/**

 * Relational pipes

 * Copyright © 2020 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 <codecvt>

#include <regex>

#include <libxml++-2.6/libxml++/libxml++.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 <relpipe/writer/Factory.h>

#include <relpipe/cli/RelpipeCLIException.h>

#include "Configuration.h"

#include "XMLNameCodec.h"

namespace relpipe {

namespace tr {

namespace xpath {

class XPathHandler : public relpipe::reader::handlers::RelationalReaderStringHandler {

private:

	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // XML is in UTF-8

	shared_ptr<relpipe::writer::RelationalWriter> relationalWriter;

	Configuration configuration;

	RelationConfiguration* currentRelationConfiguration = nullptr;

	std::vector<relpipe::reader::handlers::AttributeMetadata> currentReaderMetadata;

	std::vector<relpipe::writer::AttributeMetadata> currentWriterMetadata;

	size_t currentAttributeIndex = 0;

	size_t currentRecordNumber = 1;

	xmlpp::Node::PrefixNsMap xmlns;

	xmlpp::Document dom;

	xmlpp::Element* recordElement = nullptr;

	relpipe::in::xmltable::XMLNameCodec xmlNameCodec; // TODO: move to a common library

	void copyInputAttributesToOutput() {

		for (auto rm : currentReaderMetadata) currentWriterMetadata.push_back({rm.getAttributeName(), relationalWriter->toTypeId(rm.getTypeName())});

	}

	bool isPrependingInputAttributes() {

		return currentRelationConfiguration->inputAttributePolicy == InputAttributePolicy::Prepend

				|| (currentRelationConfiguration->inputAttributePolicy == InputAttributePolicy::Auto && currentRelationConfiguration->outputAttributes.size() == 0);

	}

	bool isAppendingInputAttributes() {

		return currentRelationConfiguration->inputAttributePolicy == InputAttributePolicy::Append;

	}

	void resetRecordElement() {

		if (recordElement) dom.get_root_node()->remove_child(recordElement);

		recordElement = dom.get_root_node()->add_child("record");

	}

	const Glib::ustring s2x(relpipe::common::type::StringX value) {

		return Glib::ustring(convertor.to_bytes(value));

	}

	const relpipe::common::type::StringX x2s(const Glib::ustring& value) {

		return convertor.from_bytes(value);

	}

	void writeInputAttributes() {

		for (xmlpp::Node* attributeNode : recordElement->get_children()) {

			if (xmlpp::Element * attributeElement = dynamic_cast<xmlpp::Element*> (attributeNode)) {

			}

		}

	}

	void writeOutputAttributes() {

		for (auto oa : currentRelationConfiguration->outputAttributes) {

		}

	}

public:

	XPathHandler(shared_ptr<relpipe::writer::RelationalWriter> relationalWriter, Configuration configuration) : relationalWriter(relationalWriter), configuration(configuration) {

		for (int i = 0; i < configuration.namespaceMappings.size(); i++) {

			std::string prefix = convertor.to_bytes(configuration.namespaceMappings[i]);

			std::string uri = convertor.to_bytes(configuration.namespaceMappings[++i]);

			xmlns[prefix] = uri;

		}

	}

	virtual ~XPathHandler() {

	}

	void startRelation(relpipe::common::type::StringX name, std::vector<relpipe::reader::handlers::AttributeMetadata> attributes) override {

		currentRelationConfiguration = nullptr;

		for (int i = 0; i < configuration.relationConfigurations.size(); i++) {

			if (std::regex_match(name, std::wregex(configuration.relationConfigurations[i].relation))) {

				currentRelationConfiguration = &configuration.relationConfigurations[i];

				break;

			}

		}

		currentReaderMetadata = attributes;

		currentWriterMetadata.clear();

		currentRecordNumber = 1;

		recordElement = nullptr;

		if (currentRelationConfiguration == nullptr) {

			copyInputAttributesToOutput();

		} else {

			if (isPrependingInputAttributes()) copyInputAttributesToOutput();

			for (auto oa : currentRelationConfiguration->outputAttributes) currentWriterMetadata.push_back({oa.name, oa.type});

			if (isAppendingInputAttributes()) copyInputAttributesToOutput();

			dom.create_root_node("relpipe-tr-xpath");

			dom.get_root_node()->add_child("relation-name")->add_child_text(s2x(name));

			resetRecordElement();

		}

		relationalWriter->startRelation(name, currentWriterMetadata, true);

	}

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

		if (currentRelationConfiguration) {

			relpipe::reader::handlers::AttributeMetadata attributeMetadata = currentReaderMetadata[currentAttributeIndex];

			xmlpp::Element* attributeElement = recordElement->add_child(xmlNameCodec.encode(s2x(attributeMetadata.getAttributeName())));

			attributeElement->set_attribute("name", s2x(attributeMetadata.getAttributeName()));

			attributeElement->set_attribute("type", s2x(attributeMetadata.getTypeName()));

			if (currentAttributeIndex == 0) {

				recordElement->set_attribute("number", std::to_string(currentRecordNumber));

			}

			currentAttributeIndex++;

			if (currentAttributeIndex == currentReaderMetadata.size()) {

				if (currentRelationConfiguration->where.empty() || recordElement->eval_to_boolean(s2x(currentRelationConfiguration->where), xmlns)) {

					if (isPrependingInputAttributes()) writeInputAttributes();

					writeOutputAttributes();

					if (isAppendingInputAttributes()) writeInputAttributes();

				}

				resetRecordElement();

				currentAttributeIndex = 0;

				currentRecordNumber++;

			}

		} else {

			relationalWriter->writeAttribute(value);

		}

	}

	void endOfPipe() {

	}

};

}

}

}