text: /**
   * Copyright (c) 2017 - 2017, Nordic Semiconductor ASA
   * 
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   * 
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
   *    such product, must reproduce the above copyright notice, this list of
   *    conditions and the following disclaimer in the documentation and/or other
   *    materials provided with the distribution.
   * 
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
   *    contributors may be used to endorse or promote products derived from this
   *    software without specific prior written permission.
   * 
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
   * 
   * 5. Any software provided in binary form under this license must not be reverse
   *    engineered, decompiled, modified and/or disassembled.
   * 
   * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
   * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   * 
   */
  
  /** @brief GATT Service server example application main file.
  
      @details This file contains the main source code for a sample server application that uses the
               GATT Service. This client can be used to send Service Changed indications. This is
               needed if your application changes its GATT tables by removing or adding
               services. If we send a Service Changed indication, a typical action is for the peer
               device to rediscover the services of our GATT database.
  
               For more information about the GATT Service, see "Defined Generic Attribute Profile Service"
               in Bluetooth Specification Version 5.0 Vol 3, Part G Section 7.
  */
  
  #include <stdint.h>
  #include <stdio.h>
  #include <string.h>
  #include "nordic_common.h"
  #include "nrf_sdm.h"
  #include "ble.h"
  #include "ble_hci.h"
  #include "ble_srv_common.h"
  #include "nrf_sdh.h"
  #include "nrf_sdh_ble.h"
  #include "nrf_sdh_soc.h"
  #include "nrf_pwr_mgmt.h"
  #include "app_util.h"
  #include "app_error.h"
  #include "app_util.h"
  #include "app_timer.h"
  #include "bsp_btn_ble.h"
  #include "peer_manager.h"
  #include "fds.h"
  #include "nrf_fstorage.h"
  #include "ble_conn_state.h"
  #include "nrf_ble_gatt.h"
  
  #include "nrf_log.h"
  #include "nrf_log_ctrl.h"
  #include "nrf_log_default_backends.h"
  
  
  #define APP_BLE_CONN_CFG_TAG      1                                /**< A tag identifying the SoftDevice BLE configuration. */
  #define APP_BLE_OBSERVER_PRIO     3                                /**< Application's BLE observer priority. You shouldn't need to modify this value. */
  #define APP_SOC_OBSERVER_PRIO     1                                /**< Applications' SoC observer priority. You shoulnd't need to modify this value. */
  
  #define SEC_PARAM_BOND            1                                /**< Perform bonding. */
  #define SEC_PARAM_MITM            0                                /**< Man In The Middle protection not required. */
  #define SEC_PARAM_LESC            0                                /**< LE Secure Connections not enabled. */
  #define SEC_PARAM_KEYPRESS        0                                /**< Keypress notifications not enabled. */
  #define SEC_PARAM_IO_CAPABILITIES BLE_GAP_IO_CAPS_NONE             /**< No I/O capabilities. */
  #define SEC_PARAM_OOB             0                                /**< Out Of Band data not available. */
  #define SEC_PARAM_MIN_KEY_SIZE    7                                /**< Minimum encryption key size. */
  #define SEC_PARAM_MAX_KEY_SIZE    16                               /**< Maximum encryption key size. */
  
  #define SCAN_INTERVAL             0x00A0                           /**< Determines scan interval in units of 0.625 millisecond. */
  #define SCAN_WINDOW               0x0050                           /**< Determines scan window in units of 0.625 millisecond. */
  
  #define MIN_CONNECTION_INTERVAL   MSEC_TO_UNITS(7.5, UNIT_1_25_MS) /**< Determines minimum connection interval in millisecond. */
  #define MAX_CONNECTION_INTERVAL   MSEC_TO_UNITS(30, UNIT_1_25_MS)  /**< Determines maximum connection interval in millisecond. */
  #define SLAVE_LATENCY             0                                /**< Determines slave latency in counts of connection events. */
  #define SUPERVISION_TIMEOUT       MSEC_TO_UNITS(4000, UNIT_10_MS)  /**< Determines supervision time-out in units of 10 millisecond. */
  
  #define TARGET_UUID               BLE_UUID_GATT                    /**< Target device name that application is looking for. */
  #define UUID16_SIZE               2                                /**< Size of 16 bit UUID */
  
