#include "processor/operator/order_by/radix_sort.h"

#include <algorithm>

#include "common/system_config.h"
#include "function/comparison/comparison_functions.h"

using namespace lbug::common;

namespace lbug {
namespace processor {

static constexpr uint16_t COUNTING_ARRAY_SIZE = 256;
static constexpr uint64_t DATA_BLOCK_SIZE = common::TEMP_PAGE_SIZE;

RadixSort::RadixSort(storage::MemoryManager* memoryManager, FactorizedTable& factorizedTable,
    OrderByKeyEncoder& orderByKeyEncoder, std::vector<StrKeyColInfo> strKeyColsInfo)
    : tmpSortingResultBlock{std::make_unique<DataBlock>(memoryManager, DATA_BLOCK_SIZE)},
      tmpTuplePtrSortingBlock{std::make_unique<DataBlock>(memoryManager, DATA_BLOCK_SIZE)},
      factorizedTable{factorizedTable}, strKeyColsInfo{std::move(strKeyColsInfo)},
      numBytesPerTuple{orderByKeyEncoder.getNumBytesPerTuple()},
      numBytesToRadixSort{numBytesPerTuple - 8} {}

void RadixSort::sortSingleKeyBlock(const DataBlock& keyBlock) {
    auto numBytesSorted = 0ul;
    auto numTuplesInKeyBlock = keyBlock.numTuples;
    std::queue<TieRange> ties;
    // We need to sort the whole keyBlock for the first radix sort, so just mark all tuples as a
    // tie.
    ties.push(TieRange{0, numTuplesInKeyBlock - 1});
    for (auto i = 0u; i < strKeyColsInfo.size(); i++) {
        const auto numBytesToSort = strKeyColsInfo[i].colOffsetInEncodedKeyBlock - numBytesSorted +
                                    strKeyColsInfo[i].getEncodingSize();
        const auto numOfTies = ties.size();
        for (auto j = 0u; j < numOfTies; j++) {
            auto keyBlockTie = ties.front();
            ties.pop();
            radixSort(keyBlock.getData() + keyBlockTie.startingTupleIdx * numBytesPerTuple,
                keyBlockTie.getNumTuples(), numBytesSorted, numBytesToSort);

            auto newTiesInKeyBlock =
                findTies(keyBlock.getData() + keyBlockTie.startingTupleIdx * numBytesPerTuple +
                             numBytesSorted,
                    keyBlockTie.getNumTuples(), numBytesToSort, keyBlockTie.startingTupleIdx);
            for (auto& newTieInKeyBlock : newTiesInKeyBlock) {
                solveStringTies(newTieInKeyBlock,
                    keyBlock.getData() + newTieInKeyBlock.startingTupleIdx * numBytesPerTuple, ties,
                    strKeyColsInfo[i]);
            }
        }
        if (ties.empty()) {
            return;
        }
        numBytesSorted += numBytesToSort;
    }

    if (numBytesSorted < numBytesPerTuple) {
        while (!ties.empty()) {
            auto tie = ties.front();
            ties.pop();
            radixSort(keyBlock.getData() + tie.startingTupleIdx * numBytesPerTuple,
                tie.getNumTuples(), numBytesSorted, numBytesToRadixSort - numBytesSorted);
        }
    }
}

void RadixSort::radixSort(uint8_t* keyBlockPtr, uint32_t numTuplesToSort, uint32_t numBytesSorted,
    uint32_t numBytesToSort) {
    // We use radixSortLSD which sorts from the least significant byte to the most significant byte.
    auto tmpKeyBlockPtr = tmpSortingResultBlock->getData();
    keyBlockPtr += numBytesSorted;
    tmpKeyBlockPtr += numBytesSorted;
    uint32_t count[COUNTING_ARRAY_SIZE];
    auto isInTmpBlock = false;
    for (auto curByteIdx = 1ul; curByteIdx <= numBytesToSort; curByteIdx++) {
        memset(count, 0, COUNTING_ARRAY_SIZE * sizeof(uint32_t));
        auto sourcePtr = isInTmpBlock ? tmpKeyBlockPtr : keyBlockPtr;
        auto targetPtr = isInTmpBlock ? keyBlockPtr : tmpKeyBlockPtr;
        auto curByteOffset = numBytesToSort - curByteIdx;
        auto sortBytePtr = sourcePtr + curByteOffset;
        // counting sort
        for (auto j = 0ul; j < numTuplesToSort; j++) {
            count[*sortBytePtr]++;
            sortBytePtr += numBytesPerTuple;
        }
        auto maxCounter = count[0];
        for (auto val = 1ul; val < COUNTING_ARRAY_SIZE; val++) {
            maxCounter = std::max(count[val], maxCounter);
            count[val] = count[val] + count[val - 1];
        }
        // If all bytes have the same value (tie), continue on the next byte.
        if (maxCounter == numTuplesToSort) {
            continue;
        }
        // Reorder the data based on the count array.
        auto sourceTuplePtr = sourcePtr + (numTuplesToSort - 1) * numBytesPerTuple;
        for (auto j = 0ul; j < numTuplesToSort; j++) {
            auto targetTupleNum = --count[*(sourceTuplePtr + curByteOffset)];
            memcpy(targetPtr + targetTupleNum * numBytesPerTuple - numBytesSorted,
                sourceTuplePtr - numBytesSorted, numBytesPerTuple);
            sourceTuplePtr -= numBytesPerTuple;
        }
        isInTmpBlock = !isInTmpBlock;
    }
    // If the data is in the tmp block, copy the data from tmp block back.
    if (isInTmpBlock) {
        memcpy(keyBlockPtr - numBytesSorted, tmpKeyBlockPtr - numBytesSorted,
            numTuplesToSort * numBytesPerTuple);
    }
}

