/* NickServ core functions
 *
 * (C) 2003-2024 Anope Team
 * Contact us at team@anope.org
 *
 * Please read COPYING and README for further details.
 *
 * Based on the original code of Epona by Lara.
 * Based on the original code of Services by Andy Church.
 */

#include "module.h"

class NickServCollide;
static std::set<NickServCollide *> collides;

/** Timer for colliding nicks to force people off of nicknames
 */
class NickServCollide final
	: public Timer
{
	NickServService *service;
	Reference<User> u;
	time_t ts;
	Reference<NickAlias> na;

public:
	NickServCollide(Module *me, NickServService *nss, User *user, NickAlias *nick, time_t delay)
		: Timer(me, delay)
		, service(nss)
		, u(user)
		, ts(user->timestamp)
		, na(nick)
	{
		collides.insert(this);
	}

	~NickServCollide() override
	{
		collides.erase(this);
	}

	User *GetUser()
	{
		return u;
	}

	NickAlias *GetNick()
	{
		return na;
	}

	void Tick() override
	{
		if (!u || !na)
			return;
		/* If they identified or don't exist anymore, don't kill them. */
		if (u->Account() == na->nc || u->timestamp > ts)
			return;

		service->Collide(u, na);
	}
};

/** Timer for removing HELD status from nicks.
 */
class NickServHeld final
	: public Timer
{
	Reference<NickAlias> na;
	Anope::string nick;
public:
	NickServHeld(Module *me, NickAlias *n, time_t l)
		: Timer(me, l)
		, na(n)
		, nick(na->nick)
	{
		n->Extend<bool>("HELD");
	}

	void Tick() override
	{
		if (na)
			na->Shrink<bool>("HELD");
	}
};

class NickServRelease;
static Anope::map<NickServRelease *> NickServReleases;

/** Timer for releasing nicks to be available for use
 */
class NickServRelease final
	: public User
	, public Timer
{
	Anope::string nick;

public:
	NickServRelease(Module *me, NickAlias *na, time_t delay)
		: User(na->nick, Config->GetModule("nickserv")->Get<const Anope::string>("enforceruser", "user"), Config->GetModule("nickserv")->Get<const Anope::string>("enforcerhost", Me->GetName()), "", "", Me, "Services Enforcer", Anope::CurTime, "", IRCD->UID_Retrieve(), NULL)
		, Timer(me, delay)
		, nick(na->nick)
	{
		/* Erase the current release timer and use the new one */
		Anope::map<NickServRelease *>::iterator nit = NickServReleases.find(this->nick);
		if (nit != NickServReleases.end())
		{
			IRCD->SendQuit(nit->second, "");
			delete nit->second;
		}

		NickServReleases.emplace(this->nick, this);

		IRCD->SendClientIntroduction(this);
	}

	~NickServRelease() override
	{
		IRCD->SendQuit(this, "");
		NickServReleases.erase(this->nick);
	}

	void Tick() override
	{
	}
};

class NickServCore final
	: public Module
	, public NickServService
{
	Reference<BotInfo> NickServ;
	std::vector<Anope::string> defaults;
	ExtensibleItem<bool> held, collided;

	void OnCancel(User *u, NickAlias *na)
	{
		if (collided.HasExt(na))
		{
			collided.Unset(na);

			new NickServHeld(this, na, Config->GetModule("nickserv")->Get<time_t>("releasetimeout", "1m"));

			if (IRCD->CanSVSHold)
				IRCD->SendSVSHold(na->nick, Config->GetModule("nickserv")->Get<time_t>("releasetimeout", "1m"));
			else
				new NickServRelease(this, na, Config->GetModule("nickserv")->Get<time_t>("releasetimeout", "1m"));
		}
	}

public:
	NickServCore(const Anope::string &modname, const Anope::string &creator) : Module(modname, creator, PSEUDOCLIENT | VENDOR),
		NickServService(this), held(this, "HELD"), collided(this, "COLLIDED")
	{
	}

	~NickServCore() override
	{
		OnShutdown();
	}

	void OnShutdown() override
	{
		/* On shutdown, restart, or mod unload, remove all of our holds for nicks (svshold or qlines)
		 * because some IRCds do not allow us to have these automatically expire
		 */
		for (const auto &[_, na] : *NickAliasList)
			this->Release(na);
	}

	void OnRestart() override
	{
		OnShutdown();
	}

	void Validate(User *u) override
	{
		NickAlias *na = NickAlias::Find(u->nick);
		if (!na)
			return;

