// Display client for MPI mesh program
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<netdb.h>
#include<fcntl.h>

#define SRVPORT 10099

int cfd; // communication file descriptor (handle on socket)

/* 3D visualization routines:  - active only when GRAPHICS is 1*/
void visualsetup()
{ 
  // declare structure to hold socket address info:
  struct sockaddr_in serveraddr;
  int retval; // many functions return values to indicate success/failure
  
  serveraddr.sin_family = AF_INET;  // always for IPv4
  serveraddr.sin_addr.s_addr = inet_addr(srvip);
  serveraddr.sin_port = htons(SRVPORT);

  cfd = socket(AF_INET,SOCK_STREAM,0); // register tcp socket with OS

  // make connection to server.
  retval = connect(cfd,(struct sockaddr*)&serveraddr,sizeof(serveraddr));
  // note the type cast to more generic type (polymorphism)
  if (retval != 0) { perror("socket failure!"); exit(1); }
  else printf("socket to display server established\n");

  // send value of N:
  int n = htonl(N); // N is a macro, so can't have a pointer to it!
  write(cfd,&n,sizeof(int));
} //setup


// function to determine byte ordering (1 for network byte ordering)
int byteorder()
{
  unsigned int x = 1;
  return *((char*)&x+3);
}

// function to swap byte ordering of doubles, returns static char*
unsigned char* swapbytes(double* n)
{ int i;
  static unsigned char y[8];
  unsigned char* x = (unsigned char*)n;
  for(i=0;i<8;i++) y[i] = x[7-i];
  return y;
}

void visualize(NROW *BB)
{
  int i;
  unsigned char* sp;  // for converting double
  if (byteorder()) // already using network byte ordering
    {
      write(cfd,BB,(N+2)*(N+2)*8);
      return;
    }
  for (i=0;i<(N+2)*(N+2);i++)
    {
      sp = swapbytes(((double*)BB)+i);
      write(cfd,sp,8);
    }
} //visualize

void visualcleanup()
{
  int n = 0;
  write(cfd,&n,sizeof(int));
  close(cfd);
}