/**

 * Relational pipes

 * Copyright © 2022 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 <iomanip>

#include <iostream>

#include <sstream>

#include <vector>

#include <stdexcept>

namespace relpipe {

namespace tr {

namespace http {

class Hex {

private:

	Hex() {

	}

	static char fromHex(wchar_t ch) {

		if (L'0' <= ch && ch <= L'9') return ch - L'0';

		else if (L'a' <= ch && ch <= L'f') return ch - L'a' + 10;

		else throw std::invalid_argument("Unable to decode hexadeximal string.");

	}

public:

	static std::stringstream fromHex(const std::wstring& hex) {

		std::stringstream octets;

		char octet = 0;

		for (size_t i = 0, limit = hex.size(); i < limit; i++) {

			if (i % 2 == 0) {

				octet = fromHex(hex[i]) << 4;

			} else {

				octet += fromHex(hex[i]);

				octets.put(octet);

			}

		}

		return octets;

	}

	static std::wstring toHex(const std::string& octets) {

		std::wstring_convert < codecvt_utf8<wchar_t>> convertor; // TODO: do not create converter each time

		std::stringstream hex;

		hex << std::hex << std::setfill('0') << std::hex;

		for (size_t i = 0, size = octets.size(); i < size; i++) hex << std::setw(2) << (0xff & octets[i]);

		return convertor.from_bytes(hex.str());

	}

	static std::wstring toTxt(const std::string& octets, bool* validEncoding = nullptr) {

		std::wstring_convert < codecvt_utf8<wchar_t>> convertor; // TODO: do not create converter each time

		try {

			if (validEncoding) *validEncoding = true;

			// TODO: use encoding from the HTTP response headers instead of the constant one?

			return convertor.from_bytes(octets);

		} catch (...) {

			if (validEncoding) *validEncoding = false;

			std::stringstream filtered;

			for (char ch : octets) filtered << (ch >= ' ' && ch < 127 ? ch : '.');

			return convertor.from_bytes(filtered.str());

		}

	}

};

}

}

}