  /**@brief Macro to unpack 16bit unsigned UUID from octet stream. */
  #define UUID16_EXTRACT(DST, SRC) \
      do                           \
      {                            \
          (*(DST))   = (SRC)[1];   \
          (*(DST)) <<= 8;          \
          (*(DST))  |= (SRC)[0];   \
      } while (0)
  
  
  /**@brief Variable length data encapsulation in terms of length and pointer to data */
  typedef struct
  {
      uint8_t * p_data;   /**< Pointer to data. */
      uint16_t  data_len; /**< Length of data. */
  }data_t;
  
  NRF_BLE_GATT_DEF(m_gatt);                                 /**< GATT module instance. */
  
  static uint16_t              m_conn_handle;               /**< Current connection handle. */
  static bool                  m_whitelist_disabled;        /**< True if whitelist has been temporarily disabled. */
  static bool                  m_memory_access_in_progress; /**< Flag to keep track of ongoing operations on persistent memory. */
  static ble_gap_scan_params_t m_scan_param;                /**< Scan parameters requested for scanning and connection. */
  static bool                  m_erase_bonds;               /**< Bool to determine if bonds should be erased before scanning starts. Based on button push upon startup. */
  
  /**@brief Connection parameters requested for connection. */
  static ble_gap_conn_params_t const m_connection_param =
  {
      (uint16_t)MIN_CONNECTION_INTERVAL, // Minimum connection.
      (uint16_t)MAX_CONNECTION_INTERVAL, // Maximum connection.
      (uint16_t)SLAVE_LATENCY,           // Slave latency.
      (uint16_t)SUPERVISION_TIMEOUT      // Supervision time-out.
  };
  
  static void scan_start(void);
  
  static char const m_target_periph_name[] = "Nordic_GATTS"; /**< If you want to connect to a peripheral using a given advertising name, type its name here. */
  static bool       is_connect_per_addr    = false;          /**< If you want to connect to a peripheral with a given address, set this to true and put the correct address in the variable below. */
  
  static ble_gap_addr_t const m_target_periph_addr =
  {
      /* Possible values for addr_type:
         BLE_GAP_ADDR_TYPE_PUBLIC,
         BLE_GAP_ADDR_TYPE_RANDOM_STATIC,
         BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE,
         BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_NON_RESOLVABLE. */
      .addr_type = BLE_GAP_ADDR_TYPE_RANDOM_STATIC,
      .addr      = {0x8D, 0xFE, 0x23, 0x86, 0x77, 0xD9}
  };
  
  /**@brief Function for asserts in the SoftDevice.
   *
   * @details This function will be called in case of an assert in the SoftDevice.
   *
   * @warning This handler is an example only and does not fit a final product. You need to analyze
   *          how your product is supposed to react in case of Assert.
   * @warning On assert from the SoftDevice, the system can only recover on reset.
   *
   * @param[in] line_num     Line number of the failing ASSERT call.
   * @param[in] p_file_name  File name of the failing ASSERT call.
   */
  void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
  {
      app_error_handler(0xDEADBEEF, line_num, p_file_name);
  }
  
  
  /**@brief Function for handling File Data Storage events.
   *
   * @param[in] p_evt  Peer Manager event.
   * @param[in] cmd
   */
  static void fds_evt_handler(fds_evt_t const * const p_evt)
  {
      if (p_evt->id == FDS_EVT_GC)
      {
          NRF_LOG_DEBUG("GC completed.");
      }
  }
  
  
  /**@brief Function for handling Peer Manager events.
   *
   * @param[in] p_evt  Peer Manager event.
   */
  static void pm_evt_handler(pm_evt_t const * p_evt)
  {
      ret_code_t err_code;
  
      switch (p_evt->evt_id)
      {
          case PM_EVT_BONDED_PEER_CONNECTED:
          {
              NRF_LOG_INFO("Connected to a previously bonded device.");
          } break;
  
          case PM_EVT_CONN_SEC_SUCCEEDED:
          {
              NRF_LOG_INFO("Connection secured: role: %d, conn_handle: 0x%x, procedure: %d.",
                           ble_conn_state_role(p_evt->conn_handle),
                           p_evt->conn_handle,
                           p_evt->params.conn_sec_succeeded.procedure);
          } break;
  
