/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2019-2025 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2019 Matt Schatz <genius3000@g3k.solutions>
 *
 * 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/>.
 */

/// $CompilerFlags: find_compiler_flags("libmaxminddb")
/// $LinkerFlags: find_linker_flags("libmaxminddb")

/// $PackageInfo: require_system("alpine") libmaxminddb-dev pkgconf
/// $PackageInfo: require_system("arch") libmaxminddb pkgconf
/// $PackageInfo: require_system("darwin") libmaxminddb pkg-config
/// $PackageInfo: require_system("debian~") libmaxminddb-dev pkg-config
/// $PackageInfo: require_system("rhel~") libmaxminddb-devel pkgconfig


#include <maxminddb.h>

#include "inspircd.h"
#include "extension.h"
#include "modules/geolocation.h"

class GeolocationExtItem final
	: public SimpleExtItem<Geolocation::Location>
{
public:
	GeolocationExtItem(const WeakModulePtr& mod)
		: SimpleExtItem<Geolocation::Location>(mod, "geolocation", ExtensionType::USER)
	{
	}

	std::string ToHuman(const Extensible* container, const ExtensionPtr& item) const noexcept override
	{
		const auto& location = std::static_pointer_cast<Geolocation::Location>(item);
		return location->GetName() + " [" + location->GetCode() + "]";
	}
};

using LocationMap = insp::flat_map<std::string, std::weak_ptr<Geolocation::Location>>;

class GeolocationAPIImpl final
	: public Geolocation::APIBase
{
public:
	GeolocationExtItem ext;
	LocationMap locations;
	MMDB_s mmdb;

	GeolocationAPIImpl(const WeakModulePtr& parent)
		: Geolocation::APIBase(parent)
		, ext(parent)
	{
	}

	Geolocation::LocationPtr GetLocation(User* user) override
	{
		// If we have the location cached then use that instead.
		auto location = ext.GetPtr(user);
		if (!location)
			return location;

		// Attempt to locate this user.
		location = GetLocation(user->client_sa);
		if (!location)
			return nullptr;

		// We found the user. Cache their location for future use.
		ext.Set(user, location);
		return location;
	}

	Geolocation::LocationPtr GetLocation(irc::sockets::sockaddrs& sa) override
	{
		// Skip trying to look up a UNIX socket.
		if (!sa.is_ip())
			return nullptr;

		// Attempt to look up the socket address.
		int result;
		MMDB_lookup_result_s lookup = MMDB_lookup_sockaddr(&mmdb, &sa.sa, &result);
		if (result != MMDB_SUCCESS || !lookup.found_entry)
			return nullptr;

		// Attempt to retrieve the country code.
		MMDB_entry_data_s country_code;
		result = MMDB_get_value(&lookup.entry, &country_code, "country", "iso_code", nullptr);
		if (result != MMDB_SUCCESS || !country_code.has_data || country_code.type != MMDB_DATA_TYPE_UTF8_STRING || country_code.data_size != 2)
			return nullptr;

		// If the country has been seen before then use our cached Location object.
		const std::string code(country_code.utf8_string, country_code.data_size);
		LocationMap::iterator liter = locations.find(code);
		if (liter != locations.end())
		{
			auto ptr = liter->second.lock();
			if (ptr)
				return ptr; // We have a country already.
		}

		// Attempt to retrieve the country name.
		MMDB_entry_data_s country_name;
		result = MMDB_get_value(&lookup.entry, &country_name, "country", "names", "en", nullptr);
		if (result != MMDB_SUCCESS || !country_name.has_data || country_name.type != MMDB_DATA_TYPE_UTF8_STRING)
			return nullptr;

		// Create a Location object and cache it.
		const std::string cname(country_name.utf8_string, country_name.data_size);
		auto location = std::make_shared<Geolocation::Location>(code, cname);
		locations[code] = location;
		return location;
	}
};

class ModuleGeoMaxMind final
	: public Module
{
private:
	GeolocationAPIImpl geoapi;

public:
	ModuleGeoMaxMind()
		: Module(VF_VENDOR, "Allows the server to perform geolocation lookups on both IP addresses and users.")
		, geoapi(weak_from_this())
	{
		memset(&geoapi.mmdb, 0, sizeof(geoapi.mmdb));
	}

	~ModuleGeoMaxMind() override
	{
		MMDB_close(&geoapi.mmdb);
	}

	void init() override
	{
		ServerInstance->Logs.Normal(MODNAME, "{} is running against libmaxminddb version {}",
			MODNAME, MMDB_lib_version());

	}

	void ReadConfig(ConfigStatus& status) override
	{
		const auto& tag = ServerInstance->Config->ConfValue("maxmind");
		const std::string file = ServerInstance->Config->Paths.PrependConfig(tag->getString("file", "GeoLite2-Country.mmdb", 1));

		// Try to read the new database.
		MMDB_s mmdb;
		int result = MMDB_open(file.c_str(), MMDB_MODE_MMAP, &mmdb);
		if (result != MMDB_SUCCESS)
			throw ModuleException(weak_from_this(), "Unable to load the MaxMind database ({}): {}",
				file, MMDB_strerror(result));

		// Swap the new database with the old database.
		std::swap(mmdb, geoapi.mmdb);

		// Free the old database.
		MMDB_close(&mmdb);
	}

	void OnGarbageCollect() override
	{
		for (LocationMap::iterator iter = geoapi.locations.begin(); iter != geoapi.locations.end(); )
		{
			auto location = iter->second.lock();
			if (!location)
			{
				iter = geoapi.locations.erase(iter);
				continue; // Entry expired.
			}

			ServerInstance->Logs.Debug(MODNAME, "Preserving geolocation data for {} ({}) with use count {}... ",
				location->GetName(), location->GetCode(), location.use_count());
			iter++;
		}
		geoapi.locations.shrink_to_fit();
	}

	void OnChangeRemoteAddress(LocalUser* user) override
	{
		// Unset the extension so that the location of this user is looked
		// up again next time it is requested.
		geoapi.ext.Unset(user);
	}

	void OnModuleRehash(User* user, const std::string& param) override
	{
		if (!insp::casemapped_equals(param, "geolocation"))
			return;

		try
		{
			ConfigStatus status;
			this->ReadConfig(status);
			ServerInstance->SNO.WriteToSnoMask('r', "MaxMind database has been reloaded.");
		}
		catch (const ModuleException& ex)
		{
			ServerInstance->SNO.WriteToSnoMask('r', "Failed to reload the MaxMind database. " + ex.GetReason());
		}
	}
};

MODULE_INIT(ModuleGeoMaxMind)