/*
    mtr  --  a network diagnostic tool
    Copyright (C) 1997,1998  Matt Kimball

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

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

#include "display.h"
#include "dns.h"
#include "net.h"

extern int Interactive;
extern int MaxPing;
extern int ForceMaxPing;
extern float WaitTime;
double dnsinterval;

static struct timeval intervaltime;
int display_offset = 0;


void select_loop() {
  fd_set readfd;
  int anyset = 0;
  int maxfd = 0;
  int dnsfd, netfd;
  int NumPing = 0;
  int paused = 0;
  struct timeval lasttime, thistime, selecttime;
  int dt;
  int rv; 

  gettimeofday(&lasttime, NULL);

  while(1) {
    dt = calc_deltatime (WaitTime);
    intervaltime.tv_sec  = dt / 1000000;
    intervaltime.tv_usec = dt % 1000000;

    FD_ZERO(&readfd);

    maxfd = 0;

    if(Interactive) {
      FD_SET(0, &readfd);
      maxfd = 1;
    }

    if (dns) {
      dnsfd = dns_waitfd();
      FD_SET(dnsfd, &readfd);
      if(dnsfd >= maxfd) maxfd = dnsfd + 1;
    } else
      dnsfd = 0;

    netfd = net_waitfd();
    FD_SET(netfd, &readfd);
    if(netfd >= maxfd) maxfd = netfd + 1;

    do {
      if(anyset || paused) {
	selecttime.tv_sec = 0;
	selecttime.tv_usec = 0;
      
	rv = select(maxfd, (void *)&readfd, NULL, NULL, &selecttime);

      } else {
	if(Interactive) display_redraw();

	gettimeofday(&thistime, NULL);

	if(thistime.tv_sec > lasttime.tv_sec + intervaltime.tv_sec ||
	   (thistime.tv_sec == lasttime.tv_sec + intervaltime.tv_sec &&
	    thistime.tv_usec >= lasttime.tv_usec + intervaltime.tv_usec)) {
	  lasttime = thistime;
	  if(NumPing >= MaxPing && (!Interactive || ForceMaxPing))
	    return;
	  if (net_send_batch())
	    NumPing++;
	}

	selecttime.tv_usec = (thistime.tv_usec - lasttime.tv_usec);
	selecttime.tv_sec = (thistime.tv_sec - lasttime.tv_sec);
	if (selecttime.tv_usec < 0) {
	  --selecttime.tv_sec;
	  selecttime.tv_usec += 1000000;
	}
	selecttime.tv_usec = intervaltime.tv_usec - selecttime.tv_usec;
	selecttime.tv_sec = intervaltime.tv_sec - selecttime.tv_sec;
	if (selecttime.tv_usec < 0) {
	  --selecttime.tv_sec;
	  selecttime.tv_usec += 1000000;
	}

	if ((selecttime.tv_sec > (time_t)dnsinterval) ||
	    ((selecttime.tv_sec == (time_t)dnsinterval) &&
	     (selecttime.tv_usec > ((time_t)(dnsinterval * 1000000) % 1000000)))) {
	  selecttime.tv_sec = (time_t)dnsinterval;
	  selecttime.tv_usec = (time_t)(dnsinterval * 1000000) % 1000000;
	}

	rv = select(maxfd, (void *)&readfd, NULL, NULL, &selecttime);
      }
    } while ((rv < 0) && (errno == EINTR));

    if (rv < 0) {
      perror ("Select failed");
      exit (1);
    }
    anyset = 0;

    /*  Have we got new packets back?  */
    if(FD_ISSET(netfd, &readfd)) {
      net_process_return();
      anyset = 1;
    }

    if (dns) {
      /* Handle any pending resolver events */
      dnsinterval = WaitTime;
      dns_events(&dnsinterval);
    }

    /*  Have we finished a nameservice lookup?  */
    if(dns && FD_ISSET(dnsfd, &readfd)) {
      dns_ack();
      anyset = 1;
    }

    /*  Has a key been pressed?  */
    if(FD_ISSET(0, &readfd)) {
      switch (display_keyaction()) {
      case ActionQuit: 
	return;
	break;
      case ActionReset:
	net_reset();
	break;
      case ActionDisplay:
        display_mode = (display_mode+1) % 3;
	break;
      case ActionClear:
	display_clear();
	break;
      case ActionPause:
	paused=1;
	break;
      case  ActionResume:
	paused=0;
	break;
      case ActionDNS:
	if (dns) {
	  use_dns = !use_dns;
	  display_clear();
	}
	break;

      case ActionScrollDown:
        display_offset += 5;
	break;
      case ActionScrollUp:
        display_offset -= 5;
	if (display_offset < 0) {
	  display_offset = 0;
	}
	break;
      }
      anyset = 1;
    }
  }
  return;
}