/**
 * Copyright (c) 2014 - 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 BLE Heart Rate Collector application main file.
 *
 * This file contains the source code for a sample heart rate collector.
 */

#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_db_discovery.h"
#include "softdevice_handler.h"
#include "app_util.h"
#include "app_error.h"
#include "boards.h"
#include "nrf_gpio.h"
#include "peer_manager.h"
#include "ble_hrs_c.h"
#include "ble_bas_c.h"
#include "app_util.h"
#include "app_timer.h"
#include "bsp.h"
#include "bsp_btn_ble.h"
#include "fds.h"
#include "fstorage.h"
#include "ble_conn_state.h"
#include "nrf_ble_gatt.h"
#define NRF_LOG_MODULE_NAME "APP"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"



#define CENTRAL_LINK_COUNT          1                                   /**< Number of central links used by the application. When changing this number remember to adjust the RAM settings*/
#define PERIPHERAL_LINK_COUNT       0                                   /**< Number of peripheral links used by the application. When changing this number remember to adjust the RAM settings*/

#define APP_TIMER_PRESCALER         0                                   /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_OP_QUEUE_SIZE     2                                   /**< Size of timer operation queues. */

#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 in octets. */
#define SEC_PARAM_MAX_KEY_SIZE      16                                  /**< Maximum encryption key size in octets. */

#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_HEART_RATE_SERVICE         /**< Target device name that application is looking for. */



/**@breif 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;


static ble_db_discovery_t    m_ble_db_discovery;           /**< Structure used to identify the DB Discovery module. */
static ble_hrs_c_t           m_ble_hrs_c;                  /**< Structure used to identify the heart rate client module. */
static ble_bas_c_t           m_ble_bas_c;                  /**< Structure used to identify the Battery Service client module. */
static ble_gap_scan_params_t m_scan_param;                 /**< Scan parameters requested for scanning and connection. */
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 nrf_ble_gatt_t        m_gatt;                       /**< Structure for gatt module*/

static bool                  m_retry_db_disc;              /**< Flag to keep track of whether the DB discovery should be retried. */
static uint16_t              m_pending_db_disc_conn = BLE_CONN_HANDLE_INVALID;  /**< Connection handle for which the DB discovery is retried. */

/**
 * @brief Connection parameters requested for connection.
 */
static const ble_gap_conn_params_t 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
};

/**@brief Names which the central applications will scan for, and which will be advertised by the peripherals.
 *  if these are set to empty strings, the UUIDs defined below will be used
 */
static const char m_target_periph_name[] = "";          /**< 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 const ble_gap_addr_t 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}
};


static void scan_start(void);


/**@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 database discovery events.
 *
 * @details This function is callback function to handle events from the database discovery module.
 *          Depending on the UUIDs that are discovered, this function should forward the events
 *          to their respective services.
 *
 * @param[in] p_event  Pointer to the database discovery event.
 */
static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
{
    ble_hrs_on_db_disc_evt(&m_ble_hrs_c, p_evt);
    ble_bas_on_db_disc_evt(&m_ble_bas_c, p_evt);
}


/**@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.\r\n");
        } break;

        case PM_EVT_CONN_SEC_SUCCEEDED:
        {
            NRF_LOG_INFO("Connection secured. Role: %d. conn_handle: %d, Procedure: %d\r\n",
                         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. */
        } 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:
        case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
        case PM_EVT_PEER_DELETE_SUCCEEDED:
        case PM_EVT_LOCAL_DB_CACHE_APPLIED:
        case PM_EVT_SERVICE_CHANGED_IND_SENT:
        case PM_EVT_SERVICE_CHANGED_IND_CONFIRMED:
        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 putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    uint32_t err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@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(const ble_gap_evt_adv_report_t *p_adv_report, const char * name_to_find)
{
    uint32_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)
{
    uint32_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 the Application's BLE Stack events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 */
static void on_ble_evt(ble_evt_t * p_ble_evt)
{
    uint32_t                err_code;
    const ble_gap_evt_t   * p_gap_evt = &p_ble_evt->evt.gap_evt;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
        {
            NRF_LOG_INFO("Connected.\r\n");
            m_pending_db_disc_conn = p_ble_evt->evt.gap_evt.conn_handle;
            m_retry_db_disc = false;
            // Discover peer's services.
            err_code = ble_db_discovery_start(&m_ble_db_discovery, m_pending_db_disc_conn);
            if (err_code == NRF_ERROR_BUSY)
            {
                NRF_LOG_INFO("ble_db_discovery_start() returned busy, will retry later.\r\n");
                m_retry_db_disc = true;
            }
            else
            {
                APP_ERROR_CHECK(err_code);
            }