std::vector<TieRange> RadixSort::findTies(uint8_t* keyBlockPtr, uint32_t numTuplesToFindTies,
    uint32_t numBytesToSort, uint32_t baseTupleIdx) const {
    std::vector<TieRange> newTiesInKeyBlock;
    auto iTuplePtr = keyBlockPtr;
    for (auto i = 0u; i < numTuplesToFindTies - 1; i++) {
        auto j = i + 1;
        auto jTuplePtr = iTuplePtr + numBytesPerTuple;
        for (; j < numTuplesToFindTies; j++) {
            if (memcmp(iTuplePtr, jTuplePtr, numBytesToSort) != 0) {
                break;
            }
            jTuplePtr += numBytesPerTuple;
        }
        j--;
        if (i != j) {
            newTiesInKeyBlock.emplace_back(TieRange(i + baseTupleIdx, j + baseTupleIdx));
        }
        iTuplePtr = jTuplePtr;
        i = j;
    }
    return newTiesInKeyBlock;
}

void RadixSort::fillTmpTuplePtrSortingBlock(TieRange& keyBlockTie, uint8_t* keyBlockPtr) {
    auto tmpTuplePtrSortingBlockPtr = (uint8_t**)tmpTuplePtrSortingBlock->getData();
    for (auto i = 0ul; i < keyBlockTie.getNumTuples(); i++) {
        tmpTuplePtrSortingBlockPtr[i] = keyBlockPtr;
        keyBlockPtr += numBytesPerTuple;
    }
}

void RadixSort::reOrderKeyBlock(TieRange& keyBlockTie, uint8_t* keyBlockPtr) {
    auto tmpTuplePtrSortingBlockPtr = (uint8_t**)tmpTuplePtrSortingBlock->getData();
    auto tmpKeyBlockPtr = tmpSortingResultBlock->getData();
    for (auto i = 0ul; i < keyBlockTie.getNumTuples(); i++) {
        memcpy(tmpKeyBlockPtr, tmpTuplePtrSortingBlockPtr[i], numBytesPerTuple);
        tmpKeyBlockPtr += numBytesPerTuple;
    }
    memcpy(keyBlockPtr, tmpSortingResultBlock->getData(),
        keyBlockTie.getNumTuples() * numBytesPerTuple);
}

template<typename TYPE>
void RadixSort::findStringTies(TieRange& keyBlockTie, uint8_t* keyBlockPtr,
    std::queue<TieRange>& ties, StrKeyColInfo& keyColInfo) {
    auto iTuplePtr = keyBlockPtr;
    for (auto i = keyBlockTie.startingTupleIdx; i < keyBlockTie.endingTupleIdx; i++) {
        bool isIValNull = OrderByKeyEncoder::isNullVal(
            iTuplePtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
        // This variable will only be used when the current column is a string column. Otherwise,
        // we just set this variable to false.
        bool isIStringLong = OrderByKeyEncoder::isLongStr(
            iTuplePtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
        TYPE iValue =
            isIValNull ?
                TYPE() :
                factorizedTable.getData<TYPE>(
                    OrderByKeyEncoder::getEncodedFTBlockIdx(iTuplePtr + numBytesToRadixSort),
                    OrderByKeyEncoder::getEncodedFTBlockOffset(iTuplePtr + numBytesToRadixSort),
                    keyColInfo.colOffsetInFT);
        auto j = i + 1;
        auto jTuplePtr = iTuplePtr + numBytesPerTuple;
        for (; j <= keyBlockTie.endingTupleIdx; j++) {
            auto jTupleInfoPtr = jTuplePtr + numBytesToRadixSort;
            bool isJValNull = OrderByKeyEncoder::isNullVal(
                jTuplePtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
            if (isIValNull && isJValNull) {
                // If the left value and the right value are nulls, we can just continue on
                // the next tuple.
                jTupleInfoPtr += numBytesPerTuple;
                continue;
            } else if (isIValNull || isJValNull) {
                // If only one value is null, we can just conclude that those two values are
                // not equal.
                break;
            }
            if constexpr (std::is_same<TYPE, string_t>::value) {
                // We do an optimization here to minimize the number of times that we fetch
                // tuples from factorizedTable. If both left and right string are short, they
                // must equal to each other (since they have the same prefix). If one string is
                // short and the other string is long, then they must not equal to each other.
                bool isJStringLong = OrderByKeyEncoder::isLongStr(
                    jTuplePtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
                if (!isIStringLong && !isJStringLong) {
                    jTupleInfoPtr += numBytesPerTuple;
                    continue;
                } else if (isIStringLong != isJStringLong) {
                    break;
                }
            }

