/**

 * 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 <libguile.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>

namespace relpipe {

namespace tr {

namespace guile {

using namespace std;

using namespace relpipe;

using namespace relpipe::reader;

using namespace relpipe::reader::handlers;

class GuileHandler : public RelationalReaderStringHadler {

private:

	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.

	shared_ptr<writer::RelationalWriter> relationalWriter;

	wregex relationNameRegEx;

	vector<AttributeMetadata> currentMetadata;

	vector<string_t> currentRecord;

	integer_t currentAttributeIndex = 0;

	boolean_t includeCurrentRecord = false;

	boolean_t filterCurrentRelation = false;

	string_t guileCode;

	SCM toGuileSymbol(const string_t& name) {

	}

	SCM toGuileString(const string_t& value) {

		return scm_from_locale_string(convertor.to_bytes(value).c_str());

	}

	SCM toGuileInteger(const string_t& value) {

		return scm_from_uint64(stoul(value));

	}

	SCM toGuileBoolean(const string_t& value) {

		return value == L"true" ? SCM_BOOL_T : SCM_BOOL_F;

	}

	void defineGuileVariable(const string_t& name, TypeId type, const string_t& value) {

		// TODO: RelationalReaderValueHadler?

		switch (type) {

			case TypeId::BOOLEAN:

				scm_define(toGuileSymbol(name), toGuileBoolean(value));

				break;

			case TypeId::INTEGER:

				scm_define(toGuileSymbol(name), toGuileInteger(value));

				break;

			case TypeId::STRING:

				scm_define(toGuileSymbol(name), toGuileString(value));

				break;

			default:

				throw cli::RelpipeCLIException(L"Unsupported type in defineGuileVariable()", cli::CLI::EXIT_CODE_UNEXPECTED_ERROR);

		}

	}

	void undefineGuileVariable(const string_t& name, TypeId type, const string_t& value) {

		scm_define(toGuileSymbol(name), scm_make_undefined_variable()); // undefined != (define n)

	}

public:

	GuileHandler(ostream& output, const vector<string_t>& arguments) {

		relationalWriter.reset(writer::Factory::create(output));

		// TODO: options and parser

		if (arguments.size() == 2) {

			relationNameRegEx = wregex(arguments[0]);

			guileCode = arguments[1];

		} else {

			throw cli::RelpipeCLIException(L"Usage: relpipe-tr-guile <relationNameRegExp>", cli::CLI::EXIT_CODE_UNKNOWN_COMMAND);

		}

	}

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

		currentMetadata = attributes;

		// TODO: move to a reusable method (or use same metadata on both reader and writer side?)

		vector<writer::AttributeMetadata> writerMetadata;

		for (AttributeMetadata readerMetadata : attributes) {

			writerMetadata.push_back({readerMetadata.getAttributeName(), relationalWriter->toTypeId(readerMetadata.getTypeName())});

		}

		currentRecord.resize(attributes.size());

		filterCurrentRelation = regex_match(name, relationNameRegEx);

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

	}

	void attribute(const string_t& value) override {

		if (filterCurrentRelation) {

			currentRecord[currentAttributeIndex] = value;

			defineGuileVariable(currentMetadata[currentAttributeIndex].getAttributeName(), currentMetadata[currentAttributeIndex].getTypeId(), value);

			currentAttributeIndex++;

			if (currentAttributeIndex > 0 && currentAttributeIndex % currentMetadata.size() == 0) {

				// TODO: support also updates in Guile

				includeCurrentRecord = scm_to_bool(scm_eval_string(toGuileString(guileCode)));

				if (includeCurrentRecord) for (string_t v : currentRecord) relationalWriter->writeAttribute(v);

				includeCurrentRecord = false;

			}

			currentAttributeIndex = currentAttributeIndex % currentMetadata.size();

		} else {

			relationalWriter->writeAttribute(value);

		}

	}

	void endOfPipe() {

	}

};

}

}

}