/*
 * Copyright 2013-2020 Software Radio Systems Limited
 *
 * This file is part of srsLTE.
 *
 * srsLTE 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.
 *
 * srsLTE 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/.
 *
 */

#include "srslte/common/log.h"
#include "srsue/hdr/stack/rrc/rrc.h"
#include <map>
#include <string>

#ifndef SRSLTE_RRC_PROCEDURES_H
#define SRSLTE_RRC_PROCEDURES_H

namespace srsue {

/********************************
 *           Events
 *******************************/

// background workers use this event to signal the result of a cell select phy procedure
struct cell_select_event_t {
  cell_select_event_t(bool c_) : cs_ret(c_) {}
  bool cs_ret;
};

/********************************
 *         Procedures
 *******************************/

class rrc::cell_search_proc
{
public:
  struct cell_search_event_t {
    phy_interface_rrc_lte::cell_search_ret_t cs_ret;
    phy_interface_rrc_lte::phy_cell_t        found_cell;
  };
  enum class state_t { phy_cell_search, si_acquire, wait_measurement, phy_cell_select };

  explicit cell_search_proc(rrc* parent_);
  srslte::proc_outcome_t init();
  srslte::proc_outcome_t step();
  srslte::proc_outcome_t step_si_acquire();
  srslte::proc_outcome_t react(const cell_search_event_t& event);
  srslte::proc_outcome_t react(const cell_select_event_t& event);
  srslte::proc_outcome_t step_wait_measurement();

  phy_interface_rrc_lte::cell_search_ret_t get_result() const { return search_result.cs_ret; }
  static const char*                       name() { return "Cell Search"; }

private:
  srslte::proc_outcome_t handle_cell_found(const phy_interface_rrc_lte::phy_cell_t& new_cell);

  // conts
  rrc* rrc_ptr;

  // state vars
  cell_search_event_t         search_result;
  srslte::proc_future_t<void> si_acquire_fut;
  state_t                     state;
};

/****************************************************************
 * TS 36.331 Sec 5.2.3 - Acquisition of an SI message procedure
 ***************************************************************/
class rrc::si_acquire_proc
{
public:
  const static int SIB_SEARCH_TIMEOUT_MS = 1000;
  struct si_acq_timer_expired {
    uint32_t timer_id;
  };
  struct sib_received_ev {
  };

  explicit si_acquire_proc(rrc* parent_);
  srslte::proc_outcome_t init(uint32_t sib_index_);
  srslte::proc_outcome_t step() { return srslte::proc_outcome_t::yield; }
  static const char*     name() { return "SI Acquire"; }
  srslte::proc_outcome_t react(si_acq_timer_expired ev);
  srslte::proc_outcome_t react(sib_received_ev ev);
  void                   then(const srslte::proc_state_t& result);

private:
  void start_si_acquire();

  // conts
  rrc*            rrc_ptr;
  srslte::log_ref log_h;

  // state
  srslte::timer_handler::unique_timer si_acq_timeout, si_acq_retry_timer;
  uint32_t                            period = 0, sched_index = 0;
  uint32_t                            sib_index = 0;
};

class rrc::serving_cell_config_proc
{
public:
  explicit serving_cell_config_proc(rrc* parent_);
  srslte::proc_outcome_t init(const std::vector<uint32_t>& required_sibs_);
  srslte::proc_outcome_t step();
  static const char*     name() { return "Serving Cell Configuration"; }

private:
  rrc*            rrc_ptr;
  srslte::log_ref log_h;

  srslte::proc_outcome_t launch_sib_acquire();

  // proc args
  std::vector<uint32_t> required_sibs;

  // state variables
  uint32_t                    req_idx = 0;
  srslte::proc_future_t<void> si_acquire_fut;
};

class rrc::cell_selection_proc
{
public:
  using cell_selection_complete_ev = srslte::proc_result_t<cs_result_t>;

  explicit cell_selection_proc(rrc* parent_);
  srslte::proc_outcome_t init();
  srslte::proc_outcome_t step();
  void                   then(const srslte::proc_result_t<cs_result_t>& proc_result) const;
  cs_result_t            get_result() const { return cs_result; }
  static const char*     name() { return "Cell Selection"; }
  srslte::proc_outcome_t react(const cell_select_event_t& event);

private:
  srslte::proc_outcome_t start_cell_selection();
  srslte::proc_outcome_t step_cell_selection(const cell_select_event_t& event);
  srslte::proc_outcome_t step_serv_cell_camp(const cell_select_event_t& event);
  srslte::proc_outcome_t step_wait_in_sync();
  srslte::proc_outcome_t step_cell_search();
  srslte::proc_outcome_t step_cell_config();

