/******************************************************************************
 *
 *  Copyright (C) 2003-2012 Broadcom Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 *  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.
 *
 ******************************************************************************/

/******************************************************************************
 *
 *  This file contains the GATT client discovery procedures and cache
 *  related functions.
 *
 ******************************************************************************/

#include "common/bt_target.h"

#if defined(GATTC_INCLUDED) && (GATTC_INCLUDED == TRUE)

#include <string.h>
#include "bta/utl.h"
#include "bta/bta_sys.h"
#include "stack/sdp_api.h"
#include "stack/sdpdefs.h"
#include "bta_gattc_int.h"
#include "stack/btm_api.h"
#include "stack/btm_ble_api.h"
#include "osi/allocator.h"
#include "stack/l2c_api.h"
#include "btm_int.h"
#include "errno.h"

// #include "osi/include/log.h"

static void bta_gattc_char_dscpt_disc_cmpl(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb);
extern void bta_to_btif_uuid(bt_uuid_t *p_dest, tBT_UUID *p_src);
static size_t bta_gattc_get_db_size_with_type(list_t *services,
                                              bt_gatt_db_attribute_type_t type,
                                              tBT_UUID *char_uuid,
                                              UINT16 start_handle, UINT16 end_handle);
static void bta_gattc_cache_write(BD_ADDR server_bda, UINT16 num_attr,
                           tBTA_GATTC_NV_ATTR *attr);
tBTA_GATTC_SERVICE*  bta_gattc_find_matching_service(const list_t *services, UINT16 handle);
tBTA_GATTC_DESCRIPTOR*  bta_gattc_get_descriptor_srcb(tBTA_GATTC_SERV *p_srcb, UINT16 handle);
tBTA_GATTC_CHARACTERISTIC*  bta_gattc_get_characteristic_srcb(tBTA_GATTC_SERV *p_srcb, UINT16 handle);
void bta_gattc_fill_gatt_db_el(btgatt_db_element_t *p_attr,
                               bt_gatt_db_attribute_type_t type,
                               UINT16 att_handle,
                               UINT16 s_handle, UINT16 e_handle,
                               UINT16 id, tBT_UUID uuid, UINT8 prop);


#if (SDP_INCLUDED == TRUE)
static tBTA_GATT_STATUS bta_gattc_sdp_service_disc(UINT16 conn_id, tBTA_GATTC_SERV *p_server_cb);
#define BTA_GATT_SDP_DB_SIZE 4096
#endif  ///SDP_INCLUDED == TRUE
#define GATT_CACHE_PREFIX "/data/misc/bluetooth/gatt_cache_"
#define GATT_CACHE_VERSION 2

static void bta_gattc_generate_cache_file_name(char *buffer, BD_ADDR bda)
{
    sprintf(buffer, "%s%02x%02x%02x%02x%02x%02x", GATT_CACHE_PREFIX,
            bda[0], bda[1], bda[2], bda[3], bda[4], bda[5]);
}

/*****************************************************************************
**  Constants and data types
*****************************************************************************/
#if (SDP_INCLUDED == TRUE)
typedef struct
{
    tSDP_DISCOVERY_DB   *p_sdp_db;
    UINT16              sdp_conn_id;
} tBTA_GATTC_CB_DATA;
#endif  ///SDP_INCLUDED == TRUE


#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
static char *bta_gattc_attr_type[] = {
    "I", /* Included Service */
    "C", /* Characteristic */
    "D" /* Characteristic Descriptor */
};
/* utility functions */

bool display_cache_attribute(void *data, void *context) 
{
    //tBTA_GATTC_CACHE_ATTR *p_attr = data;
    //APPL_TRACE_ERROR("\t Attr handle[%d] uuid[0x%04x] type[%s] prop[0x%1x]",
    //                  p_attr->handle, p_attr->uuid.uu.uuid16,
    //                  bta_gattc_attr_type[p_attr->attr_type], p_attr->property);
    return true;
}

bool display_cache_service(void *data, void *context) 
{
    tBTA_GATTC_SERVICE    *p_cur_srvc = data;
    APPL_TRACE_API("Service: handle[%d ~ %d] %s[0x%04x] inst[%d]",
              p_cur_srvc->s_handle, p_cur_srvc->e_handle,
              ((p_cur_srvc->uuid.len == 2) ? "uuid16" : "uuid128"),
              p_cur_srvc->uuid.uu.uuid16,
              p_cur_srvc->handle);

    if (p_cur_srvc->characteristics != NULL) {
        list_foreach(p_cur_srvc->characteristics, display_cache_attribute, NULL);
    }

    return true;
}

/*******************************************************************************
**
** Function         bta_gattc_display_cache_server
**
** Description      debug function to display the server cache.
**
** Returns          none.
**
*******************************************************************************/
static void bta_gattc_display_cache_server(list_t *p_cache)
{
    APPL_TRACE_ERROR("<================Start Server Cache =============>");
    list_foreach(p_cache, display_cache_service, NULL);
    APPL_TRACE_ERROR("<================End Server Cache =============>");
    APPL_TRACE_ERROR(" ");
}

/*******************************************************************************
**
** Function         bta_gattc_display_explore_record
**
** Description      debug function to display the exploration list
**
** Returns          none.
**
*******************************************************************************/
static void bta_gattc_display_explore_record(tBTA_GATTC_ATTR_REC *p_rec, UINT8 num_rec)
{
    UINT8 i;
    tBTA_GATTC_ATTR_REC *pp = p_rec;

    APPL_TRACE_ERROR("<================Start Explore Queue =============>");
    for (i = 0; i < num_rec; i ++, pp ++) {
        APPL_TRACE_ERROR("\t rec[%d] uuid[0x%04x] s_handle[%d] e_handle[%d] is_primary[%d]",
                         i + 1, pp->uuid.uu.uuid16, pp->s_handle, pp->e_handle, pp->is_primary);
    }
    APPL_TRACE_ERROR("<================ End Explore Queue =============>");
    APPL_TRACE_ERROR(" ");

}
#endif  /* BTA_GATT_DEBUG == TRUE */


/*******************************************************************************
**
** Function         bta_gattc_init_cache
**
** Description      Initialize the database cache and discovery related resources.
**
** Returns          status
**
*******************************************************************************/
tBTA_GATT_STATUS bta_gattc_init_cache(tBTA_GATTC_SERV *p_srvc_cb)
{
    if (p_srvc_cb->p_srvc_cache != NULL) {
        list_free(p_srvc_cb->p_srvc_cache);
        p_srvc_cb->p_srvc_cache = NULL;
    }

    osi_free(p_srvc_cb->p_srvc_list);

    if ((p_srvc_cb->p_srvc_list = (tBTA_GATTC_ATTR_REC *)osi_malloc(BTA_GATTC_ATTR_LIST_SIZE)) == NULL) {
        APPL_TRACE_DEBUG("No resources: GKI buffer allocation failed.");
        return BTA_GATT_NO_RESOURCES;
    } else {
        p_srvc_cb->total_srvc = 0;
        p_srvc_cb->cur_srvc_idx = 0;
        p_srvc_cb->cur_char_idx = 0;
        p_srvc_cb->next_avail_idx = 0;
        p_srvc_cb->total_attr = 0;
    }

    return BTA_GATT_OK;
}

static void characteristic_free(void *ptr)
{
  tBTA_GATTC_CHARACTERISTIC *p_char = ptr;
  list_free(p_char->descriptors);
  osi_free(p_char);
}

static void service_free(void *ptr)
{
  tBTA_GATTC_SERVICE *srvc = ptr;
  list_free(srvc->characteristics);
  list_free(srvc->included_svc);
  osi_free(srvc);
}

static void bta_gattc_free(void *ptr)
{
    osi_free(ptr);
}

void bta_gattc_insert_sec_service_to_cache(list_t *services, tBTA_GATTC_SERVICE *p_new_srvc) 
{
    // services/p_new_srvc is NULL 
    if (!services || !p_new_srvc) {
        APPL_TRACE_ERROR("%s services/p_new_srvc is NULL", __func__);
        return;
    }
    //list is empty
    if (list_is_empty(services)) {
        list_append(services, p_new_srvc);
    } else {
        //check the first service
        list_node_t *sn = list_begin(services);
        tBTA_GATTC_SERVICE *service = list_node(sn);
        if(service && p_new_srvc->e_handle < service->s_handle) {
            list_prepend(services, p_new_srvc);
        } else {
            for (list_node_t *sn = list_begin(services); sn != list_end(services); sn = list_next(sn)) {
                list_node_t *next_sn = list_next(sn);
                if(next_sn == list_end(services)) {
                    list_append(services, p_new_srvc);
                    return;
                }
                tBTA_GATTC_SERVICE *service = list_node(sn);
                tBTA_GATTC_SERVICE *next_service = list_node(next_sn);
                if (p_new_srvc->s_handle > service->e_handle && p_new_srvc->e_handle < next_service->s_handle) {
                    list_insert_after(services, sn, p_new_srvc);
                    return;
                }
            }
        }  
    }
}

/*******************************************************************************
**
** Function         bta_gattc_add_srvc_to_cache
**
** Description      Add a service into database cache.
**
** Returns          status
**
*******************************************************************************/
static tBTA_GATT_STATUS bta_gattc_add_srvc_to_cache(tBTA_GATTC_SERV *p_srvc_cb,
                                                    UINT16 s_handle, UINT16 e_handle,
                                                    tBT_UUID *p_uuid,
                                                    BOOLEAN is_primary)
{
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
    APPL_TRACE_DEBUG("Add a service into Service");
#endif

    tBTA_GATTC_SERVICE *p_new_srvc = osi_malloc(sizeof(tBTA_GATTC_SERVICE));
    if (!p_new_srvc) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        return BTA_GATT_NO_RESOURCES;
    }

