/*
    SPDX-FileCopyrightText: 2015-2020 Milian Wolff <mail@milianw.de>

    SPDX-License-Identifier: LGPL-2.1-or-later
*/

#include "accumulatedtracedata.h"
#include "analyze_config.h"

#include <algorithm>
#include <cassert>
#include <iostream>
#include <memory>

#include <boost/algorithm/string/predicate.hpp>
#include <boost/iostreams/filter/gzip.hpp>
#if ZSTD_FOUND
#if BOOST_IOSTREAMS_HAS_ZSTD
#include <boost/iostreams/filter/zstd.hpp>
#else
#include <boost-zstd/zstd.hpp>
#endif
#endif
#include <boost/iostreams/filtering_stream.hpp>

#include <boost/filesystem.hpp>

#include "util/config.h"
#include "util/linereader.h"
#include "util/pointermap.h"

#include "suppressions.h"

#ifdef __GNUC__
#define POTENTIALLY_UNUSED __attribute__((unused))
#else
#define POTENTIALLY_UNUSED
#endif

using namespace std;

namespace {

template <typename Base>
bool operator>>(LineReader& reader, Index<Base>& index)
{
    return reader.readHex(index.index);
}

template <typename Base>
ostream& operator<<(ostream& out, const Index<Base> index)
{
    out << index.index;
    return out;
}

// boost's counter filter uses an int for the count which overflows for large streams; so replace it with a work alike.
class byte_counter
{
public:
    using char_type = char;
    using category = boost::iostreams::multichar_input_filter_tag;

    uint64_t bytes() const
    {
        return m_bytes;
    }

    template <typename Source>
    std::streamsize read(Source& src, char* str, std::streamsize size)
    {
        auto const readsize = boost::iostreams::read(src, str, size);
        if (readsize == -1)
            return -1;
        m_bytes += readsize;
        return readsize;
    }

private:
    uint64_t m_bytes = 0;
};
}

AccumulatedTraceData::AccumulatedTraceData()
{
    instructionPointers.reserve(16384);
    traces.reserve(65536);
    strings.reserve(4096);
    allocations.reserve(16384);
    traceIndexToAllocationIndex.reserve(16384);
    stopIndices.reserve(4);
    opNewIpIndices.reserve(16);
}

AccumulatedTraceData::~AccumulatedTraceData() = default;

const string& AccumulatedTraceData::stringify(const StringIndex stringId) const
{
    if (!stringId || stringId.index > strings.size()) {
        static const string empty;
        return empty;
    } else {
        return strings.at(stringId.index - 1);
    }
}

string AccumulatedTraceData::prettyFunction(const string& function) const
{
    if (!shortenTemplates) {
        return function;
    }
    string ret;
    ret.reserve(function.size());
    int depth = 0;
    for (size_t i = 0; i < function.size(); ++i) {
        const auto c = function[i];
        if ((c == '<' || c == '>') && ret.size() >= 8) {
            // don't get confused by C++ operators
            const char* cmp = "operator";
            if (ret.back() == c) {
                // skip second angle bracket for operator<< or operator>>
                if (c == '<') {
                    cmp = "operator<";
                } else {
                    cmp = "operator>";
                }
            }
            if (boost::algorithm::ends_with(ret, cmp)) {
                ret.push_back(c);
                continue;
            }
        }
        if (c == '<') {
            ++depth;
            if (depth == 1) {
                ret.push_back(c);
            }
        } else if (c == '>') {
            --depth;
        }
        if (depth) {
            continue;
        }
        ret.push_back(c);
    }
    return ret;
}

bool AccumulatedTraceData::read(const string& inputFile, bool isReparsing)
{
    return read(inputFile, FirstPass, isReparsing) && read(inputFile, SecondPass, isReparsing);
}

bool AccumulatedTraceData::read(const string& inputFile, const ParsePass pass, bool isReparsing)
{
    const bool isGzCompressed = boost::algorithm::ends_with(inputFile, ".gz");
    const bool isZstdCompressed = boost::algorithm::ends_with(inputFile, ".zst");
    const bool isCompressed = isGzCompressed || isZstdCompressed;
    ifstream file(inputFile, isCompressed ? ios_base::in | ios_base::binary : ios_base::in);

