/*
    SPDX-FileCopyrightText: 2006 David Nolden <david.nolden.kdevelop@art-master.de>
    SPDX-License-Identifier: GPL-2.0-or-later
*/

#include "hashedstring.h"
#include <kdatastream.h>
#include <sstream>
#include <algorithm>
#include <iterator>
#include <set>

//It needs to be measured whether this flag should be turned on or off. It seems just to move the complexity from one position to the other, without any variant being really better.
#define USE_HASHMAP

size_t fastHashString(const QString& str);

size_t hashStringSafe(const QString& str)
{
    size_t hash = 0;
    int len = str.length();
    for (int a = 0; a < len; a++) {
        hash = str[a].unicode() + (hash * 17);
    }
    return hash;
}

size_t HashedString::hashString(const QString& str)
{
    return fastHashString(str);
}

size_t fastHashString(const QString& str)
{
    size_t hash = 0;
    if (!str.isEmpty()) {
        const QChar* curr = str.unicode();
        const QChar* end = curr + str.length();
        QChar c;
        for (; curr < end ;) {
            c = *curr;
            hash = c.unicode() + (hash * 17);
            ++curr;
        }
    }
    return hash;
}

void HashedString::initHash()
{
    m_hash = hashString(m_str);
}


class HashedStringSetData : public QSharedData
{
public:
#ifdef USE_HASHMAP
    typedef QSet<HashedString> StringSet;
#else
    typedef QSet<HashedString> StringSet; //must be a set, so the set-algorithms work
#endif
    StringSet m_files;
    mutable bool m_hashValid;
    mutable size_t m_hash;
    HashedStringSetData()
      : m_hashValid(false),
        m_hash(0)
    {
    }
    inline void invalidateHash()
    {
        m_hashValid = false;
    }

    void computeHash() const;
};

void HashedStringSetData::computeHash() const
{
    int num = 1;
    m_hash = 0;
    for (StringSet::const_iterator it = m_files.begin(); it != m_files.end(); ++it) {
        num *= 7;
        m_hash += num * (*it).hash();
    }
    m_hashValid = true;
}

HashedStringSet::HashedStringSet() {}

HashedStringSet::~HashedStringSet() {}

HashedStringSet::HashedStringSet(const HashedString& file)
{
    insert(file);
}

HashedStringSet::HashedStringSet(const HashedStringSet& rhs) : m_data(rhs.m_data) {}

HashedStringSet operator + (const HashedStringSet& lhs, const HashedStringSet& rhs)
{
    HashedStringSet ret = lhs;
    ret += rhs;

    return ret;
}

int HashedStringSet::size() const
{
    if (!m_data) return 0;
    return m_data->m_files.size();
}

HashedStringSet& HashedStringSet::operator = (const HashedStringSet& rhs)
{
    m_data = rhs.m_data;
    return *this;
}

HashedStringSet& HashedStringSet::operator +=(const HashedStringSet& rhs)
{
    if (!rhs.m_data)
        return * this;

#ifndef USE_HASHMAP
    QExplicitlySharedDataPointer<HashedStringSetData> oldData = m_data;
    if (!oldData) oldData = new HashedStringSetData();
    m_data = new HashedStringSetData();
    std::set_union(oldData->m_files.begin(), oldData->m_files.end(), rhs.m_data->m_files.begin(), rhs.m_data->m_files.end(), std::insert_iterator<HashedStringSetData::StringSet>(m_data->m_files, m_data->m_files.end()));
#else
    makeDataPrivate();
    for (HashedStringSetData::StringSet::const_iterator it = rhs.m_data->m_files.begin(); it != rhs.m_data->m_files.end(); ++it) {
        m_data->m_files.insert(*it);
    }
    /*HashedStringSetData::StringSet::const_iterator end = rhs.m_data->m_files.end();
    HashedStringSetData::StringSet& mySet(m_data->m_files);
    for(HashedStringSetData::StringSet::const_iterator it = rhs.m_data->m_files.begin(); it != end; ++it) {
      mySet.insert(*it);
    }*/

