/*
 * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The OpenAirInterface Software Alliance licenses this file to You under
 * the OAI Public License, Version 1.0  (the "License"); you may not use this file
 * except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.openairinterface.org/?page_id=698
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *-------------------------------------------------------------------------------
 * For more information about the OpenAirInterface (OAI) Software Alliance:
 *      contact@openairinterface.org
 */

/*****************************************************************************
Source      EmmDeregisteredNoCellAvailable.c

Version     0.1

Date        2012/10/03

Product     NAS stack

Subsystem   EPS Mobility Management

Author      Frederic Maurel

Description Implements the EPS Mobility Management procedures executed
        when the EMM-SAP is in EMM-DEREGISTERED.NO-CELL-AVAILABLE
        state.

        In EMM-DEREGISTERED.NO-CELL-AVAILABLE state, no E-UTRAN cell
        can be selected. A first intensive search failed when in
        substate EMM_DEREGISTERED.PLMN-SEARCH. Cells are searched for
        at a low rhythm. No EPS services are offered.

*****************************************************************************/


#include "emm_fsm.h"
#include "commonDef.h"
#include "networkDef.h"
#include "nas_log.h"

#include "emm_proc.h"

#include <assert.h>

/****************************************************************************/
/****************  E X T E R N A L    D E F I N I T I O N S  ****************/
/****************************************************************************/

/****************************************************************************/
/*******************  L O C A L    D E F I N I T I O N S  *******************/
/****************************************************************************/

/****************************************************************************/
/******************  E X P O R T E D    F U N C T I O N S  ******************/
/****************************************************************************/

/****************************************************************************
 **                                                                        **
 ** Name:    EmmDeregisteredNoCellAvailable()                          **
 **                                                                        **
 ** Description: Handles the behaviour of the UE while the EMM-SAP is in   **
 **      EMM-DEREGISTERED.NO-CELL-AVAILABLE state.                 **
 **                                                                        **
 **              3GPP TS 24.301, section 5.2.2.3.7                         **
 **      The UE shall perform cell selection and choose an appro-  **
 **      priate substate when a cell is found.                     **
 **                                                                        **
 ** Inputs:  evt:       The received EMM-SAP event                 **
 **      Others:    emm_fsm_status                             **
 **                                                                        **
 ** Outputs:     None                                                      **
 **      Return:    RETURNok, RETURNerror                      **
 **      Others:    emm_fsm_status                             **
 **                                                                        **
 ***************************************************************************/
int EmmDeregisteredNoCellAvailable(nas_user_t *user, const emm_reg_t *evt)
{
  LOG_FUNC_IN;

  int rc = RETURNerror;
  emm_data_t *emm_data = user->emm_data;
  user_api_id_t *user_api_id = user->user_api_id;

  assert(emm_fsm_get_status(user) == EMM_DEREGISTERED_NO_CELL_AVAILABLE);

  switch (evt->primitive) {
    /* TODO: network re-selection is not allowed when in No Cell
     * Available substate. The AS should search for a suitable cell
     * and notify the NAS when such a cell is found (TS 24.008 section
     * 4.2.4.1.2) */
  case _EMMREG_REGISTER_REQ:
    /*
     * The user manually re-selected a PLMN to register to
     */
    rc = emm_fsm_set_status(user, EMM_DEREGISTERED_PLMN_SEARCH);

    if (rc != RETURNerror) {
      /*
       * Notify EMM that the MT is currently searching an operator
       * to register to
       */
      rc = emm_proc_registration_notify(user_api_id, emm_data, NET_REG_STATE_ON);

      if (rc != RETURNok) {
        LOG_TRACE(WARNING, "EMM-FSM   - "
                  "Failed to notify registration update");
      }

      /*
       * Perform network re-selection procedure
       */
      rc = emm_proc_plmn_selection(user, evt->u.regist.index);
    }

    break;

  default:
    LOG_TRACE(ERROR, "EMM-FSM   - Primitive is not valid (%d)",
              evt->primitive);
    break;
  }

  LOG_FUNC_RETURN (rc);
}

/****************************************************************************/
/*********************  L O C A L    F U N C T I O N S  *********************/
/****************************************************************************/

