static void prvIncomingPublishUpdateDeltaCallback()

in source/demo-tasks/shadow_device_task.c [402:511]
69 lines of code
5 McCabe index (conditional complexity)

static void prvIncomingPublishUpdateDeltaCallback( void * pxSubscriptionContext,
                                                   MQTTPublishInfo_t * pxPublishInfo )
{
    static uint32_t ulCurrentVersion = 0; /* Remember the latest version number we've received */
    uint32_t ulVersion = 0UL;
    uint32_t ulNewState = 0UL;
    char * pcOutValue = NULL;
    uint32_t ulOutValueLength = 0UL;
    JSONStatus_t result = JSONSuccess;

    /* Remove compiler warnings about unused parameters. */
    ( void ) pxSubscriptionContext;

    configASSERT( pxPublishInfo != NULL );
    configASSERT( pxPublishInfo->pPayload != NULL );

    LogDebug( ( "/update/delta json payload:%.*s.",
                pxPublishInfo->payloadLength,
                ( const char * ) pxPublishInfo->pPayload ) );

    /* The payload will look similar to this:
     * {
     *      "state": {
     *          "powerOn": 1
     *      },
     *      "metadata": {
     *          "powerOn": {
     *              "timestamp": 1595437367
     *          }
     *      },
     *      "timestamp": 1595437367,
     *      "clientToken": "388062",
     *      "version": 12
     *  }
     */

    /* Make sure the payload is a valid json document. */
    result = JSON_Validate( pxPublishInfo->pPayload,
                            pxPublishInfo->payloadLength );

    if( result != JSONSuccess )
    {
        LogError( ( "Invalid JSON document recieved!" ) );
    }
    else
    {
        /* Obtain the version value. */
        result = JSON_Search( ( char * ) pxPublishInfo->pPayload,
                              pxPublishInfo->payloadLength,
                              "version",
                              sizeof( "version" ) - 1,
                              &pcOutValue,
                              ( size_t * ) &ulOutValueLength );

        if( result != JSONSuccess )
        {
            LogError( ( "Version field not found in JSON document!" ) );
        }
        else
        {
            /* Convert the extracted value to an unsigned integer value. */
            ulVersion = ( uint32_t ) strtoul( pcOutValue, NULL, 10 );

            /* Make sure the version is newer than the last one we received. */
            if( ulVersion <= ulCurrentVersion )
            {
                /* In this demo, we discard the incoming message
                 * if the version number is not newer than the latest
                 * that we've received before. Your application may use a
                 * different approach.
                 */
                LogWarn( ( "Recieved unexpected delta update with version %u. Current version is %u",
                           ( unsigned int ) ulVersion,
                           ( unsigned int ) ulCurrentVersion ) );
            }
            else
            {
                LogInfo( ( "Recieved delta update with version %.*s.",
                           ulOutValueLength,
                           pcOutValue ) );

                /* Set received version as the current version. */
                ulCurrentVersion = ulVersion;

                /* Get powerOn state from json documents. */
                result = JSON_Search( ( char * ) pxPublishInfo->pPayload,
                                      pxPublishInfo->payloadLength,
                                      "state.powerOn",
                                      sizeof( "state.powerOn" ) - 1,
                                      &pcOutValue,
                                      ( size_t * ) &ulOutValueLength );

                if( result != JSONSuccess )
                {
                    LogError( ( "powerOn field not found in JSON document!" ) );
                }
                else
                {
                    /* Convert the powerOn state value to an unsigned integer value. */
                    ulNewState = ( uint32_t ) strtoul( pcOutValue, NULL, 10 );

                    LogInfo( ( "Setting powerOn state to %u.",
                               ( unsigned int ) ulNewState ) );
                    /* Set the new powerOn state. */
                    ulCurrentPowerOnState = ulNewState;
                }
            }
        }
    }
}