		EventReturn MOD_RESULT;
		FOREACH_RESULT(OnNickValidate, MOD_RESULT, (u, na));
		if (MOD_RESULT == EVENT_STOP)
		{
			this->Collide(u, na);
			return;
		}
		else if (MOD_RESULT == EVENT_ALLOW)
			return;

		if (Config->GetModule("nickserv")->Get<bool>("nonicknameownership"))
			return;

		if (!na->nc->HasExt("KILL_IMMED"))
		{
			u->SendMessage(NickServ, NICK_IS_SECURE, Config->StrictPrivmsg.c_str(), NickServ->nick.c_str());
		}
		if (na->nc->HasExt("KILLPROTECT"))
		{
			if (na->nc->HasExt("KILL_IMMED"))
			{
				u->SendMessage(NickServ, FORCENICKCHANGE_NOW);
				this->Collide(u, na);
			}
			else if (na->nc->HasExt("KILL_QUICK"))
			{
				time_t killquick = Config->GetModule("nickserv")->Get<time_t>("killquick", "20s");
				u->SendMessage(NickServ, _("If you do not change within %s, I will change your nick."), Anope::Duration(killquick, u->Account()).c_str());
				new NickServCollide(this, this, u, na, killquick);
			}
			else
			{
				time_t kill = Config->GetModule("nickserv")->Get<time_t>("kill", "60s");
				u->SendMessage(NickServ, _("If you do not change within %s, I will change your nick."), Anope::Duration(kill, u->Account()).c_str());
				new NickServCollide(this, this, u, na, kill);
			}
		}

	}

	void OnUserLogin(User *u) override
	{
		NickAlias *na = NickAlias::Find(u->nick);
		if (na && *na->nc == u->Account() && !Config->GetModule("nickserv")->Get<bool>("nonicknameownership") && !na->nc->HasExt("UNCONFIRMED"))
			u->SetMode(NickServ, "REGISTERED");

		const Anope::string &modesonid = Config->GetModule(this)->Get<Anope::string>("modesonid");
		if (!modesonid.empty())
			u->SetModes(NickServ, modesonid);
	}

	void Collide(User *u, NickAlias *na) override
	{
		if (na)
			collided.Set(na);

		if (IRCD->CanSVSNick)
		{
			unsigned nicklen = IRCD->MaxNick;
			const Anope::string &guestprefix = Config->GetModule("nickserv")->Get<const Anope::string>("guestnickprefix", "Guest");

			Anope::string guestnick;

			int i = 0;
			do
			{
				guestnick = guestprefix + Anope::ToString(static_cast<uint16_t>(Anope::RandomNumber()));
				if (guestnick.length() > nicklen)
					guestnick = guestnick.substr(0, nicklen);
			}
			while (User::Find(guestnick) && i++ < 10);

			if (i == 11)
				u->Kill(*NickServ, "Services nickname-enforcer kill");
			else
			{
				u->SendMessage(*NickServ, _("Your nickname is now being changed to \002%s\002"), guestnick.c_str());
				IRCD->SendForceNickChange(u, guestnick, Anope::CurTime);
			}
		}
		else
			u->Kill(*NickServ, "Services nickname-enforcer kill");
	}

	void Release(NickAlias *na) override
	{
		if (held.HasExt(na))
		{
			if (IRCD->CanSVSHold)
				IRCD->SendSVSHoldDel(na->nick);
			else
			{
				User *u = User::Find(na->nick);
				if (u && u->server == Me)
				{
					u->Quit();
				}
			}

			held.Unset(na);
		}
		collided.Unset(na); /* clear pending collide */
	}

	void OnReload(Configuration::Conf *conf) override
	{
		const Anope::string &nsnick = conf->GetModule(this)->Get<const Anope::string>("client");

		if (nsnick.empty())
			throw ConfigException(Module::name + ": <client> must be defined");

		BotInfo *bi = BotInfo::Find(nsnick, true);
		if (!bi)
			throw ConfigException(Module::name + ": no bot named " + nsnick);

		NickServ = bi;

		spacesepstream(conf->GetModule(this)->Get<const Anope::string>("defaults", "memo_signon memo_receive")).GetTokens(defaults);
		if (defaults.empty())
		{
			defaults.emplace_back("MEMO_SIGNON");
			defaults.emplace_back("MEMO_RECEIVE");
		}
		else if (defaults[0].equals_ci("none"))
			defaults.clear();
	}

	void OnDelNick(NickAlias *na) override
	{
		User *u = User::Find(na->nick);
		if (u && u->Account() == na->nc)
		{
			IRCD->SendLogout(u);
			u->RemoveMode(NickServ, "REGISTERED");
			u->Logout();
		}
	}

	void OnDelCore(NickCore *nc) override
	{
		Log(NickServ, "nick") << "Deleting nickname group " << nc->display;