          case PM_EVT_CONN_SEC_FAILED:
          {
              /* Often, when securing fails, it shouldn't be restarted, for security reasons.
               * Other times, it can be restarted directly.
               * Sometimes it can be restarted, but only after changing some Security Parameters.
               * Sometimes, it cannot be restarted until the link is disconnected and reconnected.
               * Sometimes it is impossible, to secure the link, or the peer device does not support it.
               * How to handle this error is highly application dependent. */
              NRF_LOG_INFO("Connection security failed: role: %d, conn_handle: 0x%x, procedure: %d, error: %d.",
                           ble_conn_state_role(p_evt->conn_handle),
                           p_evt->conn_handle,
                           p_evt->params.conn_sec_failed.procedure,
                           p_evt->params.conn_sec_failed.error);
          } break;
  
          case PM_EVT_CONN_SEC_CONFIG_REQ:
          {
              // Reject pairing request from an already bonded peer.
              pm_conn_sec_config_t conn_sec_config = {.allow_repairing = false};
              pm_conn_sec_config_reply(p_evt->conn_handle, &conn_sec_config);
          } break;
  
          case PM_EVT_STORAGE_FULL:
          {
              // Run garbage collection on the flash.
              err_code = fds_gc();
              if (err_code == FDS_ERR_BUSY || err_code == FDS_ERR_NO_SPACE_IN_QUEUES)
              {
                  // Retry.
              }
              else
              {
                  APP_ERROR_CHECK(err_code);
              }
          } break;
  
          case PM_EVT_PEERS_DELETE_SUCCEEDED:
          {
              scan_start();
          } break;
  
          case PM_EVT_LOCAL_DB_CACHE_APPLY_FAILED:
          {
              // The local database has likely changed, send service changed indications.
              pm_local_database_has_changed();
          } break;
  
          case PM_EVT_PEER_DATA_UPDATE_FAILED:
          {
              // Assert.
              APP_ERROR_CHECK(p_evt->params.peer_data_update_failed.error);
          } break;
  
          case PM_EVT_PEER_DELETE_FAILED:
          {
              // Assert.
              APP_ERROR_CHECK(p_evt->params.peer_delete_failed.error);
          } break;
  
          case PM_EVT_PEERS_DELETE_FAILED:
          {
              // Assert.
              APP_ERROR_CHECK(p_evt->params.peers_delete_failed_evt.error);
          } break;
  
          case PM_EVT_ERROR_UNEXPECTED:
          {
              // Assert.
              APP_ERROR_CHECK(p_evt->params.error_unexpected.error);
          } break;
  
          case PM_EVT_CONN_SEC_START:
              break;
  
          case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
              break;
  
          case PM_EVT_PEER_DELETE_SUCCEEDED:
              break;
  
          case PM_EVT_LOCAL_DB_CACHE_APPLIED:
              break;
  
          case PM_EVT_SERVICE_CHANGED_IND_SENT:
              NRF_LOG_INFO("Sending Service Changed indication.");
              break;
  
          case PM_EVT_SERVICE_CHANGED_IND_CONFIRMED:
              NRF_LOG_INFO("Service Changed indication confirmed.");
              break;
  
          default:
              break;
      }
  }
  
  
  /**
   * @brief Parses advertisement data, providing length and location of the field in case
   *        matching data is found.
   *
   * @param[in]  Type of data to be looked for in advertisement data.
   * @param[in]  Advertisement report length and pointer to report.
   * @param[out] If data type requested is found in the data report, type data length and
   *             pointer to data will be populated here.
   *
   * @retval NRF_SUCCESS if the data type is found in the report.
   * @retval NRF_ERROR_NOT_FOUND if the data type could not be found.
   */
  static uint32_t adv_report_parse(uint8_t type, data_t * p_advdata, data_t * p_typedata)
  {
      uint32_t  index = 0;
      uint8_t * p_data;
  
      p_data = p_advdata->p_data;
  
      while (index < p_advdata->data_len)
      {
          uint8_t field_length = p_data[index];
          uint8_t field_type   = p_data[index + 1];
  
          if (field_type == type)
          {
              p_typedata->p_data   = &p_data[index + 2];
              p_typedata->data_len = field_length - 1;
              return NRF_SUCCESS;
          }
          index += field_length + 1;
      }
      return NRF_ERROR_NOT_FOUND;
  }
  