    if (!file.is_open()) {
        cerr << "Failed to open heaptrack log file: " << inputFile << endl;
        return false;
    }

    boost::iostreams::filtering_istream in;
    in.push(byte_counter()); // caution, ::read dependant on filter order
    if (isGzCompressed) {
        in.push(boost::iostreams::gzip_decompressor());
    } else if (isZstdCompressed) {
#if ZSTD_FOUND
        in.push(boost::iostreams::zstd_decompressor());
#else
        cerr << "Heaptrack was built without zstd support, cannot decompressed data file: " << inputFile << endl;
        return false;
#endif
    }
    in.push(byte_counter()); // caution, ::read dependant on filter order
    in.push(file);

    parsingState.fileSize = boost::filesystem::file_size(inputFile);

    return read(in, pass, isReparsing);
}

bool AccumulatedTraceData::read(boost::iostreams::filtering_istream& in, const ParsePass pass, bool isReparsing)
{
    LineReader reader;
    int64_t timeStamp = 0;

    vector<string> opNewStrings = {
        // 64 bit
        "operator new(unsigned long)",
        "operator new[](unsigned long)",
        // 32 bit
        "operator new(unsigned int)",
        "operator new[](unsigned int)",
    };
    vector<StringIndex> opNewStrIndices;
    opNewStrIndices.reserve(opNewStrings.size());

    vector<string> stopStrings = {"main", "__libc_start_main", "__static_initialization_and_destruction_0"};

    const auto lastPeakCost = pass != FirstPass ? totalCost.peak : 0;
    const auto lastPeakTime = pass != FirstPass ? peakTime : 0;

    totalCost = {};
    peakTime = 0;
    if (pass == FirstPass) {
        if (!filterParameters.disableBuiltinSuppressions) {
            suppressions = builtinSuppressions();
        }

        suppressions.resize(suppressions.size() + filterParameters.suppressions.size());
        std::transform(filterParameters.suppressions.begin(), filterParameters.suppressions.end(), suppressions.begin(),
                       [](const std::string& pattern) {
                           return Suppression {pattern, 0, 0};
                       });
    }
    peakRSS = 0;
    for (auto& allocation : allocations) {
        allocation.clearCost();
    }
    unsigned int fileVersion = 0;
    bool debuggeeEncountered = false;
    bool inFilteredTime = !filterParameters.minTime;

    // required for backwards compatibility
    // newer versions handle this in heaptrack_interpret already
    AllocationInfoSet allocationInfoSet;
    PointerMap pointers;
    // in older files, this contains the pointer address, in newer formats
    // it holds the allocation info index. both can be used to find temporary
    // allocations, i.e. when a deallocation follows with the same data
    uint64_t lastAllocationPtr = 0;

    const auto uncompressedCount = in.component<byte_counter>(0);
    const auto compressedCount = in.component<byte_counter>(in.size() - 2);

    parsingState.pass = pass;
    parsingState.reparsing = isReparsing;

    while (timeStamp < filterParameters.maxTime && reader.getLine(in)) {
        parsingState.readCompressedByte = compressedCount->bytes();
        parsingState.readUncompressedByte = uncompressedCount->bytes();
        parsingState.timestamp = timeStamp;

        if (reader.mode() == 's') {
            if (pass != FirstPass || isReparsing) {
                continue;
            }
            if (fileVersion >= 3) {
                // read sized string directly
                std::string string;
                reader >> string;
                strings.push_back(std::move(string));
            } else {
                // read remaining line as string, possibly including white spaces
                strings.push_back(reader.line().substr(2));
            }

