//    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_COMMON_PIPE_H
#define OPENVPN_COMMON_PIPE_H

#include <unistd.h>
#include <errno.h>

#include <string>

#include <openvpn/io/io.hpp>

#include <openvpn/common/exception.hpp>
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/common/strerror.hpp>
#include <openvpn/buffer/buflist.hpp>

namespace openvpn {
  namespace Pipe {
    class SD
    {
    public:
      SD(openvpn_io::io_context& io_context, ScopedFD& fd)
      {
	if (fd.defined())
	  sd.reset(new openvpn_io::posix::stream_descriptor(io_context, fd.release()));
      }

      bool defined() const
      {
	return bool(sd);
      }

    protected:
      std::unique_ptr<openvpn_io::posix::stream_descriptor> sd;
    };

    class SD_OUT : public SD
    {
    public:
      SD_OUT(openvpn_io::io_context& io_context, const std::string& content, ScopedFD& fd)
	: SD(io_context, fd)
      {
	if (defined())
	  {
	    buf = buf_alloc_from_string(content);
	    queue_write();
	  }
      }

    private:
      void queue_write()
      {
	sd->async_write_some(buf.const_buffer_limit(2048),
			     [this](const openvpn_io::error_code& ec, const size_t bytes_sent) {
			       if (!ec && bytes_sent < buf.size())
				 {
				   buf.advance(bytes_sent);
				   queue_write();
				 }
			       else
				 {
				   sd->close();
				 }
			     });
      }

      BufferAllocated buf;
    };

    class SD_IN : public SD
    {
    public:
      SD_IN(openvpn_io::io_context& io_context, ScopedFD& fd)
	: SD(io_context, fd)
      {
	if (defined())
	  queue_read();
      }

      const std::string content() const
      {
	return data.to_string();
      }

    private:
      void queue_read()
      {
	buf.reset(0, 2048, 0);
	sd->async_read_some(buf.mutable_buffer_clamp(),
			    [this](const openvpn_io::error_code& ec, const size_t bytes_recvd) {
			      if (!ec)
				{
				  buf.set_size(bytes_recvd);
				  data.put_consume(buf);
				  queue_read();
				}
			      else
				{
				  sd->close();
				}
			    });
      }

      BufferAllocated buf;
      BufferList data;
    };

    inline void make_pipe(int fd[2])
    {
      if (::pipe(fd) < 0)
	{
	  const int eno = errno;
	  OPENVPN_THROW_EXCEPTION("error creating pipe : " << strerror_str(eno));
	}
    }

    inline void make_pipe(ScopedFD& read, ScopedFD& write)
    {
      int fd[2];
      make_pipe(fd);
      read.reset(fd[0]);
      write.reset(fd[1]);
    }
  }
}

#endif