  
  /**
   * @brief Function for shutdown events.
   *
   * @param[in]   event       Shutdown type.
   */
  static bool shutdown_handler(nrf_pwr_mgmt_evt_t event)
  {
      ret_code_t err_code;
  
      err_code = bsp_indication_set(BSP_INDICATE_IDLE);
      APP_ERROR_CHECK(err_code);
  
      switch (event)
      {
          case NRF_PWR_MGMT_EVT_PREPARE_WAKEUP:
              // Prepare wakeup buttons.
              err_code = bsp_btn_ble_sleep_mode_prepare();
              APP_ERROR_CHECK(err_code);
              break;
  
          default:
              break;
      }
  
      return true;
  }
  
  
  NRF_PWR_MGMT_HANDLER_REGISTER(shutdown_handler, APP_SHUTDOWN_HANDLER_PRIORITY);
  
  
  /**@brief Function for searching a given name in the advertisement packets.
   *
   * @details Use this function to parse received advertising data and to find a given
   * name in them either as 'complete_local_name' or as 'short_local_name'.
   *
   * @param[in]   p_adv_report   advertising data to parse.
   * @param[in]   name_to_find   name to search.
   * @return   true if the given name was found, false otherwise.
   */
  static bool find_adv_name(ble_gap_evt_adv_report_t const * p_adv_report, char const * name_to_find)
  {
      ret_code_t err_code;
      data_t     adv_data;
      data_t     dev_name;
  
      // Initialize advertisement report for parsing
      adv_data.p_data   = (uint8_t *)p_adv_report->data;
      adv_data.data_len = p_adv_report->dlen;
  
      // search for advertising names
      err_code = adv_report_parse(BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME, &adv_data, &dev_name);
      if (err_code == NRF_SUCCESS)
      {
          if (memcmp(name_to_find, dev_name.p_data, dev_name.data_len) == 0)
          {
              return true;
          }
      }
      else
      {
          // Look for the short local name if it was not found as complete
          err_code = adv_report_parse(BLE_GAP_AD_TYPE_SHORT_LOCAL_NAME, &adv_data, &dev_name);
          if (err_code != NRF_SUCCESS)
          {
              return false;
          }
          if (memcmp(m_target_periph_name, dev_name.p_data, dev_name.data_len) == 0)
          {
              return true;
          }
      }
      return false;
  }
  
  
  /**@brief Function for searching a given addr in the advertisement packets.
   *
   * @details Use this function to parse received advertising data and to find a given
   * addr in them.
   *
   * @param[in]   p_adv_report   advertising data to parse.
   * @param[in]   p_addr   name to search.
   * @return   true if the given name was found, false otherwise.
   */
  static bool find_peer_addr(const ble_gap_evt_adv_report_t * p_adv_report,
                             const ble_gap_addr_t           * p_addr)
  {
      if (p_addr->addr_type == p_adv_report->peer_addr.addr_type)
      {
          if (memcmp(p_addr->addr, p_adv_report->peer_addr.addr,
                     sizeof(p_adv_report->peer_addr.addr)) == 0)
          {
              return true;
          }
      }
      return false;
  }
  
  
  /**@brief Function for searching a UUID in the advertisement packets.
   *
   * @details Use this function to parse received advertising data and to find a given
   * UUID in them.
   *
   * @param[in]   p_adv_report   advertising data to parse.
   * @param[in]   uuid_to_find   UUIID to search.
   * @return   true if the given UUID was found, false otherwise.
   */
  static bool find_adv_uuid(const ble_gap_evt_adv_report_t * p_adv_report,
                            const uint16_t                   uuid_to_find)
  {
      ret_code_t err_code;
      data_t     adv_data;
      data_t     type_data;
  
      // Initialize advertisement report for parsing.
      adv_data.p_data   = (uint8_t *)p_adv_report->data;
      adv_data.data_len = p_adv_report->dlen;
  
      err_code = adv_report_parse(BLE_GAP_AD_TYPE_16BIT_SERVICE_UUID_MORE_AVAILABLE,
                                  &adv_data,
                                  &type_data);
  
      if (err_code != NRF_SUCCESS)
      {
          // Look for the services in 'complete' if it was not found in 'more available'.
          err_code = adv_report_parse(BLE_GAP_AD_TYPE_16BIT_SERVICE_UUID_COMPLETE,
                                      &adv_data,
                                      &type_data);
  
          if (err_code != NRF_SUCCESS)
          {
              // If we can't parse the data, then exit.
              return false;
          }
      }
  
