#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/time.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#define LOCALSOCK
#ifdef LOCALSOCK
#include <sys/un.h>
#else
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/tcp.h>
#endif

/*#define NOBLOCK*/
#ifdef NOBLOCK
#include <fcntl.h>
#endif

#define SCHEDRT
#ifdef SCHEDRT
#include <sched.h>
#endif

#define MAX(a,b) \
  ({ typeof (a) _a = (a); \
      typeof (b) _b = (b); \
    _a > _b ? _a : _b; })

#define MIN(a,b) \
  ({ typeof (a) _a = (a); \
      typeof (b) _b = (b); \
    _a > _b ? _b : _a; })

#define NCLI 16


int
sock_init ()
{
#ifdef LOCALSOCK
#define UNIX_PATH_MAX    108
#define SOCKPTH "/tmp/alt-dbus"
    /* connection oriented local socket that preserve
     * order and packet boundaries */
    int s;
    struct sockaddr_un sockstr;
    sockstr.sun_family = AF_UNIX;
    memcpy (sockstr.sun_path, SOCKPTH, UNIX_PATH_MAX);
    if (-1 == (s = socket (PF_UNIX, SOCK_SEQPACKET, 0)))
    {
        perror ("socket");
        return 0;
    }
#else /* tcp sockets */
#define HOST 127.0.0.1
#define PORT 50101
    int s;
    struct sockaddr_in sockstr;
    sockstr.sin_family = AF_INET;
    sockstr.sin_port = htons (PORT);
    sockstr.sin_addr.s_addr = INADDR_ANY;
    memset (sockstr.sin_zero, '\0', sizeof sockstr.sin_zero);
    if(-1 == (s = socket(PF_INET, SOCK_STREAM,0)))
    {
        perror("socket");
        return 0;
    }
#endif
    if (-1 == setsockopt (s, SOL_SOCKET, SO_REUSEADDR, (int[]){1}, sizeof (int)))
    {
        perror ("setsockopt");
        return 0;
    }
    if (-1 == bind (s, (struct sockaddr *) &sockstr, sizeof (sockstr)))
    {
        perror ("bind");
        return 0;
    }
    if (-1 == listen (s, 5))
    {
        perror ("listen");
        return 0;
    }
    return s;
}

int
process (int i, char *buff)
{
    if (buff[0] == 'i')
    {
        uint32_t *ptr = (void *) buff + 1;
        printf ("%d :: %d\n", i, ntohl (*ptr));
        return 1;
    }
    return 0;
}

void
main_loop (int scket)
{
    static char rcvbuff[2048];
    int clients[NCLI] = { 0 };
    int i;
    int ret;
    fd_set master_set, work_set;
    int maxfd = scket;		/*so far it's this one */
    FD_ZERO (&work_set);
    FD_SET (scket, &work_set);
    master_set = work_set;

    while (-1 != select (maxfd + 1, &work_set, NULL, NULL, NULL))
    {
        if (FD_ISSET (scket, &work_set))
        {
            i = 0;
            while (i < sizeof clients / sizeof *clients && clients[i] > 0)
                i++;
            if (-1 == (clients[i] = accept (scket, NULL, NULL)))
            {
                perror ("accept");
                continue;
            };
            FD_SET (clients[i], &master_set);
            maxfd = MAX (clients[i], maxfd);
        }

        for (i = 0; i < sizeof clients / sizeof *clients; i++)
        {
            if (clients[i] && FD_ISSET (clients[i], &work_set))
            {
                switch (recv (clients[i], rcvbuff, sizeof rcvbuff, 0))
                {
                    case -1:
                    case 0:
                        close (clients[i]);
                        FD_CLR (clients[i], &master_set);
                        clients[i] = 0;
                        break;
                    default:
                        if(process (clients[i], rcvbuff))
                        {
#ifndef LOCALSOCK
                            setsockopt (clients[i], IPPROTO_TCP, TCP_NODELAY, (int[]){1}, sizeof (int));
                            setsockopt (clients[i], IPPROTO_TCP, TCP_CORK, (int[]){1}, sizeof (int));
#endif
    ret = send(clients[i],"ACK",4,
#ifndef NOBLOCK
            0
#else
            MSG_DONTWAIT
#endif
            );
    if(ret == -1 && (errno == EWOULDBLOCK || errno == EAGAIN))
        printf("send would block!\n");
#ifndef LOCALSOCK
                            setsockopt (clients[i], IPPROTO_TCP, TCP_NODELAY, (int[]){0}, sizeof (int));
                            setsockopt (clients[i], IPPROTO_TCP, TCP_CORK, (int[]){0}, sizeof (int));
#endif
                        }
                }
            }

        }
        work_set = master_set;

    }
    //shouldn't happen
    perror ("select");
    for (i = 0; i < sizeof clients / sizeof *clients; i++)
    {
        if (clients[i] > 0)
        {
            close (clients[i]);
        }
    }
    close (scket);
}

int
main ()
{
#ifdef SCHEDRT
           struct sched_param parms;
         parms.sched_priority = 5;
    sched_setscheduler(0,SCHED_FIFO,&parms);
#endif
    int scket;
    scket = sock_init ();
    if (scket > 0)
        main_loop (scket);

    return EXIT_SUCCESS;
}