/*
     This file is part of GNUnet.
     (C) 2011 Christian Grothoff (and other contributing authors)

     GNUnet 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 3, 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
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file ats/gnunet-service-ats_performance.c
 * @brief ats service, interaction with 'performance' API
 * @author Matthias Wachs
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet-service-ats_performance.h"
#include "gnunet-service-ats_reservations.h"
#include "ats.h"


/**
 * We keep clients that are interested in performance in a linked list.
 */
struct PerformanceClient
{
  /**
   * Next in doubly-linked list.
   */
  struct PerformanceClient * next;

  /**
   * Previous in doubly-linked list.
   */
  struct PerformanceClient * prev;
  
  /**
   * Actual handle to the client.
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Options for the client.
   */
  enum StartFlag flag;

};


/**
 * Head of linked list of all clients to this service.
 */
static struct PerformanceClient *pc_head;

/**
 * Tail of linked list of all clients to this service.
 */
static struct PerformanceClient *pc_tail;
 
/**
 * Context for sending messages to performance clients.
 */
static struct GNUNET_SERVER_NotificationContext *nc;


/**
 * Find the performance client associated with the given handle.
 *
 * @param client server handle
 * @return internal handle
 */
static struct PerformanceClient * 
find_client (struct GNUNET_SERVER_Client *client)
{
  struct PerformanceClient * pc;

  for (pc = pc_head; pc != NULL; pc = pc->next)
    if (pc->client == client)
      return pc;
  return NULL;
}


/**
 * Register a new performance client.
 *
 * @param client handle of the new client
 */
void
GAS_performance_add_client (struct GNUNET_SERVER_Client *client,
			    enum StartFlag flag)
{
  struct PerformanceClient * pc;

  GNUNET_break (NULL == find_client (client));
  pc = GNUNET_malloc (sizeof (struct PerformanceClient));
  pc->client = client;
  pc->flag = flag;
  GNUNET_SERVER_notification_context_add (nc, client);
  GNUNET_SERVER_client_keep (client);
  GNUNET_CONTAINER_DLL_insert(pc_head, pc_tail, pc);
}


/**
 * Unregister a client (which may have been a performance client,
 * but this is not assured).
 *
 * @param client handle of the (now dead) client
 */
void
GAS_performance_remove_client (struct GNUNET_SERVER_Client *client)
{
  struct PerformanceClient * pc;

  pc = find_client (client);
  if (NULL == pc)
    return;
  GNUNET_CONTAINER_DLL_remove (pc_head, pc_tail, pc);
  GNUNET_SERVER_client_drop (client);
  GNUNET_free (pc);
}


/**
 * Handle 'reservation request' messages from clients.
 *
 * @param cls unused, NULL
 * @param client client that sent the request
 * @param message the request message
 */
void
GAS_handle_reservation_request (void *cls, struct GNUNET_SERVER_Client *client,
				const struct GNUNET_MessageHeader *message)
{
  const struct ReservationRequestMessage * msg = (const struct ReservationRequestMessage *) message;
  struct ReservationResultMessage result;
  int32_t amount;
  struct GNUNET_TIME_Relative res_delay;

  if (NULL == find_client (client))
  {
    /* missing start message! */
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Received `%s' message\n",
	      "RESERVATION_REQUEST");
  amount = (int32_t) ntohl (msg->amount);
  res_delay = GAS_reservations_reserve (&msg->peer,
					amount);
  if (res_delay.rel_value > 0)
    amount = 0;
  result.header.size = htons (sizeof (struct ReservationResultMessage));
  result.header.type = htons (GNUNET_MESSAGE_TYPE_ATS_RESERVATION_RESULT);
  result.amount = htonl (amount);
  result.res_delay = GNUNET_TIME_relative_hton (res_delay);
  GNUNET_SERVER_notification_context_unicast (nc,
					      client,
					      &result.header,
					      GNUNET_NO);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Handle 'preference change' messages from clients.
 *
 * @param cls unused, NULL
 * @param client client that sent the request
 * @param message the request message
 */
void
GAS_handle_preference_change (void *cls, struct GNUNET_SERVER_Client *client,
			      const struct GNUNET_MessageHeader *message)
{
  // const struct ChangePreferenceMessage * msg = (const struct ChangePreferenceMessage *) message;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Received `%s' message\n", "PREFERENCE_CHANGE");
  // FIXME: implement later (we can safely ignore these for now)
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Initialize performance subsystem.
 *
 * @param server handle to our server
 */
void
GAS_performance_init (struct GNUNET_SERVER_Handle *server)
{
  nc = GNUNET_SERVER_notification_context_create (server, 128);
}


/**
 * Shutdown performance subsystem.
 */
void
GAS_performance_done ()
{
  GNUNET_SERVER_notification_context_destroy (nc);
  nc = NULL;
}

/* end of gnunet-service-ats_performance.c */