      // Verify if any UUID match the given UUID.
      for (uint32_t u_index = 0; u_index < (type_data.data_len / sizeof(uint16_t)); u_index++)
      {
          uint16_t extracted_uuid;
  
          UUID16_EXTRACT(&extracted_uuid, &type_data.p_data[u_index * sizeof(uint16_t)]);
  
          if (extracted_uuid == uuid_to_find)
          {
              return true;
          }
      }
      return false;
  }
  
  
  /**@brief Function for handling BLE events.
   *
   * @param[in]   p_ble_evt   Bluetooth stack event.
   * @param[in]   p_context   Unused.
   */
  static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
  {
      ret_code_t            err_code;
      ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;
  
      switch (p_ble_evt->header.evt_id)
      {
          case BLE_GAP_EVT_CONNECTED:
          {
              m_conn_handle = p_gap_evt->conn_handle;
              err_code      = bsp_indication_set(BSP_INDICATE_CONNECTED);
              APP_ERROR_CHECK(err_code);
  
              err_code = pm_conn_secure(m_conn_handle, false);
              APP_ERROR_CHECK(err_code);
  
              if (ble_conn_state_n_centrals() < NRF_SDH_BLE_CENTRAL_LINK_COUNT)
              {
                  scan_start();
              }
          } break;
  
          case BLE_GAP_EVT_ADV_REPORT:
          {
              bool do_connect = false;
              if (is_connect_per_addr)
              {
                  if (find_peer_addr(&p_gap_evt->params.adv_report, &m_target_periph_addr))
                  {
                      NRF_LOG_INFO("Address match send connect_request.");
                      do_connect = true;
                  }
              }
              else if (strlen(m_target_periph_name) != 0)
              {
                  if (find_adv_name(&p_gap_evt->params.adv_report, m_target_periph_name))
                  {
                      do_connect = true;
                      NRF_LOG_INFO("Name match send connect_request.");
                  }
              }
              else
              {
                  if (find_adv_uuid(&p_gap_evt->params.adv_report, TARGET_UUID))
                  {
                      do_connect = true;
                      NRF_LOG_INFO("UUID match send connect_request.");
                  }
              }
              if (do_connect)
              {
                  // Stop scanning.
                  (void) sd_ble_gap_scan_stop();
  
                  #if (NRF_SD_BLE_API_VERSION <= 2)
                      m_scan_param.selective = 0;
                  #endif
                  #if (NRF_SD_BLE_API_VERSION >= 3)
                      m_scan_param.use_whitelist = 0;
                  #endif
  
                  // Initiate connection.
                  err_code = sd_ble_gap_connect(&p_gap_evt->params.adv_report.peer_addr,
                                                &m_scan_param,
                                                &m_connection_param,
                                                APP_BLE_CONN_CFG_TAG);
  
                  m_whitelist_disabled = false;
  
                  if (err_code != NRF_SUCCESS)
                  {
                      NRF_LOG_ERROR("Connection Request Failed, reason %d.", err_code);
                  }
              }
          } break; // BLE_GAP_EVT_ADV_REPORT
  
          case BLE_GAP_EVT_TIMEOUT:
          {
              if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_SCAN)
              {
                  NRF_LOG_INFO("Scan timed out.");
                  scan_start();
              }
              else if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
              {
                  NRF_LOG_DEBUG("Connection Request timed out.");
              }
          } break;
  
          case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
          {
              // Accepting parameters requested by peer.
              err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle,
                                                      &p_gap_evt->params.conn_param_update_request.conn_params);
              APP_ERROR_CHECK(err_code);
          } break;
  
          case BLE_GAP_EVT_DISCONNECTED:
          {
              if (ble_conn_state_n_centrals() < NRF_SDH_BLE_CENTRAL_LINK_COUNT)
              {
                  scan_start();
              }
          } break;
  
