/*
 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2.0,
 * as published by the Free Software Foundation.
 *
 * This program is also distributed with certain software (including
 * but not limited to OpenSSL) that is licensed under separate terms,
 * as designated in a particular file or component or in included license
 * documentation.  The authors of MySQL hereby grant you an additional
 * permission to link the program and your derivative works with the
 * separately licensed software that they have included with MySQL.
 *
 * 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, version 2.0, for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
 */

// MySQL DB access module, for use by plugins and others
// For the module that implements interactive DB functionality see mod_db

#ifndef PLUGIN_X_CLIENT_MYSQLXCLIENT_XCOMPRESSION_H_
#define PLUGIN_X_CLIENT_MYSQLXCLIENT_XCOMPRESSION_H_

#include <google/protobuf/io/coded_stream.h>
#include <memory>
#include <set>

namespace xcl {

/**
  Defines if negotiation algorithm for compression should be used, and its
  tolerance level.
*/
enum class Compression_negotiation { k_disabled, k_preferred, k_required };

/**
  Enum that defines the compression algorithm that is used by
  X Protocol in 'uplink' and 'downlink'.
*/
enum class Compression_algorithm { k_none, k_deflate, k_lz4 };

/**
  Interface defining X Compression operations.

  This interface should be used internally by XProtocol and XConnection
  implementations, still it was extracted to give user a possibility
  to compress raw data and serialize them inside COMPRESSION_SINGLE
  and other messages.
*/
class XCompression {
 public:
  using Output_stream = google::protobuf::io::ZeroCopyOutputStream;
  using Input_stream = google::protobuf::io::ZeroCopyInputStream;

  using Output_stream_ptr = std::shared_ptr<Output_stream>;
  using Input_stream_ptr = std::shared_ptr<Input_stream>;

 public:
  virtual ~XCompression() = default;

  /**
    Downlink compression stream

    This method returns a stream that can be used with compression done
    on X message level. Other compression styles may operate on lower
    layers without possibility for user interaction.
  */
  virtual Input_stream_ptr downlink(Input_stream *data_stream) = 0;

  /**
    Uplink compression stream

    This method returns a stream that can be used with compression done
    on X message level. Other compression styles may operate on lower
    layers without possibility for user interaction.
  */
  virtual Output_stream_ptr uplink(Output_stream *data_stream) = 0;
};

}  // namespace xcl

#endif  // PLUGIN_X_CLIENT_MYSQLXCLIENT_XCOMPRESSION_H_