/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2020 Christos Triantafyllidis <ctria@users.noreply.github.com>
 *   Copyright (C) 2018-2020 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2014, 2018 Attila Molnar <attilamolnar@hush.com>
 *   Copyright (C) 2013-2014 Adam <Adam@anope.org>
 *
 * This file is part of InspIRCd.  InspIRCd 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, version 2.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */


#include "inspircd.h"
#include "modules/ldap.h"

namespace
{
	Module* me;
}

class LDAPOperBase : public LDAPInterface
{
 protected:
	const std::string uid;
	const std::string opername;
	const std::string password;

	void Fallback(User* user)
	{
		if (!user)
			return;

		Command* oper_command = ServerInstance->Parser.GetHandler("OPER");
		if (!oper_command)
			return;

		CommandBase::Params params;
		params.push_back(opername);
		params.push_back(password);
		ClientProtocol::TagMap tags;
		oper_command->Handle(user, CommandBase::Params(params, tags));
	}

	void Fallback()
	{
		User* user = ServerInstance->FindUUID(uid);
		Fallback(user);
	}

 public:
	LDAPOperBase(Module* mod, const std::string& uuid, const std::string& oper, const std::string& pass)
		: LDAPInterface(mod)
		, uid(uuid), opername(oper), password(pass)
	{
	}

	void OnError(const LDAPResult& err) CXX11_OVERRIDE
	{
		ServerInstance->SNO->WriteToSnoMask('a', "Error searching LDAP server: %s", err.getError().c_str());
		Fallback();
		delete this;
	}
};

class BindInterface : public LDAPOperBase
{
 public:
	BindInterface(Module* mod, const std::string& uuid, const std::string& oper, const std::string& pass)
		: LDAPOperBase(mod, uuid, oper, pass)
	{
	}

	void OnResult(const LDAPResult& r) CXX11_OVERRIDE
	{
		User* user = ServerInstance->FindUUID(uid);
		ServerConfig::OperIndex::const_iterator iter = ServerInstance->Config->oper_blocks.find(opername);

		if (!user || iter == ServerInstance->Config->oper_blocks.end())
		{
			Fallback();
			delete this;
			return;
		}

		OperInfo* ifo = iter->second;
		user->Oper(ifo);
		delete this;
	}
};

class SearchInterface : public LDAPOperBase
{
	const std::string provider;

	bool HandleResult(const LDAPResult& result)
	{
		dynamic_reference<LDAPProvider> LDAP(me, provider);
		if (!LDAP || result.empty())
			return false;

		try
		{
			const LDAPAttributes& attr = result.get(0);
			std::string bindDn = attr.get("dn");
			if (bindDn.empty())
				return false;

			LDAP->Bind(new BindInterface(this->creator, uid, opername, password), bindDn, password);
		}
		catch (LDAPException& ex)
		{
			ServerInstance->SNO->WriteToSnoMask('a', "Error searching LDAP server: " + ex.GetReason());
		}

		return true;
	}

 public:
	SearchInterface(Module* mod, const std::string& prov, const std::string &uuid, const std::string& oper, const std::string& pass)
		: LDAPOperBase(mod, uuid, oper, pass)
		, provider(prov)
	{
	}

	void OnResult(const LDAPResult& result) CXX11_OVERRIDE
	{
		if (!HandleResult(result))
			Fallback();
		delete this;
	}
};

class AdminBindInterface : public LDAPInterface
{
	const std::string provider;
	const std::string user;
	const std::string opername;
	const std::string password;
	const std::string base;
	const std::string what;

 public:
	AdminBindInterface(Module* c, const std::string& p, const std::string& u, const std::string& o, const std::string& pa, const std::string& b, const std::string& w)
		: LDAPInterface(c)
		, provider(p)
		, user(u)
		, opername(o)
		, password(pa)
		, base(b)
		, what(w)
	{
	}

	void OnResult(const LDAPResult& r) CXX11_OVERRIDE
	{
		dynamic_reference<LDAPProvider> LDAP(me, provider);
		if (LDAP)
		{
			try
			{
				LDAP->Search(new SearchInterface(this->creator, provider, user, opername, password), base, what);
			}
			catch (LDAPException& ex)
			{
				ServerInstance->SNO->WriteToSnoMask('a', "Error searching LDAP server: " + ex.GetReason());
			}
		}
		delete this;
	}

	void OnError(const LDAPResult& err) CXX11_OVERRIDE
	{
		ServerInstance->SNO->WriteToSnoMask('a', "Error binding as manager to LDAP server: " + err.getError());
		delete this;
	}
};

class ModuleLDAPOper : public Module
{
	dynamic_reference<LDAPProvider> LDAP;
	std::string base;
	std::string attribute;

 public:
	ModuleLDAPOper()
		: LDAP(this, "LDAP")
	{
		me = this;
	}

	void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
	{
		ConfigTag* tag = ServerInstance->Config->ConfValue("ldapoper");

		LDAP.SetProvider("LDAP/" + tag->getString("dbid"));
		base = tag->getString("baserdn");
		attribute = tag->getString("attribute");
	}

	ModResult OnPreCommand(std::string& command, CommandBase::Params& parameters, LocalUser* user, bool validated) CXX11_OVERRIDE
	{
		if (validated && command == "OPER" && parameters.size() >= 2)
		{
			const std::string& opername = parameters[0];
			const std::string& password = parameters[1];

			ServerConfig::OperIndex::const_iterator it = ServerInstance->Config->oper_blocks.find(opername);
			if (it == ServerInstance->Config->oper_blocks.end())
				return MOD_RES_PASSTHRU;

			ConfigTag* tag = it->second->oper_block;
			if (!tag)
				return MOD_RES_PASSTHRU;

			std::string acceptedhosts = tag->getString("host");
			if (!InspIRCd::MatchMask(acceptedhosts, user->MakeHost(), user->MakeHostIP()))
				return MOD_RES_PASSTHRU;

			if (!LDAP)
				return MOD_RES_PASSTHRU;

			try
			{
				std::string what = attribute + "=" + opername;
				LDAP->BindAsManager(new AdminBindInterface(this, LDAP.GetProvider(), user->uuid, opername, password, base, what));
				return MOD_RES_DENY;
			}
			catch (LDAPException& ex)
			{
				ServerInstance->SNO->WriteToSnoMask('a', "LDAP exception: " + ex.GetReason());
			}
		}

		return MOD_RES_PASSTHRU;
	}

	Version GetVersion() CXX11_OVERRIDE
	{
		return Version("Allows server operators to be authenticated against an LDAP database.", VF_VENDOR);
	}
};

MODULE_INIT(ModuleLDAPOper)