  #ifndef S140
          case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
          {
              NRF_LOG_DEBUG("PHY update request.");
              ble_gap_phys_t const phys =
              {
                  .rx_phys = BLE_GAP_PHY_AUTO,
                  .tx_phys = BLE_GAP_PHY_AUTO,
              };
              err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
              APP_ERROR_CHECK(err_code);
          } break;
  #endif
  
          case BLE_GATTC_EVT_TIMEOUT:
          {
              // Disconnect on GATT Client timeout event.
              NRF_LOG_DEBUG("GATT Client Timeout.");
              err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                               BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
              APP_ERROR_CHECK(err_code);
          } break;
  
          case BLE_GATTS_EVT_TIMEOUT:
          {
              // Disconnect on GATT Server timeout event.
              NRF_LOG_DEBUG("GATT Server Timeout.");
              err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                               BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
              APP_ERROR_CHECK(err_code);
          } break;
  
          default:
              break;
      }
  }
  
  
  /**
   * @brief SoftDevice SoC event handler.
   *
   * @param[in] evt_id    SoC event.
   * @param[in] p_context Context.
   */
  static void soc_evt_handler(uint32_t evt_id, void * p_context)
  {
      switch (evt_id)
      {
          case NRF_EVT_FLASH_OPERATION_SUCCESS:
          /* fall through */
          case NRF_EVT_FLASH_OPERATION_ERROR:
  
              if (m_memory_access_in_progress)
              {
                  m_memory_access_in_progress = false;
                  scan_start();
              }
              break;
  
          default:
              // No implementation needed.
              break;
      }
  }
  
  
  /**@brief Function for initializing the BLE stack.
   *
   * @details Initializes the SoftDevice and the BLE event interrupt.
    */
  static void ble_stack_init(void)
  {
      ret_code_t err_code;
  
      err_code = nrf_sdh_enable_request();
      APP_ERROR_CHECK(err_code);
  
      // Configure the BLE stack using the default settings.
      // Fetch the start address of the application RAM.
      uint32_t ram_start = 0;
      err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
      APP_ERROR_CHECK(err_code);
  
      // Enable BLE stack.
      err_code = nrf_sdh_ble_enable(&ram_start);
      APP_ERROR_CHECK(err_code);
  
      // Register handlers for BLE and SoC events.
      NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
      NRF_SDH_SOC_OBSERVER(m_soc_observer, APP_SOC_OBSERVER_PRIO, soc_evt_handler, NULL);
  }
  
  
  /**@brief Function for disabling the use of whitelist for scanning.
   */
  static void whitelist_disable(void)
  {
      if (!m_whitelist_disabled)
      {
          NRF_LOG_INFO("Whitelist temporarily disabled.");
          m_whitelist_disabled = true;
          (void) sd_ble_gap_scan_stop();
          scan_start();
      }
  }
  
  
  /**@brief Function for handling events from the BSP module.
   *
   * @param[in]   event   Event generated by button press.
   */
  void bsp_event_handler(bsp_event_t event)
  {
      ret_code_t err_code;
  
      switch (event)
      {
          case BSP_EVENT_SLEEP:
              nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);
              break;
  
          case BSP_EVENT_DISCONNECT:
              err_code = sd_ble_gap_disconnect(m_conn_handle,
                                               BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
              if (err_code != NRF_ERROR_INVALID_STATE)
              {
                  APP_ERROR_CHECK(err_code);
              }
              break;
  
          case BSP_EVENT_WHITELIST_OFF:
              whitelist_disable();
              break;
  
          case BSP_EVENT_KEY_0:
              // Note that to simplify this example, we are not actually making any changes to our
              // database (Which is normally when you would want to send this indication).
              // Acting upon this indication (doing a rediscovery) is pointless for the peer.
              pm_local_database_has_changed();
              break;
          default:
              break;
      }
  }
  
  
  /**@brief Function for the Peer Manager initialization.
   *
   * @param[in] erase_bonds  Indicates whether bonding information should be cleared from
   *                         persistent storage during initialization of the Peer Manager.
   */
  static void peer_manager_init()
  {
      ble_gap_sec_params_t sec_param;
      ret_code_t           err_code;
  
      err_code = pm_init();
      APP_ERROR_CHECK(err_code);
  
      memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));
  