    /* update service information */
    p_new_srvc->s_handle = s_handle;
    p_new_srvc->e_handle = e_handle;
    p_new_srvc->is_primary = is_primary;
    memcpy(&p_new_srvc->uuid, p_uuid, sizeof(tBT_UUID));
    p_new_srvc->handle = s_handle;
    p_new_srvc->characteristics = list_new(characteristic_free);
    p_new_srvc->included_svc = list_new(bta_gattc_free);

    if (p_srvc_cb->p_srvc_cache == NULL) {
        p_srvc_cb->p_srvc_cache = list_new(service_free);
    }

    if(is_primary) {
        list_append(p_srvc_cb->p_srvc_cache, p_new_srvc);
    } else {
        //add secondary service into list
        bta_gattc_insert_sec_service_to_cache(p_srvc_cb->p_srvc_cache, p_new_srvc);
    }
    return BTA_GATT_OK;
}

static tBTA_GATT_STATUS bta_gattc_add_char_to_cache(tBTA_GATTC_SERV *p_srvc_cb,
                                                    UINT16 attr_handle,
                                                    UINT16 value_handle,
                                                    tBT_UUID *p_uuid,
                                                    UINT8 property)
{
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
    APPL_TRACE_DEBUG("%s: Add a characteristic into Service", __func__);
    APPL_TRACE_DEBUG("handle=%d uuid16=0x%x property=0x%x",
                      value_handle, p_uuid->uu.uuid16, property);
#endif

    tBTA_GATTC_SERVICE *service = bta_gattc_find_matching_service(p_srvc_cb->p_srvc_cache, attr_handle);
    if (!service) {
        APPL_TRACE_ERROR("Illegal action to add char/descr/incl srvc for non-existing service!");
        return GATT_WRONG_STATE;
    }

    /* TODO(jpawlowski): We should use attribute handle, not value handle to refer to characteristic.
       This is just a temporary workaround.
    */
    if (service->e_handle < value_handle)
        service->e_handle = value_handle;

    tBTA_GATTC_CHARACTERISTIC *characteristic = osi_malloc(sizeof(tBTA_GATTC_CHARACTERISTIC));
    if (!characteristic) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        return BTA_GATT_NO_RESOURCES;
    }
    characteristic->handle = value_handle;
    characteristic->properties = property;
    characteristic->descriptors = list_new(bta_gattc_free);
    memcpy(&characteristic->uuid, p_uuid, sizeof(tBT_UUID));

    characteristic->service = service;
    list_append(service->characteristics, characteristic);

    return BTA_GATT_OK;
}
/*******************************************************************************
**
** Function         bta_gattc_add_attr_to_cache
**
** Description      Add an attribute into database cache buffer.
**
** Returns          status
**
*******************************************************************************/
static tBTA_GATT_STATUS bta_gattc_add_attr_to_cache(tBTA_GATTC_SERV *p_srvc_cb,
                                                    UINT16 handle,
                                                    tBT_UUID *p_uuid,
                                                    UINT8 property,
                                                    UINT16 incl_srvc_s_handle,
                                                    UINT16 incl_srvc_e_handle,
                                                    tBTA_GATTC_ATTR_TYPE type)
{
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
    APPL_TRACE_DEBUG("%s: Add a [%s] into Service", __func__, bta_gattc_attr_type[type]);
    APPL_TRACE_DEBUG("handle=%d uuid16=0x%x property=0x%x type=%d",
                      handle, p_uuid->uu.uuid16, property, type);
#endif

    tBTA_GATTC_SERVICE *service = bta_gattc_find_matching_service(p_srvc_cb->p_srvc_cache, handle);
    if (!service) {
        APPL_TRACE_ERROR("Illegal action to add char/descr/incl srvc for non-existing service!");
        return GATT_WRONG_STATE;
    }

    if (type == BTA_GATTC_ATTR_TYPE_INCL_SRVC) {
        tBTA_GATTC_INCLUDED_SVC *isvc =
            osi_malloc(sizeof(tBTA_GATTC_INCLUDED_SVC));
        if (!isvc) {
            APPL_TRACE_WARNING("%s(), no resource.", __func__);
            return BTA_GATT_NO_RESOURCES;
        }
        isvc->handle = handle;
        memcpy(&isvc->uuid, p_uuid, sizeof(tBT_UUID));
        isvc->incl_srvc_s_handle = incl_srvc_s_handle;
        isvc->incl_srvc_e_handle = incl_srvc_e_handle;
        isvc->owning_service = service;
        isvc->included_service = bta_gattc_find_matching_service(
                                    p_srvc_cb->p_srvc_cache, incl_srvc_s_handle);
        if (!isvc->included_service) {
            // if can't find included service, wait to update later
            p_srvc_cb->update_incl_srvc = true;
        }

        list_append(service->included_svc, isvc);
    } else if (type == BTA_GATTC_ATTR_TYPE_CHAR_DESCR) {
        tBTA_GATTC_DESCRIPTOR *descriptor =
            osi_malloc(sizeof(tBTA_GATTC_DESCRIPTOR));
        if (!descriptor) {
            APPL_TRACE_WARNING("%s(), no resource.", __func__);
            return BTA_GATT_NO_RESOURCES;
        }
        descriptor->handle = handle;
        memcpy(&descriptor->uuid, p_uuid, sizeof(tBT_UUID));

        if (service->characteristics == NULL ||
            list_is_empty(service->characteristics)) {
            APPL_TRACE_ERROR("%s: Illegal action to add descriptor before adding a characteristic!",
                             __func__);
            osi_free(descriptor);
            return GATT_WRONG_STATE;
        }

        tBTA_GATTC_CHARACTERISTIC *char_node = list_back(service->characteristics);

        descriptor->characteristic = char_node;
        list_append(char_node->descriptors, descriptor);
    }
    return BTA_GATT_OK;
}

/*******************************************************************************
**
** Function         bta_gattc_get_disc_range
**
** Description      get discovery stating and ending handle range.
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_get_disc_range(tBTA_GATTC_SERV *p_srvc_cb, UINT16 *p_s_hdl, UINT16 *p_e_hdl, BOOLEAN is_srvc)
{
    tBTA_GATTC_ATTR_REC *p_rec = NULL;

    if (is_srvc) {
        p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->cur_srvc_idx;
        *p_s_hdl = p_rec->s_handle;
    } else {
        p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->cur_char_idx;
        *p_s_hdl = p_rec->s_handle + 1;
    }

    *p_e_hdl = p_rec->e_handle;
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
    APPL_TRACE_DEBUG("discover range [%d ~ %d]", p_rec->s_handle, p_rec->e_handle);
#endif
    return;
}
/*******************************************************************************
**
** Function         bta_gattc_discover_pri_service
**
** Description      Start primary service discovery
**
** Returns          status of the operation.
**
*******************************************************************************/
tBTA_GATT_STATUS bta_gattc_discover_pri_service(UINT16 conn_id, tBTA_GATTC_SERV *p_server_cb,
        UINT8 disc_type)
{
    tBTA_GATTC_CLCB     *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);
    tBTA_GATT_STATUS    status =  BTA_GATT_ERROR;

    if (p_clcb) {
        if (p_clcb->transport == BTA_TRANSPORT_LE) {
            status = bta_gattc_discover_procedure(conn_id, p_server_cb, disc_type);
        } else {
 #if (SDP_INCLUDED == TRUE)
            status = bta_gattc_sdp_service_disc(conn_id, p_server_cb);
 #endif ///SDP_INCLUDED == TRUE
        }
    }

    return status;
}
/*******************************************************************************
**
** Function         bta_gattc_discover_procedure
**
** Description      Start a particular type of discovery procedure on server.
**
** Returns          status of the operation.
**
*******************************************************************************/
tBTA_GATT_STATUS bta_gattc_discover_procedure(UINT16 conn_id, tBTA_GATTC_SERV *p_server_cb,
                                              UINT8 disc_type)
{
    tGATT_DISC_PARAM param;
    BOOLEAN is_service = TRUE;

    memset(&param, 0, sizeof(tGATT_DISC_PARAM));

    if (disc_type == GATT_DISC_SRVC_ALL || disc_type == GATT_DISC_SRVC_BY_UUID) {
        param.s_handle = 1;
        param.e_handle = 0xFFFF;
    } else {
        if (disc_type == GATT_DISC_CHAR_DSCPT) {
            is_service = FALSE;
        }

        bta_gattc_get_disc_range(p_server_cb, &param.s_handle, &param.e_handle, is_service);

        if (param.s_handle > param.e_handle) {
            return GATT_ERROR;
        }
    }
    return GATTC_Discover (conn_id, disc_type, &param);

