountID m_account;
 
    TAmounts<TIn, TOut> m_amounts;
    void
    setFieldAmounts();
 
public:
    TOffer() = default;
 
    TOffer(SLE::pointer const& entry, Quality quality);
 
    Quality
    quality() const noexcept
    {
        return m_quality;
    }
 
    AccountID const&
    owner() const
    {
        return m_account;
    }
 
    TAmounts<TIn, TOut> const&
    amount() const
    {
        return m_amounts;
    }
 
    bool
    fully_consumed() const
    {
        if (m_amounts.in <= beast::zero)
            return true;
        if (m_amounts.out <= beast::zero)
            return true;
        return false;
    }
 
    void
    consume(ApplyView& view, TAmounts<TIn, TOut> const& consumed)
    {
        if (consumed.in > m_amounts.in)
            Throw<std::logic_error>("can't consume more than is available.");
 
        if (consumed.out > m_amounts.out)
            Throw<std::logic_error>("can't produce more than is available.");
 
        m_amounts -= consumed;
        setFieldAmounts();
        view.update(m_entry);
    }
 
    std::string
    id() const
    {
        return to_string(m_entry->key());
    }
 
    std::optional<uint256>
    key() const
    {
        return m_entry->key();
    }
 
    Issue const&
    issueIn() const;
    Issue const&
    issueOut() const;
 
    TAmounts<TIn, TOut>
    limitOut(TAmounts<TIn, TOut> const& offerAmount, TOut const& limit, bool roundUp) const;
 
    TAmounts<TIn, TOut>
    limitIn(TAmounts<TIn, TOut> const& offerAmount, TIn const& limit, bool roundUp) const;
 
    template <typename... Args>
    static TER
    send(Args&&... args);
 
    bool
    isFunded() const
    {
        // Offer owner is issuer; they have unlimited funds
        return m_account == issueOut().account;
    }
 
    static std::pair<std::uint32_t, std::uint32_t>
    adjustRates(std::uint32_t ofrInRate, std::uint32_t ofrOutRate)
    {
        // CLOB offer pays the transfer fee
        return {ofrInRate, ofrOutRate};
    }
 
    bool
    checkInvariant(TAmounts<TIn, TOut> const& consumed, beast::Journal j) const
    {
        if (!isFeatureEnabled(fixAMMv1_3))
            return true;
 
        if (consumed.in > m_amounts.in || consumed.out > m_amounts.out)
        {
            // LCOV_EXCL_START
            JLOG(j.error()) << "AMMOffer::checkInvariant failed: consumed " << to_string(consumed.in) << " "
                            << to_string(consumed.out) << " amounts " << to_string(m_amounts.in) << " "
                            << to_string(m_amounts.out);
 
            return false;
            // LCOV_EXCL_STOP
        }
 
        return true;
    }
};
 
using Offer = TOffer<>;
 
template <class TIn, class TOut>
TOffer<TIn, TOut>::TOffer(SLE::pointer const& entry, Quality quality)
    : m_entry(entry), m_quality(quality), m_account(m_entry->getAccountID(sfAccount))
{
    auto const tp = m_entry->getFieldAmount(sfTakerPays);
    auto const tg = m_entry->getFieldAmount(sfTakerGets);
    m_amounts.in = toAmount<TIn>(tp);
    m_amounts.out = toAmount<TOut>(tg);
    this->issIn_ = tp.issue();
    this->issOut_ = tg.issue();
}
 
template <>
inline TOffer<STAmount, STAmount>::TOffer(SLE::pointer const& entry, Quality quality)
    : m_entry(entry)
    , m_quality(quality)
    , m_account(m_entry->getAccountID(sfAccount))
    , m_amounts(m_entry->getFieldAmount(sfTakerPays), m_entry->getFieldAmount(sfTakerGets))
{
}
 
template <class TIn, class TOut>
void
TOffer<TIn, TOut>::setFieldAmounts()
{
    // LCOV_EXCL_START
#ifdef _MSC_VER
    UNREACHABLE("xrpl::TOffer::setFieldAmounts : must be specialized");
#else
    static_assert(sizeof(TOut) == -1, "Must be specialized");
#endif
    // LCOV_EXCL_STOP
}
 
template <class TIn, class TOut>
TAmounts<TIn, TOut>
TOffer<TIn, TOut>::limitOut(TAmounts<TIn, TOut> const& offerAmount, TOut const& limit, bool roundUp) const
{
    // It turns out that the ceil_out implementation has some slop in
    // it, which ceil_out_strict removes.
    return quality().ceil_out_strict(offerAmount, limit, roundUp);
}
 
template <class TIn, class TOut>
TAmounts<TIn, TOut>
TOffer<TIn, TOut>::limitIn(TAmounts<TIn, TOut> const& offerAmount, TIn const& limit, bool roundUp) const
{
    if (auto const& rules = getCurrentTransactionRules(); rules && rules->enabled(fixReducedOffersV2))
        // It turns out that the ceil_in implementation has some slop in
        // it.  ceil_in_strict removes that slop.  But removing that slop
        // affects transaction outcomes, so the change must be made using
        // an amendment.
        return quality().ceil_in_strict(offerAmount, limit, roundUp);
    return m_quality.ceil_in(offerAmount, limit);
}
 
template <class TIn, class TOut>
template <typename... Args>
TER
TOffer<TIn, TOut>::send(Args&&... args)
{
    return accountSend(std::forward<Args>(args)...);
}
 
template <>
inline void
TOffer<STAmount, STAmount>::setFieldAmounts()
{
    m_entry->setFieldAmount(sfTakerPays, m_amounts.in);
    m_entry->setFieldAmount(sfTakerGets, m_amounts.out);
}
 
template <>
inline void
TOffer<IOUAmount, IOUAmount>::setFieldAmounts()
{
    m_entry->setFieldAmount(sfTakerPays, toSTAmount(m_amounts.in, issIn_));
    m_entry->setFieldAmount(sfTakerGets, toSTAmount(m_amounts.out, issOut_));
}
 
template <>
inline void
TOffer<IOUAmount, XRPAmount>::setFieldAmounts()
{
    m_entry->setFieldAmount(sfTakerPays, toSTAmount(m_amounts.in, issIn_));
    m_entry->setFieldAmount(sfTakerGets, toSTAmount(m_amounts.out));
}
 
template <>
inline void
TOffer<XRPAmount, IOUAmount>::setFieldAmounts()
{
    m_entry->setFieldAmount(sfTakerPays, toSTAmount(m_amounts.in));
    m_entry->setFieldAmount(sfTakerGets, toSTAmount(m_amounts.out, issOut_));
}
 
template <class TIn, class TOut>
Issue const&
TOffer<TIn, TOut>::issueIn() const
{
    return this->issIn_;
}
 
template <>
inline Issue const&
TOffer<STAmount, STAmount>::issueIn() const
{
    return m_amounts.in.issue();
}
 
template <class TIn, class TOut>
Issue const&
TOffer<TIn, TOut>::issueOut() const
{
    return this->issOut_;
}
 
template <>
inline Issue const&
TOffer<STAmount, STAmount>::issueOut() const
{
    return m_amounts.out.issue();
}
 
template <class TIn, class TOut>
inline std::ostream&
operator<<(std::ostream& os, TOffer<TIn, TOut> const& offer)
{
    return os << offer.id();
}
 
}  // namespace xrpl