#include "data/BackendInterface.hpp"

#include "data/Types.hpp"
#include "util/Assert.hpp"
#include "util/log/Logger.hpp"

#include <boost/asio/spawn.hpp>
#include <xrpl/basics/base_uint.h>
#include <xrpl/basics/strHex.h>
#include <xrpl/protocol/Fees.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/Serializer.h>

#include <chrono>
#include <cstddef>
#include <cstdint>
#include <mutex>
#include <optional>
#include <shared_mutex>
#include <sstream>
#include <string>
#include <utility>
#include <vector>

/**
 * @brief This namespace implements the data access layer and related components.
 *
 * The data layer is responsible for fetching and storing data from the database.
 * Cassandra and ScyllaDB are currently supported via the `CassandraBackend` implementation.
 */
namespace data {
bool
BackendInterface::finishWrites(std::uint32_t const ledgerSequence)
{
    LOG(log_.debug()) << "Want finish writes for " << ledgerSequence;
    auto commitRes = doFinishWrites();
    if (commitRes) {
        LOG(log_.debug()) << "Successfully committed. Updating range now to " << ledgerSequence;
        updateRange(ledgerSequence);
    }
    return commitRes;
}
void
BackendInterface::writeLedgerObject(std::string&& key, std::uint32_t const seq, std::string&& blob)
{
    ASSERT(key.size() == sizeof(ripple::uint256), "Key must be 256 bits");
    doWriteLedgerObject(std::move(key), seq, std::move(blob));
}

std::optional<LedgerRange>
BackendInterface::hardFetchLedgerRangeNoThrow() const
{
    return retryOnTimeout([&]() { return hardFetchLedgerRange(); });
}

// *** state data methods
std::optional<Blob>
BackendInterface::fetchLedgerObject(
    ripple::uint256 const& key,
    std::uint32_t const sequence,
    boost::asio::yield_context yield
) const
{
    auto obj = cache_.get().get(key, sequence);
    if (obj) {
        LOG(log_.trace()) << "Cache hit - " << ripple::strHex(key);
        return obj;
    }

    auto dbObj = doFetchLedgerObject(key, sequence, yield);
    if (!dbObj) {
        LOG(log_.trace()) << "Missed cache and missed in db";
    } else {
        LOG(log_.trace()) << "Missed cache but found in db";
    }
    return dbObj;
}

std::optional<std::uint32_t>
BackendInterface::fetchLedgerObjectSeq(
    ripple::uint256 const& key,
    std::uint32_t const sequence,
    boost::asio::yield_context yield
) const
{
    auto seq = doFetchLedgerObjectSeq(key, sequence, yield);
    if (!seq)
        LOG(log_.trace()) << "Missed in db";
    return seq;
}

std::vector<Blob>
BackendInterface::fetchLedgerObjects(
    std::vector<ripple::uint256> const& keys,
    std::uint32_t const sequence,
    boost::asio::yield_context yield
) const
{
    std::vector<Blob> results;
    results.resize(keys.size());
    std::vector<ripple::uint256> misses;
    for (size_t i = 0; i < keys.size(); ++i) {
        auto obj = cache_.get().get(keys[i], sequence);
        if (obj) {
            results[i] = *obj;
        } else {
            misses.push_back(keys[i]);
        }
    }
    LOG(log_.trace()) << "Cache hits = " << keys.size() - misses.size()
                      << " - cache misses = " << misses.size();

    if (!misses.empty()) {
        auto objs = doFetchLedgerObjects(misses, sequence, yield);
        for (size_t i = 0, j = 0; i < results.size(); ++i) {
            if (results[i].empty()) {
                results[i] = objs[j];
                ++j;
            }
        }
    }

    return results;
}

// Fetches the successor to key/index
std::optional<ripple::uint256>
BackendInterface::fetchSuccessorKey(
    ripple::uint256 key,
    std::uint32_t const ledgerSequence,
    boost::asio::yield_context yield
) const
{
    auto succ = cache_.get().getSuccessor(key, ledgerSequence);
    if (succ) {
        LOG(log_.trace()) << "Cache hit - " << ripple::strHex(key);
    } else {
        LOG(log_.trace()) << "Cache miss - " << ripple::strHex(key);
    }
    return succ ? succ->key : doFetchSuccessorKey(key, ledgerSequence, yield);
}

std::optional<LedgerObject>
BackendInterface::fetchSuccessorObject(
    ripple::uint256 key,
    std::uint32_t const ledgerSequence,
    boost::asio::yield_context yield
) const
{
    auto succ = fetchSuccessorKey(key, ledgerSequence, yield);
    if (succ) {
        auto obj = fetchLedgerObject(*succ, ledgerSequence, yield);
        if (!obj)
            return {{.key = *succ, .blob = {}}};

