/*
 * channels.C: Channel event and state tracking
 * Rights to this code are documented in doc/pod/license.pod.
 *
 * Copyright © 2005-2007 Atheme Project (http://www.atheme.org)           
 */

static char const rcsid[] = "$Id: channels.C,v 1.5 2007/08/30 06:57:25 pippijn Exp $";

#include "atheme.h"
#include <account/mychan.h>

channel_map chanlist;
channel_t::callbacks channel_t::callback;
chanuser_t::callbacks chanuser_t::callback;

/*
 * init_channels()
 *
 * Initializes the channel-related heaps and DTree structures.
 *
 * Inputs:
 *     - nothing
 *
 * Outputs:
 *     - nothing
 *
 * Side Effects:
 *     - if the heaps or DTrees fail to initialize, the program will abort.
 */
void
init_channels (void)
{
#if 0
  chan_heap = BlockHeapCreate (sizeof (channel_t), HEAP_CHANNEL);
  chanuser_heap = BlockHeapCreate (sizeof (chanuser_t), HEAP_CHANUSER);
  chanban_heap = BlockHeapCreate (sizeof (chanban_t), HEAP_CHANUSER);
#endif
}

/*
 * channel_add(char const * const name, unsigned int ts, server_t *creator)
 *
 * Channel object factory.
 *
 * Inputs:
 *     - channel name
 *     - timestamp of channel creation
 *     - server that is creating the channel
 *
 * Outputs:
 *     - on success, a channel object
 *     - on failure, NULL
 *
 * Side Effects:
 *     - the channel is automatically inserted into the channel DTree
 *     - if the creator is not me.me:
 *       - channel_add hook is called
 *       - all services are joined if this is the snoop channel
 *     - if the creator is me.me these actions must be performed by the
 *       caller (i.e. join()) after joining the service
 */
channel_t *
channel_add (char const * const name, unsigned int ts, server_t *creator)
{
  channel_t *c;
  mychan_t *mc;

  if (*name != '#')
    {
      slog (LG_DEBUG, "channel_add(): got non #channel: %s", name);
      return NULL;
    }

  c = channel_find (name);

  if (c)
    {
      slog (LG_DEBUG, "channel_add(): channel already exists: %s", name);
      return c;
    }

  slog (LG_DEBUG, "channel_add(): %s by %s", name, creator->name);

  c = new channel_t;

  c->name = sstrdup (name);
  c->ts = ts;

  c->topic = NULL;
  c->topic_setter = NULL;

  c->bans.head = NULL;
  c->bans.tail = NULL;
  c->bans.count = 0;

  if ((mc = mychan_find (c->name)))
    mc->chan = c;

  chanlist[c->name] = c;

  cnt.chan++;

  if (creator != me.me)
    {
      c->callback.add (c);

      if (config_options.chan != NULL && !irccasecmp (config_options.chan, name))
	joinall (config_options.chan);
    }

  return c;
}

/*
 * channel_delete(channel_t *c)
 *
 * Destroys a channel object and its children member objects.
 *
 * Inputs:
 *     - channel object to destroy
 *
 * Outputs:
 *     - nothing
 *
 * Side Effects:
 *     - channel_delete hook is called
 *     - a channel and all attached structures are destroyed
 *     - no protocol messages are sent for any remaining members
 */
void
channel_delete (channel_t *c)
{
  mychan_t *mc;
  node_t *n, *tn;
  chanuser_t *cu;

  return_if_fail (c != NULL);

  slog (LG_DEBUG, "channel_delete(): %s", c->name);

  modestack_finalize_channel (c);

  /* If this is called from uplink_close(), there may still be services
   * in the channel. Remove them. Calling chanuser_delete() could lead
   * to a recursive call, so don't do that.
   * -- jilles */
  LIST_FOREACH_SAFE (n, tn, c->members.head)
  {
    cu = static_cast<chanuser_t *> (n->data);
    soft_assert (is_internal_client (cu->user) && !me.connected);
    node_del (&cu->cnode, &c->members);
    node_del (&cu->unode, &cu->user->channels);
    delete cu;
    cnt.chanuser--;
  }
  c->nummembers = 0;

  c->callback.remove (c);

  chanlist.erase (c->name);

  if ((mc = mychan_find (c->name)))
    mc->chan = NULL;

  clear_simple_modes (c);
  chanban_clear (c);

  sfree (c->name);
  if (c->topic != NULL)
    sfree (c->topic);
  if (c->topic_setter != NULL)
    sfree (c->topic_setter);

  delete c;

