/*
 *
 * (C) 2011-2020 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.
 */

/* RequiredLibraries: ldap_r,lber */
/* RequiredWindowsLibraries: libldap_r,liblber */

#include "module.h"
#include "modules/ldap.h"
#include <ldap.h>

class LDAPService;
static Pipe *me;

class LDAPRequest
{
 public:
	LDAPService *service;
	LDAPInterface *inter;
	LDAPMessage *message; /* message returned by ldap_ */
	LDAPResult *result; /* final result */
	struct timeval tv;
	QueryType type;

	LDAPRequest(LDAPService *s, LDAPInterface *i)
		: service(s)
		, inter(i)
		, message(NULL)
		, result(NULL)
	{
		type = QUERY_UNKNOWN;
		tv.tv_sec = 0;
		tv.tv_usec = 100000;
	}

	virtual ~LDAPRequest()
	{
		delete result;
		if (inter != NULL)
			inter->OnDelete();
		if (message != NULL)
			ldap_msgfree(message);
	}

	virtual int run() = 0;
};

class LDAPBind : public LDAPRequest
{
	Anope::string who, pass;

 public:
	LDAPBind(LDAPService *s, LDAPInterface *i, const Anope::string &w, const Anope::string &p)
		: LDAPRequest(s, i)
		, who(w)
		, pass(p)
	{
		type = QUERY_BIND;
	}

	int run() anope_override;
};

class LDAPSearch : public LDAPRequest
{
	Anope::string base;
	Anope::string filter;

 public:
	LDAPSearch(LDAPService *s, LDAPInterface *i, const Anope::string &b, const Anope::string &f)
		: LDAPRequest(s, i)
		, base(b)
		, filter(f)
	{
		type = QUERY_SEARCH;
	}

	int run() anope_override;
};

class LDAPAdd : public LDAPRequest
{
	Anope::string dn;
	LDAPMods attributes;

 public:
	LDAPAdd(LDAPService *s, LDAPInterface *i, const Anope::string &d, const LDAPMods &attr)
		: LDAPRequest(s, i)
		, dn(d)
		, attributes(attr)
	{
		type = QUERY_ADD;
	}

	int run() anope_override;
};

class LDAPDel : public LDAPRequest
{
	Anope::string dn;

 public:
	LDAPDel(LDAPService *s, LDAPInterface *i, const Anope::string &d)
		: LDAPRequest(s, i)
		, dn(d)
	{
		type = QUERY_DELETE;
	}

	int run() anope_override;
};

class LDAPModify : public LDAPRequest
{
	Anope::string base;
	LDAPMods attributes;

 public:
	LDAPModify(LDAPService *s, LDAPInterface *i, const Anope::string &b, const LDAPMods &attr)
		: LDAPRequest(s, i)
		, base(b)
		, attributes(attr)
	{
		type = QUERY_MODIFY;
	}

	int run() anope_override;
};

class LDAPService : public LDAPProvider, public Thread, public Condition
{
	Anope::string server;
	Anope::string admin_binddn;
	Anope::string admin_pass;

	LDAP *con;

	time_t last_connect;

 public:
	static LDAPMod **BuildMods(const LDAPMods &attributes)
	{
		LDAPMod **mods = new LDAPMod*[attributes.size() + 1];
		memset(mods, 0, sizeof(LDAPMod*) * (attributes.size() + 1));
		for (unsigned x = 0; x < attributes.size(); ++x)
		{
			const LDAPModification &l = attributes[x];
			mods[x] = new LDAPMod();

			if (l.op == LDAPModification::LDAP_ADD)
				mods[x]->mod_op = LDAP_MOD_ADD;
			else if (l.op == LDAPModification::LDAP_DEL)
				mods[x]->mod_op = LDAP_MOD_DELETE;
			else if (l.op == LDAPModification::LDAP_REPLACE)
				mods[x]->mod_op = LDAP_MOD_REPLACE;
			else if (l.op != 0)
				throw LDAPException("Unknown LDAP operation");
			mods[x]->mod_type = strdup(l.name.c_str());
			mods[x]->mod_values = new char*[l.values.size() + 1];
			memset(mods[x]->mod_values, 0, sizeof(char *) * (l.values.size() + 1));
			for (unsigned j = 0, c = 0; j < l.values.size(); ++j)
				if (!l.values[j].empty())
					mods[x]->mod_values[c++] = strdup(l.values[j].c_str());
		}
		return mods;
	}

