/**
 * Copyright 2013-2021 Software Radio Systems Limited
 *
 * This file is part of srsRAN.
 *
 * srsRAN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsRAN 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 Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

/**
 * @brief Dummy X2AP implementation
 *
 * Dummy X2 adapter to facilitate communication between EUTRA RRC and NR RRC
 * for EN-DC procedures.
 *
 * The class uses direct function calls instead of real X2AP ASN1 encoded
 * messages. It mainly focuses on Sec 9.1.4 of TS 36.423 Rel. 15.11
 * for E-UTRAN-NR Dual Connectivity Procedures, i.e. SgNB-*
 *
 * It furthermore provide an interface for the GTPU adapter to
 * write DL PDUs, which it then forwards to the NR PDCP.
 *
 * It also provides a method to allow the eNB to foward timing
 * signal, i.e. TTI tics, to the NR stack.
 */

#ifndef SRSENB_X2_ADAPTER_H
#define SRSENB_X2_ADAPTER_H

#include "srsgnb/hdr/stack/gnb_stack_nr.h"
#include "srsran/interfaces/enb_x2_interfaces.h"
#include "stack/enb_stack_lte.h"

namespace srsenb {

class x2_adapter final : public x2_interface
{
public:
  x2_adapter(enb_stack_lte* eutra_stack_, gnb_stack_nr* nr_stack_) :
    nr_stack(nr_stack_), eutra_stack(eutra_stack_), logger(srslog::fetch_basic_logger("X2"))
  {}

  /// rrc_nr_interface_rrc
  void sgnb_addition_request(uint16_t eutra_rnti, const sgnb_addition_req_params_t& params) override
  {
    if (nr_stack == nullptr) {
      logger.error("SgNB Addition Requested for inexistent NR stack");
      return;
    }
    nr_stack->sgnb_addition_request(eutra_rnti, params);
  }
  void sgnb_reconfiguration_complete(uint16_t eutra_rnti, const asn1::dyn_octstring& reconfig_response) override
  {
    if (nr_stack == nullptr) {
      logger.error("SgNB Addition Requested for inexistent NR stack");
      return;
    }
    nr_stack->sgnb_reconfiguration_complete(eutra_rnti, reconfig_response);
  }

  /// rrc_eutra_interface_rrc_nr
  void sgnb_addition_ack(uint16_t eutra_rnti, sgnb_addition_ack_params_t params) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->sgnb_addition_ack(eutra_rnti, params);
  }
  void sgnb_addition_reject(uint16_t eutra_rnti) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->sgnb_addition_reject(eutra_rnti);
  }
  void sgnb_addition_complete(uint16_t eutra_rnti, uint16_t nr_rnti) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->sgnb_addition_complete(eutra_rnti, nr_rnti);
  }
  void sgnb_inactivity_timeout(uint16_t eutra_rnti) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->sgnb_inactivity_timeout(eutra_rnti);
  }

  void sgnb_release_ack(uint16_t eutra_rnti) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->sgnb_release_ack(eutra_rnti);
  }

  void set_activity_user(uint16_t eutra_rnti) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->set_activity_user(eutra_rnti);
  }

  void sgnb_release_request(uint16_t nr_rnti) override
  {
    if (nr_stack == nullptr) {
      logger.error("SgNB Addition Requested for inexistent NR stack");
      return;
    }
    nr_stack->sgnb_release_request(nr_rnti);
  }

  // pdcp_interface_gtpu
  void write_sdu(uint16_t rnti, uint32_t lcid, srsran::unique_byte_buffer_t sdu, int pdcp_sn = -1) override
  {
    if (nr_stack == nullptr) {
      return;
    }
    nr_stack->write_sdu(rnti, lcid, std::move(sdu), pdcp_sn);
  }
  std::map<uint32_t, srsran::unique_byte_buffer_t> get_buffered_pdus(uint16_t rnti, uint32_t lcid) override
  {
    if (nr_stack == nullptr) {
      return {};
    }
    return nr_stack->get_buffered_pdus(rnti, lcid);
  }

  // gtpu_interface_pdcp
  void write_pdu(uint16_t rnti, uint32_t bearer_id, srsran::unique_byte_buffer_t pdu) override
  {
    if (eutra_stack == nullptr) {
      return;
    }
    eutra_stack->write_pdu(rnti, bearer_id, std::move(pdu));
  }

private:
  enb_stack_lte*        eutra_stack = nullptr;
  gnb_stack_nr*         nr_stack    = nullptr;
  srslog::basic_logger& logger;
};

} // namespace srsenb

#endif // SRSENB_X2_ADAPTER_H