  cnt.chan--;
}

/*
 * channel_find(char const * const name)
 *
 * Looks up a channel object.
 *
 * Inputs:
 *     - name of channel to look up
 *
 * Outputs:
 *     - on success, the channel object
 *     - on failure, NULL
 *
 * Side Effects:
 *     - none
 */
channel_t *
channel_find (char const * const name)
{
  channel_map::iterator it = chanlist.find (name);
  if (it == chanlist.end ())
    return NULL;

  return it->second;
}

/*
 * chanban_add(channel_t *c, char const * const mask, int type)
 *
 * Channel ban factory.
 *
 * Inputs:
 *     - channel that the ban belongs to
 *     - banmask
 *     - type of ban, e.g. 'b' or 'e'
 *
 * Outputs:
 *     - on success, a new channel ban object
 *     - on failure, NULL
 *
 * Side Effects:
 *     - the created channel ban object is added to the channel automatically.
 */
chanban_t *
chanban_add (channel_t *c, char const * const mask, int type)
{
  chanban_t *cb;
  node_t *n;

  if (mask == NULL)
    {
      slog (LG_ERROR, "chanban_add(): NULL +%c mask", type);
      return NULL;
    }
  /* this would break protocol and/or cause crashes */
  if (*mask == '\0' || *mask == ':' || strchr (mask, ' '))
    {
      slog (LG_ERROR, "chanban_add(): trying to add invalid +%c %s to channel %s", type, mask, c->name);
      return NULL;
    }

  cb = chanban_find (c, mask, type);

  if (cb)
    {
      slog (LG_DEBUG, "chanban_add(): channel ban %s:%s already exists", c->name, cb->mask);
      return NULL;
    }

  slog (LG_DEBUG, "chanban_add(): %s +%c %s", c->name, type, mask);

  n = node_create ();
  cb = new chanban_t;

  cb->chan = c;
  cb->mask = sstrdup (mask);
  cb->type = type;

  node_add (cb, n, &c->bans);

  return cb;
}

/*
 * chanban_delete(chanban_t *c)
 *
 * Destroys a channel ban.
 *
 * Inputs:
 *     - channel ban object to destroy
 *
 * Outputs:
 *     - nothing
 *
 * Side Effects:
 *     - the channel ban is automatically removed from the channel that owned it
 */
void
chanban_delete (chanban_t *c)
{
  node_t *n;

  if (!c)
    {
      slog (LG_DEBUG, "chanban_delete(): called for nonexistant ban");
      return;
    }

  n = node_find (c, &c->chan->bans);
  node_del (n, &c->chan->bans);
  node_free (n);

  sfree (c->mask);
  delete c;
}

/*
 * chanban_find(channel_t *chan, char const * const mask, int type)
 *
 * Looks up a channel ban.
 *
 * Inputs:
 *     - channel that the ban is supposedly on
 *     - mask that is being looked for
 *     - type of ban that is being looked for
 *
 * Outputs:
 *     - on success, returns the channel ban object requested
 *     - on failure, returns NULL
 *
 * Side Effects:
 *     - none
 */
chanban_t *
chanban_find (channel_t *c, char const * const mask, int type)
{
  chanban_t *cb;
  node_t *n;

  LIST_FOREACH (n, c->bans.head)
  {
    cb = static_cast<chanban_t *> (n->data);

    if (cb->type == type && !irccasecmp (cb->mask, mask))
      return cb;
  }

  return NULL;
}

/*
 * chanban_clear(channel_t *c)
 *
 * Destroys all channel bans attached to a channel.
 *
 * Inputs:
 *     - channel to clear banlist on
 *
 * Outputs:
 *     - nothing
 *
 * Side Effects:
 *     - the banlist on the channel is cleared
 *     - no protocol messages are sent
 */
void
chanban_clear (channel_t *c)
{
  node_t *n, *tn;

  LIST_FOREACH_SAFE (n, tn, c->bans.head)
  {
    /* inefficient but avoids code duplication -- jilles */
    chanban_delete (static_cast<chanban_t *> (n->data));
  }
}

/*
 * chanuser_add(channel_t *c, char const * const nick)
 *
 * Channel user factory.
 *
 * Inputs:
 *     - channel that the user should belong to
 *     - nick/UID with any appropriate prefixes (e.g. ~, &, @, %, +)
 *       (if the user has a UID it must be used)
 *
 * Outputs:
 *     - on success, a new channel user object
 *     - on failure (NULL channel, or user kicked by channel_join hook), NULL
 *
 * Side Effects:
 *     - the channel user object is automatically associated to its parents
 *     - channel_join hook is called
 */

