#pragma once

#include <memory>

#include "envoy/buffer/buffer.h"

#include "zlib.h"

namespace Envoy {

namespace Extensions {

namespace Compression {

namespace Gzip {

namespace Common {

/**

 * Shared code between the compressor and the decompressor.

 */

class Base {

public:

  Base(uint64_t chunk_size, std::function<void(z_stream*)> zstream_deleter);

  /**

   * It returns the checksum of all output produced so far. Compressor's checksum at the end of

   * the stream has to match decompressor's checksum produced at the end of the decompression.

   * Likewise, the decompressor's checksum has to match the compressor's checksum at the end of

   * compression.

   * @return uint64_t CRC-32 if a gzip stream is being read or Adler-32 for other compression

   * types.

   */

  uint64_t checksum();

protected:

  void updateOutput(Buffer::Instance& output_buffer);

  const uint64_t chunk_size_;

  bool initialized_{false};

  const std::unique_ptr<unsigned char[]> chunk_char_ptr_;

  const std::unique_ptr<z_stream, std::function<void(z_stream*)>> zstream_ptr_;

};

} // namespace Common

} // namespace Gzip

} // namespace Compression

} // namespace Extensions

} // namespace Envoy