//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2020 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    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 Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.

#ifndef OPENVPN_HTTP_URLENCODE_H
#define OPENVPN_HTTP_URLENCODE_H

#include <string>
#include <vector>

#include <openvpn/common/exception.hpp>
#include <openvpn/common/split.hpp>
#include <openvpn/common/string.hpp>
#include <openvpn/common/hexstr.hpp>
#include <openvpn/common/unicode.hpp>
#include <openvpn/http/parseutil.hpp>

namespace openvpn {
  namespace URL {
    OPENVPN_EXCEPTION(url_error);

    inline std::string encode(const std::string& str)
    {
      std::string ret;
      ret.reserve(str.length() * 2); // just a guess
      for (auto &c : str)
	{
	  if (HTTP::Util::is_escaped(c))
	    {
	      ret += '%';
	      ret += render_hex_number((unsigned char)c, true);
	    }
	  else
	    ret += c;
	}
      return ret;
    }

    inline std::string decode(const std::string& encoded)
    {
      enum State {
	TEXT,
	PERCENT,
	DIGIT
      };

      int value = 0;
      State state = TEXT;
      std::string ret;
      ret.reserve(encoded.size()); // just a guess

      for (auto &c : encoded)
	{
	  switch (state)
	    {
	    case TEXT:
	      {
		if (c == '%')
		  state = PERCENT;
		else
		  ret += c;
		break;
	      }
	    case PERCENT:
	      {
		const int v = parse_hex_char(c);
		if (v < 0)
		  throw url_error(std::string("decode error after %: ") + encoded);
		value = v;
		state = DIGIT;
		break;
	      }
	    case DIGIT:
	      {
		const int v = parse_hex_char(c);
		if (v < 0)
		  throw url_error(std::string("decode error after %: ") + encoded);
		ret += static_cast<unsigned char>((value * 16) + v);
		state = TEXT;
	      }
	    }
	}
      if (state != TEXT)
	throw url_error(std::string("decode error: %-encoding item not closed out: ") + encoded);
      if (!Unicode::is_valid_utf8(ret))
	throw url_error(std::string("not UTF-8: ") + encoded);
      return ret;
    }

    inline std::vector<std::string> decode_path(std::string path)
    {
      std::vector<std::string> list;
      if (!path.empty() && path[0] == '/')
	path = path.substr(1);
      Split::by_char_void<decltype(list), NullLex, Split::NullLimit>(list, path, '/');
      for (auto &i : list)
	i = decode(i);
      return list;
    }
  }
}

#endif