      // Security parameters to be used for all security procedures.
      sec_param.bond           = SEC_PARAM_BOND;
      sec_param.mitm           = SEC_PARAM_MITM;
      sec_param.lesc           = SEC_PARAM_LESC;
      sec_param.keypress       = SEC_PARAM_KEYPRESS;
      sec_param.io_caps        = SEC_PARAM_IO_CAPABILITIES;
      sec_param.oob            = SEC_PARAM_OOB;
      sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
      sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
      sec_param.kdist_own.enc  = 1;
      sec_param.kdist_own.id   = 1;
      sec_param.kdist_peer.enc = 1;
      sec_param.kdist_peer.id  = 1;
  
      err_code = pm_sec_params_set(&sec_param);
      APP_ERROR_CHECK(err_code);
  
      err_code = pm_register(pm_evt_handler);
      APP_ERROR_CHECK(err_code);
  
      err_code = fds_register(fds_evt_handler);
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Clear bond information from persistent storage.
   */
  static void delete_bonds(void)
  {
      ret_code_t err_code;
  
      NRF_LOG_INFO("Erase bonds.");
      err_code = pm_peers_delete();
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Retrive a list of peer manager peer IDs.
   *
   * @param[inout] p_peers   The buffer where to store the list of peer IDs.
   * @param[inout] p_size    In: The size of the @p p_peers buffer.
   *                         Out: The number of peers copied in the buffer.
   */
  static void peer_list_get(pm_peer_id_t * p_peers, uint32_t * p_size)
  {
      pm_peer_id_t peer_id;
      uint32_t     peers_to_copy;
  
      peers_to_copy = (*p_size < BLE_GAP_WHITELIST_ADDR_MAX_COUNT) ?
                      *p_size : BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
  
      peer_id = pm_next_peer_id_get(PM_PEER_ID_INVALID);
      *p_size = 0;
  
      while ((peer_id != PM_PEER_ID_INVALID) && (peers_to_copy--))
      {
          p_peers[(*p_size)++] = peer_id;
          peer_id              = pm_next_peer_id_get(peer_id);
      }
  }
  
  
  static void whitelist_load()
  {
      ret_code_t   ret;
      pm_peer_id_t peers[8];
      uint32_t     peer_cnt;
  
      memset(peers, PM_PEER_ID_INVALID, sizeof(peers));
      peer_cnt = (sizeof(peers) / sizeof(pm_peer_id_t));
  
      // Load all peers from flash and whitelist them.
      peer_list_get(peers, &peer_cnt);
  
      ret = pm_whitelist_set(peers, peer_cnt);
      APP_ERROR_CHECK(ret);
  
      // Setup the device identies list.
      // Some SoftDevices do not support this feature.
      ret = pm_device_identities_list_set(peers, peer_cnt);
      if (ret != NRF_ERROR_NOT_SUPPORTED)
      {
          APP_ERROR_CHECK(ret);
      }
  }
  
  
  /**@brief Function to start scanning.
   */
  static void scan_start(void)
  {
      // If there is any pending write to flash, defer scanning until it completes.
      if (nrf_fstorage_is_busy(NULL))
      {
          m_memory_access_in_progress = true;
          return;
      }
  
      // Whitelist buffers.
      ble_gap_addr_t whitelist_addrs[8];
      ble_gap_irk_t  whitelist_irks[8];
  
      memset(whitelist_addrs, 0x00, sizeof(whitelist_addrs));
      memset(whitelist_irks, 0x00, sizeof(whitelist_irks));
  
      uint32_t addr_cnt = (sizeof(whitelist_addrs) / sizeof(ble_gap_addr_t));
      uint32_t irk_cnt  = (sizeof(whitelist_irks) / sizeof(ble_gap_irk_t));
  
      #if (NRF_SD_BLE_API_VERSION <= 2)
  
      ble_gap_addr_t * p_whitelist_addrs[8];
      ble_gap_irk_t  * p_whitelist_irks[8];
  
      for (uint32_t i = 0; i < 8; i++)
      {
          p_whitelist_addrs[i] = &whitelist_addrs[i];
          p_whitelist_irks[i]  = &whitelist_irks[i];
      }
  
      ble_gap_whitelist_t whitelist =
      {
          .pp_addrs = p_whitelist_addrs,
          .pp_irks  = p_whitelist_irks,
      };
  
      #endif
  
      // Reload the whitelist and whitelist all peers.
      whitelist_load();
  
      ret_code_t ret;
  