#endif
    return *this;
}

HashedStringSet& HashedStringSet::operator -=(const HashedStringSet& rhs)
{
    if (!m_data) return *this;
    if (!rhs.m_data) return *this;
#ifndef USE_HASHMAP
    QExplicitlySharedDataPointer<HashedStringSetData> oldData = m_data;
    m_data = new HashedStringSetData();
    std::set_difference(oldData->m_files.begin(), oldData->m_files.end(), rhs.m_data->m_files.begin(), rhs.m_data->m_files.end(), std::insert_iterator<HashedStringSetData::StringSet>(m_data->m_files, m_data->m_files.end()));
#else
    makeDataPrivate();
    HashedStringSetData::StringSet::const_iterator end = rhs.m_data->m_files.end();
    HashedStringSetData::StringSet& mySet(m_data->m_files);
    for (HashedStringSetData::StringSet::const_iterator it = rhs.m_data->m_files.begin(); it != end; ++it) {
        mySet.remove(*it);
    }

#endif
    return *this;
}


void HashedStringSet::makeDataPrivate()
{
    if (!m_data) {
        m_data = new HashedStringSetData();
        return ;
    }
    m_data.detach();
}

bool HashedStringSet::operator[] (const HashedString& rhs) const
{
    //if (rhs.str() == "*")
    //return true; /// * stands for "any file"
    if (!m_data)
        return false;
    return m_data->m_files.find(rhs) != m_data->m_files.end();
}

void HashedStringSet::insert(const HashedString& str)
{
    if (str.str().isEmpty()) return;
    makeDataPrivate();
    m_data->m_files.insert(str);
    m_data->invalidateHash();
}

bool HashedStringSet::operator <= (const HashedStringSet& rhs) const
{
    if (!m_data)
        return true;
    if (m_data->m_files.empty())
        return true;
    if (!rhs.m_data)
        return false;
#ifndef USE_HASHMAP
    return std::includes(rhs.m_data->m_files.begin(), rhs.m_data->m_files.end(), m_data->m_files.begin(), m_data->m_files.end());
#else
    const HashedStringSetData::StringSet& otherSet(rhs.m_data->m_files);
    HashedStringSetData::StringSet::const_iterator end = rhs.m_data->m_files.end();
    HashedStringSetData::StringSet::const_iterator myEnd = m_data->m_files.end();

    for (HashedStringSetData::StringSet::const_iterator it = m_data->m_files.begin(); it != myEnd; ++it) {
        HashedStringSetData::StringSet::const_iterator i = otherSet.find(*it);
        if (i == end) return false;
    }
    return true;
#endif
}

bool HashedStringSet::operator == (const HashedStringSet& rhs) const
{
    if (hash() != rhs.hash()) return false;

    bool empty1 = false;
    if (!m_data)
        empty1 = true;
    else if (m_data->m_files.empty())
        empty1 = true;
    bool empty2 = false;
    if (!rhs.m_data)
        empty2 = true;
    else if (rhs.m_data->m_files.empty())
        empty2 = true;

    if (empty1 && empty2)
        return true;
    if (empty1 || empty2)
        return false;

    return m_data->m_files == rhs.m_data->m_files;
}

size_t HashedStringSet::hash() const
{
    if (!m_data) return 0;
    if (!m_data->m_hashValid) m_data->computeHash();
    return m_data->m_hash;
}

void HashedStringSet::read(QDataStream& stream)
{
    bool b;
    stream >> b;
    if (b) {
        m_data = new HashedStringSetData();
        int cnt;
        stream >> cnt;
        HashedString s;
        for (int a = 0; a < cnt; a++) {
            stream >> s;
            m_data->m_files.insert(s);
        }
    } else {
        m_data = nullptr;
    }
}

void HashedStringSet::write(QDataStream& stream) const
{
    bool b = m_data;
    stream << b;
    if (b) {
        int cnt = m_data->m_files.size();
        stream << cnt;
        for (HashedStringSetData::StringSet::const_iterator it = m_data->m_files.begin(); it != m_data->m_files.end(); ++it) {
            stream << *it;
        }
    }
}

std::string HashedStringSet::print() const
{
    std::ostringstream s;
    if (m_data) {
        for (HashedStringSetData::StringSet::const_iterator it = m_data->m_files.begin(); it != m_data->m_files.end(); ++it) {
            s << (*it).str().toLatin1().data() << "\n";
        }
    }
    return s.str();
}

