#include "config.h"
#include <assert.h>
#include <dlfcn.h>
#include <pcap.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <arpa/inet.h>

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


#include "module_run.h"
#include "module_default.h"
#include "test_module.h"
#include "utils.h"



static void test_module_loop(oflops_context *ctx, test_module *mod);
static void process_event(oflops_context *ctx, test_module * mod, struct pollfd *fd);
static void process_control_event(oflops_context *ctx, test_module * mod, struct pollfd *fd);
static void process_pcap_event(oflops_context *ctx, test_module * mod, struct pollfd *fd, oflops_channel_name ch);


/******************************************************
 * setup the test
 * 	
 */
int setup_test_module(oflops_context *ctx, int ix_mod)
{
  struct test_module *mod = ctx->tests[ix_mod];
  int i;
  //Setup
  setup_snmp_channel(ctx);
  for(i=0;i<ctx->n_channels;i++)
    setup_channel( ctx, mod, i);

  timer_init(ctx);
  mod->start(ctx);
  return 1;
}


/******************************************************
 * call the main loop
 * 	
 */
int run_test_module(oflops_context *ctx, int ix_mod)
{

  struct test_module *mod = ctx->tests[ix_mod];
  /* int i; */
  /* //Setup */
  /* setup_snmp_channel(ctx); */
  /* for(i=0;i<ctx->n_channels;i++) */
  /* 	setup_channel( ctx, mod, i); */

  //Run
  test_module_loop(ctx,mod);
  mod->destroy(ctx);

  //Teardown
  teardown_snmp_channel(ctx);

  if((ctx->channels[OFLOPS_CONTROL].dump != NULL) && (ctx->dump_controller))
    pcap_dump_close(ctx->channels[OFLOPS_CONTROL].dump);
	
  return 0;
}

/******************************************************
 * running traffic generation
 * 	
 */
int run_traffic_generation(oflops_context *ctx, int ix_mod)
{
  struct test_module *mod = ctx->tests[ix_mod];
  //Run
  mod->handle_traffic_generation(ctx);
  return 0;
}

/********************************************************
 * main loop()
 * 	1) setup poll
 * 	2) call poll with a min timeout of the next event
 * 	3) dispatch events as appropriate
 */
static void test_module_loop(oflops_context *ctx, test_module *mod)
{
  struct pollfd * poll_set;
  int fds = 0;
  int snmpblock = 0;
  fd_set fdset;
  struct timeval timeout;
  int ret;
  int len; 
  int ch;
  int n_fds=0;
	
  len = sizeof(struct pollfd) * (ctx->n_channels + 1);
  poll_set = malloc_and_check(len);

  while(!ctx->should_end )
    {
      n_fds=0;
      bzero(poll_set,len);

      //Channels poll
      for(ch=0; ch< ctx->n_channels; ch++)
	{
	  poll_set[n_fds].fd = ctx->channels[ch].pcap_fd;
	  poll_set[n_fds].events = 0;
	  if( ctx->channels[ch].pcap_handle)
	    poll_set[n_fds].events = POLLIN;
	  //if ( msgbuf_count_buffered(ctx->channels[ch].outgoing) > 0)
	  //    poll_set[n_fds].events |= POLLOUT;
	  if( poll_set[n_fds].events != 0)
	    n_fds++;
	}
      poll_set[n_fds].fd = ctx->control_fd;	// add the control channel at the end
      poll_set[n_fds].events = POLLIN;
      if ( msgbuf_count_buffered(ctx->control_outgoing) > 0)
	poll_set[n_fds].events |= POLLOUT;
      n_fds++;

      //SNMP poll
      FD_ZERO(&fdset);
      timeout.tv_sec = 0;
      timeout.tv_usec = 1;
      snmp_select_info(&fds, &fdset, &timeout, &snmpblock);
      fds = select(fds, &fdset, NULL,NULL, &timeout);
      if (fds)
	snmp_read(&fdset);
      //else
      //snmp_timeout();
      
      //Timer poll
      /*next_event = timer_get_next_event(ctx);
	while(next_event <= 0 )
	{
	timer_run_next_event(ctx);
	next_event = timer_get_next_event(ctx);
	}*/
      ret = poll(poll_set, n_fds, -1); //next_event);

      if(( ret == -1 ) && ( errno != EINTR))
	perror_and_exit("poll",1);
      else if(ret == 0 ) {
	//if(ctx->should_end == 1) {fprintf(stderr, "finishing poll loop\n"); break;}
	//		  else fprintf(stderr, "not finished yet\n");
	continue; //timer_run_next_event(ctx);
      }
      else // found something to read
	{
	  int i;	
	  for(i=0; i<n_fds; i++)
	    if(poll_set[i].revents & (POLLIN | POLLOUT))
	      process_event(ctx, mod, &poll_set[i]);
	}
    }
}

