/**
 * Relational pipes
 * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)
 *
 * This program 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 3 of the License.
 *
 * 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/>.
 */
#pragma once

#include <mqueue.h>
#include <string>
#include <stdexcept>
#include <cstring>

namespace relpipe {
namespace in {
namespace posixmq {

class PosixMQ {
private:
	const static size_t MSG_SIZE = 8192; // TODO: configurable/dynamic
	std::string queueName;
	mqd_t handle = -2;
	bool unlinkOnClose = false;

	PosixMQ(std::string queueName, mqd_t handle, bool unlinkOnClose) : queueName(queueName), handle(handle), unlinkOnClose(unlinkOnClose) {
	}

public:

	virtual ~PosixMQ() {
		if (handle >= 0) mq_close(handle);
		if (unlinkOnClose) mq_unlink(queueName.c_str());
	}

	static PosixMQ* open(std::string queueName, bool unlinkOnClose = false) {
		mqd_t handle = mq_open(queueName.c_str(), O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
		if (handle >= 0) return new PosixMQ(queueName, handle, unlinkOnClose);
		else throw std::logic_error("Unable to open PosixMQ: " + queueName + " error: " + strerror(errno));
	}

	void send(std::string message) {
		int result = mq_send(handle, message.c_str(), message.size(), 0);
		if (result) throw std::logic_error("Unable to send message to" + queueName + " error: " + strerror(errno));
	}

	std::string receive() {
		char buffer[MSG_SIZE + 1];
		memset(buffer, 0, MSG_SIZE + 1);
		ssize_t msgSize = mq_receive(handle, buffer, MSG_SIZE, nullptr);

		if (msgSize > sizeof (buffer))throw std::logic_error("Invalid PosixMQ message size.");
		else if (msgSize >= 0) return std::string(buffer, msgSize);
		else throw std::logic_error("Unable to receive PosixMQ message from " + queueName + " error: " + strerror(errno));
	}

};

}
}
}