/**

 * 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:

	size_t MSG_SIZE = 8192; // TODO: configurable/dynamic

	std::string queueName;

	mqd_t handle = -2;

	PosixMQ(std::string queueName, mqd_t handle) : queueName(queueName), handle(handle) {

	}

public:

	virtual ~PosixMQ() {

		if (handle >= 0) mq_close(handle);

	}

	static PosixMQ* open(std::string queueName) {

		mqd_t handle = mq_open(queueName.c_str(), O_RDONLY | O_CREAT);

		if (handle >= 0) return new PosixMQ(queueName, handle);

		else throw std::logic_error("Unable to open PosixMQ: " + 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 >= 0) return std::string(buffer);

		else throw std::logic_error("Unable to receive PosixMQ message from " + queueName + " error: " + strerror(errno));

	}

	void unlink() {

		mq_unlink(queueName.c_str());

	}

};

}

}

}