// Copyright 2021, 2022 Peter Dimov.
// Copyright 2023 Joaquin M Lopez Munoz.
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt

#define _SILENCE_CXX17_OLD_ALLOCATOR_MEMBERS_DEPRECATION_WARNING
#define _SILENCE_CXX20_CISO646_REMOVED_WARNING

#include <boost/unordered_map.hpp>
#include <boost/unordered/unordered_node_map.hpp>
#include <boost/unordered/unordered_flat_map.hpp>
#include <boost/endian/conversion.hpp>
#include <boost/core/detail/splitmix64.hpp>
#include <boost/container_hash/hash.hpp>
#include <boost/config.hpp>
#ifdef HAVE_ABSEIL
# include "absl/container/node_hash_map.h"
# include "absl/container/flat_hash_map.h"
#endif
#ifdef HAVE_ANKERL_UNORDERED_DENSE
# include "ankerl/unordered_dense.h"
#endif
#include <unordered_map>
#include <vector>
#include <memory>
#include <cstdint>
#include <iostream>
#include <iomanip>
#include <chrono>
#include <cstring>

using namespace std::chrono_literals;

static void print_time( std::chrono::steady_clock::time_point & t1, char const* label, std::uint64_t s, std::size_t size )
{
    auto t2 = std::chrono::steady_clock::now();

    std::cout << label << ": " << ( t2 - t1 ) / 1ms << " ms (s=" << s << ", size=" << size << ")\n";

    t1 = t2;
}

constexpr unsigned N = 2'000'000;
constexpr int K = 10;

struct uuid
{
    unsigned char data[ 16 ];

    uuid(): data()
    {
    }

    uuid( std::uint64_t low, std::uint64_t high ) noexcept
    {
        boost::endian::store_little_u64( data + 0, low );
        boost::endian::store_little_u64( data + 8, high );
    }

    inline friend std::size_t hash_value( uuid const& u ) noexcept
    {
        std::uint64_t low  = boost::endian::load_little_u64( u.data + 0 );
        std::uint64_t high = boost::endian::load_little_u64( u.data + 8 );

        std::size_t r = 0;

        boost::hash_combine( r, low );
        boost::hash_combine( r, high );

        return r;
    }

    inline friend bool operator==( uuid const& u1, uuid const& u2 ) noexcept
    {
        return std::memcmp( u1.data, u2.data, 16 ) == 0;
    }
};

namespace std
{

template<> struct hash< ::uuid >
{
    std::size_t operator()( uuid const& u ) const noexcept
    {
        return hash_value( u );
    }
};

} // namespace std

static std::vector< uuid > indices1, indices2, indices3;

static void init_indices()
{
    indices1.push_back( {} );

    for( unsigned i = 1; i <= N*2; ++i )
    {
        indices1.push_back( { i, 0 } );
    }

    indices2.push_back( {} );

    {
        boost::detail::splitmix64 rng;

        for( unsigned i = 1; i <= N*2; ++i )
        {
            indices2.push_back( { rng(), rng() } );
        }
    }

    indices3.push_back( {} );

    for( unsigned i = 1; i <= N*2; ++i )
    {
        uuid k( i, 0 );
        std::reverse( k.data + 0, k.data + 16 );

        indices3.push_back( k );
    }
}

template<class Map> BOOST_NOINLINE void test_insert( Map& map, std::chrono::steady_clock::time_point & t1 )
{
    for( unsigned i = 1; i <= N; ++i )
    {
        map.insert( { indices1[ i ], i } );
    }

    print_time( t1, "Consecutive insert",  0, map.size() );

    for( unsigned i = 1; i <= N; ++i )
    {
        map.insert( { indices2[ i ], i } );
    }

    print_time( t1, "Random insert",  0, map.size() );

    for( unsigned i = 1; i <= N; ++i )
    {
        map.insert( { indices3[ i ], i } );
    }

    print_time( t1, "Consecutive reversed insert",  0, map.size() );

    std::cout << std::endl;
}

template<class Map> BOOST_NOINLINE void test_lookup( Map& map, std::chrono::steady_clock::time_point & t1 )
{
    std::uint64_t s;

    s = 0;

    for( int j = 0; j < K; ++j )
    {
        for( unsigned i = 1; i <= N * 2; ++i )
        {
            auto it = map.find( indices1[ i ] );
            if( it != map.end() ) s += it->second;
        }
    }

    print_time( t1, "Consecutive lookup",  s, map.size() );

    s = 0;

    for( int j = 0; j < K; ++j )
    {
        for( unsigned i = 1; i <= N * 2; ++i )
        {
            auto it = map.find( indices2[ i ] );
            if( it != map.end() ) s += it->second;
        }
    }

    print_time( t1, "Random lookup",  s, map.size() );

    s = 0;

    for( int j = 0; j < K; ++j )
    {
        for( unsigned i = 1; i <= N * 2; ++i )
        {
            auto it = map.find( indices3[ i ] );
            if( it != map.end() ) s += it->second;
        }
    }

    print_time( t1, "Consecutive reversed lookup",  s, map.size() );

    std::cout << std::endl;
}

template<class Map> BOOST_NOINLINE void test_iteration( Map& map, std::chrono::steady_clock::time_point & t1 )
{
    auto it = map.begin();

    while( it != map.end() )
    {
        if( it->second & 1 )
        {
            if constexpr( std::is_void_v< decltype( map.erase( it ) ) > )
            {
                map.erase( it++ );
            }
            else
            {
                it = map.erase( it );
            }
        }
        else
        {
            ++it;
        }
    }