		/* Clean up this nick core from any users online */
		for (std::list<User *>::iterator it = nc->users.begin(); it != nc->users.end();)
		{
			User *user = *it++;
			IRCD->SendLogout(user);
			user->RemoveMode(NickServ, "REGISTERED");
			user->Logout();
			FOREACH_MOD(OnNickLogout, (user));
		}
		nc->users.clear();
	}

	void OnChangeCoreDisplay(NickCore *nc, const Anope::string &newdisplay) override
	{
		Log(LOG_NORMAL, "nick", NickServ) << "Changing " << nc->display << " nickname group display to " << newdisplay;
	}

	void OnNickIdentify(User *u) override
	{
		Configuration::Block *block = Config->GetModule(this);

		if (block->Get<bool>("modeonid", "yes"))
		{
			for (const auto &[_, cc] : u->chans)
			{
				Channel *c = cc->chan;
				if (c)
					c->SetCorrectModes(u, true);
			}
		}

		const Anope::string &modesonid = block->Get<const Anope::string>("modesonid");
		if (!modesonid.empty())
			u->SetModes(NickServ, modesonid);

		if (block->Get<bool>("forceemail", "yes") && u->Account()->email.empty())
		{
			u->SendMessage(NickServ, _("You must now supply an email for your nick.\n"
							"This email will allow you to retrieve your password in\n"
							"case you forget it."));
			u->SendMessage(NickServ, _("Type \002%s%s SET EMAIL \037email\037\002 in order to set your email."),
				Config->StrictPrivmsg.c_str(), NickServ->nick.c_str());
		}

		for (auto *c : collides)
		{
			if (c->GetUser() == u && c->GetNick() && c->GetNick()->nc == u->Account())
			{
				delete c;
				break;
			}
		}
	}

	void OnNickGroup(User *u, NickAlias *target) override
	{
		if (!target->nc->HasExt("UNCONFIRMED"))
			u->SetMode(NickServ, "REGISTERED");
	}

	void OnNickUpdate(User *u) override
	{
		for (const auto &[_, cc] : u->chans)
		{
			Channel *c = cc->chan;
			if (c)
				c->SetCorrectModes(u, true);
		}
	}

	void OnUserConnect(User *u, bool &exempt) override
	{
		if (u->Quitting() || !u->server->IsSynced() || u->server->IsULined())
			return;

		const NickAlias *na = NickAlias::Find(u->nick);

		const Anope::string &unregistered_notice = Config->GetModule(this)->Get<const Anope::string>("unregistered_notice");
		if (!Config->GetModule("nickserv")->Get<bool>("nonicknameownership") && !unregistered_notice.empty() && !na && !u->Account())
			u->SendMessage(NickServ, unregistered_notice.replace_all_cs("%n", u->nick));
		else if (na && !u->IsIdentified(true))
			this->Validate(u);
	}

	void OnPostUserLogoff(User *u) override
	{
		NickAlias *na = NickAlias::Find(u->nick);
		if (na)
			OnCancel(u, na);
	}

	void OnServerSync(Server *s) override
	{
		for (const auto &[_, u] : UserListByNick)
		{
			if (u->server == s)
			{
				if (u->HasMode("REGISTERED") && !u->IsIdentified(true))
					u->RemoveMode(NickServ, "REGISTERED");
				if (!u->IsIdentified())
					this->Validate(u);
			}
		}
	}

	void OnUserNickChange(User *u, const Anope::string &oldnick) override
	{
		NickAlias *old_na = NickAlias::Find(oldnick), *na = NickAlias::Find(u->nick);
		/* If the new nick isn't registered or it's registered and not yours */
		if (!na || na->nc != u->Account())
		{
			/* Remove +r, but keep an account associated with the user */
			u->RemoveMode(NickServ, "REGISTERED");

			this->Validate(u);
		}
		else
		{
			/* Reset +r and re-send account (even though it really should be set at this point) */
			IRCD->SendLogin(u, na);
			if (!Config->GetModule("nickserv")->Get<bool>("nonicknameownership") && na->nc == u->Account() && !na->nc->HasExt("UNCONFIRMED"))
				u->SetMode(NickServ, "REGISTERED");
			Log(u, "", NickServ) << u->GetMask() << " automatically identified for group " << u->Account()->display;
		}

		if (!u->nick.equals_ci(oldnick) && old_na)
			OnCancel(u, old_na);
	}

	void OnUserModeSet(const MessageSource &setter, User *u, const Anope::string &mname) override
	{
		if (u->server->IsSynced() && mname == "REGISTERED" && !u->IsIdentified(true))
			u->RemoveMode(NickServ, mname);
	}