QDataStream& operator << (QDataStream& stream, const HashedString& str)
{
    stream << str.m_str;
    stream << str.m_hash;
    return stream;
}

QDataStream& operator >> (QDataStream& stream, HashedString& str)
{
    stream >> str.m_str;
    stream >> str.m_hash;
    return stream;
}

void HashedStringSetGroup::addSet(size_t id, const HashedStringSet& set)
{
    if (set.m_data && !set.m_data->m_files.empty()) {
        m_sizeMap[ id ] = set.size();
        for (HashedStringSetData::StringSet::const_iterator it = set.m_data->m_files.begin(); it != set.m_data->m_files.end(); ++it) {
            GroupMap::iterator itr = m_map.find(*it);
            if (itr == m_map.end()) {
                itr = m_map.insert(*it, ItemSet());
            }
            itr->insert(id);
        }
    } else {
        m_global.insert(id);
    }
}

void HashedStringSetGroup::disableSet(size_t id)
{
    m_disabled.insert(id);
}

void HashedStringSetGroup::enableSet(size_t id)
{
    m_disabled.erase(id);
}

bool HashedStringSetGroup::isDisabled(size_t id) const
{
    return m_disabled.find(id) != m_disabled.end();
}

void HashedStringSetGroup::removeSet(size_t id)
{
    m_disabled.erase(id);
    m_global.erase(id);
    m_sizeMap.remove(id);
    for (GroupMap::iterator it = m_map.begin(); it != m_map.end(); ++it) {
        it->erase(id);
    }
}

void HashedStringSetGroup::findGroups(HashedStringSet strings, ItemSet& target) const
{
    target.clear();
    if (!strings.m_data) {
        std::set_difference(m_global.begin(), m_global.end(), m_disabled.begin(), m_disabled.end(), std::insert_iterator<ItemSet>(target, target.end()));
        return;
    }
    //This might yet be optimized by sorting the sets according to their size, and starting the intersectioning with the smallest ones.
    QHash<size_t, uint> hitCounts;

    for (HashedStringSetData::StringSet::const_iterator it = strings.m_data->m_files.begin(); it != strings.m_data->m_files.end(); ++it) {
        GroupMap::const_iterator itr = m_map.find(*it);
        if (itr == m_map.end()) {
            //There are no string-sets that include the currently searched for string
            continue;
        }

        for (ItemSet::const_iterator it2 = itr->begin(); it2 != itr->end(); ++it2) {
            QHash<size_t, uint>::iterator v = hitCounts.find(*it2);
            if (v != hitCounts.end()) {
                ++(*v);
            } else {
                hitCounts[*it2] = 1;
            }
        }
    }

    //Now count together all groups that are completely within the given string-set(their hitCount equals their size)
    ItemSet found;
    for (QHash<size_t, uint>::const_iterator it = hitCounts.constBegin(); it != hitCounts.constEnd(); ++it) {
        if (it.value() == (*m_sizeMap.find(it.key())))
            found.insert(it.key());
    }


    std::set_union(found.begin(), found.end(), m_global.begin(), m_global.end(), std::insert_iterator<ItemSet>(target, target.end()));

    target.swap(found);
    target.clear();
    std::set_difference(found.begin(), found.end(), m_disabled.begin(), m_disabled.end(), std::insert_iterator<ItemSet>(target, target.end()));
}

uint qHash(const HashedString &key)
{
    return key.hash();
}
