/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2025 Sadie Powell <sadie@witchery.services>
 *
 * 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/>.
 */

/// BEGIN CMAKE
/// target_require_package(${TARGET} "tre" "TRE" "tre::tre")
/// END CMAKE

/// $PackageInfo: require_system("arch") pkgconf tre
/// $PackageInfo: require_system("darwin") pkg-config tre
/// $PackageInfo: require_system("debian~") libtre-dev pkg-config


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

#include <sys/types.h>
#include <tre/regex.h>

class TREPattern final
	: public Regex::Pattern
{
private:
	regex_t regex;

public:
	TREPattern(const WeakModulePtr& mod, const std::string& pattern, uint8_t options)
		: Regex::Pattern(pattern, options)
	{
		int flags = REG_EXTENDED | REG_NOSUB;
		if (options & Regex::OPT_CASE_INSENSITIVE)
			flags &= REG_ICASE;

		int error = regcomp(&regex, pattern.c_str(), flags);
		if (!error)
			return;

		// Retrieve the size of the error message and allocate a buffer.
		size_t errorsize = regerror(error, &regex, nullptr, 0);
		std::vector<char> errormsg(errorsize);

		// Retrieve the error message and free the buffer.
		regerror(error, &regex, &errormsg[0], errormsg.size());
		regfree(&regex);

		throw Regex::Exception(mod, pattern, std::string(&errormsg[0], errormsg.size()));
	}

	~TREPattern() override
	{
		regfree(&regex);
	}

	bool IsMatch(const std::string& text) override
	{
		return !regexec(&regex, text.c_str(), 0, nullptr, 0);
	}

	std::optional<Regex::MatchCollection> Matches(const std::string& text) override
	{
		if (!IsMatch(text))
			return std::nullopt;

		// The tre engine does not support any kind of capture.
		static const Regex::Captures unusedc;
		static const Regex::NamedCaptures unusednc;

		return Regex::MatchCollection(unusedc, unusednc);
	}
};

class ModuleRegexTRE final
	: public Module
{
 private:
	Regex::SimpleEngine<TREPattern> regex;

 public:
	ModuleRegexTRE()
		: Module(VF_VENDOR, "Provides the tre regular expression engine which uses the TRE library.")
		, regex(weak_from_this(), "tre")
	{
	}
};

MODULE_INIT(ModuleRegexTRE)