#pragma once

#include <string>

#include "envoy/buffer/buffer.h"

#include "source/extensions/filters/network/thrift_proxy/app_exception_impl.h"

#include "source/extensions/filters/network/thrift_proxy/metadata.h"

#include "source/extensions/filters/network/thrift_proxy/thrift.h"

#include "source/extensions/filters/network/thrift_proxy/transport.h"

#include "absl/types/optional.h"

namespace Envoy {

namespace Extensions {

namespace NetworkFilters {

namespace ThriftProxy {

/**

 * HeaderTransportImpl implements the Thrift Header transport.

 * See https://github.com/apache/thrift/blob/master/doc/specs/HeaderFormat.md and

 * https://github.com/apache/thrift/blob/master/lib/cpp/src/thrift/transport/THeaderTransport.h

 * (for constants not specified in the spec).

 */

class HeaderTransportImpl : public Transport {

public:

  // Transport

  const std::string& name() const override { return TransportNames::get().HEADER; }

  TransportType type() const override { return TransportType::Header; }

  bool decodeFrameStart(Buffer::Instance& buffer, MessageMetadata& metadata) override;

  bool decodeFrameEnd(Buffer::Instance& buffer) override;

  void encodeFrame(Buffer::Instance& buffer, const MessageMetadata& metadata,

                   Buffer::Instance& message) override;

  static bool isMagic(uint16_t word) { return word == Magic; }

  static constexpr int32_t MaxFrameSize = 0x3FFFFFFF;

private:

  static constexpr uint16_t Magic = 0x0FFF;

  static int16_t drainVarIntI16(Buffer::Instance& buffer, int32_t& header_size, const char* desc);

  static int32_t drainVarIntI32(Buffer::Instance& buffer, int32_t& header_size, const char* desc);

  static std::string drainVarString(Buffer::Instance& buffer, int32_t& header_size,

                                    const char* desc);

  static void writeVarString(Buffer::Instance& buffer, const absl::string_view str);

  absl::optional<AppExceptionType> exception_;

  std::string exception_reason_;

};

} // namespace ThriftProxy

} // namespace NetworkFilters

} // namespace Extensions

} // namespace Envoy