        return {{.key = *succ, .blob = *obj}};
    }
    return {};
}

BookOffersPage
BackendInterface::fetchBookOffers(
    ripple::uint256 const& book,
    std::uint32_t const ledgerSequence,
    std::uint32_t const limit,
    boost::asio::yield_context yield
) const
{
    // TODO try to speed this up. This can take a few seconds. The goal is
    // to get it down to a few hundred milliseconds.
    BookOffersPage page;
    ripple::uint256 const bookEnd = ripple::getQualityNext(book);
    ripple::uint256 uTipIndex = book;
    std::vector<ripple::uint256> keys;
    auto getMillis = [](auto diff) {
        return std::chrono::duration_cast<std::chrono::milliseconds>(diff).count();
    };
    auto begin = std::chrono::system_clock::now();
    std::uint32_t numSucc = 0;
    std::uint32_t numPages = 0;
    long succMillis = 0;
    long pageMillis = 0;
    while (keys.size() < limit) {
        auto mid1 = std::chrono::system_clock::now();
        auto offerDir = fetchSuccessorObject(uTipIndex, ledgerSequence, yield);
        auto mid2 = std::chrono::system_clock::now();
        numSucc++;
        succMillis += getMillis(mid2 - mid1);
        if (!offerDir || offerDir->key >= bookEnd) {
            LOG(log_.trace()) << "offerDir.has_value() " << offerDir.has_value() << " breaking";
            break;
        }
        uTipIndex = offerDir->key;
        while (keys.size() < limit) {
            ++numPages;
            ripple::STLedgerEntry const sle{
                ripple::SerialIter{offerDir->blob.data(), offerDir->blob.size()}, offerDir->key
            };
            auto indexes = sle.getFieldV256(ripple::sfIndexes);
            keys.insert(keys.end(), indexes.begin(), indexes.end());
            auto next = sle.getFieldU64(ripple::sfIndexNext);
            if (next == 0u) {
                LOG(log_.trace()) << "Next is empty. breaking";
                break;
            }
            auto nextKey = ripple::keylet::page(uTipIndex, next);
            auto nextDir = fetchLedgerObject(nextKey.key, ledgerSequence, yield);
            ASSERT(nextDir.has_value(), "Next dir must exist");
            offerDir->blob = *nextDir;
            offerDir->key = nextKey.key;
        }
        auto mid3 = std::chrono::system_clock::now();
        pageMillis += getMillis(mid3 - mid2);
    }
    auto mid = std::chrono::system_clock::now();
    auto objs = fetchLedgerObjects(keys, ledgerSequence, yield);
    for (size_t i = 0; i < keys.size() && i < limit; ++i) {
        LOG(log_.trace()) << "Key = " << ripple::strHex(keys[i])
                          << " blob = " << ripple::strHex(objs[i])
                          << " ledgerSequence = " << ledgerSequence;
        ASSERT(!objs[i].empty(), "Ledger object can't be empty");
        page.offers.push_back({keys[i], objs[i]});
    }
    auto end = std::chrono::system_clock::now();
    LOG(log_.debug()) << "Fetching " << std::to_string(keys.size()) << " offers took "
                      << std::to_string(getMillis(mid - begin))
                      << " milliseconds. Fetching next dir took " << std::to_string(succMillis)
                      << " milliseconds. Fetched next dir " << std::to_string(numSucc) << " times"
                      << " Fetching next page of dir took " << std::to_string(pageMillis)
                      << " milliseconds"
                      << ". num pages = " << std::to_string(numPages)
                      << ". Fetching all objects took " << std::to_string(getMillis(end - mid))
                      << " milliseconds. total time = " << std::to_string(getMillis(end - begin))
                      << " milliseconds"
                      << " book = " << ripple::strHex(book);

    return page;
}

std::optional<LedgerRange>
BackendInterface::hardFetchLedgerRange() const
{
    return synchronous([this](auto yield) { return hardFetchLedgerRange(yield); });
}

std::optional<LedgerRange>
BackendInterface::fetchLedgerRange() const
{
    std::shared_lock const lck(rngMtx_);
    return range_;
}

void
BackendInterface::updateRange(uint32_t newMax)
{
    std::scoped_lock const lck(rngMtx_);

    if (range_.has_value() and newMax < range_->maxSequence) {
        ASSERT(
            false,
            "Range shouldn't exist yet or newMax should be at least range->maxSequence. newMax = "
            "{}, "
            "range->maxSequence = {}",
            newMax,
            range_->maxSequence
        );
    }

