//    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/>.

// Environmental variables

#ifndef OPENVPN_COMMON_ENVIRON_H
#define OPENVPN_COMMON_ENVIRON_H

#include <string>
#include <cstring>
#include <vector>
#include <utility>

#include <openvpn/common/size.hpp>

extern char **environ;

namespace openvpn {

  class Environ : public std::vector<std::string>
  {
  public:
    static std::string find_static(const std::string& name)
    {
      for (char **e = ::environ; *e != NULL; ++e)
	{
	  const char *eq = ::strchr(*e, '=');
	  if (eq && eq > *e)
	    {
	      const size_t namelen = eq - *e;
	      if (name.length() == namelen && ::strncmp(name.c_str(), *e, namelen) == 0)
		return std::string(eq+1);
	    }
	}
      return "";
    }

    void load_from_environ()
    {
      reserve(64);
      for (char **e = ::environ; *e != NULL; ++e)
	emplace_back(*e);
    }

    std::string to_string() const
    {
      std::string ret;
      ret.reserve(512);
      for (const auto &s : *this)
	{
	  ret += s;
	  ret += '\n';
	}
      return ret;
    }

    int find_index(const std::string& name) const
    {
      for (size_type i = 0; i < size(); ++i)
	{
	  const std::string& s = (*this)[i];
	  const size_t pos = s.find_first_of('=');
	  if (pos != std::string::npos)
	    {
	      if (name == s.substr(0, pos))
		return i;
	    }
	  else
	    {
	      if (name == s)
		return i;
	    }
	}
      return -1;
    }

    std::string find(const std::string& name) const
    {
      const int i = find_index(name);
      if (i >= 0)
	return value(i);
      else
	return "";
    }

    std::string value(const size_t idx) const
    {
      const std::string& s = (*this)[idx];
      const size_t pos = s.find_first_of('=');
      if (pos != std::string::npos)
	return s.substr(pos+1);
      else
	return "";
    }

    void assign(const std::string& name, const std::string& value)
    {
      std::string nv = name + '=' + value;
      const int i = find_index(name);
      if (i >= 0)
	(*this)[i] = std::move(nv);
      else
	push_back(std::move(nv));
    }
  };

}
#endif