            uint8_t result = UINT8_MAX;
            function::NotEquals::operation<TYPE, TYPE>(iValue,
                factorizedTable.getData<TYPE>(
                    OrderByKeyEncoder::getEncodedFTBlockIdx(jTupleInfoPtr),
                    OrderByKeyEncoder::getEncodedFTBlockOffset(jTupleInfoPtr),
                    keyColInfo.colOffsetInFT),
                result, nullptr /* leftVector */, nullptr /* rightVector */);
            if (result) {
                break;
            }
            jTuplePtr += numBytesPerTuple;
        }
        j--;
        if (i != j) {
            ties.push(TieRange(i, j));
        }
        i = j;
        iTuplePtr = jTuplePtr;
    }
}

void RadixSort::solveStringTies(TieRange& keyBlockTie, uint8_t* keyBlockPtr,
    std::queue<TieRange>& ties, StrKeyColInfo& keyColInfo) {
    fillTmpTuplePtrSortingBlock(keyBlockTie, keyBlockPtr);
    auto tmpTuplePtrSortingBlockPtr = (uint8_t**)tmpTuplePtrSortingBlock->getData();
    std::sort(tmpTuplePtrSortingBlockPtr, tmpTuplePtrSortingBlockPtr + keyBlockTie.getNumTuples(),
        [this, keyColInfo](const uint8_t* leftPtr, const uint8_t* rightPtr) -> bool {
            auto isLeftNull = OrderByKeyEncoder::isNullVal(
                leftPtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
            auto isRightNull = OrderByKeyEncoder::isNullVal(
                rightPtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
            // Handle null value comparison.
            if (isLeftNull && isRightNull) {
                // If left and right strings are both null, we can't conclude that the left string
                // is smaller than the right string.
                return false;
            } else if (isLeftNull) {
                return !keyColInfo.isAscOrder;
            } else if (isRightNull) {
                return keyColInfo.isAscOrder;
            }

            // We only need to fetch the actual strings from the
            // factorizedTable when both left and right strings are long string.
            auto isLeftLongStr = OrderByKeyEncoder::isLongStr(
                leftPtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
            auto isRightLongStr = OrderByKeyEncoder::isLongStr(
                rightPtr + keyColInfo.colOffsetInEncodedKeyBlock, keyColInfo.isAscOrder);
            if (!isLeftLongStr && !isRightLongStr) {
                // If left and right are both short string and have the same prefix, we can't
                // conclude that the left string is smaller than the right string.
                return false;
            } else if (isLeftLongStr && !isRightLongStr) {
                // If left string is a long string and right string is a short string, we can
                // conclude that the left string must be greater than the right string.
                return !keyColInfo.isAscOrder;
            } else if (isRightLongStr && !isLeftLongStr) {
                // If right string is a long string and left string is a short string, we can
                // conclude that the right string must be greater than the left string.
                return keyColInfo.isAscOrder;
            }
            auto leftTupleInfoPtr = leftPtr + numBytesToRadixSort;
            auto rightTupleInfoPtr = rightPtr + numBytesToRadixSort;
            const auto leftBlockIdx = OrderByKeyEncoder::getEncodedFTBlockIdx(leftTupleInfoPtr);
            const auto leftBlockOffset =
                OrderByKeyEncoder::getEncodedFTBlockOffset(leftTupleInfoPtr);
            const auto rightBlockIdx = OrderByKeyEncoder::getEncodedFTBlockIdx(rightTupleInfoPtr);
            const auto rightBlockOffset =
                OrderByKeyEncoder::getEncodedFTBlockOffset(rightTupleInfoPtr);
            auto leftStr = factorizedTable.getData<string_t>(leftBlockIdx, leftBlockOffset,
                keyColInfo.colOffsetInFT);
            auto rightStr = factorizedTable.getData<string_t>(rightBlockIdx, rightBlockOffset,
                keyColInfo.colOffsetInFT);
            return keyColInfo.isAscOrder ? leftStr < rightStr : leftStr > rightStr;
        });
    reOrderKeyBlock(keyBlockTie, keyBlockPtr);
    findStringTies<string_t>(keyBlockTie, keyBlockPtr, ties, keyColInfo);
}

} // namespace processor
} // namespace lbug
