#include <sys/socket.h>
#include <sys/un.h>

#include <unistd.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <thread>
#include <chrono>


// $ g++ --std=gnu++17 af_unix.cpp

const char* const path = "address";
const int count = 1000;
const int size = BUFSIZ * 2;

int client()
{
    const int fd = socket( AF_UNIX, SOCK_DGRAM, 0);

    if( fd == -1)
    {
        perror( "socket error");
        return -1;
    }

    struct sockaddr_un address{};

    strcpy( address.sun_path, path);
    address.sun_family = AF_UNIX;

    char buffer[size] = {};

    for( int idx = 0; idx < count; ++idx)
    {
        memcpy( buffer, &idx, sizeof idx);

        const ssize_t result = sendto( fd, buffer, size, 0, (struct sockaddr*)&address, sizeof address);

        if( result == -1 || result != size)
        {
            perror( "sendto error");
            return -1;
        }
    }

    close( fd);
    return 0;
}

int server()
{
    const int fd = socket( AF_UNIX, SOCK_DGRAM, 0);

    if( fd == -1)
    {
        perror( "socket error");
        return -1;
    }

    struct sockaddr_un address{};

    strcpy( address.sun_path, path);
    address.sun_family = AF_UNIX;

    const int result = bind( fd, (struct sockaddr*)&address, sizeof address);

    if( result == -1)
    {
        perror( "bind error");
        return -1;
    }

    return fd;
}

int main( int argc, char* argv[])
{
    const int fd = server( );

    if( fd != -1)
    {
        fprintf( stdout, "%d\tnumber of packages\n", count);
        fprintf( stdout, "%d\tbytes per package\n", size);

        std::thread{ [&](){client( );}}.detach();

        std::this_thread::sleep_for( std::chrono::microseconds( 500));
    
        char buffer[size] = {};

        for( int idx = 0; idx < count; ++idx)
        {
            const ssize_t result = recv( fd, buffer, size, 0);

            if( result == -1 || result != size)
            {
                perror("recv error");
                unlink( path);
                return -1;
            }

            int index = 0;
            memcpy( &index, buffer, sizeof idx);

            if( index != idx)
            {
                fprintf( stderr, "expected %d but got %d\n", idx, index);
                unlink( path);
                return -1;
            }
        }

        close( fd);
        unlink( path);
    }

    return 0;
}