  // consts
  rrc* rrc_ptr;

  // state variables
  enum class search_state_t { cell_selection, serv_cell_camp, wait_in_sync, cell_config, cell_search };
  cs_result_t                                                     cs_result;
  search_state_t                                                  state;
  uint32_t                                                        neigh_index;
  srslte::proc_future_t<phy_interface_rrc_lte::cell_search_ret_t> cell_search_fut;
  srslte::proc_future_t<void>                                     serv_cell_cfg_fut;
  bool                                                            discard_serving = false;
};

class rrc::plmn_search_proc
{
public:
  explicit plmn_search_proc(rrc* parent_);
  srslte::proc_outcome_t init();
  srslte::proc_outcome_t step();
  void                   then(const srslte::proc_state_t& result) const;
  static const char*     name() { return "PLMN Search"; }

private:
  // consts
  rrc*            rrc_ptr;
  srslte::log_ref log_h;

  // state variables
  found_plmn_t                                                    found_plmns[MAX_FOUND_PLMNS];
  int                                                             nof_plmns = 0;
  srslte::proc_future_t<phy_interface_rrc_lte::cell_search_ret_t> cell_search_fut;
};

class rrc::connection_request_proc
{
public:
  explicit connection_request_proc(rrc* parent_);
  srslte::proc_outcome_t init(srslte::establishment_cause_t cause_, srslte::unique_byte_buffer_t dedicated_info_nas_);
  srslte::proc_outcome_t step();
  void                   then(const srslte::proc_state_t& result);
  srslte::proc_outcome_t react(const cell_selection_proc::cell_selection_complete_ev& e);
  static const char*     name() { return "Connection Request"; }

private:
  // const
  rrc*            rrc_ptr;
  srslte::log_ref log_h;
  // args
  srslte::establishment_cause_t cause;
  srslte::unique_byte_buffer_t  dedicated_info_nas;

  // state variables
  enum class state_t { cell_selection, config_serving_cell, wait_t300 } state;
  cs_result_t                 cs_ret;
  srslte::proc_future_t<void> serv_cfg_fut;
};

class rrc::process_pcch_proc
{
public:
  struct paging_complete {
    bool outcome;
  };

  explicit process_pcch_proc(rrc* parent_);
  srslte::proc_outcome_t init(const asn1::rrc::paging_s& paging_);
  srslte::proc_outcome_t step();
  srslte::proc_outcome_t react(paging_complete e);
  static const char*     name() { return "Process PCCH"; }

private:
  // args
  rrc*                rrc_ptr;
  srslte::log_ref     log_h;
  asn1::rrc::paging_s paging;

  // vars
  uint32_t paging_idx = 0;
  enum class state_t { next_record, nas_paging, serv_cell_cfg } state;
  srslte::proc_future_t<void> serv_cfg_fut;
};

class rrc::go_idle_proc
{
public:
  explicit go_idle_proc(rrc* rrc_);
  srslte::proc_outcome_t init();
  srslte::proc_outcome_t step();
  srslte::proc_outcome_t react(bool timeout);
  static const char*     name() { return "Go Idle"; }

private:
  static const uint32_t rlc_flush_timeout = 2000;

  rrc*                                rrc_ptr;
  srslte::timer_handler::unique_timer rlc_flush_timer;
};

class rrc::cell_reselection_proc
{
public:
  cell_reselection_proc(rrc* rrc_);
  srslte::proc_outcome_t init();
  srslte::proc_outcome_t step();
  static const char*     name() { return "Cell Reselection"; }

private:
  rrc* rrc_ptr;

  srslte::proc_future_t<cs_result_t> cell_selection_fut;
};

class rrc::connection_reest_proc
{
public:
  explicit connection_reest_proc(rrc* rrc_);
  srslte::proc_outcome_t init(asn1::rrc::reest_cause_e cause);
  srslte::proc_outcome_t step();
  static const char*     name() { return "Connection re-establishment"; }
  uint32_t               get_source_earfcn() const { return reest_source_freq; }

private:
  enum class state_t { cell_reselection, cell_configuration } state;

  rrc*                     rrc_ptr           = nullptr;
  asn1::rrc::reest_cause_e reest_cause       = asn1::rrc::reest_cause_e::nulltype;
  uint16_t                 reest_rnti        = 0;
  uint16_t                 reest_source_pci  = 0;
  uint32_t                 reest_source_freq = 0;

  srslte::proc_outcome_t step_cell_reselection();
  srslte::proc_outcome_t step_cell_configuration();
  srslte::proc_outcome_t cell_criteria();
};

} // namespace srsue

#endif // SRSLTE_RRC_PROCEDURES_H