/**
 * 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/>.
 */
#include <vector>
#include <memory>
#include <locale>
#include <algorithm>

#include <librdkafka/rdkafkacpp.h>

#include <relpipe/writer/RelationalWriter.h>
#include <relpipe/writer/RelpipeWriterException.h>
#include <relpipe/writer/AttributeMetadata.h>
#include <relpipe/writer/Factory.h>
#include <relpipe/writer/TypeId.h>

#include <relpipe/cli/CLI.h>
#include <condition_variable>
#include <unistd.h>

#include "KafkaCommand.h"
#include "Hex.h"

using namespace std;
using namespace relpipe::cli;
using namespace relpipe::writer;

namespace relpipe {
namespace in {
namespace kafka {

static void check(RdKafka::Conf::ConfResult result, const std::string& errString) {
	if (result != RdKafka::Conf::CONF_OK) {
		throw std::logic_error("Unable to configure Kafka: " + errString);
	}
}

static void check(RdKafka::ErrorCode result, const std::string& errString) {
	if (result != RdKafka::ERR_NO_ERROR) {
		throw std::logic_error("Kafka error: " + errString);
	}
}

static void check(std::shared_ptr<RdKafka::KafkaConsumer> kafkaConsumer, const std::string& errString) {
	if (kafkaConsumer.get() == nullptr) {
		throw std::logic_error("Unable to create Kafka consumer: " + errString);
	}
}

void KafkaCommand::process(std::shared_ptr<writer::RelationalWriter> writer, Configuration& configuration) {
	vector<AttributeMetadata> metadata;

	std::string errString;
	std::shared_ptr<RdKafka::Conf> consumerConf(RdKafka::Conf::create(RdKafka::Conf::ConfType::CONF_GLOBAL));

	// TODO: configurable groupId, clientId and other parameters
	std::string groupId = "relpipe-in-kafka-group-" + std::to_string(getpid());
	std::string clientId = "relpipe-in-kafka-client-" + std::to_string(getpid());

	check(consumerConf->set("client.id", clientId, errString), errString);
	check(consumerConf->set("group.id", groupId, errString), errString);
	check(consumerConf->set("bootstrap.servers", "plaintext://127.0.0.1:9092", errString), errString);
	//check(consumerConf->set("auto.offset.reset", "earliest", errString), errString);
	//check(consumerConf->set("debug", "all", errString), errString);

	std::shared_ptr<RdKafka::KafkaConsumer> kafkaConsumer(RdKafka::KafkaConsumer::create(consumerConf.get(), errString));
	check(kafkaConsumer, errString);

	check(kafkaConsumer->subscribe({"relpipe"}), errString);


	writer->startRelation(configuration.relation,{
		{L"queue", TypeId::STRING},
		{L"text", TypeId::STRING},
		{L"data", TypeId::STRING}
	}, true);

	for (int i = configuration.messageCount; continueProcessing && i > 0;) {
		shared_ptr<RdKafka::Message> message(kafkaConsumer->consume(100));
		if (message.get() && message->err() == 0) {
			std::string payload = message->payload() ? std::string((const char*) message->payload(), message->len()) : std::string("");
			writer->writeAttribute(convertor.from_bytes(message->topic_name()));
			writer->writeAttribute(Hex::toTxt(payload));
			writer->writeAttribute(Hex::toHex(payload));
			i--;
		} else if (message->err() == RdKafka::ErrorCode::ERR__TIMED_OUT) {
			// timeout → try again
		} else if (message->err() == RdKafka::ErrorCode::ERR__PARTITION_EOF) {
			// reached the end of the topic/partition → try again
		} else {
			std::string m = "error while reading message: " + (message.get() ? message->errstr() : "message is missing");
			writer->writeAttribute(configuration.queue);
			writer->writeAttribute(Hex::toTxt(m));
			writer->writeAttribute(Hex::toHex(m));
			break;
		}
	}

	// TODO: wrap and close even on exception
	check(kafkaConsumer->close(), errString);

}

KafkaCommand::~KafkaCommand() {
}

}
}
}