}
/*******************************************************************************
**
** Function         bta_gattc_start_disc_include_srvc
**
** Description      Start discovery for included service
**
** Returns          status of the operation.
**
*******************************************************************************/
tBTA_GATT_STATUS bta_gattc_start_disc_include_srvc(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    return bta_gattc_discover_procedure(conn_id, p_srvc_cb, GATT_DISC_INC_SRVC);
}
/*******************************************************************************
**
** Function         bta_gattc_start_disc_char
**
** Description      Start discovery for characteristic
**
** Returns          status of the operation.
**
*******************************************************************************/
tBTA_GATT_STATUS bta_gattc_start_disc_char(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    p_srvc_cb->total_char = 0;

    return bta_gattc_discover_procedure(conn_id, p_srvc_cb, GATT_DISC_CHAR);
}
/*******************************************************************************
**
** Function         bta_gattc_start_disc_char_dscp
**
** Description      Start discovery for characteristic descriptor
**
** Returns          none.
**
*******************************************************************************/
void bta_gattc_start_disc_char_dscp(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    APPL_TRACE_DEBUG("starting discover characteristics descriptor");

    if (bta_gattc_discover_procedure(conn_id, p_srvc_cb, GATT_DISC_CHAR_DSCPT) != 0) {
        bta_gattc_char_dscpt_disc_cmpl(conn_id, p_srvc_cb);
    }

}

void bta_gattc_update_include_service(const list_t *services) {
    if (!services || list_is_empty(services)) {
        return;
    }
    for (list_node_t *sn = list_begin(services); sn != list_end(services); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *service = list_node(sn);
        if(!service && list_is_empty(service->included_svc)) break;
        for (list_node_t *sn = list_begin(service->included_svc); sn != list_end(service->included_svc); sn = list_next(sn)) {
            tBTA_GATTC_INCLUDED_SVC *include_service = list_node(sn);
            if(include_service && !include_service->included_service) {
                //update
                include_service->included_service = bta_gattc_find_matching_service(services, include_service->incl_srvc_s_handle);
                if(!include_service->included_service) { 
                    //not match, free it
                    list_remove(service->included_svc, include_service);
                    osi_free(include_service);    
                }
            }
        }

    }
}

/*******************************************************************************
**
** Function         bta_gattc_explore_srvc
**
** Description      process the service discovery complete event
**
** Returns          status
**
*******************************************************************************/
static void bta_gattc_explore_srvc(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    tBTA_GATTC_ATTR_REC *p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->cur_srvc_idx;
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    APPL_TRACE_DEBUG("Start service discovery: srvc_idx = %d", p_srvc_cb->cur_srvc_idx);

    p_srvc_cb->cur_char_idx = p_srvc_cb->next_avail_idx = p_srvc_cb->total_srvc;

    if (p_clcb == NULL) {
        APPL_TRACE_ERROR("unknown connection ID");
        return;
    }
    /* start expore a service if there is service not been explored */
    if (p_srvc_cb->cur_srvc_idx < p_srvc_cb->total_srvc) {
        /* add the first service into cache */
        if (bta_gattc_add_srvc_to_cache (p_srvc_cb,
                                         p_rec->s_handle,
                                         p_rec->e_handle,
                                         &p_rec->uuid,
                                         p_rec->is_primary) == 0) {
            /* start discovering included services */
            bta_gattc_start_disc_include_srvc(conn_id, p_srvc_cb);
            return;
        }
    }
    // if update_incl_srvc is true, update include service
    if(p_srvc_cb->update_incl_srvc) {
        bta_gattc_update_include_service(p_srvc_cb->p_srvc_cache);
        p_srvc_cb->update_incl_srvc = false;
    }
    /* no service found at all, the end of server discovery*/
    APPL_TRACE_DEBUG("%s no more services found", __func__);

#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
    bta_gattc_display_cache_server(p_srvc_cb->p_srvc_cache);
#endif

    //server discover end, update connection parameters
#if BLE_INCLUDED == TRUE
    if (p_clcb->transport == BTA_TRANSPORT_LE) {
        L2CA_EnableUpdateBleConnParams(p_clcb->p_srcb->server_bda, TRUE);
    }
#endif
#if(GATTC_CACHE_NVS == TRUE)
    /* save cache to NV */
    p_clcb->p_srcb->state = BTA_GATTC_SERV_SAVE;
    bta_gattc_cache_save(p_clcb->p_srcb, p_clcb->bta_conn_id);
#endif
    bta_gattc_reset_discover_st(p_clcb->p_srcb, BTA_GATT_OK);
}
/*******************************************************************************
**
** Function         bta_gattc_incl_srvc_disc_cmpl
**
** Description      process the relationship discovery complete event
**
** Returns          status
**
*******************************************************************************/
static void bta_gattc_incl_srvc_disc_cmpl(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    p_srvc_cb->cur_char_idx = p_srvc_cb->total_srvc;

    /* start discoverying characteristic */
    bta_gattc_start_disc_char(conn_id, p_srvc_cb);
}
/*******************************************************************************
**
** Function         bta_gattc_char_disc_cmpl
**
** Description      process the characteristic discovery complete event
**
** Returns          status
**
*******************************************************************************/
static void bta_gattc_char_disc_cmpl(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    tBTA_GATTC_ATTR_REC *p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->cur_char_idx;

    /* if there are characteristic needs to be explored */
    if (p_srvc_cb->total_char > 0) {
        /* add the first characteristic into cache */
        bta_gattc_add_char_to_cache (p_srvc_cb,
                                     p_rec->char_decl_handle,
                                     p_rec->s_handle,
                                     &p_rec->uuid,
                                     p_rec->property);

        /* start discoverying characteristic descriptor , if failed, disc for next char */
        bta_gattc_start_disc_char_dscp(conn_id, p_srvc_cb);
    } else { /* otherwise start with next service */
        p_srvc_cb->cur_srvc_idx ++;

        bta_gattc_explore_srvc (conn_id, p_srvc_cb);
    }
}
/*******************************************************************************
**
** Function         bta_gattc_char_dscpt_disc_cmpl
**
** Description      process the char descriptor discovery complete event
**
** Returns          status
**
*******************************************************************************/
static void bta_gattc_char_dscpt_disc_cmpl(UINT16 conn_id, tBTA_GATTC_SERV *p_srvc_cb)
{
    tBTA_GATTC_ATTR_REC *p_rec = NULL;

    if (--p_srvc_cb->total_char > 0) {
        p_rec = p_srvc_cb->p_srvc_list + (++ p_srvc_cb->cur_char_idx);
        /* add the next characteristic into cache */
        bta_gattc_add_char_to_cache (p_srvc_cb,
                                     p_rec->char_decl_handle,
                                     p_rec->s_handle,
                                     &p_rec->uuid,
                                     p_rec->property);

        /* start discoverying next characteristic for char descriptor */
        bta_gattc_start_disc_char_dscp(conn_id, p_srvc_cb);
    } else
        /* all characteristic has been explored, start with next service if any */
    {
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
        APPL_TRACE_ERROR("all char has been explored");
#endif
        p_srvc_cb->cur_srvc_idx ++;
        bta_gattc_explore_srvc (conn_id, p_srvc_cb);
    }

}
static BOOLEAN bta_gattc_srvc_in_list(tBTA_GATTC_SERV *p_srvc_cb, UINT16 s_handle,
                                      UINT16 e_handle, tBT_UUID uuid)
{
    tBTA_GATTC_ATTR_REC *p_rec = NULL;
    UINT8   i;
    BOOLEAN exist_srvc = FALSE;
    UNUSED(uuid);

    if (!GATT_HANDLE_IS_VALID(s_handle) || !GATT_HANDLE_IS_VALID(e_handle)) {
        APPL_TRACE_ERROR("invalid included service handle: [0x%04x ~ 0x%04x]", s_handle, e_handle);
        exist_srvc = TRUE;
    } else {
        for (i = 0; i < p_srvc_cb->next_avail_idx; i ++) {
            p_rec = p_srvc_cb->p_srvc_list + i;

            /* a new service should not have any overlap with other service handle range */
            if (p_rec->s_handle == s_handle || p_rec->e_handle == e_handle) {
                exist_srvc = TRUE;
                break;
            }
        }
    }
    return exist_srvc;
}
/*******************************************************************************
**
** Function         bta_gattc_add_srvc_to_list
**
** Description      Add a service into explore pending list
**
** Returns          status
**
*******************************************************************************/
static tBTA_GATT_STATUS bta_gattc_add_srvc_to_list(tBTA_GATTC_SERV *p_srvc_cb,
                                                   UINT16 s_handle, UINT16 e_handle,
                                                   tBT_UUID uuid, BOOLEAN is_primary)
{
    tBTA_GATTC_ATTR_REC *p_rec = NULL;
    tBTA_GATT_STATUS    status = BTA_GATT_OK;

    if (p_srvc_cb->p_srvc_list && p_srvc_cb->next_avail_idx < BTA_GATTC_MAX_CACHE_CHAR) {
        p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->next_avail_idx;

        APPL_TRACE_DEBUG("%s handle=%d, service type=0x%04x",
                         __func__, s_handle, uuid.uu.uuid16);

        p_rec->s_handle     = s_handle;
        p_rec->e_handle     = e_handle;
        p_rec->is_primary   = is_primary;
        memcpy(&p_rec->uuid, &uuid, sizeof(tBT_UUID));

        p_srvc_cb->total_srvc ++;
        p_srvc_cb->next_avail_idx ++;
    } else {
        /* allocate bigger buffer ?? */
        status = GATT_DB_FULL;

