#pragma once

#include <cstdint>

#include <string>

#include "envoy/buffer/buffer.h"

#include "source/common/protobuf/protobuf.h"

namespace Envoy {

namespace Buffer {

class ZeroCopyInputStreamImpl : public virtual Protobuf::io::ZeroCopyInputStream {

public:

  // Create input stream with one buffer, and finish immediately

  ZeroCopyInputStreamImpl(Buffer::InstancePtr&& buffer);

  // Create input stream with empty buffer

  ZeroCopyInputStreamImpl();

  // Add a buffer to input stream, will consume all buffer from parameter

  // if the stream is not finished

  void move(Buffer::Instance& instance);

  // Mark the stream is finished

  // Protobuf::io::ZeroCopyInputStream

  // See

  // https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.io.zero_copy_stream#ZeroCopyInputStream

  // for each method details.

  // Note Next() will return true with no data until more data is available if the stream is not

  // finished. It is the caller's responsibility to finish the stream or wrap with

  // LimitingInputStream before passing to protobuf code to avoid a spin loop.

  bool Next(const void** data, int* size) override;

  void BackUp(int count) override;

  bool Skip(int count) override;

protected:

  // The last slice is kept to support limited BackUp() calls.

  // This function will drain it.

  void drainLastSlice();

  Buffer::InstancePtr buffer_;

  uint64_t position_{0};

  bool finished_{false};

private:

  uint64_t byte_count_{0};

};

} // namespace Buffer

} // namespace Envoy