            StringIndex index;
            index.index = strings.size();

            auto opNewIt = find(opNewStrings.begin(), opNewStrings.end(), strings.back());
            if (opNewIt != opNewStrings.end()) {
                opNewStrIndices.push_back(index);
                opNewStrings.erase(opNewIt);
            } else {
                auto stopIt = find(stopStrings.begin(), stopStrings.end(), strings.back());
                if (stopIt != stopStrings.end()) {
                    stopIndices.push_back(index);
                    stopStrings.erase(stopIt);
                }
            }
        } else if (reader.mode() == 't') {
            if (pass != FirstPass || isReparsing) {
                continue;
            }
            TraceNode node;
            reader >> node.ipIndex;
            reader >> node.parentIndex;
            // skip operator new and operator new[] at the beginning of traces
            while (find(opNewIpIndices.begin(), opNewIpIndices.end(), node.ipIndex) != opNewIpIndices.end()) {
                node = findTrace(node.parentIndex);
            }
            traces.push_back(node);
        } else if (reader.mode() == 'i') {
            if (pass != FirstPass || isReparsing) {
                continue;
            }
            InstructionPointer ip;
            reader >> ip.instructionPointer;
            reader >> ip.moduleIndex;
            auto readFrame = [&reader](Frame* frame) {
                return (reader >> frame->functionIndex) && (reader >> frame->fileIndex) && (reader >> frame->line);
            };
            if (readFrame(&ip.frame)) {
                Frame inlinedFrame;
                while (readFrame(&inlinedFrame)) {
                    ip.inlined.push_back(inlinedFrame);
                }
            }

            instructionPointers.push_back(ip);
            if (find(opNewStrIndices.begin(), opNewStrIndices.end(), ip.frame.functionIndex) != opNewStrIndices.end()) {
                IpIndex index;
                index.index = instructionPointers.size();
                opNewIpIndices.push_back(index);
            }
        } else if (reader.mode() == '+') {
            if (!inFilteredTime) {
                continue;
            }
            AllocationInfo info;
            AllocationInfoIndex allocationIndex;
            if (fileVersion >= 1) {
                if (!(reader >> allocationIndex)) {
                    cerr << "failed to parse line: " << reader.line() << ' ' << __LINE__ << endl;
                    continue;
                } else if (allocationIndex.index >= allocationInfos.size()) {
                    cerr << "allocation index out of bounds: " << allocationIndex
                         << ", maximum is: " << allocationInfos.size() << endl;
                    continue;
                }
                info = allocationInfos[allocationIndex.index];
                lastAllocationPtr = allocationIndex.index;
            } else { // backwards compatibility
                uint64_t ptr = 0;
                TraceIndex traceIndex;
                if (!(reader >> info.size) || !(reader >> traceIndex) || !(reader >> ptr)) {
                    cerr << "failed to parse line: " << reader.line() << ' ' << __LINE__ << endl;
                    continue;
                }
                info.allocationIndex = mapToAllocationIndex(traceIndex);
                if (allocationInfoSet.add(info.size, traceIndex, &allocationIndex)) {
                    allocationInfos.push_back(info);
                }
                pointers.addPointer(ptr, allocationIndex);
                lastAllocationPtr = ptr;
            }

            if (pass != FirstPass) {
                auto& allocation = allocations[info.allocationIndex.index];
                allocation.leaked += info.size;
                ++allocation.allocations;

                handleAllocation(info, allocationIndex);
            }

            ++totalCost.allocations;
            totalCost.leaked += info.size;
            if (totalCost.leaked > totalCost.peak) {
                totalCost.peak = totalCost.leaked;
                peakTime = timeStamp;

                if (pass == SecondPass && totalCost.peak == lastPeakCost && peakTime == lastPeakTime) {
                    for (auto& allocation : allocations) {
                        allocation.peak = allocation.leaked;
                    }
                }
            }
        } else if (reader.mode() == '-') {
            if (!inFilteredTime) {
                continue;
            }
            AllocationInfoIndex allocationInfoIndex;
            bool temporary = false;
            if (fileVersion >= 1) {
                if (!(reader >> allocationInfoIndex)) {
                    cerr << "failed to parse line: " << reader.line() << endl;
                    continue;
                }
                temporary = lastAllocationPtr == allocationInfoIndex.index;
            } else { // backwards compatibility
                uint64_t ptr = 0;
                if (!(reader >> ptr)) {
                    cerr << "failed to parse line: " << reader.line() << endl;
                    continue;
                }
                auto taken = pointers.takePointer(ptr);
                if (!taken.second) {
                    // happens when we attached to a running application
                    continue;
                }
                allocationInfoIndex = taken.first;
                temporary = lastAllocationPtr == ptr;
            }
            lastAllocationPtr = 0;