            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);

            if (ble_conn_state_n_centrals() < NRF_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.\r\n");
                    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.\r\n");
                }
            }
            else
            {
                if (find_adv_uuid(&p_gap_evt->params.adv_report, TARGET_UUID))
                {
                    do_connect = true;
                    NRF_LOG_INFO("UUID match send connect_request.\r\n");
                }
            }
            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);

                m_whitelist_disabled = false;

                if (err_code != NRF_SUCCESS)
                {
                    NRF_LOG_ERROR("Connection Request Failed, reason %d.\r\n", err_code);
                }
            }
        } break; // BLE_GAP_EVT_ADV_REPORT

        case BLE_GAP_EVT_DISCONNECTED:
        {
            NRF_LOG_INFO("Disconnected, reason 0x%x.\r\n",
                         p_ble_evt->evt.gap_evt.params.disconnected.reason);

            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);

            // Reset DB discovery structure.
            memset(&m_ble_db_discovery, 0 , sizeof (m_ble_db_discovery));

            if (ble_conn_state_n_centrals() < NRF_BLE_CENTRAL_LINK_COUNT)
            {
                scan_start();
            }
        } break;

        case BLE_GAP_EVT_TIMEOUT:
        {
            if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_SCAN)
            {
                NRF_LOG_DEBUG("Scan timed out.\r\n");
                scan_start();
            }
            else if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
            {
                NRF_LOG_INFO("Connection Request timed out.\r\n");
            }
        } 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_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.\r\n");
            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.\r\n");
            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 Function for handling the Application's system events.
 *
 * @param[in]   sys_evt   system event.
 */
static void on_sys_evt(uint32_t sys_evt)
{
    switch (sys_evt)
    {
        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 dispatching a BLE stack event to all modules with a BLE stack event handler.
 *
 * @details This function is called from the scheduler in the main loop after a BLE stack event has
 *  been received.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 */
static void ble_evt_dispatch(ble_evt_t * p_ble_evt)
{
    // Modules which depend on ble_conn_state, like Peer Manager,
    // should have their callbacks invoked after ble_conn_state's.
    ble_conn_state_on_ble_evt(p_ble_evt);
    pm_on_ble_evt(p_ble_evt);
    ble_db_discovery_on_ble_evt(&m_ble_db_discovery, p_ble_evt);
    ble_hrs_c_on_ble_evt(&m_ble_hrs_c, p_ble_evt);
    ble_bas_c_on_ble_evt(&m_ble_bas_c, p_ble_evt);
    bsp_btn_ble_on_ble_evt(p_ble_evt);
    nrf_ble_gatt_on_ble_evt(&m_gatt, p_ble_evt);
    on_ble_evt(p_ble_evt);
}


/**@brief Function for dispatching a system event to interested modules.
 *
 * @details This function is called from the System event interrupt handler after a system
 *          event has been received.
 *
 * @param[in]   sys_evt   System stack event.
 */
static void sys_evt_dispatch(uint32_t sys_evt)
{
    fs_sys_event_handler(sys_evt);
    on_sys_evt(sys_evt);
}


/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    uint32_t err_code;

    nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;