    updateRangeImpl(newMax);
}

void
BackendInterface::forceUpdateRange(uint32_t newMax)
{
    std::scoped_lock const lck(rngMtx_);
    updateRangeImpl(newMax);
}

void
BackendInterface::setRange(uint32_t min, uint32_t max, bool force)
{
    std::scoped_lock const lck(rngMtx_);

    if (!force) {
        ASSERT(min <= max, "Range min must be less than or equal to max");
        ASSERT(not range_.has_value(), "Range was already set");
    }

    range_ = {.minSequence = min, .maxSequence = max};
}

LedgerPage
BackendInterface::fetchLedgerPage(
    std::optional<ripple::uint256> const& cursor,
    std::uint32_t const ledgerSequence,
    std::uint32_t const limit,
    bool outOfOrder,
    boost::asio::yield_context yield
)
{
    LedgerPage page;

    std::vector<ripple::uint256> keys;
    bool reachedEnd = false;

    while (keys.size() < limit && !reachedEnd) {
        ripple::uint256 const& curCursor = [&]() {
            if (!keys.empty())
                return keys.back();
            return (cursor ? *cursor : kFIRST_KEY);
        }();

        std::uint32_t const seq = outOfOrder ? range_->maxSequence : ledgerSequence;
        auto succ = fetchSuccessorKey(curCursor, seq, yield);

        if (!succ) {
            reachedEnd = true;
        } else {
            keys.push_back(*succ);
        }
    }

    auto objects = fetchLedgerObjects(keys, ledgerSequence, yield);
    for (size_t i = 0; i < objects.size(); ++i) {
        if (!objects[i].empty()) {
            page.objects.push_back({keys[i], std::move(objects[i])});
        } else if (!outOfOrder) {
            LOG(log_.error()) << "Deleted or non-existent object in successor table. key = "
                              << ripple::strHex(keys[i]) << " - seq = " << ledgerSequence;
            std::stringstream msg;
            for (size_t j = 0; j < objects.size(); ++j) {
                msg << " - " << ripple::strHex(keys[j]);
            }
            LOG(log_.error()) << msg.str();

            if (corruptionDetector_.has_value())
                corruptionDetector_->onCorruptionDetected();
        }
    }
    if (!keys.empty() && !reachedEnd)
        page.cursor = keys.back();

    return page;
}

std::optional<ripple::Fees>
BackendInterface::fetchFees(std::uint32_t const seq, boost::asio::yield_context yield) const
{
    ripple::Fees fees;

    auto key = ripple::keylet::fees().key;
    auto bytes = fetchLedgerObject(key, seq, yield);

    if (!bytes) {
        LOG(log_.error()) << "Could not find fees";
        return {};
    }

    ripple::SerialIter it(bytes->data(), bytes->size());
    ripple::SLE const sle{it, key};

    // XRPFees amendment introduced new fields for fees calculations.
    // New fields are set and the old fields are removed via `set_fees` tx.
    // Fallback to old fields if `set_fees` was not yet used to update the fields on this tx.
    auto hasNewFields = false;
    {
        auto const baseFeeXRP = sle.at(~ripple::sfBaseFeeDrops);
        auto const reserveBaseXRP = sle.at(~ripple::sfReserveBaseDrops);
        auto const reserveIncrementXRP = sle.at(~ripple::sfReserveIncrementDrops);

        if (baseFeeXRP)
            fees.base = baseFeeXRP->xrp();

        if (reserveBaseXRP)
            fees.reserve = reserveBaseXRP->xrp();

        if (reserveIncrementXRP)
            fees.increment = reserveIncrementXRP->xrp();

        hasNewFields = baseFeeXRP || reserveBaseXRP || reserveIncrementXRP;
    }

    if (not hasNewFields) {
        // Fallback to old fields
        auto const baseFee = sle.at(~ripple::sfBaseFee);
        auto const reserveBase = sle.at(~ripple::sfReserveBase);
        auto const reserveIncrement = sle.at(~ripple::sfReserveIncrement);

        if (baseFee)
            fees.base = baseFee.value();

        if (reserveBase)
            fees.reserve = reserveBase.value();

        if (reserveIncrement)
            fees.increment = reserveIncrement.value();
    }

    return fees;
}

void
BackendInterface::updateRangeImpl(uint32_t newMax)
{
    if (!range_.has_value()) {
        range_ = {.minSequence = newMax, .maxSequence = newMax};
    } else {
        range_->maxSequence = newMax;
    }
}

}  // namespace data