            const auto& info = allocationInfos[allocationInfoIndex.index];
            totalCost.leaked -= info.size;
            if (temporary) {
                ++totalCost.temporary;
            }

            if (pass != FirstPass) {
                auto& allocation = allocations[info.allocationIndex.index];
                allocation.leaked -= info.size;
                if (temporary) {
                    ++allocation.temporary;
                }
            }
        } else if (reader.mode() == 'a') {
            if (pass != FirstPass || isReparsing) {
                continue;
            }
            AllocationInfo info;
            TraceIndex traceIndex;
            if (!(reader >> info.size) || !(reader >> traceIndex)) {
                cerr << "failed to parse line: " << reader.line() << endl;
                continue;
            }
            info.allocationIndex = mapToAllocationIndex(traceIndex);
            allocationInfos.push_back(info);

        } else if (reader.mode() == '#') {
            // comment or empty line
            continue;
        } else if (reader.mode() == 'c') {
            int64_t newStamp = 0;
            if (!(reader >> newStamp)) {
                cerr << "Failed to read time stamp: " << reader.line() << endl;
                continue;
            }
            inFilteredTime = newStamp >= filterParameters.minTime && newStamp <= filterParameters.maxTime;
            if (inFilteredTime) {
                handleTimeStamp(timeStamp, newStamp, false, pass);
            }
            timeStamp = newStamp;
        } else if (reader.mode() == 'R') { // RSS timestamp
            if (!inFilteredTime) {
                continue;
            }
            int64_t rss = 0;
            reader >> rss;
            if (rss > peakRSS) {
                peakRSS = rss;
            }
        } else if (reader.mode() == 'X') {
            if (debuggeeEncountered) {
                cerr << "Duplicated debuggee entry - corrupt data file?" << endl;
                return false;
            }
            debuggeeEncountered = true;
            if (pass != FirstPass && !isReparsing) {
                handleDebuggee(reader.line().c_str() + 2);
            }
        } else if (reader.mode() == 'A') {
            if (pass != FirstPass || isReparsing)
                continue;
            totalCost = {};
            fromAttached = true;
        } else if (reader.mode() == 'v') {
            unsigned int heaptrackVersion = 0;
            reader >> heaptrackVersion;
            if (!(reader >> fileVersion) && heaptrackVersion == 0x010200) {
                // backwards compatibility: before the 1.0.0, I actually
                // bumped the version to 0x010200 already and used that
                // as file version. This is what we now consider v1 of the
                // file format
                fileVersion = 1;
            }
            if (fileVersion > HEAPTRACK_FILE_FORMAT_VERSION) {
                cerr << "The data file has version " << hex << fileVersion << " and was written by heaptrack version "
                     << hex << heaptrackVersion << ")\n"
                     << "This is not compatible with this build of heaptrack (version " << hex << HEAPTRACK_VERSION
                     << "), which can read file format version " << hex << HEAPTRACK_FILE_FORMAT_VERSION << " and below"
                     << endl;
                return false;
            }
            if (fileVersion >= 3) {
                reader.setExpectedSizedStrings(true);
            }
        } else if (reader.mode() == 'I') { // system information
            reader >> systemInfo.pageSize;
            reader >> systemInfo.pages;
        } else if (reader.mode() == 'S') { // embedded suppression
            if (pass != FirstPass || filterParameters.disableEmbeddedSuppressions) {
                continue;
            }
            auto suppression = parseSuppression(reader.line().substr(2));
            if (!suppression.empty()) {
                suppressions.push_back({std::move(suppression), 0, 0});
            }
        } else {
            cerr << "failed to parse line: " << reader.line() << endl;
        }
    }