	static void FreeMods(LDAPMod **mods)
	{
		for (int i = 0; mods[i] != NULL; ++i)
		{
			free(mods[i]->mod_type);
			for (int j = 0; mods[i]->mod_values[j] != NULL; ++j)
				free(mods[i]->mod_values[j]);
			delete [] mods[i]->mod_values;
		}
		delete [] mods;
	}

 private:
	void Connect()
	{
		int i = ldap_initialize(&this->con, this->server.c_str());
		if (i != LDAP_SUCCESS)
			throw LDAPException("Unable to connect to LDAP service " + this->name + ": " + ldap_err2string(i));

		const int version = LDAP_VERSION3;
		i = ldap_set_option(this->con, LDAP_OPT_PROTOCOL_VERSION, &version);
		if (i != LDAP_OPT_SUCCESS)
			throw LDAPException("Unable to set protocol version for " + this->name + ": " + ldap_err2string(i));

		const struct timeval tv = { 0, 0 };
		i = ldap_set_option(this->con, LDAP_OPT_NETWORK_TIMEOUT, &tv);
		if (i != LDAP_OPT_SUCCESS)
			throw LDAPException("Unable to set timeout for " + this->name + ": " + ldap_err2string(i));
	}

	void Reconnect()
	{
		/* Only try one connect a minute. It is an expensive blocking operation */
		if (last_connect > Anope::CurTime - 60)
			throw LDAPException("Unable to connect to LDAP service " + this->name + ": reconnecting too fast");
		last_connect = Anope::CurTime;

		ldap_unbind_ext(this->con, NULL, NULL);

		Connect();
	}

	void QueueRequest(LDAPRequest *r)
	{
		this->Lock();
		this->queries.push_back(r);
		this->Wakeup();
		this->Unlock();
	}

 public:
	typedef std::vector<LDAPRequest *> query_queue;
	query_queue queries, results;
	Mutex process_mutex; /* held when processing requests not in either queue */

	LDAPService(Module *o, const Anope::string &n, const Anope::string &s, const Anope::string &b, const Anope::string &p) : LDAPProvider(o, n), server(s), admin_binddn(b), admin_pass(p), last_connect(0)
	{
		Connect();
	}

	~LDAPService()
	{
		/* At this point the thread has stopped so we don't need to hold process_mutex */

		this->Lock();

		for (unsigned int i = 0; i < this->queries.size(); ++i)
		{
			LDAPRequest *req = this->queries[i];

			/* queries have no results yet */
			req->result = new LDAPResult();
			req->result->type = req->type;
			req->result->error = "LDAP Interface is going away";
			if (req->inter)
				req->inter->OnError(*req->result);

			delete req;
		}
		this->queries.clear();

		for (unsigned int i = 0; i < this->results.size(); ++i)
		{
			LDAPRequest *req = this->results[i];

			/* even though this may have already finished successfully we return that it didn't */
			req->result->error = "LDAP Interface is going away";
			if (req->inter)
				req->inter->OnError(*req->result);

			delete req;
		}

		this->Unlock();

		ldap_unbind_ext(this->con, NULL, NULL);
	}

	void BindAsAdmin(LDAPInterface *i) anope_override
	{
		this->Bind(i, this->admin_binddn, this->admin_pass);
	}

	void Bind(LDAPInterface *i, const Anope::string &who, const Anope::string &pass) anope_override
	{
		LDAPBind *b = new LDAPBind(this, i, who, pass);
		QueueRequest(b);
	}

	void Search(LDAPInterface *i, const Anope::string &base, const Anope::string &filter) anope_override
	{
		if (i == NULL)
			throw LDAPException("No interface");