	EventReturn OnPreHelp(CommandSource &source, const std::vector<Anope::string> &params) override
	{
		if (!params.empty() || source.c || source.service != *NickServ)
			return EVENT_CONTINUE;
		if (!Config->GetModule("nickserv")->Get<bool>("nonicknameownership"))
			source.Reply(_("\002%s\002 allows you to register a nickname and\n"
				"prevent others from using it. The following\n"
				"commands allow for registration and maintenance of\n"
				"nicknames; to use them, type \002%s%s \037command\037\002.\n"
				"For more information on a specific command, type\n"
				"\002%s%s %s \037command\037\002.\n"), NickServ->nick.c_str(), Config->StrictPrivmsg.c_str(), NickServ->nick.c_str(), Config->StrictPrivmsg.c_str(), NickServ->nick.c_str(), source.command.c_str());
		else
			source.Reply(_("\002%s\002 allows you to register an account.\n"
				"The following commands allow for registration and maintenance of\n"
				"accounts; to use them, type \002%s%s \037command\037\002.\n"
				"For more information on a specific command, type\n"
				"\002%s%s %s \037command\037\002.\n"), NickServ->nick.c_str(), Config->StrictPrivmsg.c_str(), NickServ->nick.c_str(), Config->StrictPrivmsg.c_str(), NickServ->nick.c_str(), source.command.c_str());
		return EVENT_CONTINUE;
	}

	void OnPostHelp(CommandSource &source, const std::vector<Anope::string> &params) override
	{
		if (!params.empty() || source.c || source.service != *NickServ)
			return;
		if (source.IsServicesOper())
			source.Reply(_(" \n"
				"Services Operators can also drop any nickname without needing\n"
				"to identify for the nick, and may view the access list for\n"
				"any nickname."));
		time_t nickserv_expire = Config->GetModule(this)->Get<time_t>("expire", "1y");
		if (nickserv_expire >= 86400)
			source.Reply(_(" \n"
				"Accounts that are not used anymore are subject to\n"
				"the automatic expiration, i.e. they will be deleted\n"
				"after %lu days if not used."), (unsigned long)nickserv_expire / 86400);
	}

	void OnNickCoreCreate(NickCore *nc) override
	{
		/* Set default flags */
		for (const auto &def : defaults)
			nc->Extend<bool>(def.upper());
	}

	void OnUserQuit(User *u, const Anope::string &msg) override
	{
		if (u->server && !u->server->GetQuitReason().empty() && Config->GetModule(this)->Get<bool>("hidenetsplitquit"))
			return;

		/* Update last quit and last seen for the user */
		NickAlias *na = NickAlias::Find(u->nick);
		if (na && !na->nc->HasExt("NS_SUSPENDED") && u->IsIdentified(true))
		{
			na->last_seen = Anope::CurTime;
			na->last_quit = msg;
		}
	}

	void OnExpireTick() override
	{
		if (Anope::NoExpire || Anope::ReadOnly)
			return;

		time_t nickserv_expire = Config->GetModule(this)->Get<time_t>("expire", "90d");

		for (nickalias_map::const_iterator it = NickAliasList->begin(), it_end = NickAliasList->end(); it != it_end; )
		{
			NickAlias *na = it->second;
			++it;

			User *u = User::Find(na->nick, true);
			if (u && u->IsIdentified(true))
				na->last_seen = Anope::CurTime;

			bool expire = false;

			if (nickserv_expire && Anope::CurTime - na->last_seen >= nickserv_expire)
				expire = true;

			if (na->nc->na == na && na->nc->aliases->size() > 1 && Config->GetModule("nickserv")->Get<bool>("preservedisplay"))
				expire = false;

			FOREACH_MOD(OnPreNickExpire, (na, expire));

			if (expire)
			{
				Log(LOG_NORMAL, "nickserv/expire", NickServ) << "Expiring nickname " << na->nick << " (group: " << na->nc->display << ") (email: " << (na->nc->email.empty() ? "none" : na->nc->email) << ")";
				FOREACH_MOD(OnNickExpire, (na));
				delete na;
			}
		}
	}

	void OnNickInfo(CommandSource &source, NickAlias *na, InfoFormatter &info, bool show_hidden) override
	{
		if (!na->nc->HasExt("UNCONFIRMED"))
		{
			time_t nickserv_expire = Config->GetModule(this)->Get<time_t>("expire", "1y");
			if (!na->HasExt("NS_NO_EXPIRE") && nickserv_expire && !Anope::NoExpire && (source.HasPriv("nickserv/auspex") || na->last_seen != Anope::CurTime))
				info[_("Expires")] = Anope::strftime(na->last_seen + nickserv_expire, source.GetAccount());
		}
		else
		{
			time_t unconfirmed_expire = Config->GetModule("ns_register")->Get<time_t>("unconfirmedexpire", "1d");
			info[_("Expires")] = Anope::strftime(na->time_registered + unconfirmed_expire, source.GetAccount());
		}
	}
};

MODULE_INIT(NickServCore)