        APPL_TRACE_ERROR("service not added, no resources or wrong state");
    }
    return status;
}
/*******************************************************************************
**
** Function         bta_gattc_add_char_to_list
**
** Description      Add a characteristic into explore pending list
**
** Returns          status
**
*******************************************************************************/
static tBTA_GATT_STATUS bta_gattc_add_char_to_list(tBTA_GATTC_SERV *p_srvc_cb,
                                                   UINT16 decl_handle, UINT16 value_handle,
                                                   tBT_UUID uuid, UINT8 property)
{
    tBTA_GATTC_ATTR_REC *p_rec = NULL;
    tBTA_GATT_STATUS    status = BTA_GATT_OK;

    if (p_srvc_cb->p_srvc_list == NULL) {
        APPL_TRACE_ERROR("No service available, unexpected char discovery result");
        status = BTA_GATT_INTERNAL_ERROR;
    } else if (p_srvc_cb->next_avail_idx < BTA_GATTC_MAX_CACHE_CHAR) {

        p_rec = p_srvc_cb->p_srvc_list + p_srvc_cb->next_avail_idx;

        p_srvc_cb->total_char ++;

        p_rec->s_handle = value_handle;
        p_rec->char_decl_handle = decl_handle;
        p_rec->property = property;
        p_rec->e_handle = (p_srvc_cb->p_srvc_list + p_srvc_cb->cur_srvc_idx)->e_handle;
        memcpy(&p_rec->uuid, &uuid, sizeof(tBT_UUID));

        /* update the endind handle of pervious characteristic if available */
        if (p_srvc_cb->total_char > 1) {
            p_rec -= 1;
            p_rec->e_handle = decl_handle - 1;
        }
        p_srvc_cb->next_avail_idx ++;
    } else {
        APPL_TRACE_ERROR("char not added, no resources");
        /* allocate bigger buffer ?? */
        status = BTA_GATT_DB_FULL;
    }
    return status;

}
/*******************************************************************************
**
** Function         bta_gattc_sdp_callback
**
** Description      Process the discovery result from sdp
**
** Returns          void
**
*******************************************************************************/
#if (SDP_INCLUDED == TRUE)
void bta_gattc_sdp_callback(UINT16 sdp_status, void* user_data)
{
    tSDP_DISC_REC       *p_sdp_rec = NULL;
    tBT_UUID            service_uuid;
    tSDP_PROTOCOL_ELEM  pe;
    UINT16              start_handle = 0, end_handle = 0;
    tBTA_GATTC_CB_DATA  *cb_data = user_data;
    tBTA_GATTC_SERV     *p_srvc_cb = bta_gattc_find_scb_by_cid(cb_data->sdp_conn_id);

    if (((sdp_status == SDP_SUCCESS) || (sdp_status == SDP_DB_FULL)) && p_srvc_cb != NULL) {
        do {
            /* find a service record, report it */
            p_sdp_rec = SDP_FindServiceInDb(cb_data->p_sdp_db, 0, p_sdp_rec);
            if (p_sdp_rec) {
                if (SDP_FindServiceUUIDInRec(p_sdp_rec, &service_uuid)) {

                    if (SDP_FindProtocolListElemInRec(p_sdp_rec, UUID_PROTOCOL_ATT, &pe)) {
                        start_handle    = (UINT16) pe.params[0];
                        end_handle      = (UINT16) pe.params[1];

#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
                        APPL_TRACE_EVENT("Found ATT service [0x%04x] handle[0x%04x ~ 0x%04x]",
                                         service_uuid.uu.uuid16, start_handle, end_handle);
#endif

                        if (GATT_HANDLE_IS_VALID(start_handle) && GATT_HANDLE_IS_VALID(end_handle) &&
                                p_srvc_cb != NULL) {
                            /* discover services result, add services into a service list */
                            bta_gattc_add_srvc_to_list(p_srvc_cb,
                                                       start_handle,
                                                       end_handle,
                                                       service_uuid,
                                                       TRUE);
                        } else {
                            APPL_TRACE_ERROR("invalid start_handle = %d end_handle = %d",
                                             start_handle, end_handle);
                        }
                    }


                }
            }
        } while (p_sdp_rec);
    }

    if ( p_srvc_cb != NULL)
    {
        /* start discover primary service */
        bta_gattc_explore_srvc(cb_data->sdp_conn_id, p_srvc_cb);
    }
    else
    {
        APPL_TRACE_ERROR("GATT service discovery is done on unknown connection");
    }

    /* both were allocated in bta_gattc_sdp_service_disc */
    osi_free(cb_data->p_sdp_db);
    osi_free(cb_data);
}
#endif  ///SDP_INCLUDED == TRUE

/*******************************************************************************
**
** Function         bta_gattc_sdp_service_disc
**
** Description      Start DSP Service Discovert
**
** Returns          void
**
*******************************************************************************/
#if (SDP_INCLUDED == TRUE)
static tBTA_GATT_STATUS bta_gattc_sdp_service_disc(UINT16 conn_id, tBTA_GATTC_SERV *p_server_cb)
{
    tSDP_UUID       uuid;
    UINT16          num_attrs = 2;
    UINT16          attr_list[2];

    memset (&uuid, 0, sizeof(tSDP_UUID));

    uuid.len = LEN_UUID_16;
    uuid.uu.uuid16 = UUID_PROTOCOL_ATT;

    /*
     * On success, cb_data will be freed inside bta_gattc_sdp_callback,
     * otherwise it will be freed within this function.
     */
    tBTA_GATTC_CB_DATA *cb_data =
        (tBTA_GATTC_CB_DATA *)osi_malloc(sizeof(tBTA_GATTC_CB_DATA));
    cb_data->p_sdp_db = (tSDP_DISCOVERY_DB *)osi_malloc(BTA_GATT_SDP_DB_SIZE);
    if (!cb_data || cb_data->p_sdp_db) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        return BTA_GATT_NO_RESOURCES;
    }
    attr_list[0] = ATTR_ID_SERVICE_CLASS_ID_LIST;
    attr_list[1] = ATTR_ID_PROTOCOL_DESC_LIST;

    SDP_InitDiscoveryDb(cb_data->p_sdp_db, BTA_GATT_SDP_DB_SIZE, 1,
                         &uuid, num_attrs, attr_list);

    if (!SDP_ServiceSearchAttributeRequest2(p_server_cb->server_bda,
                                          cb_data->p_sdp_db, &bta_gattc_sdp_callback, cb_data))
    {
        osi_free(cb_data->p_sdp_db);
        osi_free(cb_data);
        return BTA_GATT_ERROR;
    }

    cb_data->sdp_conn_id = conn_id;
    return BTA_GATT_OK;
}
#endif  ///SDP_INCLUDED == TRUE

/*******************************************************************************
**
** Function         bta_gattc_disc_res_cback
**                  bta_gattc_disc_cmpl_cback
**
** Description      callback functions to GATT client stack.
**
** Returns          void
**
*******************************************************************************/
void bta_gattc_disc_res_cback (UINT16 conn_id, tGATT_DISC_TYPE disc_type, tGATT_DISC_RES *p_data)
{
    tBTA_GATTC_SERV *p_srvc_cb = NULL;
    BOOLEAN          pri_srvc;
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    p_srvc_cb = bta_gattc_find_scb_by_cid(conn_id);

    if (p_srvc_cb != NULL && p_clcb != NULL && p_clcb->state == BTA_GATTC_DISCOVER_ST) {
        p_srvc_cb->total_attr++;
        switch (disc_type) {
        case GATT_DISC_SRVC_ALL:
            /* discover services result, add services into a service list */
            bta_gattc_add_srvc_to_list(p_srvc_cb,
                                       p_data->handle,
                                       p_data->value.group_value.e_handle,
                                       p_data->value.group_value.service_type,
                                       TRUE);

            break;
        case GATT_DISC_SRVC_BY_UUID:
            bta_gattc_add_srvc_to_list(p_srvc_cb,
                                       p_data->handle,
                                       p_data->value.group_value.e_handle,
                                       p_data->value.group_value.service_type,
                                       TRUE);
            break;

        case GATT_DISC_INC_SRVC:
            /* add included service into service list if it's secondary or it never showed up
               in the primary service search */
            pri_srvc = bta_gattc_srvc_in_list(p_srvc_cb,
                                              p_data->value.incl_service.s_handle,
                                              p_data->value.incl_service.e_handle,
                                              p_data->value.incl_service.service_type);

            if (!pri_srvc)
                bta_gattc_add_srvc_to_list(p_srvc_cb,
                                           p_data->value.incl_service.s_handle,
                                           p_data->value.incl_service.e_handle,
                                           p_data->value.incl_service.service_type,
                                           FALSE);
            /* add into database */
            bta_gattc_add_attr_to_cache(p_srvc_cb,
                                        p_data->handle,
                                        &p_data->value.incl_service.service_type,
                                        pri_srvc,
                                        p_data->value.incl_service.s_handle,
                                        p_data->value.incl_service.e_handle,
                                        BTA_GATTC_ATTR_TYPE_INCL_SRVC);
            break;

        case GATT_DISC_CHAR:
            /* add char value into database */
            bta_gattc_add_char_to_list(p_srvc_cb,
                                       p_data->handle,
                                       p_data->value.dclr_value.val_handle,
                                       p_data->value.dclr_value.char_uuid,
                                       p_data->value.dclr_value.char_prop);
            break;

        case GATT_DISC_CHAR_DSCPT:
            bta_gattc_add_attr_to_cache(p_srvc_cb,
                                        p_data->handle, 
                                        &p_data->type, 
                                        0,
                                        0 /* incl_srvc_s_handle */,
                                        0 /* incl_srvc_e_handle */,
                                        BTA_GATTC_ATTR_TYPE_CHAR_DESCR);
            break;
        }
    }
}
void bta_gattc_disc_cmpl_cback (UINT16 conn_id, tGATT_DISC_TYPE disc_type, tGATT_STATUS status)
{
    tBTA_GATTC_SERV *p_srvc_cb;
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if ( p_clcb && (status != GATT_SUCCESS || p_clcb->status != GATT_SUCCESS) ) {
        if (status == GATT_SUCCESS)
            p_clcb->status = status;
        bta_gattc_sm_execute(p_clcb, BTA_GATTC_DISCOVER_CMPL_EVT, NULL);
        return;
    }
    p_srvc_cb = bta_gattc_find_scb_by_cid(conn_id);