		LDAPSearch *s = new LDAPSearch(this, i, base, filter);
		QueueRequest(s);
	}

	void Add(LDAPInterface *i, const Anope::string &dn, LDAPMods &attributes) anope_override
	{
		LDAPAdd *add = new LDAPAdd(this, i, dn, attributes);
		QueueRequest(add);
	}

	void Del(LDAPInterface *i, const Anope::string &dn) anope_override
	{
		LDAPDel *del = new LDAPDel(this, i, dn);
		QueueRequest(del);
	}

	void Modify(LDAPInterface *i, const Anope::string &base, LDAPMods &attributes) anope_override
	{
		LDAPModify *mod = new LDAPModify(this, i, base, attributes);
		QueueRequest(mod);
	}

 private:
	void BuildReply(int res, LDAPRequest *req)
	{
		LDAPResult *ldap_result = req->result = new LDAPResult();
		req->result->type = req->type;

		if (res != LDAP_SUCCESS)
		{
			ldap_result->error = ldap_err2string(res);
			return;
		}

		if (req->message == NULL)
		{
			return;
		}

		/* a search result */

		for (LDAPMessage *cur = ldap_first_message(this->con, req->message); cur; cur = ldap_next_message(this->con, cur))
		{
			LDAPAttributes attributes;

			char *dn = ldap_get_dn(this->con, cur);
			if (dn != NULL)
			{
				attributes["dn"].push_back(dn);
				ldap_memfree(dn);
				dn = NULL;
			}

			BerElement *ber = NULL;

			for (char *attr = ldap_first_attribute(this->con, cur, &ber); attr; attr = ldap_next_attribute(this->con, cur, ber))
			{
				berval **vals = ldap_get_values_len(this->con, cur, attr);
				int count = ldap_count_values_len(vals);

				std::vector<Anope::string> attrs;
				for (int j = 0; j < count; ++j)
					attrs.push_back(vals[j]->bv_val);
				attributes[attr] = attrs;

				ldap_value_free_len(vals);
				ldap_memfree(attr);
			}

			if (ber != NULL)
				ber_free(ber, 0);

			ldap_result->messages.push_back(attributes);
		}
	}

	void SendRequests()
	{
		process_mutex.Lock();

		query_queue q;
		this->Lock();
		queries.swap(q);
		this->Unlock();

		if (q.empty())
		{
			process_mutex.Unlock();
			return;
		}

		for (unsigned int i = 0; i < q.size(); ++i)
		{
			LDAPRequest *req = q[i];
			int ret = req->run();

			if (ret == LDAP_SERVER_DOWN || ret == LDAP_TIMEOUT)
			{
				/* try again */
				try
				{
					Reconnect();
				}
				catch (const LDAPException &)
				{
				}

				ret = req->run();
			}

			BuildReply(ret, req);

			this->Lock();
			results.push_back(req);
			this->Unlock();
		}

		me->Notify();

		process_mutex.Unlock();
	}

 public:
	void Run() anope_override
	{
		while (!this->GetExitState())
		{
			this->Lock();
			/* Queries can be non empty if one is pushed during SendRequests() */
			if (queries.empty())
				this->Wait();
			this->Unlock();

			SendRequests();
		}
	}

	LDAP* GetConnection()
	{
		return con;
	}
};

class ModuleLDAP : public Module, public Pipe
{
	std::map<Anope::string, LDAPService *> LDAPServices;

 public:

	ModuleLDAP(const Anope::string &modname, const Anope::string &creator) : Module(modname, creator, EXTRA | VENDOR)
	{
		me = this;
	}

	~ModuleLDAP()
	{
		for (std::map<Anope::string, LDAPService *>::iterator it = this->LDAPServices.begin(); it != this->LDAPServices.end(); ++it)
		{
			it->second->SetExitState();
			it->second->Wakeup();
			it->second->Join();
			delete it->second;
		}
		LDAPServices.clear();
	}

	void OnReload(Configuration::Conf *config) anope_override
	{
		Configuration::Block *conf = config->GetModule(this);

		for (std::map<Anope::string, LDAPService *>::iterator it = this->LDAPServices.begin(); it != this->LDAPServices.end();)
		{
			const Anope::string &cname = it->first;
			LDAPService *s = it->second;
			int i;

