/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2020 Software Radio Systems Limited
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the distribution.
 *
 */

#include <map>
#include <string.h>

#include "common_enb.h"
#include "srslte/common/buffer_pool.h"
#include "srslte/common/logmap.h"
#include "srslte/common/threads.h"
#include "srslte/interfaces/enb_interfaces.h"
#include "srslte/srslte.h"

#ifndef SRSENB_GTPU_H
#define SRSENB_GTPU_H

namespace srsenb {

class gtpu final : public gtpu_interface_rrc, public gtpu_interface_pdcp
{
public:
  gtpu();

  int  init(std::string               gtp_bind_addr_,
            std::string               mme_addr_,
            std::string               m1u_multiaddr_,
            std::string               m1u_if_addr_,
            pdcp_interface_gtpu*      pdcp_,
            stack_interface_gtpu_lte* stack_,
            bool                      enable_mbsfn = false);
  void stop();

  // gtpu_interface_rrc
  uint32_t add_bearer(uint16_t rnti, uint32_t lcid, uint32_t addr, uint32_t teid_out) override;
  void     rem_bearer(uint16_t rnti, uint32_t lcid) override;
  void     mod_bearer_rnti(uint16_t old_rnti, uint16_t new_rnti) override;
  void     rem_user(uint16_t rnti) override;

  // gtpu_interface_pdcp
  void write_pdu(uint16_t rnti, uint32_t lcid, srslte::unique_byte_buffer_t pdu) override;

  // stack interface
  void handle_gtpu_s1u_rx_packet(srslte::unique_byte_buffer_t pdu, const sockaddr_in& addr);
  void handle_gtpu_m1u_rx_packet(srslte::unique_byte_buffer_t pdu, const sockaddr_in& addr);

private:
  static const int GTPU_PORT = 2152;

  srslte::byte_buffer_pool* pool  = nullptr;
  stack_interface_gtpu_lte* stack = nullptr;

  bool                         enable_mbsfn = false;
  std::string                  gtp_bind_addr;
  std::string                  mme_addr;
  srsenb::pdcp_interface_gtpu* pdcp = nullptr;
  srslte::log_ref              gtpu_log;

  // Class to create
  class m1u_handler
  {
  public:
    explicit m1u_handler(gtpu* gtpu_) : parent(gtpu_) {}
    ~m1u_handler();
    m1u_handler(const m1u_handler&) = delete;
    m1u_handler(m1u_handler&&)      = delete;
    m1u_handler& operator=(const m1u_handler&) = delete;
    m1u_handler& operator=(m1u_handler&&) = delete;
    bool         init(std::string m1u_multiaddr_, std::string m1u_if_addr_);
    void         handle_rx_packet(srslte::unique_byte_buffer_t pdu, const sockaddr_in& addr);

  private:
    gtpu*                parent = nullptr;
    pdcp_interface_gtpu* pdcp   = nullptr;
    srslte::log_ref      gtpu_log;
    std::string          m1u_multiaddr;
    std::string          m1u_if_addr;

    bool initiated    = false;
    int  m1u_sd       = -1;
    int  lcid_counter = 0;
  };
  m1u_handler m1u;

  typedef struct {
    uint32_t teids_in[SRSENB_N_RADIO_BEARERS];
    uint32_t teids_out[SRSENB_N_RADIO_BEARERS];
    uint32_t spgw_addrs[SRSENB_N_RADIO_BEARERS];
  } bearer_map;
  std::map<uint16_t, bearer_map> rnti_bearers;

  typedef struct {
    uint16_t rnti;
    uint16_t lcid;
  } rnti_lcid_t;
  std::map<uint32_t, rnti_lcid_t> teidin_to_rntilcid_map;

  // Tx sequence number for signaling messages
  uint32_t tx_seq = 0;

  // Socket file descriptor
  int fd = -1;

  void echo_response(in_addr_t addr, in_port_t port, uint16_t seq);
  void error_indication(in_addr_t addr, in_port_t port, uint32_t err_teid);

  /****************************************************************************
   * TEID to RNIT/LCID helper functions
   ***************************************************************************/
  uint32_t    next_teid_in = 0;
  uint32_t    allocate_teidin(uint16_t rnti, uint16_t lcid);
  void        free_teidin(uint16_t rnti, uint16_t lcid);
  void        free_teidin(uint16_t rnti);
  rnti_lcid_t teidin_to_rntilcid(uint32_t teidin);
  uint32_t    rntilcid_to_teidin(uint16_t rnti, uint16_t lcid);
};

} // namespace srsenb

#endif // SRSENB_GTPU_H