    if (pass == FirstPass && !isReparsing) {
        totalTime = timeStamp + 1;
        filterParameters.maxTime = totalTime;
    }

    handleTimeStamp(timeStamp, timeStamp + 1, true, pass);

    return true;
}

namespace { // helpers for diffing

template <typename IndexT, typename SortF>
vector<IndexT> sortedIndices(size_t numIndices, SortF sorter)
{
    vector<IndexT> indices;
    indices.resize(numIndices);
    for (size_t i = 0; i < numIndices; ++i) {
        indices[i].index = (i + 1);
    }
    sort(indices.begin(), indices.end(), sorter);
    return indices;
}

vector<StringIndex> remapStrings(vector<string>& lhs, const vector<string>& rhs)
{
    tsl::robin_map<string, StringIndex> stringRemapping;

    // insert known strings in lhs into the map for lookup below
    StringIndex stringIndex;
    {
        stringRemapping.reserve(lhs.size());
        for (const auto& string : lhs) {
            ++stringIndex.index;
            stringRemapping.insert(make_pair(string, stringIndex));
        }
    }

    // now insert the missing strings form rhs into lhs
    // and create a remapped string vector, keeping the order
    // of the strings in rhs, but mapping into the string vector from lhs
    vector<StringIndex> map;
    {
        map.reserve(rhs.size() + 1);
        map.push_back({});
        for (const auto& string : rhs) {
            auto it = stringRemapping.find(string);
            if (it == stringRemapping.end()) {
                // a string that only occurs in rhs, but not lhs
                // add it to lhs to make sure we can find it again later on
                ++stringIndex.index;
                lhs.push_back(string);
                map.push_back(stringIndex);
            } else {
                map.push_back(it->second);
            }
        }
    }
    return map;
}

// replace by std::identity once we can leverage C++20
struct identity
{
    template <typename T>
    const T& operator()(const T& t) const
    {
        return t;
    }

    template <typename T>
    T operator()(T&& t) const
    {
        return std::move(t);
    }
};

template <typename IpMapper>
int compareTraceIndices(const TraceIndex& lhs, const AccumulatedTraceData& lhsData, const TraceIndex& rhs,
                        const AccumulatedTraceData& rhsData, IpMapper ipMapper)
{
    if (!lhs && !rhs) {
        return 0;
    } else if (lhs && !rhs) {
        return 1;
    } else if (rhs && !lhs) {
        return -1;
    } else if (&lhsData == &rhsData && lhs == rhs) {
        // fast-path if both indices are equal and we compare the same data
        return 0;
    }

    const auto& lhsTrace = lhsData.findTrace(lhs);
    const auto& rhsTrace = rhsData.findTrace(rhs);

    const int parentComparsion =
        compareTraceIndices(lhsTrace.parentIndex, lhsData, rhsTrace.parentIndex, rhsData, ipMapper);
    if (parentComparsion != 0) {
        return parentComparsion;
    } // else fall-through to below, parents are equal

    const auto& lhsIp = lhsData.findIp(lhsTrace.ipIndex);
    const auto& rhsIp = ipMapper(rhsData.findIp(rhsTrace.ipIndex));
    if (lhsIp.equalWithoutAddress(rhsIp)) {
        return 0;
    }
    return lhsIp.compareWithoutAddress(rhsIp) ? -1 : 1;
}

POTENTIALLY_UNUSED void printCost(const AllocationData& data)
{
    cerr << data.allocations << " (" << data.temporary << "), " << data.peak << " (" << data.leaked << ")\n";
}

