/**

 * Relational pipes

 * Copyright © 2019 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, either version 3 of the License, or

 * (at your option) any later version.

 *

 * 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 <memory>

#include <string>

#include <vector>

#include <iostream>

#include <sstream>

#include <locale>

#include <codecvt>

#include <regex>

#include <unistd.h>

#include <wait.h>

#include <ext/stdio_filebuf.h>

#include <relpipe/reader/typedefs.h>

#include <relpipe/reader/TypeId.h>

#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>

#include <relpipe/reader/handlers/AttributeMetadata.h>

#include <relpipe/writer/Factory.h>

#include <relpipe/cli/RelpipeCLIException.h>

#include "Configuration.h"

namespace relpipe {

namespace tr {

namespace awk {

using namespace std;

using namespace relpipe;

using namespace relpipe::reader;

using namespace relpipe::reader::handlers;

class AwkHandler : public RelationalReaderStringHandler {

private:

	Configuration configuration;

	writer::RelationalWriter* relationalWriter;

	int awkInputWriterFD = -1;

	void createPipe(int& readerFD, int& writerFD) {

		int fds[2];

		int result = pipe(fds);

		readerFD = fds[0];

		writerFD = fds[1];

		if (result < 0) throw cli::RelpipeCLIException(L"Unable to create a pipe.", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exceptions?

	}

	void redirectFD(int oldfd, int newfd) {

		int result = dup2(oldfd, newfd);

		if (result < 0) throw cli::RelpipeCLIException(L"Unable redirect FD.", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exceptions?

	}

	void closeOrThrow(int fd) {

		int error = close(fd);

		if (error) throw cli::RelpipeCLIException(L"Unable to close FD: " + to_wstring(fd) + L" from PID: " + to_wstring(getpid()), cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exceptions?

	}

	void cleanUp() {

		if (awkInputWriterFD >= 0) {

			closeOrThrow(awkInputWriterFD);

			__pid_t waitResult1 = wait(NULL);

			__pid_t waitResult2 = wait(NULL);

			awkInputWriterFD = -1;

		}

	}

public:

	AwkHandler(writer::RelationalWriter* relationalWriter, Configuration& configuration) : relationalWriter(relationalWriter), configuration(configuration) {

	}

	void startRelation(string_t name, vector<AttributeMetadata> attributes) override {

		cleanUp();

		int awkInputReaderFD;

		int awkOutputReaderFD;

		int awkOutputWriterFD;

		createPipe(awkInputReaderFD, awkInputWriterFD);

		createPipe(awkOutputReaderFD, awkOutputWriterFD);

		__pid_t awkPid = fork();

		if (awkPid < 0) {

			throw cli::RelpipeCLIException(L"Unable to fork AWK process.", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exceptions?

		} else if (awkPid == 0) {

			// AWK child process

			closeOrThrow(awkInputWriterFD);

			closeOrThrow(awkOutputReaderFD);

			redirectFD(awkInputReaderFD, STDIN_FILENO);

			redirectFD(awkOutputWriterFD, STDOUT_FILENO);

			execlp("awk", "awk", "{print \"AWK says: line \" NR \" = \" $0;}", nullptr);

		} else {

			// Parent process

			closeOrThrow(awkInputReaderFD);

			closeOrThrow(awkOutputWriterFD);

			__pid_t writerPid = fork();

			if (writerPid < 0) {

				throw cli::RelpipeCLIException(L"Unable to fork Writer process.", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exceptions?

			} else if (writerPid == 0) {

				// Writer child process

				closeOrThrow(awkInputWriterFD);

				__gnu_cxx::stdio_filebuf<wchar_t> awkOutputReaderBuffer(awkOutputReaderFD, std::ios::in);

				std::wistream awkOutputReader(&awkOutputReaderBuffer);

				relationalWriter->startRelation(L"writer_debug",{

					{L"message", writer::TypeId::STRING},

				}, true);

				for (wchar_t ch = awkOutputReader.get(); awkOutputReader.good(); ch = awkOutputReader.get()) {

					relationalWriter->writeAttribute(string_t(1, ch));

				}

				closeOrThrow(awkOutputReaderFD);

				exit(0);

			} else {

				// Parent process

				closeOrThrow(awkOutputReaderFD);

			}

		}

	}

	void attribute(const string_t& value) override {

		dprintf(awkInputWriterFD, "attribute!\n");

	}

	void endOfPipe() {

		cleanUp();

	}

};

}

}

}