/*******************************************************
 * static void process_event(oflops_context *ctx, test_module * mod, struct pollfd *pfd)
 * a channel got an event
 * 	map the event to the correct channel, and call the appropriate event handler
 *
 * 	FIXME: for efficency, we really should have a faster fd-> channel map, but 
 * 		since the number of channels is small, we can just be fugly
 */


static void process_event(oflops_context *ctx, test_module * mod, struct pollfd *pfd)
{
  int ch;
  if(pfd->fd == ctx->control_fd)
    return process_control_event(ctx, mod, pfd);
  // this is inefficient, but ok since there are really typically only ~8  cases
  for(ch=0; ch< ctx->n_channels; ch++)
    if (pfd->fd == ctx->channels[ch].pcap_fd)
      return process_pcap_event(ctx, mod, pfd,ch);
  // only get here if we've screwed up somehow
  fprintf(stderr, "Event on unknown fd %d .. dying", pfd->fd);
  abort();
}

/***********************************************************************************************
 * static void process_control_event(oflops_context *ctx, test_module * mod, struct pollfd *fd);
 * 	if POLLIN is set, read an openflow message from the control channel
 * 	FIXME: handle a control channel reset here
 */
static void process_control_event(oflops_context *ctx, test_module * mod, struct pollfd *pfd)
{
  char * neobuf;
  static char * buf; 
  static int buflen   = -1;
  static int bufstart =  0;       // begin of unprocessed data
  static int bufend   =  0;       // end of unprocessed data
  unsigned int msglen;
  struct ofp_header * ofph;
  int count;

  if ( buflen == - 1 )
    {
      buflen = BUFLEN;
      buf = malloc_and_check(BUFLEN);
    }
  if(bufend >= buflen )   // if we've filled up our buffer, resize it
    {
      buflen *=2 ;
      buf = realloc_and_check(buf, buflen);
    }

  if(pfd->revents & POLLOUT)
    {
      if(msgbuf_write(ctx->control_outgoing,ctx->control_fd, 0) < 0)
	perror_and_exit("control write()",1);
    }

  if(!(pfd->revents & POLLIN))		// nothing to read, return
    return;
  count = read(pfd->fd,&buf[bufend], buflen - bufend);
  if(count < 0)
    {
      perror("process_control_event:read() ::");
      return ;
    }
  if(count == 0)
    {
      fprintf(stderr, "Switch Control Connection reset! wtf!?!...exiting\n");
      exit(0);
    }
  bufend += count;            // extend buf by amount read
  count = bufend - bufstart;  // re-purpose count

  while(count > 0 )
    {
      if(count <  sizeof(ofph))   // if we didn't get full openflow header
	return;                 // come back later

      ofph = (struct ofp_header * ) &buf[bufstart];
      msglen = ntohs(ofph->length);
      if( ( msglen > count) ||    // if we don't yet have the whole msg
	  (buflen < (msglen + bufstart)))  // or our buffer is full
	return;     // get the rest on the next pass

      neobuf = malloc_and_check(msglen);
      memcpy(neobuf, ofph, msglen);

      switch(ofph->type)
        {
	case OFPT_PACKET_IN:
	  mod->of_event_packet_in(ctx, (struct ofp_packet_in *)neobuf);
	  break;
	case OFPT_FLOW_EXPIRED:
#ifdef HAVE_OFP_FLOW_EXPIRED
	  mod->of_event_flow_removed(ctx, (struct ofp_flow_expired *)neobuf);
#elif defined(HAVE_OFP_FLOW_REMOVED)
	  mod->of_event_flow_removed(ctx, (struct ofp_flow_removed *)neobuf);
#else
#error "Unknown version of openflow"
#endif
	  break;
	case OFPT_PORT_STATUS:
	  mod->of_event_port_status(ctx, (struct ofp_port_status *)neobuf);
	  break;
	case OFPT_ECHO_REQUEST:
	  mod->of_event_echo_request(ctx, (struct ofp_header *)neobuf);
	  break;
	default:
	  if(ofph->type > OFPT_STATS_REPLY)   // FIXME: update for new openflow versions
	    {
	      fprintf(stderr, "%s:%zd :: Data buffer probably trashed : unknown openflow type %d\n",
		      __FILE__, __LINE__, ofph->type);
	      abort();
	    }
	  mod->of_event_other(ctx, (struct ofp_header * ) neobuf);
	  break;
        };
      free(neobuf);               
      bufstart += msglen;
      count = bufend - bufstart;  // repurpose count
    }       // end while()

  if ( bufstart >= bufend)        // if no outstanding bytes
    bufstart = bufend = 0;      // reset our buffer
}


