/**

 * 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

 *

 * 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 <map>

#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>

#include "Configuration.h"

#include "GuileException.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 RelationalReaderValueHandler {

private:

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

	Configuration configuration;

	writer::RelationalWriter* relationalWriter;

	RelationConfiguration* currentRelationConfiguration = nullptr;

	vector<AttributeMetadata> currentReaderMetadata;

	vector<writer::AttributeMetadata> currentWriterMetadata;

	std::map<string_t, string_t> currenVariablesMapping;

	integer_t currentAttributeIndex = 0;

	boolean_t includeCurrentRecord = false;

	void add(vector<AttributeMetadata>& readerAttributes, vector<writer::AttributeMetadata>& writerAttributes) {

		for (AttributeMetadata readerAttributes : readerAttributes)

			writerAttributes.push_back({

				readerAttributes.getAttributeName(),

				relationalWriter->toTypeId(readerAttributes.getTypeName())

			});

	}

	void generateVariableMappings() {

		currenVariablesMapping.clear();

		for (AttributeMetadata m : currentReaderMetadata) currenVariablesMapping[m.getAttributeName()] = L"";

		for (writer::AttributeMetadata m : currentWriterMetadata) currenVariablesMapping[m.attributeName] = L"";

		for (std::pair<string_t, string_t> m : currenVariablesMapping) {

			currenVariablesMapping[m.first] = escapeAwkVariableName(m.first);

		}

	}

	/**

	 * @param attributeName name from relational pipe

	 * @return variable name in Guile

	 */

	string_t a2v(const string_t& attributeName) {

		if (currenVariablesMapping.find(attributeName) != currenVariablesMapping.end()) return currenVariablesMapping[attributeName];

		else throw GuileException(L"Unable to find value in currenVariablesMapping");

	}

	template <typename K, typename V> bool containsValue(std::map<K, V> map, V value) { // TODO: common function (Guile, AWK)

		for (std::pair<K, V> p : map) if (p.second == value) return true;

		return false;

	}

	string_t escapeAwkVariableName(const string_t& attributeName, bool addPrefix = true) {

		std::wregex badCharacters(L"\\s");

		string_t name = std::regex_replace(attributeName, badCharacters, L"-");

		if (addPrefix) name = L"$" + name; // $ = standard attribute-variable prefix

		if (containsValue(currenVariablesMapping, name)) return escapeAwkVariableName(L"$" + name, false); // $ = different prefix added to distinguish two attributes with ambiguous names

		else return name;

	}

	void debugVariableMapping(const string_t& relationName) {

		relationalWriter->startRelation(relationName + L".variableMapping",{

			{L"attribute", writer::TypeId::STRING},

			{L"variable", writer::TypeId::STRING},

		}, true);

		for (std::pair<string_t, string_t> m : currenVariablesMapping) {

			relationalWriter->writeAttribute(m.first);

			relationalWriter->writeAttribute(m.second);

		}

	}

	SCM toGuileSymbol(const string_t& name) {

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

	}

	/**

	 * @param code guile source code e.g. (+ 1 2 3) or #t

	 * @param defaultReturnValue is returned if code is empty

	 * @return result of code execution or defaultReturnValue

	 */

	SCM evalGuileCode(const string_t& code, SCM defaultReturnValue = SCM_BOOL_F) {

		if (code.size()) return scm_eval_string(toGuileValue(&code, typeid (string_t), TypeId::STRING));

		else return defaultReturnValue;

	}

	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));

	}

	/**

	 * TODO: use a common method

	 */

	bool parseBoolean(const string_t& value) {

		if (value == L"true") return true;

		else if (value == L"false") return false;

		else throw relpipe::cli::RelpipeCLIException(L"Unable to parse boolean value: " + value + L" (expecting true or false)", relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);

	}

	void defineGuileVariable(const DefinitionRecipe& definition) {

		switch (relationalWriter->toTypeId(definition.type)) {

			case writer::TypeId::BOOLEAN:

			{

				boolean_t value = parseBoolean(definition.value);

				defineGuileVariable(definition.name, &value, typeid (value), TypeId::BOOLEAN);

				break;

			}

			case writer::TypeId::INTEGER:

			{

				integer_t value = stoul(definition.value);

				defineGuileVariable(definition.name, &value, typeid (value), TypeId::INTEGER);

				break;

			}

			case writer::TypeId::STRING:

			{

				defineGuileVariable(definition.name, &definition.value, typeid (definition.value), TypeId::STRING);

				break;

			}

			default:

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

		}

	}

	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);

		}

	}

	/**

	 * Read from the Guile variables and write to relational output stream.

	 */

	void writeCurrentRecord() {

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

	}

	void writeMoreRecords() {

		while (scm_to_bool(evalGuileCode(currentRelationConfiguration->guileHasMoreRecords, SCM_BOOL_F))) writeCurrentRecord();

	}

public:

	GuileHandler(writer::RelationalWriter* relationalWriter, Configuration& configuration) : relationalWriter(relationalWriter), configuration(configuration) {

	}

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

		if (currentRelationConfiguration) {

			evalGuileCode(currentRelationConfiguration->guileAfterRecords);

			writeMoreRecords();

			for (DefinitionRecipe definition : currentRelationConfiguration->definitions) undefineGuileVariable(definition.name);

		}

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

		for (DefinitionRecipe definition : configuration.definitions) defineGuileVariable(definition);

		currentRelationConfiguration = nullptr;

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

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

				currentRelationConfiguration = &configuration.relationConfigurations[i];

				for (DefinitionRecipe definition : currentRelationConfiguration->definitions) defineGuileVariable(definition);

				break; // it there are multiple matches, only the first configuration is used

			}

		}

		currentReaderMetadata = attributes;

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

		currentWriterMetadata.clear();

		if (currentRelationConfiguration && currentRelationConfiguration->writerMetadata.size()) {

			if (currentRelationConfiguration->inputAttributesPrepend) add(currentReaderMetadata, currentWriterMetadata);

			currentWriterMetadata.insert(currentWriterMetadata.end(), currentRelationConfiguration->writerMetadata.begin(), currentRelationConfiguration->writerMetadata.end());

			if (currentRelationConfiguration->inputAttributesAppend) add(currentReaderMetadata, currentWriterMetadata);

		} else {

			add(currentReaderMetadata, currentWriterMetadata);

		}

		generateVariableMappings();

		if (currentRelationConfiguration->debugVariableMapping) debugVariableMapping(name);

		if (!currentRelationConfiguration || !currentRelationConfiguration->drop) relationalWriter->startRelation(name, currentWriterMetadata, true);

		if (currentRelationConfiguration) {

			// TODO: better variable name, object, function?

			defineGuileVariable(L"relpipe-relation-name", &name, typeid (name), TypeId::STRING);

			evalGuileCode(currentRelationConfiguration->guileBeforeRecords);

		}

	}

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

		if (currentRelationConfiguration) {

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

			currentAttributeIndex++;

			// TODO: > 0 ?:

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

				evalGuileCode(currentRelationConfiguration->guileForEach);

				includeCurrentRecord = scm_to_bool(evalGuileCode(currentRelationConfiguration->guileWhere, SCM_BOOL_T));

				if (includeCurrentRecord && !currentRelationConfiguration->drop) writeCurrentRecord();

				includeCurrentRecord = false;

				writeMoreRecords();

			}

			currentAttributeIndex = currentAttributeIndex % currentReaderMetadata.size();

		} else {

			relationalWriter->writeAttribute(value, type);

		}

	}

	void endOfPipe() {

		if (currentRelationConfiguration) {

			evalGuileCode(currentRelationConfiguration->guileAfterRecords);

			writeMoreRecords();

		}

	}

};

}

}

}