    // Initialize the SoftDevice handler module.
    SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL);

    ble_enable_params_t ble_enable_params;
    err_code = softdevice_enable_get_default_config(NRF_BLE_CENTRAL_LINK_COUNT,
                                                    NRF_BLE_PERIPHERAL_LINK_COUNT,
                                                    &ble_enable_params);
    APP_ERROR_CHECK(err_code);

    //Check the ram settings against the used number of links
    CHECK_RAM_START_ADDR(NRF_BLE_CENTRAL_LINK_COUNT, NRF_BLE_PERIPHERAL_LINK_COUNT);

    // Enable BLE stack.
#if (NRF_SD_BLE_API_VERSION == 3)
    ble_enable_params.gatt_enable_params.att_mtu = NRF_BLE_GATT_MAX_MTU_SIZE;
#endif

    err_code = softdevice_enable(&ble_enable_params);
    APP_ERROR_CHECK(err_code);

    // Register with the SoftDevice handler module for BLE events.
    err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
    APP_ERROR_CHECK(err_code);

    // Register with the SoftDevice handler module for System events.
    err_code = softdevice_sys_evt_handler_set(sys_evt_dispatch);
    APP_ERROR_CHECK(err_code);
}



/**@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(bool erase_bonds)
{
    ble_gap_sec_params_t sec_param;
    ret_code_t err_code;

    err_code = pm_init();
    APP_ERROR_CHECK(err_code);

    if (erase_bonds)
    {
        err_code = pm_peers_delete();
        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);
}


/**@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.\r\n");
        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)
{
    uint32_t err_code;
    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            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;

        default:
            break;
    }
}


/**@brief Heart Rate Collector Handler.
 */
static void hrs_c_evt_handler(ble_hrs_c_t * p_hrs_c, ble_hrs_c_evt_t * p_hrs_c_evt)
{
    uint32_t err_code;

    switch (p_hrs_c_evt->evt_type)
    {
        case BLE_HRS_C_EVT_DISCOVERY_COMPLETE:
            err_code = ble_hrs_c_handles_assign(p_hrs_c ,
                                                p_hrs_c_evt->conn_handle,
                                                &p_hrs_c_evt->params.peer_db);
            APP_ERROR_CHECK(err_code);

            // Initiate bonding.
            err_code = pm_conn_secure(p_hrs_c_evt->conn_handle, false);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }

            // Heart rate service discovered. Enable notification of Heart Rate Measurement.
            err_code = ble_hrs_c_hrm_notif_enable(p_hrs_c);
            APP_ERROR_CHECK(err_code);

            NRF_LOG_DEBUG("Heart rate service discovered.\r\n");
            break;

        case BLE_HRS_C_EVT_HRM_NOTIFICATION:
        {
            NRF_LOG_INFO("Heart Rate = %d.\r\n", p_hrs_c_evt->params.hrm.hr_value);
            for (int i = 0; i < p_hrs_c_evt->params.hrm.rr_intervals_cnt; i++)
            {
                NRF_LOG_DEBUG("rr_interval = %d.\r\n", p_hrs_c_evt->params.hrm.rr_intervals[i]);
            }
            break;
        }

        default:
            break;
    }
}


/**@brief Battery level Collector Handler.
 */
static void bas_c_evt_handler(ble_bas_c_t * p_bas_c, ble_bas_c_evt_t * p_bas_c_evt)
{
    uint32_t err_code;

    switch (p_bas_c_evt->evt_type)
    {
        case BLE_BAS_C_EVT_DISCOVERY_COMPLETE:
        {
            err_code = ble_bas_c_handles_assign(p_bas_c,
                                                p_bas_c_evt->conn_handle,
                                                &p_bas_c_evt->params.bas_db);
            APP_ERROR_CHECK(err_code);

            // Initiate bonding.
            err_code = pm_conn_secure(p_bas_c_evt->conn_handle, false);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }

            // Batttery service discovered. Enable notification of Battery Level.
            NRF_LOG_DEBUG("Battery Service discovered. Reading battery level.\r\n");

            err_code = ble_bas_c_bl_read(p_bas_c);
            APP_ERROR_CHECK(err_code);

            NRF_LOG_DEBUG("Enabling Battery Level Notification.\r\n");
            err_code = ble_bas_c_bl_notif_enable(p_bas_c);
            APP_ERROR_CHECK(err_code);

        } break;

        case BLE_BAS_C_EVT_BATT_NOTIFICATION:
            NRF_LOG_INFO("Battery Level received %d %%.\r\n", p_bas_c_evt->params.battery_level);
            break;

        case BLE_BAS_C_EVT_BATT_READ_RESP:
            NRF_LOG_INFO("Battery Level Read as %d %%.\r\n", p_bas_c_evt->params.battery_level);
            break;

        default:
            break;
    }
}


/**
 * @brief Heart rate collector initialization.
 */
static void hrs_c_init(void)
{
    ble_hrs_c_init_t hrs_c_init_obj;

    hrs_c_init_obj.evt_handler = hrs_c_evt_handler;

    uint32_t err_code = ble_hrs_c_init(&m_ble_hrs_c, &hrs_c_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**
 * @brief Battery level collector initialization.
 */
static void bas_c_init(void)
{
    ble_bas_c_init_t bas_c_init_obj;

    bas_c_init_obj.evt_handler = bas_c_evt_handler;

    uint32_t err_code = ble_bas_c_init(&m_ble_bas_c, &bas_c_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**
 * @brief Database discovery collector initialization.
 */
static void db_discovery_init(void)
{
    uint32_t err_code = ble_db_discovery_init(db_disc_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Retrieve 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)
{
    uint32_t flash_busy;

    // If there is any pending write to flash, defer scanning until it completes.
    (void) fs_queued_op_count_get(&flash_busy);

    if (flash_busy != 0)
    {
        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.\r\n");

    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)
{
    bsp_event_t startup_event;

    uint32_t err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS,
                                 APP_TIMER_TICKS(100, APP_TIMER_PRESCALER),
                                 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 the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);
}


/** @brief Function for the Power manager.
 */
static void power_manage(void)
{
    uint32_t err_code = sd_app_evt_wait();
    APP_ERROR_CHECK(err_code);
}


/* GATT generic Event handler. */
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t * p_evt)
{
    NRF_LOG_INFO("GATT MTU on link %d changed to %d\r\n",
                 p_evt->conn_handle,
                 p_evt->att_mtu_effective);
    if (m_retry_db_disc)
    {
        ret_code_t err_code;
        NRF_LOG_DEBUG("Retrying DB discovery.\r\n");
        m_retry_db_disc = false;
        // Discover peer's services.
        err_code = ble_db_discovery_start(&m_ble_db_discovery, m_pending_db_disc_conn);
        if (err_code == NRF_ERROR_BUSY)
        {
            NRF_LOG_DEBUG("ble_db_discovery_start() returned busy, will retry later.\r\n");
            m_retry_db_disc = true;
        }
        else
        {
            APP_ERROR_CHECK(err_code);
        }
    }
}


/* GATT Module init. */
void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
    APP_ERROR_CHECK(err_code);
}


int main(void)
{
    bool erase_bonds;

    // Initialize.
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);
    buttons_leds_init(&erase_bonds);
    log_init();
    ble_stack_init();
    peer_manager_init(erase_bonds);
    if (erase_bonds == true)
    {
        NRF_LOG_INFO("Bonds erased!\r\n");
    }
    gatt_init();
    db_discovery_init();
    hrs_c_init();
    bas_c_init();

    // Start scanning for peripherals and initiate connection
    // with devices that advertise Heart Rate UUID.
    NRF_LOG_INFO("Heart rate collector example.\r\n");
    scan_start();

    for (;;)
    {
        if (NRF_LOG_PROCESS() == false)
        {
            power_manage();
        }
    }
}