POTENTIALLY_UNUSED void printTrace(const AccumulatedTraceData& data, TraceIndex index)
{
    do {
        const auto trace = data.findTrace(index);
        const auto& ip = data.findIp(trace.ipIndex);
        cerr << index << " (" << trace.ipIndex << ", " << trace.parentIndex << ")" << '\t'
             << data.stringify(ip.frame.functionIndex) << " in " << data.stringify(ip.moduleIndex) << " at "
             << data.stringify(ip.frame.fileIndex) << ':' << ip.frame.line << '\n';
        for (const auto& inlined : ip.inlined) {
            cerr << '\t' << data.stringify(inlined.functionIndex) << " at " << data.stringify(inlined.fileIndex) << ':'
                 << inlined.line << '\n';
        }
        index = trace.parentIndex;
    } while (index);
    cerr << "---\n";
}

template <class ForwardIt, class BinaryPredicateCompare, class BinaryOpReduce>
ForwardIt inplace_unique_reduce(ForwardIt first, ForwardIt last, BinaryPredicateCompare cmp, BinaryOpReduce reduce)
{
    if (first == last)
        return last;

    ForwardIt result = first;
    while (++first != last) {
        if (cmp(*result, *first)) {
            reduce(*result, *first);
        } else if (++result != first) {
            *result = std::move(*first);
        }
    }
    return ++result;
}
}

void AccumulatedTraceData::diff(const AccumulatedTraceData& base)
{
    totalCost -= base.totalCost;
    totalTime -= base.totalTime;
    peakRSS -= base.peakRSS;
    systemInfo.pages -= base.systemInfo.pages;
    systemInfo.pageSize -= base.systemInfo.pageSize;

    // step 1: sort allocations for efficient lookup and to prepare for merging equal allocations

    std::sort(allocations.begin(), allocations.end(), [this](const Allocation& lhs, const Allocation& rhs) {
        return compareTraceIndices(lhs.traceIndex, *this, rhs.traceIndex, *this, identity {}) < 0;
    });

    // step 2: now merge equal allocations

    allocations.erase(inplace_unique_reduce(
                          allocations.begin(), allocations.end(),
                          [this](const Allocation& lhs, const Allocation& rhs) {
                              return compareTraceIndices(lhs.traceIndex, *this, rhs.traceIndex, *this, identity {})
                                  == 0;
                          },
                          [](Allocation& lhs, const Allocation& rhs) { lhs += rhs; }),
                      allocations.end());

    // step 3: map string indices from rhs to lhs data

    const auto& stringMap = remapStrings(strings, base.strings);
    auto remapString = [&stringMap](StringIndex& index) {
        if (index) {
            index.index = stringMap[index.index].index;
        }
    };
    auto remapFrame = [&remapString](Frame frame) -> Frame {
        remapString(frame.functionIndex);
        remapString(frame.fileIndex);
        return frame;
    };
    auto remapIp = [&remapString, &remapFrame](InstructionPointer ip) -> InstructionPointer {
        remapString(ip.moduleIndex);
        ip.frame = remapFrame(ip.frame);
        for (auto& inlined : ip.inlined) {
            inlined = remapFrame(inlined);
        }
        return ip;
    };

    // step 4: iterate over rhs data and find matching traces
    //         if no match is found, copy the data over

    auto sortedIps = sortedIndices<IpIndex>(instructionPointers.size(), [this](const IpIndex& lhs, const IpIndex& rhs) {
        return findIp(lhs).compareWithoutAddress(findIp(rhs));
    });

    // map an IpIndex from the rhs data into the lhs data space, or copy the data
    // if it does not exist yet
    auto remapIpIndex = [&sortedIps, this, &base, &remapIp](IpIndex rhsIndex) -> IpIndex {
        if (!rhsIndex) {
            return rhsIndex;
        }

        const auto& rhsIp = base.findIp(rhsIndex);
        const auto& lhsIp = remapIp(rhsIp);

        auto it = lower_bound(sortedIps.begin(), sortedIps.end(), lhsIp,
                              [this](const IpIndex& lhs, const InstructionPointer& rhs) {
                                  return findIp(lhs).compareWithoutAddress(rhs);
                              });
        if (it != sortedIps.end() && findIp(*it).equalWithoutAddress(lhsIp)) {
            return *it;
        }

        instructionPointers.push_back(lhsIp);

        IpIndex ret;
        ret.index = instructionPointers.size();
        sortedIps.insert(it, ret);

        return ret;
    };