    if (p_srvc_cb != NULL) {
        switch (disc_type) {
        case GATT_DISC_SRVC_ALL:
        case GATT_DISC_SRVC_BY_UUID:
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
            bta_gattc_display_explore_record(p_srvc_cb->p_srvc_list, p_srvc_cb->next_avail_idx);
#endif
            bta_gattc_explore_srvc(conn_id, p_srvc_cb);
            break;

        case GATT_DISC_INC_SRVC:
            bta_gattc_incl_srvc_disc_cmpl(conn_id, p_srvc_cb);

            break;

        case GATT_DISC_CHAR:
#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
            bta_gattc_display_explore_record(p_srvc_cb->p_srvc_list, p_srvc_cb->next_avail_idx);
#endif
            bta_gattc_char_disc_cmpl(conn_id, p_srvc_cb);
            break;

        case GATT_DISC_CHAR_DSCPT:
            bta_gattc_char_dscpt_disc_cmpl(conn_id, p_srvc_cb);
            break;
        }
    }
}
/*******************************************************************************
**
** Function         bta_gattc_search_service
**
** Description      search local cache for matching service record.
**
** Returns          FALSE if map can not be found.
**
*******************************************************************************/
void bta_gattc_search_service(tBTA_GATTC_CLCB *p_clcb, tBT_UUID *p_uuid)
{
    tBTA_GATTC          cb_data;

    if (!p_clcb->p_srcb->p_srvc_cache || list_is_empty(p_clcb->p_srcb->p_srvc_cache))
        return;

    for (list_node_t *sn = list_begin(p_clcb->p_srcb->p_srvc_cache);
         sn != list_end(p_clcb->p_srcb->p_srvc_cache); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cache = list_node(sn);

        if (!bta_gattc_uuid_compare(p_uuid, &p_cache->uuid, FALSE))
            continue;

#if (defined BTA_GATT_DEBUG && BTA_GATT_DEBUG == TRUE)
        APPL_TRACE_DEBUG("found service [0x%04x], inst[%d] handle [%d]",
                          p_cache->uuid.uu.uuid16,
                          p_cache->handle,
                          p_cache->s_handle);
#endif
        if (!p_clcb->p_rcb->p_cback)
            continue;

        memset(&cb_data, 0, sizeof(tBTA_GATTC));

        cb_data.srvc_res.conn_id = p_clcb->bta_conn_id;
        cb_data.srvc_res.service_uuid.inst_id = p_cache->handle;
        cb_data.srvc_res.start_handle = p_cache->s_handle;
        cb_data.srvc_res.end_handle = p_cache->e_handle;
        cb_data.srvc_res.is_primary = p_cache->is_primary;
        memcpy(&cb_data.srvc_res.service_uuid.uuid, &p_cache->uuid, sizeof(tBT_UUID));
        (* p_clcb->p_rcb->p_cback)(BTA_GATTC_SEARCH_RES_EVT, &cb_data);
    }
}

list_t* bta_gattc_get_services_srcb(tBTA_GATTC_SERV *p_srcb) {
    if (!p_srcb || !p_srcb->p_srvc_cache || list_is_empty(p_srcb->p_srvc_cache))
        return NULL;

    return p_srcb->p_srvc_cache;
}

const list_t* bta_gattc_get_services(UINT16 conn_id) {
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL )
        return NULL;

    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;

    return bta_gattc_get_services_srcb(p_srcb);
}

tBTA_GATTC_SERVICE*  bta_gattc_find_matching_service(const list_t *services, UINT16 handle) {
    if (!services || list_is_empty(services))
        return NULL;

    for (list_node_t *sn = list_begin(services);
         sn != list_end(services); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *service = list_node(sn);

        if (handle >= service->s_handle && handle <= service->e_handle)
            return service;
    }

    return NULL;
}

const tBTA_GATTC_SERVICE*  bta_gattc_get_service_for_handle_srcb(tBTA_GATTC_SERV *p_srcb, UINT16 handle) 
{
    const list_t *services = bta_gattc_get_services_srcb(p_srcb);

    return bta_gattc_find_matching_service(services, handle);
}

const tBTA_GATTC_SERVICE*  bta_gattc_get_service_for_handle(UINT16 conn_id, UINT16 handle) 
{
    const list_t *services = bta_gattc_get_services(conn_id);

    return bta_gattc_find_matching_service(services, handle);
}

tBTA_GATTC_CHARACTERISTIC*  bta_gattc_get_characteristic_srcb(tBTA_GATTC_SERV *p_srcb, UINT16 handle) 
{
    const tBTA_GATTC_SERVICE* service = bta_gattc_get_service_for_handle_srcb(p_srcb, handle);

    if (!service)
        return NULL;

    for (list_node_t *cn = list_begin(service->characteristics);
         cn != list_end(service->characteristics); cn = list_next(cn)) {
        tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);
        if (handle == p_char->handle)
            return p_char;
    }

    return NULL;
}

tBTA_GATTC_CHARACTERISTIC*  bta_gattc_get_characteristic(UINT16 conn_id, UINT16 handle) 
{
   tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL )
        return NULL;

    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;
    return bta_gattc_get_characteristic_srcb(p_srcb, handle);
}

tBTA_GATTC_DESCRIPTOR*  bta_gattc_get_descriptor_srcb(tBTA_GATTC_SERV *p_srcb, UINT16 handle) 
{
    const tBTA_GATTC_SERVICE* service = bta_gattc_get_service_for_handle_srcb(p_srcb, handle);

    if (!service) {
        return NULL;
    }

    for (list_node_t *cn = list_begin(service->characteristics);
         cn != list_end(service->characteristics); cn = list_next(cn)) {
        tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);
        for (list_node_t *dn = list_begin(p_char->descriptors);
             dn != list_end(p_char->descriptors); dn = list_next(dn)) {
            tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);
            if (handle == p_desc->handle)
                return p_desc;
        }
    }

    return NULL;
}

tBTA_GATTC_DESCRIPTOR*  bta_gattc_get_descriptor(UINT16 conn_id, UINT16 handle) 
{
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL )
        return NULL;

    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;
    return bta_gattc_get_descriptor_srcb(p_srcb, handle);
}

void bta_gattc_get_service_with_uuid(UINT16 conn_id, tBT_UUID *svc_uuid,
                                     btgatt_db_element_t **svc_db,
                                     int *count)
{
    const list_t* svc = bta_gattc_get_services(conn_id);
    if(!svc) {
        APPL_TRACE_WARNING("%s(), no service.", __func__);
        *svc_db = NULL;
        *count = 0;
        return;
    }
    size_t db_size = list_length(svc);
    void *buffer = osi_malloc(db_size*sizeof(btgatt_db_element_t));
    if (!buffer) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        *svc_db = NULL;
        *count = 0;
        return;
    }
    btgatt_db_element_t *curr_db_attr = buffer;
    db_size = 0;
    for (list_node_t *sn = list_begin(svc);
         sn != list_end(svc); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);
        if (svc_uuid == NULL || bta_gattc_uuid_compare(svc_uuid, &p_cur_srvc->uuid, TRUE)) {
            bta_gattc_fill_gatt_db_el(curr_db_attr,
                                      p_cur_srvc->is_primary ?
                                      BTGATT_DB_PRIMARY_SERVICE :
                                      BTGATT_DB_SECONDARY_SERVICE,
                                      0 /* att_handle */,
                                      p_cur_srvc->s_handle /* s_handle */,
                                      p_cur_srvc->e_handle /* e_handle */,
                                      p_cur_srvc->s_handle,
                                      p_cur_srvc->uuid,
                                      0 /* prop */);
            db_size++;
            curr_db_attr++;
        }
    }

    *svc_db = buffer;
    *count = db_size;
}

/*******************************************************************************
**
** Function         bta_gattc_fill_gatt_db_el
**
** Description      fill a btgatt_db_element_t value
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_fill_gatt_db_el(btgatt_db_element_t *p_attr,
                               bt_gatt_db_attribute_type_t type,
                               UINT16 att_handle,
                               UINT16 s_handle, UINT16 e_handle,
                               UINT16 id, tBT_UUID uuid, UINT8 prop)
{
    p_attr->type             = type;
    p_attr->attribute_handle = att_handle;
    p_attr->start_handle     = s_handle;
    p_attr->end_handle       = e_handle;
    p_attr->id               = id;
    p_attr->properties       = prop;
    bta_to_btif_uuid(&p_attr->uuid, &uuid);
}

void bta_gattc_get_db_with_opration(UINT16 conn_id,
                                                      bt_gatt_get_db_op_t op,
                                                      UINT16 char_handle,
                                                      tBT_UUID *incl_uuid,
                                                      tBT_UUID *char_uuid,
                                                      tBT_UUID *descr_uuid,
                                                      UINT16 start_handle, UINT16 end_handle,
                                                      btgatt_db_element_t **char_db,
                                                      int *count)
{
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL) {
        *count = 0;
        *char_db = NULL;
        return;
    }

