/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2010 InspIRCd Development Team
 * See: http://wiki.inspircd.org/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#include "inspircd.h"
#include <sstream>
#include <list>
#include "m_sqlutils.h"

/* $ModDesc: Provides some utilities to SQL client modules, such as mapping queries to users and channels */
/* $ModDep: m_sqlutils.h */

typedef std::map<unsigned long, User*> IdUserMap;
typedef std::map<unsigned long, Channel*> IdChanMap;
typedef std::list<unsigned long> AssocIdList;

class ModuleSQLutils : public Module
{
private:
	IdUserMap iduser;
	IdChanMap idchan;
	SimpleExtItem<AssocIdList> idExt;

public:
	ModuleSQLutils() : idExt("sqlutils_list", this)
	{
	}

	void init()
	{
		Implementation eventlist[] = { I_OnChannelDelete, I_OnUnloadModule, I_OnUserDisconnect };
		ServerInstance->Modules->Attach(eventlist, this, 3);
	}

	void OnRequest(Request& request)
	{
		if(strcmp(SQLUTILAU, request.id) == 0)
		{
			AssociateUser* req = (AssociateUser*)&request;

			iduser.insert(std::make_pair(req->id, req->user));

			AttachList(req->user, req->id);
		}
		else if(strcmp(SQLUTILAC, request.id) == 0)
		{
			AssociateChan* req = (AssociateChan*)&request;

			idchan.insert(std::make_pair(req->id, req->chan));

			AttachList(req->chan, req->id);
		}
		else if(strcmp(SQLUTILUA, request.id) == 0)
		{
			UnAssociate* req = (UnAssociate*)&request;

			/* Unassociate a given query ID with all users and channels
			 * it is associated with.
			 */

			DoUnAssociate(iduser, req->id);
			DoUnAssociate(idchan, req->id);
		}
		else if(strcmp(SQLUTILGU, request.id) == 0)
		{
			GetAssocUser* req = (GetAssocUser*)&request;

			IdUserMap::iterator iter = iduser.find(req->id);

			if(iter != iduser.end())
			{
				req->user = iter->second;
			}
		}
		else if(strcmp(SQLUTILGC, request.id) == 0)
		{
			GetAssocChan* req = (GetAssocChan*)&request;

			IdChanMap::iterator iter = idchan.find(req->id);

			if(iter != idchan.end())
			{
				req->chan = iter->second;
			}
		}
	}

	void OnUserDisconnect(LocalUser* user)
	{
		/* A user is disconnecting, first we need to check if they have a list of queries associated with them.
		 * Then, if they do, we need to erase each of them from our IdUserMap (iduser) so when the module that
		 * associated them asks to look them up then it gets a NULL result and knows to discard the query.
		 */
		AssocIdList* il = idExt.get(user);

		if(il)
		{
			for(AssocIdList::iterator listiter = il->begin(); listiter != il->end(); listiter++)
			{
				IdUserMap::iterator iter;

				iter = iduser.find(*listiter);

				if(iter != iduser.end())
				{
					if(iter->second != user)
					{
						ServerInstance->Logs->Log("m_sqlutils",DEBUG, "BUG: ID associated with user %s doesn't have the same User* associated with it in the map (erasing anyway)", user->nick.c_str());
					}

					iduser.erase(iter);
				}
				else
				{
					ServerInstance->Logs->Log("m_sqlutils",DEBUG, "BUG: user %s was extended with sqlutils_queryids but there was nothing matching in the map", user->nick.c_str());
				}
			}

			idExt.unset(user);
		}
	}

	void AttachList(Extensible* obj, unsigned long id)
	{
		AssocIdList* il = idExt.get(obj);

		if (!il)
		{
			/* Doesn't already exist, create a new list and attach it. */
			il = new AssocIdList;
			idExt.set(obj, il);
		}

		/* Now either way we have a valid list in il, attached. */
		il->push_back(id);
	}

	void RemoveFromList(Extensible* obj, unsigned long id)
	{
		AssocIdList* il = idExt.get(obj);

		if (il)
		{
			/* Only do anything if the list exists... (which it ought to) */
			il->remove(id);

			if(il->empty())
			{
				/* If we just emptied it.. */
				idExt.unset(obj);
			}
		}
	}

	template <class T> void DoUnAssociate(T &map, unsigned long id)
	{
		/* For each occurence of 'id' (well, only one..it's not a multimap) in 'map'
		 * remove it from the map, take an Extensible* value from the map and remove
		 * 'id' from the list of query IDs attached to it.
		 */
		typename T::iterator iter = map.find(id);

		if(iter != map.end())
		{
			/* Found a value indexed by 'id', call RemoveFromList()
			 * on it with 'id' to remove 'id' from the list attached
			 * to the value.
			 */
			RemoveFromList(iter->second, id);
		}
	}

	void OnChannelDelete(Channel* chan)
	{
		/* A channel is being destroyed, first we need to check if it has a list of queries associated with it.
		 * Then, if it does, we need to erase each of them from our IdChanMap (idchan) so when the module that
		 * associated them asks to look them up then it gets a NULL result and knows to discard the query.
		 */
		AssocIdList* il = idExt.get(chan);

		if (il)
		{
			for(AssocIdList::iterator listiter = il->begin(); listiter != il->end(); listiter++)
			{
				IdChanMap::iterator iter;

				iter = idchan.find(*listiter);

				if(iter != idchan.end())
				{
					if(iter->second != chan)
					{
						ServerInstance->Logs->Log("m_sqlutils",DEBUG, "BUG: ID associated with channel %s doesn't have the same Channel* associated with it in the map (erasing anyway)", chan->name.c_str());
					}
					idchan.erase(iter);
				}
				else
				{
					ServerInstance->Logs->Log("m_sqlutils",DEBUG, "BUG: channel %s was extended with sqlutils_queryids but there was nothing matching in the map", chan->name.c_str());
				}
			}

			idExt.unset(chan);
		}
	}

	Version GetVersion()
	{
		return Version("Provides some utilities to SQL client modules, such as mapping queries to users and channels", VF_VENDOR);
	}

};

MODULE_INIT(ModuleSQLutils)