/**
 * Relational pipes
 * 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 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 <relpipe/reader/typedefs.h>
#include <relpipe/reader/TypeId.h>
#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>
#include <relpipe/reader/handlers/AttributeMetadata.h>

#include "RelpipeCSVWriterException.h"

namespace relpipe {
namespace out {
namespace csv {

using namespace relpipe;
using namespace relpipe::reader;
using namespace relpipe::reader::handlers;

class CSVHandler : public RelationalReaderStringHadler {
private:
	std::ostream& output;
	const char QUOTE = '"';
	std::wstring_convert<std::codecvt_utf8<wchar_t>> convertor; // TODO: local system encoding or generate CSV always in UTF-8 like XML?
	std::vector<AttributeMetadata> firstAttributes;
	integer_t valueCount = 0;
public:

	CSVHandler(std::ostream& output) : output(output) {
	}

	void startRelation(string_t name, std::vector<AttributeMetadata> attributes) override {
		if (firstAttributes.empty()) {
			firstAttributes = attributes;
			for (auto attr : attributes) attribute(attr.getAttributeName());
		} else {
			// TODO: UNION ALL if data types and attribute count matches
			throw RelpipeCSVWriterException(L"Only a single relation can be converted to the CSV format.");
		}
	}

	void attribute(const string_t& value) override {
		valueCount++;

		if (value.size() > 0) {
			output << QUOTE;
			for (auto ch : convertor.to_bytes(value)) {
				if (ch == QUOTE) output << QUOTE << QUOTE;
				else output << ch;
			}
			output << QUOTE;
		}

		if (valueCount % firstAttributes.size()) {
			output << ",";
		} else {
			output << "\r\n";
			valueCount = 0;
		}
	}

	void endOfPipe() {
		output.flush();
	}

};

}
}
}