/**

 * 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 <assert.h>

#include <libguile.h>

#include <relpipe/reader/typedefs.h>

#include <relpipe/reader/TypeId.h>

#include <relpipe/reader/handlers/RelationalReaderValueHandler.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 RelationalReaderValueHadler {

private:

	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings or use always UTF-8 between C++ and Guile

	shared_ptr<writer::RelationalWriter> relationalWriter;

	wregex relationNameRegEx;

	vector<AttributeMetadata> currentReaderMetadata;

	vector<writer::AttributeMetadata> currentWriterMetadata;

	vector<string_t> currentRecord;

	integer_t currentAttributeIndex = 0;

	boolean_t includeCurrentRecord = false;

	boolean_t filterCurrentRelation = false;

	string_t guileCodeWhereCondition;

	/**

	 * @param attributeName name from relational pipe

	 * @return variable name in Guile

	 */

	string_t a2v(const string_t& attributeName) {

		// TODO: escape spaces and special characters

		return L"$" + attributeName;

	}

	SCM toGuileSymbol(const string_t& name) {

		return scm_string_to_symbol(scm_from_locale_string(convertor.to_bytes(name).c_str()));

	}

	SCM evalGuileCode(const string_t& value) {

		return scm_eval_string(toGuileValue(&value, typeid (string_t), TypeId::STRING));

	}

	SCM toGuileValue(const void* value, const std::type_info& typeInfo, TypeId type) {

		switch (type) {

			case TypeId::BOOLEAN:

			{

				assert(typeInfo == typeid (boolean_t));

				auto* typedValue = static_cast<const boolean_t*> (value);

				return *typedValue ? SCM_BOOL_T : SCM_BOOL_F;

			}

			case TypeId::INTEGER:

			{

				assert(typeInfo == typeid (integer_t));

				auto* typedValue = static_cast<const integer_t*> (value);

				return scm_from_uint64(*typedValue);

			}

			case TypeId::STRING:

			{

				assert(typeInfo == typeid (string_t));

				auto* typedValue = static_cast<const string_t*> (value);

				return scm_from_locale_string(convertor.to_bytes(*typedValue).c_str());

			}

			default:

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

		}

	}

	void defineGuileVariable(const string_t& name, const void* value, const std::type_info& typeInfo, TypeId type) {

		scm_define(toGuileSymbol(name), toGuileValue(value, typeInfo, type));

	}

	void undefineGuileVariable(const string_t& name) {

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

		// TODO: or use: scm_variable_unset_x() ?

	}

	void writeGuileValueToAttribute(const writer::AttributeMetadata& attribute) {

		string_t variableName = a2v(attribute.attributeName);

		SCM guileValue = scm_eval_string(toGuileValue(&variableName, typeid (variableName), TypeId::STRING));

		switch (attribute.typeId) {

			case writer::TypeId::BOOLEAN:

			{

				boolean_t value = scm_to_bool(guileValue);

				return relationalWriter->writeAttribute(&value, typeid (value));

			}

			case writer::TypeId::INTEGER:

			{

				integer_t value = scm_to_uint64(guileValue);

				return relationalWriter->writeAttribute(&value, typeid (value));

			}

			case writer::TypeId::STRING:

			{

				char* ch = scm_to_locale_string(guileValue);

				string_t value = convertor.from_bytes(ch);

				free(ch);

				return relationalWriter->writeAttribute(&value, typeid (value));

			}

			default:

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

		}

	}

public:

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

		} else {

		}

	}

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

		for (auto attribute : currentReaderMetadata) undefineGuileVariable(attribute.getAttributeName());

		currentReaderMetadata = attributes;

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

		// TODO: allow structural changes during transformation

		// TODO: clear Guile variables for attributes from previous relation

		currentWriterMetadata.clear();

		for (AttributeMetadata readerMetadata : attributes) {

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

		}

		currentRecord.resize(attributes.size());

		filterCurrentRelation = regex_match(name, relationNameRegEx);

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

	}

	void attribute(const void* value, const std::type_info& type) override {

		if (filterCurrentRelation) {

			defineGuileVariable(a2v(currentReaderMetadata[currentAttributeIndex].getAttributeName()), value, type, currentReaderMetadata[currentAttributeIndex].getTypeId());

			currentAttributeIndex++;

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

				includeCurrentRecord = scm_to_bool(evalGuileCode(guileCodeWhereCondition));

				if (includeCurrentRecord) for (auto attribute : currentWriterMetadata) writeGuileValueToAttribute(attribute);

				includeCurrentRecord = false;

			}

			currentAttributeIndex = currentAttributeIndex % currentReaderMetadata.size();

		} else {

			relationalWriter->writeAttribute(value, type);

		}

	}

	void endOfPipe() {

	}

};

}

}

}