			++it;

			for (i = 0; i < conf->CountBlock("ldap"); ++i)
				if (conf->GetBlock("ldap", i)->Get<const Anope::string>("name", "ldap/main") == cname)
					break;

			if (i == conf->CountBlock("ldap"))
			{
				Log(LOG_NORMAL, "ldap") << "LDAP: Removing server connection " << cname;

				s->SetExitState();
				s->Wakeup();
				s->Join();
				delete s;
				this->LDAPServices.erase(cname);
			}
		}

		for (int i = 0; i < conf->CountBlock("ldap"); ++i)
		{
			Configuration::Block *ldap = conf->GetBlock("ldap", i);

			const Anope::string &connname = ldap->Get<const Anope::string>("name", "ldap/main");

			if (this->LDAPServices.find(connname) == this->LDAPServices.end())
			{
				const Anope::string &server = ldap->Get<const Anope::string>("server", "127.0.0.1");
				const Anope::string &admin_binddn = ldap->Get<const Anope::string>("admin_binddn");
				const Anope::string &admin_password = ldap->Get<const Anope::string>("admin_password");

				try
				{
					LDAPService *ss = new LDAPService(this, connname, server, admin_binddn, admin_password);
					ss->Start();
					this->LDAPServices.insert(std::make_pair(connname, ss));

					Log(LOG_NORMAL, "ldap") << "LDAP: Successfully initialized server " << connname << " (" << server << ")";
				}
				catch (const LDAPException &ex)
				{
					Log(LOG_NORMAL, "ldap") << "LDAP: " << ex.GetReason();
				}
			}
		}
	}

	void OnModuleUnload(User *, Module *m) anope_override
	{
		for (std::map<Anope::string, LDAPService *>::iterator it = this->LDAPServices.begin(); it != this->LDAPServices.end(); ++it)
		{
			LDAPService *s = it->second;

			s->process_mutex.Lock();
			s->Lock();

			for (unsigned int i = s->queries.size(); i > 0; --i)
			{
				LDAPRequest *req = s->queries[i - 1];
				LDAPInterface *li = req->inter;

				if (li && li->owner == m)
				{
					s->queries.erase(s->queries.begin() + i - 1);
					delete req;
				}
			}
			for (unsigned int i = s->results.size(); i > 0; --i)
			{
				LDAPRequest *req = s->results[i - 1];
				LDAPInterface *li = req->inter;

				if (li && li->owner == m)
				{
					s->results.erase(s->results.begin() + i - 1);
					delete req;
				}
			}

			s->Unlock();
			s->process_mutex.Unlock();
		}
	}

	void OnNotify() anope_override
	{
		for (std::map<Anope::string, LDAPService *>::iterator it = this->LDAPServices.begin(); it != this->LDAPServices.end(); ++it)
		{
			LDAPService *s = it->second;

			LDAPService::query_queue results;
			s->Lock();
			results.swap(s->results);
			s->Unlock();

			for (unsigned int i = 0; i < results.size(); ++i)
			{
				LDAPRequest *req = results[i];
				LDAPInterface *li = req->inter;
				LDAPResult *r = req->result;

				if (li != NULL)
				{
					if (!r->getError().empty())
					{
						Log(this) << "Error running LDAP query: " << r->getError();
						li->OnError(*r);
					}
					else
						li->OnResult(*r);
				}

				delete req;
			}
		}
	}
};

int LDAPBind::run()
{
	berval cred;
	cred.bv_val = strdup(pass.c_str());
	cred.bv_len = pass.length();

	int i = ldap_sasl_bind_s(service->GetConnection(), who.c_str(), LDAP_SASL_SIMPLE, &cred, NULL, NULL, NULL);

	free(cred.bv_val);

	return i;
}

int LDAPSearch::run()
{
	return ldap_search_ext_s(service->GetConnection(), base.c_str(), LDAP_SCOPE_SUBTREE, filter.c_str(), NULL, 0, NULL, NULL, &tv, 0, &message);
}

int LDAPAdd::run()
{
	LDAPMod **mods = LDAPService::BuildMods(attributes);
	int i = ldap_add_ext_s(service->GetConnection(), dn.c_str(), mods, NULL, NULL);
	LDAPService::FreeMods(mods);
	return i;
}

int LDAPDel::run()
{
	return ldap_delete_ext_s(service->GetConnection(), dn.c_str(), NULL, NULL);
}

int LDAPModify::run()
{
	LDAPMod **mods = LDAPService::BuildMods(attributes);
	int i = ldap_modify_ext_s(service->GetConnection(), base.c_str(), mods, NULL, NULL);
	LDAPService::FreeMods(mods);
	return i;
}

MODULE_INIT(ModuleLDAP)
