# &adminguide;

## Overview

This module provides time recurrence matching functions. The format of recurrence definitions is based on Internet Calendaring and Scheduling Core Object Specification (Calendar COS - RFC 2445). It also provides a port of the Perl Time::Period module for generic time period matching.

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- None.

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- None

## Parameters

### `separator` (str)

Separator character used to delimit attributes in time recurrence definitions.

Default value is '|'.

#### Set `separator` parameter

    ...
    modparam("tmrec", "separator", ";")
    ...

## Functions

### `tmrec_match(timerec [, timestamp])`

Match a time recurrence rule against the timestamp (UNIX epoch format). If the timestamp parameter is missing, the current UNIX epoch time is used.

The parameters can include pseudo-variables.

The timerec parameter is a list of attributes defined by RFC2445, delimited by the 'separator' (module parameter) character. The format of timerec parameter, using '|' as the separator, is (all in one line without white spaces):

    ...
    [startdate]|[duration]|[frequency]|[until]|[interval]|[byday]
      |[bymonthday]|[byyearday]|[byweekno]|[bymonth]
    ...

When an attribute is not specified, the corresponding place must be left empty, provided that one or more additional attributes follow.

Description of time recurrence attributes:

- startdate - date for the start of the first period.

- duration - the duration of the time period. For a recurring interval, the duration parameter MUST be small enough such that subsequent intervals do not overlap. For non-recurring intervals, durations of any positive length are permitted. Zero-length duration means forever. Negative-length durations are not allowed.

  See RFC 2445 for the format of duration. In short for common cases when the duration doesn't exceed a data, it must start with PT followed by the value for hours, minutes or seconds - e.g., a duration of 8 hours must be written as PT8H.

- frequency - can be one of the following values: daily - specify repeating periods based on an interval of a day or more; weekly - specify repeating periods based on an interval of a week or more; monthly - specify repeating periods based on an interval of a month or more; yearly - specify repeating periods based on an interval of a year or more. These values are case-insensitive.

- until - defines an iCalendar COS DATE or DATE-TIME value which bounds the recurrence rule in an inclusive manner. If the value specified by until is synchronized with the specified recurrence, this date or date-time becomes the last instance of the recurrence. If it is not present, the recurrence is considered to repeat forever.

- interval - a positive integer representing how often the recurrence rule repeats. The default value is 1, meaning every day for a daily rule, every week for a weekly rule, every month for a monthly rule and every year for a yearly rule.

- byday - a comma-separated list short codes of days of the week. The days are specified as: MO for Monday; TU for Tuesday; WE for Wednesday; TH for Thursday; FR for Friday; SA for Saturday; SU for Sunday. These values are case insensitive.

  Each byday value can also be prefixed by a positive (+n) or negative (-n) integer. If present, this indicates the n-th occurrence of the specific day within the monthly or yearly recurrence. For example, within a monthly rule, +1MO (or simply 1MO) represents the first Monday within the month, whereas -1MO represents the last Monday of the month. If an integer modifier is not present, it means all days of this type within the specified frequency. For example, within a monthly rule, MO represents all Mondays within the month.

- bymonthday - a comma-separated list of days of the month. Valid values are 1 to 31 or -31 to -1. For example, -10 represents the tenth to the last day of the month.

- byyearday - a comma-separated list of days of the year. Valid values are 1 to 366 or -366 to -1. For example, -1 represents the last day of the year (December 31st) and -306 represents the 306th day before the last day of the year (March 1st).

- byweekno - a comma-separated list of ordinals specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.

- bymonth - parameter specifies a comma-separated list of months of the year. Valid values are 1 to 12.

A recurrence is specified by including the frequency parameter, which indicates the type of the recurrence rule. Parameters other than startdate and duration SHOULD NOT be specified unless frequency is set.

If invalid byxxx parameter values are found (ie, bymonthday=30 in February), they are simply ignored.

Byxxx parameters modify the recurrence rule matching. The Byxxx rule, as an attribute for a period of time which is greater than or equal to the frequency, generally reduces or limits the number of occurrences for the recurrence definition. For example, frequency=daily bymonth=3 reduces the number of recurrence instances from all days (if the bymonth parameter is not present) to all days in March. Byxxx parameters for a period of time less than the frequency generally increases or expands the number of occurrences of the recurrence. For example, frequency=yearly bymonth=8,9 increases the number of days within the yearly recurrence set from 1 (if bymonth parameter is not present) to 2.

