/**

 * Relational pipes (library)

 * Copyright © 2018 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 Lesser General Public License as published by the Free Software Foundation;

 *  - GNU General Public License as published by the Free Software Foundation;

 *

 * 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 <string>

#include <iostream>

#include <vector>

#include <relpipe/protocol/constants.h>

#include <memory>

#include "../include/relpipe/reader/typedefs.h"

#include "../include/relpipe/reader/RelationalReader.h"

#include "../include/relpipe/reader/TypeId.h"

#include "../include/relpipe/reader/handlers/RelationalReaderBaseHandler.h"

#include "../include/relpipe/reader/handlers/RelationalReaderStringHandler.h"

#include "../include/relpipe/reader/handlers/RelationalReaderValueHandler.h"

#include "AttributeMetadataPrivate.h"

#include "DataTypeReaderBase.h"

#include "types/BooleanDataTypeReader.h"

#include "types/IntegerDataTypeReader.h"

#include "types/StringDataTypeReader.h"

namespace relpipe {

namespace reader {

using namespace relpipe::protocol;

using StringHandler = relpipe::reader::handlers::RelationalReaderStringHandler;

using ValuesHandler = relpipe::reader::handlers::RelationalReaderValueHandler;

using AttributeMetadata = relpipe::reader::handlers::AttributeMetadata;

using AttributeMetadataPrivate = relpipe::reader::handlers::AttributeMetadataPrivate;

class StreamRelationalReader : public RelationalReader {

private:

	std::istream &input;

	types::BooleanDataTypeReader booleanReader;

	types::IntegerDataTypeReader integerReader;

	types::StringDataTypeReader stringReader;

	std::vector<DataTypeReaderBase*> readers = {&booleanReader, &integerReader, &stringReader};

	std::vector<StringHandler*> stringHandlers;

	std::vector<ValuesHandler*> valuesHandlers;

	/**

	 * count of columns in the current table

	 */

	integer_t columnCount;

	/**

	 * number of column (0 = first) that will be written; after writing, the number is increased and prepared for next one

	 */

	integer_t currentColumn;

	/**

	 * types of columns in the current table

	 */

	std::vector<TypeId> columnTypes;

	std::vector<string_t> columnNames;

	std::vector<AttributeMetadata> columns;

	/**

	 * TODO: remove?

	 */

	string_t readString(std::istream &input, const TypeId typeId) {

		for (DataTypeReaderBase* reader : readers) if (reader->supports(typeId)) return reader->readString(input);

		throw RelpipeReaderException(L"Unsupported data type: " + (int) typeId);

	}

	void read(std::istream &input, std::function<void(const void *, const std::type_info&) > handler, const TypeId typeId) {

		for (DataTypeReaderBase* reader : readers) if (reader->supports(typeId)) return reader->read(input, handler);

		throw RelpipeReaderException(L"Unsupported data type: " + (int) typeId);

	}

	void read(std::istream &input, std::function<void(const string_t&, const void *, const std::type_info&) > handler, const TypeId typeId) {

		for (DataTypeReaderBase* reader : readers) if (reader->supports(typeId)) return reader->read(input, handler);

		throw RelpipeReaderException(L"Unsupported data type: " + (int) typeId);

	}

	void endOfPipe() {

		for (StringHandler* handler : stringHandlers) handler->endOfPipe();

		for (ValuesHandler* handler : valuesHandlers) handler->endOfPipe();

	}

public:

	StreamRelationalReader(std::istream &input) :

	input(input) {

	}

	string_t toTypeCode(const TypeId typeId) override {

		for (DataTypeReaderBase* reader : readers) if (reader->supports(typeId)) return reader->getTypeCode();

		throw RelpipeReaderException(L"Unsupported data type: " + static_cast<integer_t> (typeId));

	}

	void addHandler(StringHandler* handler) override {

		stringHandlers.push_back(handler);

	}

	void addHandler(ValuesHandler* handler) override {

		valuesHandlers.push_back(handler);

	}

	void process() override {

		while (true) {

			integer_t dataPart;

			try {

				dataPart = integerReader.readValue(input);

				// output << "dataPart: " << dataPart << endl;

			} catch (RelpipeReaderException e) {

				if (input.eof() && input.gcount() == 0) {

					if (dataPart == DATA_PART_ROW) {

						// last part was row

						// input was fully read

						// we are finished

						// TODO: printCachedData(output); ???

						endOfPipe();

						return;

					} else if (dataPart == DATA_PART_START) {

						// Empty relation might be weird but it is valid data.

						// Actually, it is not so weird as it looks.

						// fwprintf(stderr, L"Warning: The table has no rows. Weird… but OK.\n");

						endOfPipe();

						return;

					} else {

						// in current format, there is no other data part

						// so this will never happen

						// but maybe later…

						throw RelpipeReaderException(L"Unexpected EOF");

					}

				} else if (input.eof()) {

					fwprintf(stderr, L"Error: found some unexpected data on the input stream: %d\n", input.gcount());

					throw e;

				} else {

					// other error

					throw e;

				}

			}

			if (dataPart == DATA_PART_START) {

				// Print data of previous table

				// TODO: if (values.size() > 0) printCachedData(output); ???

				// Read table name

				string_t tableName = stringReader.readValue(input);

				// Read column count

				columnCount = integerReader.readValue(input);

				columnTypes.clear();

				columnNames.clear();

				columns.clear();

				columnTypes.reserve(columnCount);

				columnNames.reserve(columnCount);

				columns.reserve(columnCount);

				// Read column names

				for (int i = 0; i < columnCount; i++) {

					columnNames.push_back(stringReader.readValue(input));

				}

				// Read column types

				for (int i = 0; i < columnCount; i++) {

					TypeId typeId = (TypeId) integerReader.readValue(input); // TODO: přetypování OK?

					string_t typeCode = toTypeCode(typeId); // validate typeId TODO: je potřeba?

					columnTypes.push_back(typeId);

					// put together names, type ids and type codes:

					columns.push_back(std::shared_ptr<AttributeMetadataPrivate>(new AttributeMetadataPrivate({columnNames[i], columnTypes[i], typeCode})));

				}

				for (StringHandler* handler : stringHandlers) handler->startRelation(tableName, columns);

				for (ValuesHandler* handler : valuesHandlers) handler->startRelation(tableName, columns);

			} else if (dataPart == DATA_PART_ROW) {

				for (int i = 0; i < columnCount; i++) {

					TypeId typeId = columnTypes[i];

					if (stringHandlers.empty()) {

						read(input, [&](const void * rawValue, const std::type_info & typeInfo) {

							for (ValuesHandler* handler : valuesHandlers) handler->attribute(rawValue, typeInfo);

						}, typeId);

					} else {

						read(input, [&](const string_t& stringValue, const void * rawValue, const std::type_info & typeInfo) {

							for (StringHandler* handler : stringHandlers) handler->attribute(stringValue);

							for (ValuesHandler* handler : valuesHandlers) handler->attribute(rawValue, typeInfo);

						}, typeId);

					}

				}

			} else {

				throw RelpipeReaderException(L"Unknown data part");

			}

		}

		throw RelpipeReaderException(L"Unexpected exception"); // should never happen

	}

};

}

}