/*
 * Rewritten 06/23/05 by nenolod:
 *
 * Iterate through the list of prefix characters we know about.
 * Continue to do so until all prefixes are covered. Then add the
 * nick to the channel, with the privs he has acquired thus far.
 *
 * Once, and only once we have done that do we start in on checking
 * privileges. Otherwise we have a very inefficient way of doing
 * things. It worked fine for shrike, but the old code was restricted
 * to handling only @, @+ and + as prefixes.
 */
chanuser_t *
chanuser_add (channel_t *c, char const * const nickname)
{
  char const *nick = nickname;
  user_t *u;
  chanuser_t *cu, *tcu;
  unsigned int flags = 0;
  int i = 0;

  if (c == NULL)
    return NULL;

  if (*c->name != '#')
    {
      slog (LG_DEBUG, "chanuser_add(): got non #channel: %s", c->name);
      return NULL;
    }

  while (*nick != '\0')
    {
      for (i = 0; prefix_mode_list[i].mode; i++)
	if (*nick == prefix_mode_list[i].mode)
	  {
	    flags |= prefix_mode_list[i].value;
	    break;
	  }
      if (!prefix_mode_list[i].mode)
	break;
      nick++;
    }

  u = user_find (nick);
  if (u == NULL)
    {
      slog (LG_DEBUG, "chanuser_add(): nonexist user: %s", nick);
      return NULL;
    }

  tcu = chanuser_find (c, u);
  if (tcu != NULL)
    {
      slog (LG_DEBUG, "chanuser_add(): user is already present: %s -> %s", c->name, u->nick);

      /* could be an OPME or other desyncher... */
      tcu->modes |= flags;

      return tcu;
    }

  slog (LG_DEBUG, "chanuser_add(): %s -> %s", c->name, u->nick);

  cu = new chanuser_t;

  cu->chan = c;
  cu->user = u;
  cu->modes |= flags;

  c->nummembers++;

  node_add (cu, &cu->cnode, &c->members);
  node_add (cu, &cu->unode, &u->channels);

  cnt.chanuser++;

  /* Return NULL if a hook function kicked the user out */
  return cu->callback.join (cu) ? cu : NULL;
}

/*
 * chanuser_delete(channel_t *c, user_t *user)
 *
 * Destroys a channel user object.
 *
 * Inputs:
 *     - channel the user is on
 *     - the user itself
 *
 * Outputs:
 *     - nothing
 *
 * Side Effects:
 *     if the user is on the channel:
 *     - a channel user object is removed from the
 *       channel's userlist and the user's channellist.
 *     - channel_part hook is called
 *     - if this empties the channel and the channel is not set permanent
 *       (ircd->perm_mode), channel_delete() is called (q.v.)
 */
void
chanuser_delete (channel_t *c, user_t *user)
{
  chanuser_t *cu;

  if (!c)
    {
      slog (LG_DEBUG, "chanuser_delete(): called with NULL chan");
      return;
    }

  if (!user)
    {
      slog (LG_DEBUG, "chanuser_delete(): called with NULL user");
      return;
    }

  cu = chanuser_find (c, user);
  if (cu == NULL)
    return;

  /* this is called BEFORE we remove the user */
  cu->callback.part (cu);

  slog (LG_DEBUG, "chanuser_delete(): %s -> %s (%d)", cu->chan->name, cu->user->nick, cu->chan->nummembers - 1);

  node_del (&cu->cnode, &c->members);
  node_del (&cu->unode, &user->channels);

  delete cu;

  c->nummembers--;
  cnt.chanuser--;

  if (c->nummembers == 0 && !(c->modes & ircd->perm_mode))
    {
      /* empty channels die */
      slog (LG_DEBUG, "chanuser_delete(): `%s' is empty, removing", c->name);

      channel_delete (c);
    }
}

/*
 * chanuser_find(channel_t *c, user_t *user)
 *
 * Looks up a channel user object.
 *
 * Inputs:
 *     - channel object that the user is on
 *     - target user object
 *
 * Outputs:
 *     - on success, a channel user object
 *     - on failure, NULL
 *
 * Side Effects:
 *     - none
 */
chanuser_t *
chanuser_find (channel_t *c, user_t *user)
{
  node_t *n;
  chanuser_t *cu;

  if ((!c) || (!user))
    return NULL;

  /* choose shortest list to search -- jilles */
  if (LIST_LENGTH (&user->channels) < LIST_LENGTH (&c->members))
    {
      LIST_FOREACH (n, user->channels.head)
      {
	cu = (chanuser_t *) n->data;

	if (cu->chan == c)
	  return cu;
      }
    }
  else
    {
      LIST_FOREACH (n, c->members.head)
      {
	cu = (chanuser_t *) n->data;

	if (cu->user == user)
	  return cu;
      }
    }

  return NULL;
}