If multiple Byxxx parameters are specified, then after evaluating the specified frequency and interval parameters, the Byxxx parameters are applied to the current set of evaluated occurrences in the following order: bymonth, byweekno, byyearday, bymonthday, byday; then until is evaluated.

Next is an example of evaluating multiple Byxxx parameters.

startdate=20100101T093000 duration=PT10H30M frequency=yearly interval=4 bymonth=3 byday=SU

First, the interval=4 would be applied to frequency=yearly to match on every 4th year . Then, bymonth=1 would be applied to match on every March, every 4th year. Then, byday=SU would be applied to match on every Sunday in March, every 4th year, from 9:30 to 20:00 . The start and end hours:minutes have been retrieved from the startdate and duration parameters.

This function can be used in ANY_ROUTE.

#### `tmrec_match` usage

    ...
    	if(tmrec_match("20120101T000000|PT24H|weekly|||SA,SU")
            xdbg("it is weekend!\n");
        if(tmrec_match("20120101T083000|PT10H|weekly|||MO,TU,WE,TH,FR")
            xdbg("it is with working hours\n");
    ...

### `is_leap_year([year])`

Return true if the value from parameter is a leap year. If the parameter is missing, then the year from the current time is taken.

The parameter can be pseudo-variable.

This function can be used in ANY_ROUTE.

#### `is_leap_year` usage

    ...
    if(is_leap_year("2010"))
    ...

### `time_period_match(period [, timestamp])`

Matches the point in time specified by the timestamp parameter, or the current time if the parameter is missing, against the given period specification. Returns 1 if it matches, -1 if it doesn't, and a value <= -2 if there was an error.

The time period specification follows the Perl Time::Period module. It is a string and consists of zero or more sub-period specifications, separated by commas. The period matches if at least one of the sub-periods matches, or if no sub-periods were given at all (an empty string).

Each sub-period is a list of one or more scale definitions, optionally separated by space characters. The sub-period matches if all of the given scales within that sub-period match. For each scale given, a single value or a range of values (which is two values separated by a hyphen) can be specified. Multiple values or multiple ranges (or a combination thereof) within a single scale is also possible. If a certain scale is specified more than once, the previous values or ranges for that scale are extended by the newly given ones. If a particular scale is not mentioned at all within a sub-period, then no matching is performed for that scale.

The following scales are supported and understood. Each scale also has a respective short code, either one can be used. A single scale definition consists of the scale name, followed by an opening brace, followed by the list of values, followed by a closing brace.

- year or yr - Either given as a full 4-digit number >= 1970, or as a 2-digit number, in which case it will be understood to be within the current century.

- month or mo - Month of the year, either a number between 1 and 12, or at least the first 3 letters of a spelled out month name, e.g. jan, janua or january will all work.

- week or wk - Week of the month, a number between 1 and 6. The first day of the week is Sunday.

- yday or yd - Day of the year, a number between 1 and 366.

- mday or md - Day of the month, a number between 1 and 31.

- wday or wd - Day of the week, either a number between 1 and 7, or at least the first 2 letters of a spelled out weekday name (analogous to the month scale). Sunday is the first day of the week.

- hour or hr - A number between 0 and 23. Unlike the Perl Time::Period module, am or pm specifications are not supported.

- minute or min - A number between 0 and 59.

- second or sec - A number between 0 and 60 (to allow for leap seconds).

The parameters can include pseudo-variables. Whitespace (more precisely, the space character only) can occur anywhere, but is optional. Ranges in all scales (with the exception of the year scale) are allowed to wrap-around, e.g. a weekday scale of {fri-tue} is equivalent to {fri-sat,sun-tue}.

#### `time_period_match` usage

    ...
    if(time_period_match("wd{2-6} hr{8-16}, wd{2-6} hr{17} min{0-29}"))
    	xdbg("Monday to Friday, 8:00 to 17:30\n");

    if(time_period_match("wday { sat sun }, wday {mo-fr} hr {17-8},wd{mo-wed}hr{15 16 9}"))
    	xdbg("We're closed - open only Monday to Wednesday 10:00-15:00, Thursday and Friday 9:00-17:00");
    ...