/*
     This file is part of GNUnet.
     Copyright (C)

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file rps/gnunet-rps.c
 * @brief random peer sampling
 * @author Julius Bünger
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_rps_service.h"
#include <inttypes.h>

static int ret;

/**
 * RPS handle
 */
static struct GNUNET_RPS_Handle *rps_handle;

/**
 * Request handle
 */
static struct GNUNET_RPS_Request_Handle *req_handle;

/**
 * PeerID (Option --seed)
 */
static struct GNUNET_PeerIdentity peer_id;

/**
 * @brief Do we want to receive updates of the view? (Option --view)
 */
static int view_update;

/**
 * @brief Do we want to receive updates of the view? (Option --view)
 */
static int stream_input;

/**
 * @brief Number of updates we want to receive
 */
static uint64_t num_view_updates;


/**
 * Task run when user presses CTRL-C to abort.
 * Cancels pending request and disconnects.
 *
 * @param cls NULL
 */
static void
do_shutdown (void *cls)
{
  (void) cls;

  if (NULL != req_handle)
    GNUNET_RPS_request_cancel (req_handle);
  GNUNET_RPS_disconnect (rps_handle);
}


/**
 * Callback called on receipt of reply.
 * Prints replied PeerIDs.
 *
 * @param cls closure
 * @param n number of peers
 * @param recv_peers the received peers
 */
static void
reply_handle (void *cls,
              uint64_t n,
              const struct GNUNET_PeerIdentity *recv_peers)
{
  uint64_t i;

  (void) cls;

  req_handle = NULL;
  for (i = 0; i < n; i++)
  {
    fprintf (stdout, "%s\n",
             GNUNET_i2s_full (&recv_peers[i]));
  }
  ret = 0;

  GNUNET_SCHEDULER_shutdown ();
}


/**
 * Callback called on receipt view update.
 * Prints view.
 *
 * @param n number of peers
 * @param recv_peers the received peers
 */
static void
view_update_handle (void *cls,
                    uint64_t n,
                    const struct GNUNET_PeerIdentity *recv_peers)
{
  uint64_t i;

  (void) cls;

  if (0 == n)
  {
    fprintf (stdout, "Empty view\n");
  }
  req_handle = NULL;
  for (i = 0; i < n; i++)
  {
    fprintf (stdout, "%s\n",
             GNUNET_i2s_full (&recv_peers[i]));
  }

  if (1 == num_view_updates)
  {
    ret = 0;
    GNUNET_SCHEDULER_shutdown ();
  }
  else if (1 < num_view_updates)
  {
    num_view_updates--;
  }
}


/**
 * Callback called on receipt of peer from biased stream
 *
 * @param num_peers number of peers
 * @param recv_peers the received peers
 */
static void
stream_input_handle (void *cls,
                     uint64_t num_peers,
                     const struct GNUNET_PeerIdentity *recv_peers)
{
  uint64_t i;

  (void) cls;

  if (0 == num_peers)
  {
    fprintf (stdout, "No peer was returned\n");
  }
  req_handle = NULL;
  for (i = 0; i < num_peers; i++)
  {
    fprintf (stdout, "%s\n",
             GNUNET_i2s_full (&recv_peers[i]));
  }
}


/**
 * Main function that will be run by the scheduler.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param cfg configuration
 */
static void
run (void *cls,
     char *const *args,
     const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  static uint64_t num_peers;
  static struct GNUNET_PeerIdentity zero_pid;

  (void) cls;
  (void) cfgfile;

  rps_handle = GNUNET_RPS_connect (cfg);
  if (NULL == rps_handle)
  {
    fprintf (stderr, "Failed to connect to the rps service\n");
    return;
  }

  if ((0 == memcmp (&zero_pid, &peer_id, sizeof(peer_id))) &&
      (! view_update) &&
      (! stream_input))
  {   /* Request n PeerIDs */
      /* If number was specified use it, else request single peer. */
    if ((NULL == args[0]) ||
        (0 == sscanf (args[0], "%lu", &num_peers)) )
    {
      num_peers = 1;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Requesting %" PRIu64 " PeerIDs\n", num_peers);
    req_handle = GNUNET_RPS_request_peers (rps_handle, num_peers, reply_handle,
                                           NULL);
    GNUNET_SCHEDULER_add_shutdown (&do_shutdown, NULL);
  }
  else if (view_update)
  {
    /* Get updates of view */
    if ((NULL == args[0]) ||
        (0 == sscanf (args[0], "%lu", &num_view_updates)) )
    {
      num_view_updates = 0;
    }
    GNUNET_RPS_view_request (rps_handle, num_view_updates, view_update_handle,
                             NULL);
    if (0 != num_view_updates)
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Requesting %" PRIu64 " view updates\n", num_view_updates);
    else
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Requesting continuous view updates\n");
    GNUNET_SCHEDULER_add_shutdown (&do_shutdown, NULL);
  }
  else if (stream_input)
  {
    /* Get updates of view */
    GNUNET_RPS_stream_request (rps_handle, stream_input_handle, NULL);
    GNUNET_SCHEDULER_add_shutdown (&do_shutdown, NULL);
  }
  else
  {   /* Seed PeerID */
    GNUNET_RPS_seed_ids (rps_handle, 1, &peer_id);
    fprintf (stdout, "Seeded PeerID %s\n", GNUNET_i2s_full (&peer_id));
    ret = 0;
    GNUNET_SCHEDULER_add_now (&do_shutdown, NULL);
  }
}


/**
 * The main function to rps.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  const char helpstr[] =
    "Get random GNUnet peers. If none is specified a single is requested.";
  struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_option_base32_auto ('s',
                                      "seed",
                                      "PEER_ID",
                                      gettext_noop ("Seed a PeerID"),
                                      &peer_id),
    GNUNET_GETOPT_option_flag ('V',
                               "view",
                               gettext_noop (
                                 "Get updates of view (0 for infinite updates)"),
                               &view_update),
    GNUNET_GETOPT_option_flag ('S',
                               "stream",
                               gettext_noop ("Get peers from biased stream"),
                               &stream_input),
    GNUNET_GETOPT_OPTION_END
  };

  return (GNUNET_OK ==
          GNUNET_PROGRAM_run (argc,
                              argv,
                              "gnunet-rps [NUMBER_OF_PEERS]",
                              gettext_noop
                                (helpstr),
                              options, &run, NULL)) ? ret : 1;
}


/* end of gnunet-rps.c */
