/**
 * 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 <memory>
#include <string>
#include <vector>
#include <iostream>
#include <sstream>
#include <locale>
#include <codecvt>
#include <unistd.h>

#include <librdkafka/rdkafkacpp.h>

#include <relpipe/common/type/typedefs.h>
#include <relpipe/reader/TypeId.h>
#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>
#include <relpipe/reader/handlers/AttributeMetadata.h>

#include "Configuration.h"
#include "Hex.h"

namespace relpipe {
namespace out {
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::Producer> kafkaProducer, const std::string& errString) {
	if (kafkaProducer.get() == nullptr) {
		throw std::logic_error("Unable to create Kafka producer: " + errString);
	}
}

class KafkaHandler : public relpipe::reader::handlers::RelationalReaderStringHandler {
private:
	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.
	Configuration configuration;
	std::shared_ptr<RdKafka::Producer> kafkaProducer;

	struct CurrentRelation {
		relpipe::common::type::StringX name;
		std::vector<relpipe::reader::handlers::AttributeMetadata> attributes;
		relpipe::common::type::Integer attributeIndex = 0;
		std::string currentValue;
	} currentRelation;

	void connect() {
		if (!kafkaProducer) {
			std::string errString;
			std::shared_ptr<RdKafka::Conf> producerConf(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(producerConf->set("client.id", clientId, errString), errString);
			check(producerConf->set("group.id", groupId, errString), errString);
			check(producerConf->set("bootstrap.servers", "plaintext://127.0.0.1:9092", errString), errString); // "host1:9092,host2:9092"    "192.168.1.56:9092"
			//check(consumerConf->set("debug", "all", errString), errString);

			kafkaProducer.reset(RdKafka::Producer::create(producerConf.get(), errString));
			check(kafkaProducer, errString);
		}
	}

	void sendMessage(const std::string& payload) {
		std::string errString;
		check(kafkaProducer->produce(
				convertor.to_bytes(configuration.queue),
				RdKafka::Topic::PARTITION_UA,
				RdKafka::Producer::RK_MSG_COPY,
				const_cast<char *> (payload.c_str()), payload.size(),
				nullptr, 0,
				0,
				nullptr), errString);
	}

public:

	KafkaHandler(Configuration configuration) : configuration(configuration) {
	}

	void startRelation(relpipe::common::type::StringX name, std::vector<relpipe::reader::handlers::AttributeMetadata> attributes) override {
		currentRelation = CurrentRelation{name, attributes};
		connect();
	}

	void attribute(const relpipe::common::type::StringX& value) override {

		auto attributeName = currentRelation.attributes[currentRelation.attributeIndex].getAttributeName();
		if (attributeName == L"text") currentRelation.currentValue = convertor.to_bytes(value);
		else if (attributeName == L"data") currentRelation.currentValue = Hex::fromHex(value).str();

		currentRelation.attributeIndex++;
		if (currentRelation.attributeIndex == currentRelation.attributes.size()) {
			currentRelation.attributeIndex = 0;
			sendMessage(currentRelation.currentValue);
		}

	}

	void endOfPipe() {
		std::string errString;
		check(kafkaProducer->flush(60000), errString);
	}

};

}
}
}