    // copy the rhs trace index and the data it references into the lhs data,
    // recursively
    function<TraceIndex(TraceIndex)> copyTrace = [this, &base, remapIpIndex,
                                                  &copyTrace](TraceIndex rhsIndex) -> TraceIndex {
        if (!rhsIndex) {
            return rhsIndex;
        }

        // new location, add it
        const auto& rhsTrace = base.findTrace(rhsIndex);

        TraceNode node;
        node.parentIndex = copyTrace(rhsTrace.parentIndex);
        node.ipIndex = remapIpIndex(rhsTrace.ipIndex);

        traces.push_back(node);
        TraceIndex ret;
        ret.index = traces.size();

        return ret;
    };

    // find an equivalent trace or copy the data over if it does not exist yet
    // a trace is equivalent if the complete backtrace has equal InstructionPointer
    // data while ignoring the actual pointer address
    for (const auto& rhsAllocation : base.allocations) {

        assert(rhsAllocation.traceIndex);
        auto it = lower_bound(allocations.begin(), allocations.end(), rhsAllocation.traceIndex,
                              [&base, this, remapIp](const Allocation& lhs, const TraceIndex& rhs) -> bool {
                                  return compareTraceIndices(lhs.traceIndex, *this, rhs, base, remapIp) < 0;
                              });

        if (it == allocations.end()
            || compareTraceIndices(it->traceIndex, *this, rhsAllocation.traceIndex, base, remapIp) != 0) {
            Allocation lhsAllocation;
            lhsAllocation.traceIndex = copyTrace(rhsAllocation.traceIndex);
            it = allocations.insert(it, lhsAllocation);
        }

        (*it) -= rhsAllocation;
    }

    // step 5: remove allocations that don't show any differences
    //         note that when there are differences in the backtraces,
    //         we can still end up with merged backtraces that have a total
    //         of 0, but different "tails" of different origin with non-zero cost
    allocations.erase(remove_if(allocations.begin(), allocations.end(),
                                [&](const Allocation& allocation) -> bool { return allocation == AllocationData(); }),
                      allocations.end());
}

AllocationIndex AccumulatedTraceData::mapToAllocationIndex(const TraceIndex traceIndex)
{
    AllocationIndex allocationIndex;
    if (traceIndex < m_maxAllocationTraceIndex) {
        // only need to search when the trace index is previously known
        auto it = lower_bound(traceIndexToAllocationIndex.begin(), traceIndexToAllocationIndex.end(), traceIndex,
                              [](const pair<TraceIndex, AllocationIndex>& indexMap,
                                 const TraceIndex traceIndex) -> bool { return indexMap.first < traceIndex; });
        if (it != traceIndexToAllocationIndex.end() && it->first == traceIndex) {
            return it->second;
        }
        // new allocation
        allocationIndex.index = allocations.size();
        traceIndexToAllocationIndex.insert(it, make_pair(traceIndex, allocationIndex));
        Allocation allocation;
        allocation.traceIndex = traceIndex;
        allocations.push_back(allocation);
    } else if (traceIndex == m_maxAllocationTraceIndex && !allocations.empty()) {
        // reuse the last allocation
        assert(allocations[m_maxAllocationIndex.index].traceIndex == traceIndex);
        allocationIndex = m_maxAllocationIndex;
    } else {
        // new allocation
        allocationIndex.index = allocations.size();
        traceIndexToAllocationIndex.push_back(make_pair(traceIndex, allocationIndex));
        Allocation allocation;
        allocation.traceIndex = traceIndex;
        m_maxAllocationIndex.index = allocations.size();
        allocations.push_back(allocation);
        m_maxAllocationTraceIndex = traceIndex;
    }
    return allocationIndex;
}

const InstructionPointer& AccumulatedTraceData::findIp(const IpIndex ipIndex) const
{
    static const InstructionPointer invalid;
    if (!ipIndex || ipIndex.index > instructionPointers.size()) {
        return invalid;
    } else {
        return instructionPointers[ipIndex.index - 1];
    }
}