    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;
    if (!p_srcb->p_srvc_cache || list_is_empty(p_srcb->p_srvc_cache)) {
        APPL_TRACE_DEBUG("the service cache is empty.");
        *count = 0;
        *char_db = NULL;
        return;
    }

    size_t db_size = ((end_handle - start_handle + 1) < p_srcb->total_attr) ? (end_handle - start_handle + 1) : p_srcb->total_attr;
    if (!db_size) {
        APPL_TRACE_DEBUG("the db size is 0.");
        *count = 0;
        *char_db = NULL;
        return;
    }

    void *buffer = osi_malloc(db_size*sizeof(btgatt_db_element_t));

    if (!buffer) {
        APPL_TRACE_DEBUG("the buffer is NULL.");
        *count = 0;
        *char_db = NULL;
        return;
    }
    btgatt_db_element_t *curr_db_attr = buffer;
    db_size = 0;
    for (list_node_t *sn = list_begin(p_srcb->p_srvc_cache);
         sn != list_end(p_srcb->p_srvc_cache); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        if (p_cur_srvc->e_handle < start_handle) {
            continue;
        }

        if (p_cur_srvc->s_handle > end_handle) {
            break;
        }

        if (op == GATT_OP_GET_INCLUDE_SVC) {
            if (!p_cur_srvc->included_svc || list_is_empty(p_cur_srvc->included_svc))
                continue;

            for (list_node_t *isn = list_begin(p_cur_srvc->included_svc);
                 isn != list_end(p_cur_srvc->included_svc); isn = list_next(isn)) {
                tBTA_GATTC_INCLUDED_SVC *p_isvc = list_node(isn);

                if (p_isvc->handle < start_handle) {
                    continue;
                }

                if (p_isvc->handle > end_handle) {
                    *char_db = buffer;
                    *count = db_size;
                    return;
                }
                if (!incl_uuid || bta_gattc_uuid_compare(&p_isvc->uuid, incl_uuid, TRUE)) {
                    bta_gattc_fill_gatt_db_el(curr_db_attr,
                                              BTGATT_DB_INCLUDED_SERVICE,
                                              p_isvc->handle,
                                              p_isvc->incl_srvc_s_handle /* s_handle */,
                                              p_isvc->incl_srvc_e_handle /* e_handle */,
                                              p_isvc->handle,
                                              p_isvc->uuid,
                                              0 /* property */);
                    curr_db_attr++;
                    db_size++;
                }
            }
            continue;
        }

        if (!p_cur_srvc->characteristics || list_is_empty(p_cur_srvc->characteristics)) {
            continue;
        }

        for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
             cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
            tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);
            if(op == GATT_OP_GET_ALL_CHAR || op == GATT_OP_GET_CHAR_BY_UUID) {
                if (p_char->handle < start_handle) {
                    continue;
                }
            }

            if (p_char->handle > end_handle) {
                *char_db = buffer;
                *count = db_size;
                return;
            }
            if ((op == GATT_OP_GET_ALL_CHAR || op == GATT_OP_GET_CHAR_BY_UUID) &&
                (char_uuid == NULL || bta_gattc_uuid_compare(&p_char->uuid, char_uuid, TRUE))) {
                APPL_TRACE_DEBUG("%s(), uuid match.", __func__);
                bta_gattc_fill_gatt_db_el(curr_db_attr,
                                          BTGATT_DB_CHARACTERISTIC,
                                          p_char->handle,
                                          0 /* s_handle */,
                                          0 /* e_handle */,
                                          p_char->handle,
                                          p_char->uuid,
                                          p_char->properties);
                curr_db_attr++;
                db_size++;
                continue;
            }

            if (!p_char->descriptors || list_is_empty(p_char->descriptors)) {
                continue;
            }

            if ((op == GATT_OP_GET_DESCRI_BY_HANDLE || op == GATT_OP_GET_ALL_DESCRI) && (p_char->handle != char_handle)) {
                continue;
            }

            if ((op == GATT_OP_GET_DESCRI_BY_UUID) &&
                !bta_gattc_uuid_compare(&p_char->uuid, char_uuid, TRUE)) {
                continue;
            }

            if (op == GATT_OP_GET_ALL_DESCRI || op == GATT_OP_GET_DESCRI_BY_UUID || op == GATT_OP_GET_DESCRI_BY_HANDLE) {
                for (list_node_t *dn = list_begin(p_char->descriptors);
                     dn != list_end(p_char->descriptors); dn = list_next(dn)) {
                    tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);

                    if (p_desc->handle < start_handle) {
                        continue;
                    }
                    if (p_desc->handle > end_handle) {
                        *char_db = buffer;
                        *count = db_size;
                        return;
                    }
                    if (((op == GATT_OP_GET_ALL_DESCRI || op == GATT_OP_GET_DESCRI_BY_UUID) &&
                        (descr_uuid == NULL || bta_gattc_uuid_compare(&p_desc->uuid, descr_uuid, TRUE))) ||
                        (op == GATT_OP_GET_DESCRI_BY_HANDLE && bta_gattc_uuid_compare(&p_desc->uuid, descr_uuid, TRUE))) {
                        bta_gattc_fill_gatt_db_el(curr_db_attr,
                                                  BTGATT_DB_DESCRIPTOR,
                                                  p_desc->handle,
                                                  0 /* s_handle */,
                                                  0 /* e_handle */,
                                                  p_desc->handle,
                                                  p_desc->uuid,
                                                  0 /* property */);
                        curr_db_attr++;
                        db_size++;
                    }
                }
            }
            
        }
    }

    *char_db = buffer;
    *count = db_size;
}

static size_t bta_gattc_get_db_size_with_type(list_t *services,
                                              bt_gatt_db_attribute_type_t type,
                                              tBT_UUID *char_uuid,
                                              UINT16 start_handle, UINT16 end_handle)
{
    if (!services || list_is_empty(services)) {
        return 0;
    }

    size_t db_size = 0;
    UINT16 svc_length = list_length(services) - 1;

    for (list_node_t *sn = list_begin(services);
         sn != list_end(services); sn = list_next(sn), svc_length--) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        if (p_cur_srvc->e_handle < start_handle) {
            continue;
        }

        if (p_cur_srvc->s_handle > end_handle) {
            break;
        }

        if (type == BTGATT_DB_PRIMARY_SERVICE || type == BTGATT_DB_SECONDARY_SERVICE) {
            if ((type == BTGATT_DB_PRIMARY_SERVICE && p_cur_srvc->is_primary) || 
                (type == BTGATT_DB_SECONDARY_SERVICE && !p_cur_srvc->is_primary)) {
                // if the current service is the last service in the db, need to ensure the current service start handle is not less than the start_handle.
                if (!svc_length) {
                    if (p_cur_srvc->s_handle >= start_handle) {
                        db_size++;
                    }
                } else {
                    db_size++;
                }
            }
            continue;
        }

        if (p_cur_srvc->included_svc && (type == BTGATT_DB_INCLUDED_SERVICE)) {
            for (list_node_t *isn = list_begin(p_cur_srvc->included_svc);
                 isn != list_end(p_cur_srvc->included_svc); isn = list_next(isn)) {
                tBTA_GATTC_INCLUDED_SVC *p_isvc = list_node(isn);

                if (p_isvc->handle < start_handle) {
                    continue;
                }

                if (p_isvc->handle > end_handle) {
                    return db_size;
                }
                db_size++;
            }
            continue;
        }

        if (!p_cur_srvc->characteristics || list_is_empty(p_cur_srvc->characteristics)) {
            continue;
        }

        if (char_uuid != NULL) {
            for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
                cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
                tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);

                if (p_char->handle < start_handle) {
                    continue;
                }

                if (p_char->handle > end_handle) {
                    return db_size;
                }

                if ((type == BTGATT_DB_CHARACTERISTIC) && bta_gattc_uuid_compare(&p_char->uuid, char_uuid, TRUE)) {
                    db_size++;
                    continue;
                }

                if (p_char->descriptors && (type == BTGATT_DB_DESCRIPTOR) && bta_gattc_uuid_compare(&p_char->uuid, char_uuid, TRUE)) {
                    for (list_node_t *dn = list_begin(p_char->descriptors);
                         dn != list_end(p_char->descriptors); dn = list_next(dn)) {
                        tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);

                        if (p_desc->handle < start_handle) {
                            continue;
                        }

                        if (p_desc->handle > end_handle) {
                            return db_size;
                        }
                        db_size++;
                    }
                }
            }
        } else {
            if (type == BTGATT_DB_CHARACTERISTIC) {
                for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
                     cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
                    tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);

                    if (p_char->handle < start_handle) {
                        continue;
                    }

                    if (p_char->handle > end_handle) {
                        return db_size;
                    }
                    db_size++;
                }
            }
        }

