/**

 * 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, 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 <cstdlib>

#include <iostream>

#include <string>

#include <sstream>

#include <vector>

#include <algorithm>

#include <xercesc/sax2/SAX2XMLReader.hpp>

#include <xercesc/sax2/XMLReaderFactory.hpp>

#include <xercesc/sax2/DefaultHandler.hpp>

#include <xercesc/sax2/Attributes.hpp>

#include <xercesc/util/XMLString.hpp>

#include <relpipe/writer/typedefs.h>

#include "StreamInputSource.h"

#include "XercesStringConvertor.h"

namespace relpipe {

namespace in {

namespace xml {

using namespace relpipe::writer;

using namespace xercesc;

class XMLCommand {

private:

	class RelpipeSaxHandler : public xercesc::DefaultHandler {

	private:

		const wstring XMLNS = L"tag:globalcode.info,2018:relpipe";

		unique_ptr<RelationalWriter> writer;

		XercesStringConvertor xConvertor;

		wstring currentRelationName;

		vector<AttributeMetadata> currentAttributes;

		wstringstream currentValue;

		void resetCurrentValue() {

			currentValue.str(L"");

			currentValue.clear();

		}

		string_t getAttributeName(const Attributes& attrs, string_t uri, string_t localname) {

			// TODO: less string conversions, better performance

			XMLCh* xUri = xConvertor.toXercesString(uri);

			XMLCh* xLocalName = xConvertor.toXercesString(localname);

			string_t value = xConvertor.toString(attrs.getValue(xUri, xLocalName));

			XMLString::release(&xUri);

			XMLString::release(&xLocalName);

			return value;

		}

		void startElement(const string_t uri, const string_t localname, const string_t qname, const Attributes& attrs) {

			if (uri == XMLNS) {

				if (localname == L"name") {

					resetCurrentValue();

				} else if (localname == L"attributes-metadata") {

					currentAttributes.clear();

				} else if (localname == L"attribute-metadata") {

					AttributeMetadata am;

					am.attributeName = getAttributeName(attrs, L"", L"name");

					am.typeId = writer->toTypeId(getAttributeName(attrs, L"", L"type"));

					currentAttributes.push_back(am);

				} else if (localname == L"attribute") {

					resetCurrentValue();

				}

			}

		}

		void endElement(const string_t uri, const string_t localname, const string_t qname) {

			if (uri == XMLNS) {

				if (localname == L"name") {

					currentRelationName = currentValue.str();

				} else if (localname == L"attributes-metadata") {

					writer->startRelation(currentRelationName, currentAttributes, true);

				} else if (localname == L"attribute") {

					writer->writeAttribute(currentValue.str());

				}

			}

		}

		void characters(const string_t chars) {

			// There should be no null bytes in XML, 0x00 is invalid here.

		}

	public:

		RelpipeSaxHandler(std::ostream& output) : DefaultHandler(), writer(Factory::create(output)) {

		}

		virtual ~RelpipeSaxHandler() {

		}

		void startElement(const XMLCh * const uri, const XMLCh * const localname, const XMLCh * const qname, const Attributes& attrs) override {

			startElement(xConvertor.toString(uri), xConvertor.toString(localname), xConvertor.toString(qname), attrs);

		}

		void endElement(const XMLCh * const uri, const XMLCh * const localname, const XMLCh * const qname) override {

			endElement(xConvertor.toString(uri), xConvertor.toString(localname), xConvertor.toString(qname));

		}

		void characters(const XMLCh * const chars, const XMLSize_t length) override {

			characters(xConvertor.toString(chars));

		}

	};

public:

	void process(std::istream& input, std::ostream& output) {

		XMLPlatformUtils::Initialize();

		unique_ptr<SAX2XMLReader> parser(XMLReaderFactory::createXMLReader());

		parser->setFeature(XMLUni::fgSAX2CoreValidation, true);

		parser->setFeature(XMLUni::fgSAX2CoreNameSpaces, true);

		// TODO: optional unbuffered mode for more fluent output?

		// http://xerces.apache.org/xerces-c/program-sax2-3.html#SAX2Features

		// parser->setProperty(XMLUni::fgXercesLowWaterMark, ...);

		// parser->setInputBufferSize(...);

		RelpipeSaxHandler saxHandler(output);

		parser->setContentHandler(&saxHandler);

		parser->setErrorHandler(&saxHandler);

		StreamInputSource inputSource(input);

		parser->parse(inputSource);

	}

};

}

}

}