    print_time( t1, "Iterate and erase odd elements",  0, map.size() );

    std::cout << std::endl;
}

template<class Map> BOOST_NOINLINE void test_erase( Map& map, std::chrono::steady_clock::time_point & t1 )
{
    for( unsigned i = 1; i <= N; ++i )
    {
        map.erase( indices1[ i ] );
    }

    print_time( t1, "Consecutive erase",  0, map.size() );

    for( unsigned i = 1; i <= N; ++i )
    {
        map.erase( indices2[ i ] );
    }

    print_time( t1, "Random erase",  0, map.size() );

    for( unsigned i = 1; i <= N; ++i )
    {
        map.erase( indices3[ i ] );
    }

    print_time( t1, "Consecutive reversed erase",  0, map.size() );

    std::cout << std::endl;
}

// counting allocator

static std::size_t s_alloc_bytes = 0;
static std::size_t s_alloc_count = 0;

template<class T> struct allocator
{
    using value_type = T;

    allocator() = default;

    template<class U> allocator( allocator<U> const & ) noexcept
    {
    }

    template<class U> bool operator==( allocator<U> const & ) const noexcept
    {
        return true;
    }

    template<class U> bool operator!=( allocator<U> const& ) const noexcept
    {
        return false;
    }

    T* allocate( std::size_t n ) const
    {
        s_alloc_bytes += n * sizeof(T);
        s_alloc_count++;

        return std::allocator<T>().allocate( n );
    }

    void deallocate( T* p, std::size_t n ) const noexcept
    {
        s_alloc_bytes -= n * sizeof(T);
        s_alloc_count--;

        std::allocator<T>().deallocate( p, n );
    }
};

//

struct record
{
    std::string label_;
    long long time_;
    std::size_t bytes_;
    std::size_t count_;
};

static std::vector<record> times;

template<template<class...> class Map> BOOST_NOINLINE void test( char const* label )
{
    std::cout << label << ":\n\n";

    s_alloc_bytes = 0;
    s_alloc_count = 0;

    Map<uuid, std::uint64_t> map;

    auto t0 = std::chrono::steady_clock::now();
    auto t1 = t0;

    test_insert( map, t1 );

    std::cout << "Memory: " << s_alloc_bytes << " bytes in " << s_alloc_count << " allocations\n\n";

    record rec = { label, 0, s_alloc_bytes, s_alloc_count };

    test_lookup( map, t1 );
    test_iteration( map, t1 );
    test_lookup( map, t1 );
    test_erase( map, t1 );

    auto tN = std::chrono::steady_clock::now();
    std::cout << "Total: " << ( tN - t0 ) / 1ms << " ms\n\n";

    rec.time_ = ( tN - t0 ) / 1ms;
    times.push_back( rec );
}

// aliases using the counting allocator

template<class K, class V> using allocator_for = ::allocator< std::pair<K const, V> >;

template<class K, class V> using std_unordered_map =
    std::unordered_map<K, V, std::hash<K>, std::equal_to<K>, allocator_for<K, V>>;

template<class K, class V> using boost_unordered_map =
    boost::unordered_map<K, V, boost::hash<K>, std::equal_to<K>, allocator_for<K, V>>;

template<class K, class V> using boost_unordered_node_map =
    boost::unordered_node_map<K, V, boost::hash<K>, std::equal_to<K>, allocator_for<K, V>>;

template<class K, class V> using boost_unordered_flat_map =
    boost::unordered_flat_map<K, V, boost::hash<K>, std::equal_to<K>, allocator_for<K, V>>;

#ifdef HAVE_ABSEIL

template<class K, class V> using absl_node_hash_map =
    absl::node_hash_map<K, V, absl::container_internal::hash_default_hash<K>, absl::container_internal::hash_default_eq<K>, allocator_for<K, V>>;

template<class K, class V> using absl_flat_hash_map =
    absl::flat_hash_map<K, V, absl::container_internal::hash_default_hash<K>, absl::container_internal::hash_default_eq<K>, allocator_for<K, V>>;

#endif

#ifdef HAVE_ANKERL_UNORDERED_DENSE

template<class K, class V> using ankerl_unordered_dense_map =
    ankerl::unordered_dense::map<K, V, ankerl::unordered_dense::hash<K>, std::equal_to<K>, ::allocator< std::pair<K, V> >>;

#endif

int main()
{
    init_indices();

    test<std_unordered_map>( "std::unordered_map" );
    test<boost_unordered_map>( "boost::unordered_map" );
    test<boost_unordered_node_map>( "boost::unordered_node_map" );
    test<boost_unordered_flat_map>( "boost::unordered_flat_map" );

#ifdef HAVE_ANKERL_UNORDERED_DENSE

    test<ankerl_unordered_dense_map>( "ankerl::unordered_dense::map" );

#endif

#ifdef HAVE_ABSEIL

    test<absl_node_hash_map>( "absl::node_hash_map" );
    test<absl_flat_hash_map>( "absl::flat_hash_map" );

#endif

    std::cout << "---\n\n";

    for( auto const& x: times )
    {
        std::cout << std::setw( 30 ) << ( x.label_ + ": " ) << std::setw( 5 ) << x.time_ << " ms, " << std::setw( 9 ) << x.bytes_ << " bytes in " << x.count_ << " allocations\n";
    }
}

#ifdef HAVE_ABSEIL
# include "absl/container/internal/raw_hash_set.cc"
# include "absl/hash/internal/hash.cc"
# include "absl/hash/internal/low_level_hash.cc"
# include "absl/hash/internal/city.cc"
#endif