TraceNode AccumulatedTraceData::findTrace(const TraceIndex traceIndex) const
{
    if (!traceIndex || traceIndex.index > traces.size()) {
        return {};
    } else {
        return traces[traceIndex.index - 1];
    }
}

bool AccumulatedTraceData::isStopIndex(const StringIndex index) const
{
    return find(stopIndices.begin(), stopIndices.end(), index) != stopIndices.end();
}

struct SuppressionStringMatch
{
    static constexpr auto NO_MATCH = std::numeric_limits<std::size_t>::max();

    SuppressionStringMatch(std::size_t index = NO_MATCH)
        : suppressionIndex(index)
    {
    }

    explicit operator bool() const
    {
        return suppressionIndex != NO_MATCH;
    }

    std::size_t suppressionIndex;
};

void AccumulatedTraceData::applyLeakSuppressions()
{
    totalLeakedSuppressed = 0;

    if (suppressions.empty()) {
        return;
    }

    // match all strings once against all suppression rules
    bool hasAnyMatch = false;
    std::vector<SuppressionStringMatch> suppressedStrings(strings.size());
    std::transform(strings.begin(), strings.end(), suppressedStrings.begin(), [&](const auto& string) {
        auto it = std::find_if(suppressions.begin(), suppressions.end(), [&string](const Suppression& suppression) {
            return matchesSuppression(suppression.pattern, string);
        });
        if (it == suppressions.end()) {
            return SuppressionStringMatch();
        } else {
            hasAnyMatch = true;
            return SuppressionStringMatch(static_cast<std::size_t>(std::distance(suppressions.begin(), it)));
        }
    });
    if (!hasAnyMatch) {
        // nothing matched the suppressions, we can return early
        return;
    }

    auto isSuppressedString = [&suppressedStrings](StringIndex index) {
        if (index && index.index <= suppressedStrings.size()) {
            return suppressedStrings[index.index - 1];
        } else {
            return SuppressionStringMatch();
        }
    };
    auto isSuppressedFrame = [&isSuppressedString](Frame frame) {
        auto match = isSuppressedString(frame.functionIndex);
        if (match) {
            return match;
        }
        return isSuppressedString(frame.fileIndex);
    };

    // now match all instruction pointers against the suppressed strings
    std::vector<SuppressionStringMatch> suppressedIps(instructionPointers.size());
    std::transform(instructionPointers.begin(), instructionPointers.end(), suppressedIps.begin(), [&](const auto& ip) {
        auto match = isSuppressedString(ip.moduleIndex);
        if (match) {
            return match;
        }
        match = isSuppressedFrame(ip.frame);
        if (match) {
            return match;
        }
        for (const auto& inlined : ip.inlined) {
            match = isSuppressedFrame(inlined);
            if (match) {
                return match;
            }
        }
        return SuppressionStringMatch();
    });
    suppressedStrings = {};
    auto isSuppressedIp = [&suppressedIps](IpIndex index) {
        if (index && index.index <= suppressedIps.size()) {
            return suppressedIps[index.index - 1];
        }
        return SuppressionStringMatch();
    };

    // now match all trace indices against the suppressed instruction pointers
    std::vector<SuppressionStringMatch> suppressedTraces(traces.size());
    auto isSuppressedTrace = [&suppressedTraces](TraceIndex index) {
        if (index && index.index <= suppressedTraces.size()) {
            return suppressedTraces[index.index - 1];
        }
        return SuppressionStringMatch();
    };
    std::transform(traces.begin(), traces.end(), suppressedTraces.begin(), [&](const auto& trace) {
        auto match = isSuppressedTrace(trace.parentIndex);
        if (match) {
            return match;
        }
        return isSuppressedIp(trace.ipIndex);
    });
    suppressedIps = {};

    // now finally zero all the matching allocations
    for (auto& allocation : allocations) {
        auto match = isSuppressedTrace(allocation.traceIndex);
        if (match) {
            totalLeakedSuppressed += allocation.leaked;

            auto& suppression = suppressions[match.suppressionIndex];
            ++suppression.matches;
            suppression.leaked += allocation.leaked;

            totalCost.leaked -= allocation.leaked;
            allocation.leaked = 0;
        }
    }
}
