#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>


/* portul folosit */
#define PORT 4256

struct operation
{
    int number1;
    int number2;
    int number3;
    int number4;
    int number5;
};

/* codul de eroare returnat de anumite apeluri */
extern int errno;

/* programul */
int main (int argc, char * argv[])
{
  struct sockaddr_in server;    /* structurile folosite de server si client */
  struct sockaddr_in from;
  struct operation request;    /* cererea primita de server */
  int sd;            /* descriptorul de socket */
  int port;
  
  /* setare port in cazul specificarii explicite */
  if (argc > 1)
  {
    port = atoi(argv[1]);
  }
  else
    port = PORT;

  /* cream un socket */
  if ((sd = socket (AF_INET, SOCK_STREAM, 0)) == -1)
    {
      perror ("Eroare la socket().\n");
      return errno;
    }

  /* pregatim structurile de date */
  bzero (&server, sizeof (server));
  bzero (&from, sizeof (from));
  
  /* umplem structura folosita de server */
  server.sin_family = AF_INET;    
      /* stabilirea familiei de socket-uri */
  server.sin_addr.s_addr = htonl (INADDR_ANY);
      /* acceptam orice adresa */
  server.sin_port = htons (port);
      /* utilizam un port utilizator */

  /* atasam socketul */
  if (bind (sd, (struct sockaddr *) &server, sizeof (struct sockaddr)) == -1)
    {
      perror ("Eroare la bind().\n");
      return errno;
    }

  /* punem serverul sa asculte daca vin clienti sa se conecteze */
  if (listen (sd, 3) == -1)
    {
      perror ("Eroare la listen().\n");
      return errno;
    }

  /* servim in mod iterativ clientii... */
  while (1)
    {
      int client;
      int length = sizeof (from);

      printf ("Asteptam la portul %d...\n", port);
      fflush (stdout);

      /* acceptam un client (ne vom bloca pina la realizarea conexiunii) */
      client = accept (sd, (struct sockaddr *) &from, &length);

      /* eroare la acceptarea conexiunii de la un client */
      if (client < 0)
    {
      perror ("Eroare la accept().\n");
      continue;
    }

      /* am realizat conexiunea, asteptam mesajul... */
      bzero (&request, sizeof(struct operation));
      printf ("Asteptam cererea...\n");
      fflush (stdout);
      
      /* citirea mesajului */
      int nrbytes = recv (client, &request, sizeof(struct operation), 0);
      if (nrbytes <= 0)
    {
      perror ("Eroare la read() de la client.\n");
      close (client);    /* inchidem conexiunea cu clientul */
      continue;        /* continuam sa ascultam... */
    }

      if (nrbytes < sizeof(struct operation))
      {
        perror ("Date primite incomplet");
    close (client);
    continue;
      }

      request.number1 = ntohl(request.number1);
      request.number2 = ntohl(request.number2);
      request.number3 = ntohl(request.number3);
      request.number4 = ntohl(request.number4);
      request.number5 = ntohl(request.number5);

      printf ("Cerere primita... \n In curs de rezolvare: %d %d %d %d %d \n", 
               request.number1, request.number2, request.number3, request.number4, request.number5);
      
      /* rezolvarea cererii */

int magic;
int a=0;
int b=0;
int c=0;
int d=0;
int e=0;
int min=0;
int result;


magic = rand() % 1001; /* generarea numarului magic de la 1 la 1000*/


/* diferenta dintre numarul magic si numerele primite */

if (magic >= request.number1)
a = magic - request.number1;
else
a = request.number1 - magic;

if (magic >= request.number2)
b = magic - request.number2;
else
b = request.number2 - magic;

if (magic >= request.number3)
c = magic - request.number3;
else
c = request.number3 - magic;

if (magic >= request.number4)
d = magic - request.number4;
else
d = request.number4 - magic;

if (magic >= request.number5)
e = magic - request.number5;
else
e = request.number5 - magic;

printf("\nnumar magic: %d\n", magic);
printf("numerele sunt: %d %d %d %d %d\n", a, b, c, d, e);
/* verificare care numar este mai aproape de numarul magic */

if (a > b)
min = b;
else min = a;

if (min > c)
min = c;

if (min > d)
min = d;

if (min > e)
{
min = e;
//result = min;
}
    printf("diferenta minima este: %d", min);
    /*selectam numarul care este mai apropiat de numarul magic*/
    if (min == a)
        result = request.number1;
    if (min == b)
        result = request.number2;
    if (min == c)
        result = request.number3;
    if (min == d)
        result = request.number4;
    else
        result = request.number5;
        
      result = htonl(result);

      /* returnam rapunsul clientului */
      if (send (client, &result, sizeof(int),0) <= 0)
    {
      perror ("Eroare la write() catre client.\n");
      continue;        /* continuam sa ascultam */
    }
      else
    printf (" trasmitere cu succes.\n");
      /* am terminat cu acest client, inchidem conexiunea */
      close (client);
    }                /* while */
}                /* main */