/**
 * 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());
		}
	}
};

}
}
}