/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *  event.c: Event functions.
 *
 *  Copyright (c) 1998-2000 Regents of the University of California
 *  Copyright (c) 2000-2014 ircd-hybrid development team
 *
 *  Code borrowed from the squid web cache by Adrian Chadd.
 *  Original header:
 *
 *  DEBUG: section 41   Event Processing
 *  AUTHOR: Henrik Nordstrom
 *
 *  SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
 *  ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from the
 *  Internet community.  Development is led by Duane Wessels of the
 *  National Laboratory for Applied Network Research and funded by the
 *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
 *  the Regents of the University of California.  Please see the
 *  COPYRIGHT file for full details.  Squid incorporates software
 *  developed and/or copyrighted by other sources.  Please see the
 *  CREDITS file for full details.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *  USA
 *
 *  $Id$
 */

/*
 * How it's used:
 *
 * Should be pretty self-explanatory. Events are added to the static
 * array event_table with a frequency time telling eventRun how often
 * to execute it.
 */

#include "stdinc.h"
#include "list.h"
#include "ircd.h"
#include "event.h"
#include "client.h"
#include "send.h"
#include "memory.h"
#include "log.h"
#include "numeric.h"
#include "rng_mt.h"


static const char *last_event_ran = NULL;
static struct ev_entry event_table[MAX_EVENTS];
static time_t event_time_min = -1;
static int eventFind(EVH *func, void *arg);

/*
 * void eventAdd(const char *name, EVH *func, void *arg, time_t when)
 *
 * Input: Name of event, function to call, arguments to pass, and frequency
 *	  of the event.
 * Output: None
 * Side Effects: Adds the event to the event list.
 */
void
eventAdd(const char *name, EVH *func, void *arg, time_t when)
{
  int i;

  /* find first inactive index, or use next index */
  for (i = 0; i < MAX_EVENTS; i++)
  {
    if (event_table[i].active == 0)
    {
      event_table[i].func = func;
      event_table[i].name = name;
      event_table[i].arg = arg;
      event_table[i].when = CurrentTime + when;
      event_table[i].frequency = when;
      event_table[i].active = 1;

      if ((event_table[i].when < event_time_min) || (event_time_min == -1))
        event_time_min = event_table[i].when;

      return;
    }
  }
  /* XXX if reach here, its an error */
  ilog(LOG_TYPE_IRCD, "Event table is full! (%d)", i);
}

/*
 * void eventDelete(EVH *func, void *arg)
 *
 * Input: Function handler, argument that was passed.
 * Output: None
 * Side Effects: Removes the event from the event list
 */
void
eventDelete(EVH *func, void *arg)
{
  int i = eventFind(func, arg);

  if (i == -1)
    return;

  event_table[i].name = NULL;
  event_table[i].func = NULL;
  event_table[i].arg = NULL;
  event_table[i].active = 0;
}

/*
 * void eventAddIsh(const char *name, EVH *func, void *arg, time_t delta_isa)
 *
 * Input: Name of event, function to call, arguments to pass, and frequency
 *	  of the event.
 * Output: None
 * Side Effects: Adds the event to the event list within +- 1/3 of the
 *	         specified frequency.
 */
void
eventAddIsh(const char *name, EVH *func, void *arg, time_t delta_ish)
{
  if (delta_ish >= 3)
  {
    const time_t two_third = (2 * delta_ish) / 3;
    delta_ish = two_third + ((genrand_int32() % 1000) * two_third) / 1000;
      /*
       * XXX I hate the above magic, I don't even know if its right.
       * Grr. -- adrian
       */
  }

  eventAdd(name, func, arg, delta_ish);
}

/*
 * void eventRun(void)
 *
 * Input: None
 * Output: None
 * Side Effects: Runs pending events in the event list
 */
void
eventRun(void)
{
  int i;

  for (i = 0; i < MAX_EVENTS; i++)
  {
    if (event_table[i].active && (event_table[i].when <= CurrentTime))
    {
      last_event_ran = event_table[i].name;
      event_table[i].func(event_table[i].arg);
      event_table[i].when = CurrentTime + event_table[i].frequency;
      event_time_min = -1;
    }
  }
}

/*
 * time_t eventNextTime(void)
 *
 * Input: None
 * Output: Specifies the next time eventRun() should be run
 * Side Effects: None
 */
time_t
eventNextTime(void)
{
  int i;

  if (event_time_min == -1)
  {
    for (i = 0; i < MAX_EVENTS; i++)
    {
      if (event_table[i].active && ((event_table[i].when < event_time_min) || (event_time_min == -1)))
        event_time_min = event_table[i].when;
    }
  }

  return event_time_min;
}

/*
 * void eventInit(void)
 *
 * Input: None
 * Output: None
 * Side Effects: Initializes the event system.
 */
void
eventInit(void)
{
  last_event_ran = NULL;
  memset(event_table, 0, sizeof(event_table));
}

/*
 * int eventFind(EVH *func, void *arg)
 *
 * Input: Event function and the argument passed to it
 * Output: Index to the slow in the event_table
 * Side Effects: None
 */
static int
eventFind(EVH *func, void *arg)
{
  int i;

  for (i = 0; i < MAX_EVENTS; i++)
    if ((event_table[i].func == func) &&
        (event_table[i].arg == arg) &&
         event_table[i].active)
      return i;

  return -1;
}

/*
 * void show_events(struct Client *source_p)
 *
 * Input: Client requesting the event
 * Output: List of events
 * Side Effects: None
 */
void
show_events(struct Client *source_p)
{
  int i;

  if (last_event_ran)
  {
    sendto_one(source_p, ":%s %d %s :Last event to run: %s",
               me.name, RPL_STATSDEBUG, source_p->name, last_event_ran);
    sendto_one(source_p, ":%s %d %s : ",
      me.name, RPL_STATSDEBUG, source_p->name);
  }

  sendto_one(source_p,
    ":%s %d %s : Operation                    Next Execution",
    me.name, RPL_STATSDEBUG, source_p->name);
  sendto_one(source_p,
    ":%s %d %s : -------------------------------------------",
    me.name, RPL_STATSDEBUG, source_p->name);

  for (i = 0; i < MAX_EVENTS; i++)
  {
    if (event_table[i].active)
    {
      sendto_one(source_p, ":%s %d %s : %-28s %-4d seconds",
                 me.name, RPL_STATSDEBUG, source_p->name,
                 event_table[i].name,
                 (int)(event_table[i].when - CurrentTime));
    }
  }
}

/*
 * void set_back_events(time_t by)
 * Input: Time to set back events by.
 * Output: None.
 * Side-effects: Sets back all events by "by" seconds.
 */
void
set_back_events(time_t by)
{
  int i;

  event_time_min = -1;

  for (i = 0; i < MAX_EVENTS; i++)
  {
    if (event_table[i].when > by)
      event_table[i].when -= by;
    else
      event_table[i].when = 0;
  }
}