    }

    return db_size;
}

/*******************************************************************************
** Returns          number of elements inside db from start_handle to end_handle
*******************************************************************************/
static size_t bta_gattc_get_db_size(list_t *services,
                                    UINT16 start_handle, UINT16 end_handle) 
{
    if (!services || list_is_empty(services))
        return 0;

    size_t db_size = 0;
    UINT16 svc_length = list_length(services) - 1;
    for (list_node_t *sn = list_begin(services);
         sn != list_end(services); sn = list_next(sn), svc_length--) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        if (p_cur_srvc->e_handle < start_handle) {
            continue;
        }

        if (p_cur_srvc->s_handle > end_handle) {
            break;
        }

        if (!svc_length) {
            if (p_cur_srvc->s_handle >= start_handle) {
                db_size++;
            }
        } else {
            db_size++;
        }
        
        if (!p_cur_srvc->characteristics || list_is_empty(p_cur_srvc->characteristics))
            continue;

        for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
             cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
            tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);

            if (p_char->handle < start_handle) {
                continue;
            }
            if (p_char->handle > end_handle) {
                return db_size;
            }
            db_size++;

            if (p_char->descriptors) {
                for (list_node_t *dn = list_begin(p_char->descriptors);
                     dn != list_end(p_char->descriptors); dn = list_next(dn)) {
                    tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);
                    if (p_desc->handle < start_handle) {
                        continue;
                    }
                    if (p_desc->handle > end_handle) {
                        return db_size;
                    }
                    db_size++;
                }
            }
        }

        if (p_cur_srvc->included_svc) {
            for (list_node_t *isn = list_begin(p_cur_srvc->included_svc);
                 isn != list_end(p_cur_srvc->included_svc); isn = list_next(isn)) {
                tBTA_GATTC_INCLUDED_SVC *p_isvc = list_node(isn);

                if (p_isvc->handle < start_handle) {
                    continue;
                }

                if (p_isvc->handle > end_handle) {
                    return db_size;
                }
                db_size++;
            }
        }
    }

    return db_size;
}

void bta_gattc_get_db_size_handle(UINT16 conn_id, UINT16 start_handle, UINT16 end_handle, int *count)
{
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL) {
        *count = 0;
        return;
    }
    
    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;
    if (!p_srcb->p_srvc_cache || list_is_empty(p_srcb->p_srvc_cache)) {
        *count = 0;
        return;
    }

    *count = bta_gattc_get_db_size(p_srcb->p_srvc_cache, start_handle, end_handle);
}

void bta_gattc_get_db_size_with_type_handle(UINT16 conn_id, bt_gatt_db_attribute_type_t type,
                                            UINT16 start_handle, UINT16 end_handle, UINT16 char_handle, int *count)
{
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL) {
        *count = 0;
        return;
    }
    
    tBTA_GATTC_SERV *p_srcb = p_clcb->p_srcb;
    if (!p_srcb->p_srvc_cache || list_is_empty(p_srcb->p_srvc_cache)) {
        *count = 0;
        return;
    }

    if (type == BTGATT_DB_DESCRIPTOR) {
        if (char_handle == BTA_GATTC_INVALID_HANDLE) {
            *count = 0;
            return;
        } else {
            tBTA_GATTC_CHARACTERISTIC *char_db = bta_gattc_get_characteristic(conn_id, char_handle);
            *count = char_db ? list_length(char_db->descriptors) : 0;
            return;
        }
    }
    *count = bta_gattc_get_db_size_with_type(p_srcb->p_srvc_cache, type, NULL, start_handle, end_handle);
    
}

/*******************************************************************************
**
** Function         bta_gattc_get_gatt_db_impl
**
** Description      copy the server GATT database into db parameter.
**
** Parameters       p_srvc_cb: server.
**                  db: output parameter which will contain GATT database copy.
**                      Caller is responsible for freeing it.
**                  count: output parameter which will contain number of
**                  elements in database.
**
** Returns          None.
**
*******************************************************************************/
static void bta_gattc_get_gatt_db_impl(tBTA_GATTC_SERV *p_srvc_cb,
                                       UINT16 start_handle, UINT16 end_handle,
                                       btgatt_db_element_t **db,
                                       int *count)
{
    APPL_TRACE_DEBUG("%s: start_handle 0x%04x, end_handle 0x%04x",
                     __func__, start_handle, end_handle);

    if (!p_srvc_cb->p_srvc_cache || list_is_empty(p_srvc_cb->p_srvc_cache)) {
        *count = 0;
        *db = NULL;
        return;
    }

    size_t db_size = bta_gattc_get_db_size(p_srvc_cb->p_srvc_cache, start_handle, end_handle);

    void* buffer = osi_malloc(db_size * sizeof(btgatt_db_element_t));
    if (!buffer) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        *db = NULL;
        *count = 0;
        return;
    }
    btgatt_db_element_t *curr_db_attr = buffer;

    for (list_node_t *sn = list_begin(p_srvc_cb->p_srvc_cache);
         sn != list_end(p_srvc_cb->p_srvc_cache); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        if (p_cur_srvc->e_handle < start_handle) {
            continue;
        }

        if (p_cur_srvc->s_handle > end_handle) {
            break;
        }

        bta_gattc_fill_gatt_db_el(curr_db_attr,
                                  p_cur_srvc->is_primary ?
                                  BTGATT_DB_PRIMARY_SERVICE :
                                  BTGATT_DB_SECONDARY_SERVICE,
                                  0 /* att_handle */,
                                  p_cur_srvc->s_handle,
                                  p_cur_srvc->e_handle,
                                  p_cur_srvc->s_handle,
                                  p_cur_srvc->uuid,
                                  0 /* prop */);
        curr_db_attr++;

        if (p_cur_srvc->characteristics && !list_is_empty(p_cur_srvc->characteristics)) {

            for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
                 cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
                tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);

                if (p_char->handle < start_handle) {
                    continue;
                }

                if (p_char->handle > end_handle) {
                    *db = buffer;
                    *count = db_size;
                    return;
                }
                bta_gattc_fill_gatt_db_el(curr_db_attr,
                                          BTGATT_DB_CHARACTERISTIC,
                                          p_char->handle,
                                          0 /* s_handle */,
                                          0 /* e_handle */,
                                          p_char->handle,
                                          p_char->uuid,
                                          p_char->properties);
                curr_db_attr++;

                if (!p_char->descriptors || list_is_empty(p_char->descriptors))
                    continue;

                for (list_node_t *dn = list_begin(p_char->descriptors);
                     dn != list_end(p_char->descriptors); dn = list_next(dn)) {
                    tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);

                    if (p_desc->handle < start_handle) {
                        continue;
                    }

                    if (p_desc->handle > end_handle) {
                        *db = buffer;
                        *count = db_size;
                        return;
                    }
                    bta_gattc_fill_gatt_db_el(curr_db_attr,
                                              BTGATT_DB_DESCRIPTOR,
                                              p_desc->handle,
                                              0 /* s_handle */,
                                              0 /* e_handle */,
                                              p_desc->handle,
                                              p_desc->uuid,
                                              0 /* property */);
                    curr_db_attr++;
                }
            }
        }

        if (!p_cur_srvc->included_svc || list_is_empty(p_cur_srvc->included_svc))
            continue;

        for (list_node_t *isn = list_begin(p_cur_srvc->included_svc);
             isn != list_end(p_cur_srvc->included_svc); isn = list_next(isn)) {
            tBTA_GATTC_INCLUDED_SVC *p_isvc = list_node(isn);

            if (p_isvc->handle < start_handle) {
                continue;
            }

            if (p_isvc->handle > end_handle) {
                *db = buffer;
                *count = db_size;
                return;
            }
            bta_gattc_fill_gatt_db_el(curr_db_attr,
                                      BTGATT_DB_INCLUDED_SERVICE,
                                      p_isvc->handle,
                                      0 /* s_handle */,
                                      0 /* e_handle */,
                                      p_isvc->handle,
                                      p_isvc->uuid,
                                      0 /* property */);
            curr_db_attr++;
        }
    }

    *db = buffer;
    *count = db_size;
}

/*******************************************************************************
**
** Function         bta_gattc_get_gatt_db
**
** Description      copy the server GATT database into db parameter.
**
** Parameters       conn_id: connection ID which identify the server.
**                  db: output parameter which will contain GATT database copy.
**                      Caller is responsible for freeing it.
**                  count: number of elements in database.
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_get_gatt_db(UINT16 conn_id, UINT16 start_handle, UINT16 end_handle, btgatt_db_element_t **db, int *count)
{
    tBTA_GATTC_CLCB *p_clcb = bta_gattc_find_clcb_by_conn_id(conn_id);

    if (p_clcb == NULL) {
        APPL_TRACE_ERROR("Unknown conn ID: %d", conn_id);
        return;
    }

    if (p_clcb->state != BTA_GATTC_CONN_ST) {
        APPL_TRACE_ERROR("server cache not available, CLCB state = %d",
                         p_clcb->state);
        return;
    }

    if (!p_clcb->p_srcb || p_clcb->p_srcb->p_srvc_list || /* no active discovery */
        !p_clcb->p_srcb->p_srvc_cache) {
        APPL_TRACE_ERROR("No server cache available");
        return;
    }

    bta_gattc_get_gatt_db_impl(p_clcb->p_srcb, start_handle, end_handle, db, count);
}

/*******************************************************************************
**
** Function         bta_gattc_rebuild_cache
**
** Description      rebuild server cache from NV cache.
**
** Parameters
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_rebuild_cache(tBTA_GATTC_SERV *p_srvc_cb, UINT16 num_attr,
                             tBTA_GATTC_NV_ATTR *p_attr)
{
    /* first attribute loading, initialize buffer */
    APPL_TRACE_DEBUG("%s: bta_gattc_rebuild_cache, num_attr = %d", __func__, num_attr);

    list_free(p_srvc_cb->p_srvc_cache);
    p_srvc_cb->p_srvc_cache = NULL;

    while (num_attr > 0 && p_attr != NULL) {
        switch (p_attr->attr_type) {
        case BTA_GATTC_ATTR_TYPE_SRVC:
                bta_gattc_add_srvc_to_cache(p_srvc_cb,
                                            p_attr->s_handle,
                                            p_attr->e_handle,
                                            &p_attr->uuid,
                                            p_attr->is_primary);
                break;

            case BTA_GATTC_ATTR_TYPE_CHAR:
                //TODO(jpawlowski): store decl_handle properly.
                bta_gattc_add_char_to_cache(p_srvc_cb,
                                            p_attr->s_handle,
                                            p_attr->s_handle,
                                            &p_attr->uuid,
                                            p_attr->prop);
                break;

            case BTA_GATTC_ATTR_TYPE_CHAR_DESCR:
                bta_gattc_add_attr_to_cache(p_srvc_cb,
                                             p_attr->s_handle,
                                             &p_attr->uuid,
                                             p_attr->prop,
                                             p_attr->incl_srvc_s_handle,
                                             p_attr->incl_srvc_e_handle,
                                             p_attr->attr_type);
                break;
            case BTA_GATTC_ATTR_TYPE_INCL_SRVC:
                bta_gattc_add_attr_to_cache(p_srvc_cb,
                                            p_attr->s_handle,
                                            &p_attr->uuid,
                                            p_attr->prop,
                                            p_attr->incl_srvc_s_handle,
                                            p_attr->incl_srvc_e_handle,
                                            p_attr->attr_type);
                break;
        }
        p_attr ++;
        num_attr --;
    }
}