      // Get the whitelist previously set using pm_whitelist_set().
      ret = pm_whitelist_get(whitelist_addrs, &addr_cnt,
                             whitelist_irks, &irk_cnt);
  
      m_scan_param.active   = 0;
      m_scan_param.interval = SCAN_INTERVAL;
      m_scan_param.window   = SCAN_WINDOW;
  
      if (((addr_cnt == 0) && (irk_cnt == 0)) ||
          (m_whitelist_disabled))
      {
          // Don't use whitelist.
          #if (NRF_SD_BLE_API_VERSION <= 2)
              m_scan_param.selective   = 0;
              m_scan_param.p_whitelist = NULL;
          #endif
          #if (NRF_SD_BLE_API_VERSION >= 3)
              m_scan_param.use_whitelist  = 0;
              m_scan_param.adv_dir_report = 0;
          #endif
          m_scan_param.timeout  = 0x0000; // No timeout.
      }
      else
      {
          // Use whitelist.
          #if (NRF_SD_BLE_API_VERSION <= 2)
              whitelist.addr_count     = addr_cnt;
              whitelist.irk_count      = irk_cnt;
              m_scan_param.selective   = 1;
              m_scan_param.p_whitelist = &whitelist;
          #endif
          #if (NRF_SD_BLE_API_VERSION >= 3)
              m_scan_param.use_whitelist  = 1;
              m_scan_param.adv_dir_report = 0;
          #endif
          m_scan_param.timeout  = 0x001E; // 30 seconds.
      }
  
      NRF_LOG_INFO("Starting scan.");
  
      ret = sd_ble_gap_scan_start(&m_scan_param);
      APP_ERROR_CHECK(ret);
  
      ret = bsp_indication_set(BSP_INDICATE_SCANNING);
      APP_ERROR_CHECK(ret);
  }
  
  
  /**@brief Function for initializing buttons and leds.
   *
   * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
   */
  static void buttons_leds_init(bool * p_erase_bonds)
  {
      ret_code_t  err_code;
      bsp_event_t startup_event;
  
      err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS, bsp_event_handler);
      APP_ERROR_CHECK(err_code);
  
      err_code = bsp_btn_ble_init(NULL, &startup_event);
      APP_ERROR_CHECK(err_code);
  
      *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
  }
  
  
  /**@brief Function for initializing logging. */
  static void log_init(void)
  {
      ret_code_t err_code = NRF_LOG_INIT(NULL);
  
      APP_ERROR_CHECK(err_code);
  
      NRF_LOG_DEFAULT_BACKENDS_INIT();
  }
  
  
  /**@brief Function for initializing the timer. */
  static void timer_init(void)
  {
      ret_code_t err_code = app_timer_init();
  
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Function for initializing the GATT module. */
  static void gatt_init(void)
  {
      ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
  
      APP_ERROR_CHECK(err_code);
  }
  
  
  /** @brief Function for initializing the Power manager. */
  static void power_init(void)
  {
      ret_code_t err_code = nrf_pwr_mgmt_init();
  
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Function for handling the idle state (main loop). If there is no pending log operation,
            then sleep until next the next event occurs.
   */
  static void idle_state_handle(void)
  {
      if (NRF_LOG_PROCESS() == false)
      {
          nrf_pwr_mgmt_run();
      }
  }
  
  
  /**@brief Function for starting a scan, or instead trigger it from peer manager (after
            deleting bonds).
  
     @param[in] p_erase_bonds Pointer to a bool to determine if bonds will be deleted before scanning.
  */
  void scanning_start(bool * p_erase_bonds)
  {
      // Start scanning for peripherals and initiate connection
      // with devices that advertise GATT Service UUID.
      if (*p_erase_bonds == true)
      {
          // Scan is started by the PM_EVT_PEERS_DELETE_SUCCEEDED event.
          delete_bonds();
      }
      else
      {
          scan_start();
      }
  }
  
  /**@brief Function for initializing all the modules used in this example application.
   */
  static void modules_init(void)
  {
      log_init();
      timer_init();
      power_init();
      buttons_leds_init(&m_erase_bonds);
      ble_stack_init();
      gatt_init();
      peer_manager_init();
  }
  
  int main(void)
  {
      // Initialize.
      modules_init();
      whitelist_load();
  
      // Start execution.
      NRF_LOG_INFO("GATT Service server started.");
      scanning_start(&m_erase_bonds);
  
      // Enter main loop.
      for (;;)
      {
          idle_state_handle();
      }
  }
  
  