/**********************************************************************************************
 * static void process_pcap_event(oflops_context *ctx, test_module * mod, struct pollfd *fd, oflops_channel_name ch);
 * 	front end to oflops_pcap_handler
 * 		make sure all of the memory is kosher before and after
 * 		pcap's callback thing has always annoyed me
 */
static void process_pcap_event(oflops_context *ctx, test_module * mod, struct pollfd *pfd, oflops_channel_name ch)
{
  struct pcap_event_wrapper wrap;
  int count;

  if(pfd->revents & POLLOUT)
    {
      int err;
      if((err=msgbuf_write(ctx->channels[ch].outgoing,ctx->channels[ch].raw_sock, ctx->channels[ch].packet_len) < 0) && 
	 (err != EAGAIN) && (err != EWOULDBLOCK ) && (err != EINTR))
	perror_and_exit("channel write()",1);
    }
  if(!(pfd->revents & POLLIN))		// nothing to read, return
    return;
  // read the next packet from the appropriate pcap socket
  assert(ctx->channels[ch].pcap_handle);
  count = pcap_dispatch(ctx->channels[ch].pcap_handle, 1, oflops_pcap_handler, (u_char *) & wrap);
  if((ch == OFLOPS_CONTROL) && (ctx->dump_controller)) 
    pcap_dump((u_char *)ctx->channels[ch].dump, &wrap.pe->pcaphdr, wrap.pe->data);
  if (count == 0)
    return;
  if (count < 0)
    {
      fprintf(stderr,"process_pcap_event:pcap_dispatch returned %d :: %s \n", count,
	      pcap_geterr(ctx->channels[ch].pcap_handle));
      return;
    }
  // dispatch it to the test module
  mod->handle_pcap_event(ctx, wrap.pe, ch);
  // clean up our mess
  pcap_event_free(wrap.pe);
  return;
}
/*************************************************************************
 * int load_test_module(oflops_context *ctx, 
 * 			char * mod_filename, char * initstr);
 * 	open this module and strip symbols out of it
 * 	and call init() on it
 */
int load_test_module(oflops_context *ctx, char * mod_filename, char * initstr)
{
  void * handle;
  test_module * mod;
  mod = malloc_and_check(sizeof(*mod));
  bzero(mod,sizeof(*mod));

  // open module for dyn symbols
  handle = dlopen(mod_filename,RTLD_NOW);
  if(handle == NULL)
    {	
      fprintf(stderr,"Error reading symbols from %s : %s\n",
	      mod_filename, dlerror());
      return 1;
    }
  mod->name = dlsym(handle,"name");
  mod->start = dlsym(handle,"start");
  if(!mod->name)
    fprintf( stderr, "Module %s does not contain a name() function\n", mod_filename);
  if(!mod->start)
    fprintf( stderr, "Module %s does not contain a start() function\n", mod_filename);
  if(!mod->name || !mod->start)
    {
      free(mod);
      dlclose(handle);
      return 1;	// fail for now
    }

#define symbol_fetch(X)				\
  mod->X = dlsym(handle, #X);			\
  if(!mod->X)					\
    mod->X = default_module_##X
  symbol_fetch(init);
  symbol_fetch(destroy);
  symbol_fetch(get_pcap_filter);
  symbol_fetch(handle_pcap_event);
  symbol_fetch(of_event_packet_in);
  symbol_fetch(of_event_flow_removed);
  symbol_fetch(of_event_echo_request);
  symbol_fetch(of_event_port_status);
  symbol_fetch(of_event_other);
  symbol_fetch(handle_timer_event);
  symbol_fetch(handle_snmp_event);
  symbol_fetch(handle_traffic_generation);
#undef symbol_fetch
  if(ctx->n_tests >= ctx->max_tests)
    {
      ctx->max_tests *=2;
      ctx->tests = realloc_and_check(ctx->tests, ctx->max_tests * sizeof(struct test_modules *));
    }
  ctx->tests[ctx->n_tests++] = mod;
  mod->symbol_handle=handle;
	
  if(mod->init)
    mod->init(ctx, initstr);
  return 0;
}