/*******************************************************************************
**
** Function         bta_gattc_fill_nv_attr
**
** Description      fill a NV attribute entry value
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_fill_nv_attr(tBTA_GATTC_NV_ATTR *p_attr, UINT8 type, UINT16 s_handle,
                            UINT16 e_handle, tBT_UUID uuid, UINT8 prop, UINT16 incl_srvc_s_handle,
                            UINT16 incl_srvc_e_handle, BOOLEAN is_primary)
{
    p_attr->s_handle    = s_handle;
    p_attr->e_handle    = e_handle;
    p_attr->attr_type   = type;
    p_attr->is_primary  = is_primary;
    p_attr->id          = 0;
    p_attr->prop        = prop;
    p_attr->incl_srvc_s_handle = incl_srvc_s_handle;
    p_attr->incl_srvc_e_handle = incl_srvc_e_handle;

    memcpy(&p_attr->uuid, &uuid, sizeof(tBT_UUID));
}
/*******************************************************************************
**
** Function         bta_gattc_cache_save
**
** Description      save the server cache into NV
**
** Returns          None.
**
*******************************************************************************/
void bta_gattc_cache_save(tBTA_GATTC_SERV *p_srvc_cb, UINT16 conn_id)
{
    if (!p_srvc_cb->p_srvc_cache || list_is_empty(p_srvc_cb->p_srvc_cache))
        return;

    int i = 0;
    size_t db_size = bta_gattc_get_db_size(p_srvc_cb->p_srvc_cache, 0x0000, 0xFFFF);
    tBTA_GATTC_NV_ATTR *nv_attr = osi_malloc(db_size * sizeof(tBTA_GATTC_NV_ATTR));
    // This step is very importent, if not clear the memory, the hasy key base on the attribute case will be not corret.
    if (nv_attr != NULL) {
        memset(nv_attr, 0, db_size * sizeof(tBTA_GATTC_NV_ATTR));
    }

    if (!nv_attr) {
        APPL_TRACE_WARNING("%s(), no resource.", __func__);
        return;
    }
    for (list_node_t *sn = list_begin(p_srvc_cb->p_srvc_cache);
         sn != list_end(p_srvc_cb->p_srvc_cache); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        bta_gattc_fill_nv_attr(&nv_attr[i++],
                                BTA_GATTC_ATTR_TYPE_SRVC,
                               p_cur_srvc->s_handle,
                               p_cur_srvc->e_handle,
                               p_cur_srvc->uuid,
                               0 /* properties */,
                               0 /* incl_srvc_s_handle */,
                               0 /* incl_srvc_e_handle */,
                               p_cur_srvc->is_primary);
    }

    for (list_node_t *sn = list_begin(p_srvc_cb->p_srvc_cache);
         sn != list_end(p_srvc_cb->p_srvc_cache); sn = list_next(sn)) {
        tBTA_GATTC_SERVICE *p_cur_srvc = list_node(sn);

        if (!p_cur_srvc->characteristics || list_is_empty(p_cur_srvc->characteristics))
            continue;

        for (list_node_t *cn = list_begin(p_cur_srvc->characteristics);
             cn != list_end(p_cur_srvc->characteristics); cn = list_next(cn)) {
            tBTA_GATTC_CHARACTERISTIC *p_char = list_node(cn);

            bta_gattc_fill_nv_attr(&nv_attr[i++],
                                   BTA_GATTC_ATTR_TYPE_CHAR,
                                   p_char->handle,
                                   0,
                                   p_char->uuid,
                                   p_char->properties,
                                   0 /* incl_srvc_s_handle */,
                                   0 /* incl_srvc_e_handle */,
                                   FALSE);

            if (!p_char->descriptors || list_is_empty(p_char->descriptors))
                continue;

            for (list_node_t *dn = list_begin(p_char->descriptors);
                 dn != list_end(p_char->descriptors); dn = list_next(dn)) {
                tBTA_GATTC_DESCRIPTOR *p_desc = list_node(dn);

                bta_gattc_fill_nv_attr(&nv_attr[i++],
                                       BTA_GATTC_ATTR_TYPE_CHAR_DESCR,
                                       p_desc->handle,
                                       0,
                                       p_desc->uuid,
                                       0 /* properties */,
                                       0 /* incl_srvc_s_handle */,
                                       0 /* incl_srvc_e_handle */,
                                       FALSE);
            }
        }

        if (!p_cur_srvc->included_svc || list_is_empty(p_cur_srvc->included_svc))
            continue;

        for (list_node_t *an = list_begin(p_cur_srvc->included_svc);
             an != list_end(p_cur_srvc->included_svc); an = list_next(an)) {
            tBTA_GATTC_INCLUDED_SVC *p_isvc = list_node(an);

            bta_gattc_fill_nv_attr(&nv_attr[i++],
                                   BTA_GATTC_ATTR_TYPE_INCL_SRVC,
                                   p_isvc->handle,
                                   0,
                                   p_isvc->uuid,
                                   0 /* properties */,
                                   p_isvc->included_service->s_handle,
                                   p_isvc->included_service->e_handle,
                                   FALSE);
        }
    }

    /* TODO: Gattc cache write/read need to be added in IDF 3.1*/
    bta_gattc_cache_write(p_srvc_cb->server_bda, db_size, nv_attr);
    osi_free(nv_attr);
}

/*******************************************************************************
**
** Function         bta_gattc_cache_load
**
** Description      Load GATT cache from storage for server.
**
** Parameter        p_clcb: pointer to server clcb, that will
**                          be filled from storage
** Returns          true on success, false otherwise
**
*******************************************************************************/
bool bta_gattc_cache_load(tBTA_GATTC_CLCB *p_clcb)
{
    /* open NV cache and send call in */
    tBTA_GATT_STATUS status = BTA_GATT_OK;
    UINT8 index = 0;
    tBTA_GATTC_NV_ATTR  *attr = NULL;

    if ((status = bta_gattc_co_cache_open(p_clcb->p_srcb->server_bda, true, &index)) != BTA_GATT_OK) {
        APPL_TRACE_DEBUG("%s(), gattc cache open fail, index = %x", __func__, index);
        return false;
    }

    size_t num_attr = bta_gattc_get_cache_attr_length(index) / sizeof(tBTA_GATTC_NV_ATTR);

    if (!num_attr) {
        return false;
    }
    //don't forget to set the total attribute number.
    p_clcb->p_srcb->total_attr = num_attr;
    APPL_TRACE_DEBUG("%s(), index = %x, num_attr = %d", __func__, index, num_attr);
    if ((attr = osi_malloc(sizeof(tBTA_GATTC_NV_ATTR) * num_attr)) == NULL) {
        APPL_TRACE_ERROR("%s, No Memory.", __func__);
        return false;
    }
    if ((status = bta_gattc_co_cache_load(attr, index)) != BTA_GATT_OK) {
        APPL_TRACE_DEBUG("%s(), gattc cache load fail, status = %x", __func__, status);
        return false;
    }
    p_clcb->searched_service_source = BTA_GATTC_SERVICE_INFO_FROM_NVS_FLASH;
    bta_gattc_rebuild_cache(p_clcb->p_srcb, num_attr, attr);
    //free the attr buffer after used.
    osi_free(attr);
    return true;
}

/*******************************************************************************
**
** Function         bta_gattc_cache_write
**
** Description      This callout function is executed by GATT when a server cache
**                  is available to save.
**
** Parameter        server_bda: server bd address of this cache belongs to
**                  num_attr: number of attribute to be save.
**                  attr: pointer to the list of attributes to save.
** Returns
**
*******************************************************************************/
static void bta_gattc_cache_write(BD_ADDR server_bda, UINT16 num_attr,
                           tBTA_GATTC_NV_ATTR *attr)
{
    bta_gattc_co_cache_save(server_bda, num_attr, attr);
}

/*******************************************************************************
**
** Function         bta_gattc_cache_reset
**
** Description      This callout function is executed by GATTC to reset cache in
**                  application
**
** Parameter        server_bda: server bd address of this cache belongs to
**
** Returns          void.
**
*******************************************************************************/
void bta_gattc_cache_reset(BD_ADDR server_bda)
{
    BTIF_TRACE_DEBUG("%s", __func__);
    char fname[255] = {0};
    bta_gattc_generate_cache_file_name(fname, server_bda);
    bta_gattc_co_cache_reset(server_bda);
    //unlink(fname);
}
#endif /* BTA_GATT_INCLUDED */

