/**

 * Relational pipes

 * Copyright © 2020 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, version 3 of the License.

 *

 * 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 <sstream>

#include <codecvt>

#include <arpa/inet.h>

using namespace std;

using namespace relpipe::writer;

namespace relpipe {

namespace in {

namespace ini {

namespace lib {

private:

	wstring_convert < codecvt_utf8<wchar_t>> convertor; // INI parser works with UTF-8

	bool readHex(const char* hexadecimal, size_t hexLength, uint8_t* resultBuffer, size_t binLength) {

		if (hexLength != binLength * 2) return false;

		for (size_t i = 0; i < binLength; i++) {

			uint8_t value = 0;

			char a = hexadecimal[i * 2];

			char b = hexadecimal[i * 2 + 1];

			if (a >= '0' && a <= '9') value += (a - '0')*16;

			else if (a >= 'a' && a <= 'f') value += (a - 'a' + 10)*16;

			else if (a >= 'A' && a <= 'F') value += (a - 'A' + 10)*16;

			else return false;

			if (b >= '0' && b <= '9') value += b - '0';

			else if (b >= 'a' && b <= 'f') value += b - 'a' + 10;

			else if (b >= 'A' && b <= 'F') value += b - 'A' + 10;

			else return false;

			if (resultBuffer) resultBuffer[i] = value;

		}

		return true;

	}

		std::stringstream result;

		for (int i = 0, length = s.size(); i < length; i++) {

			char ch = s[i];

			if (i + 1 < length && ch == ESC) {

				ch = s[i + 1];

				if (ch == 'u') {

					// TODO: simplify, clean-up, verify (but seems working)

					i++;

					int hexLength = 4;

					if (i + hexLength < length) {

						uint16_t u16;

						bool hexOK = readHex(s.c_str() + i + 1, hexLength, (uint8_t*) & u16, sizeof (u16));

						if (hexOK) result << convertor.to_bytes(ntohs(u16));

						else throw std::logic_error(std::string("Invalid unicode escape sequence: invalid HEX"));

						i += hexLength;

					} else {

						throw std::logic_error(std::string("Invalid unicode escape sequence: missing characters"));

					}

				else result.put(ESC); // keep the escape sequence for later unescaping phase

			} else if (ch == ESC) {

				throw std::logic_error(std::string("Missing escape sequence")); // this should not happen

			} else {

				result.put(ch);

			}

		}

		return result.str();

	}

};

}

}

}

}