typedef enum
{
    ZBX_TREND_PERIOD_HOUR = 1,
    ZBX_TREND_PERIOD_DAY,
    ZBX_TREND_PERIOD_WEEK,
    ZBX_TREND_PERIOD_MONTH,
    ZBX_TREND_PERIOD_YEAR
}
zbx_trend_period_base_t;
 
/******************************************************************************
 *                                                                            *
 * Function: zbx_trends_parse_range                                           *
 *                                                                            *
 * Purpose: parse trend function period arguments into time range             *
 *                                                                            *
 * Parameters: from         - [IN] the time the period shift is calculated    *
 *                                 from                                       *
 *             period       - [IN] the history period                         *
 *             period_shift - [IN] the history period shift                   *
 *             start        - [OUT] the period start time in seconds since    *
 *                                  Epoch                                     *
 *             end          - [OUT] the period end time in seconds since      *
 *                                  Epoch                                     *
 *             error        - [OUT] the error message if parsing failed       *
 *                                                                            *
 * Return value: SUCCEED - period was parsed successfully                     *
 *               FAIL    - invalid time period was specified                  *
 *                                                                            *
 * Comments: Daylight saving changes are applied when parsing ranges with     *
 *           day+ used as period base (now/?).                                *
 *                                                                            *
 *           Example period_shift values:                                     *
 *             now/d                                                          *
 *             now/d-1h                                                       *
 *             now/d+1h                                                       *
 *             now/d+1h/w                                                     *
 *             now/d/w/h+1h+2h                                                *
 *             now-1d/h                                                       *
 *                                                                            *
 ******************************************************************************/
int     zbx_trends_parse_range(time_t from, const char *period, const char *period_shift, int *start, int *end,
                char **error)