Merge "L2CAP ERTM initial commit"

  using UpperQueueDownEnd = common::BidiQueueEnd<UpperEnqueue, UpperDequeue>;

  ErtmController(Cid cid, Cid remote_cid, UpperQueueDownEnd* channel_queue_end, os::Handler* handler,

                 Scheduler* scheduler);

  ~ErtmController();

  // Segmentation is handled here

  void OnSdu(std::unique_ptr<packet::BasePacketBuilder> sdu) override;

  void OnPdu(BasicFrameView pdu) override;

  std::unique_ptr<BasicFrameBuilder> GetNextPacket() override;

 private:

  [[maybe_unused]] Cid cid_;

  [[maybe_unused]] Cid remote_cid_;

  [[maybe_unused]] os::EnqueueBuffer<UpperEnqueue> enqueue_buffer_;

  [[maybe_unused]] os::Handler* handler_;

  std::queue<std::unique_ptr<BasicFrameBuilder>> pdu_queue_;

  [[maybe_unused]] Scheduler* scheduler_;

  // TODO: Support FCS

  [[maybe_unused]] FcsType fcs_type_ = FcsType::NO_FCS;

  class PacketViewForReassembly : public packet::PacketView<kLittleEndian> {

   public:

    PacketViewForReassembly(const PacketView& packetView) : PacketView(packetView) {}

    PacketViewForReassembly(nullptr_t) : PacketView(nullptr) {}

    void AppendPacketView(packet::PacketView<kLittleEndian> to_append) {

      Append(to_append);

    }

  };

  class CopyablePacketBuilder : public packet::BasePacketBuilder {

   public:

    CopyablePacketBuilder(std::unique_ptr<packet::BasePacketBuilder> builder) : builder_(builder.release()) {}

    void Serialize(BitInserter& it) const override;

    size_t size() const override;

    std::unique_ptr<packet::BasePacketBuilder> Create();

   private:

    std::shared_ptr<packet::BasePacketBuilder> builder_;

  };

  PacketViewForReassembly reassembly_stage_{nullptr};

  SegmentationAndReassembly sar_state_ = SegmentationAndReassembly::END;

  void stage_for_reassembly(SegmentationAndReassembly sar, const packet::PacketView<kLittleEndian>& payload);

  void send_pdu(std::unique_ptr<BasicFrameBuilder> pdu);

  void close_channel();

  // Configuration options

  // TODO: Configure these number

  [[maybe_unused]] uint16_t local_tx_window_ = 10;

  [[maybe_unused]] uint16_t local_max_transmit_ = 20;

  [[maybe_unused]] uint16_t local_retransmit_timeout_ms_ = 2000;

  [[maybe_unused]] uint16_t local_monitor_timeout_ms_ = 12000;

  [[maybe_unused]] uint16_t local_mps_ = 1010;

  [[maybe_unused]] uint16_t remote_tx_window_ = 10;

  [[maybe_unused]] uint16_t remote_max_transmit_ = 20;

  [[maybe_unused]] uint16_t remote_retransmit_timeout_ms_ = 2000;

  [[maybe_unused]] uint16_t remote_monitor_timeout_ms_ = 12000;

  [[maybe_unused]] uint16_t remote_mps_ = 1010;

  struct impl;

  std::unique_ptr<impl> pimpl_;

};

}  // namespace internal