# Copyright (c) 1996-2021 Sullivan Beck. All rights reserved.
# This program is free software; you can redistribute it and/or modify it
# under the same terms as Perl itself.

=pod

=head1 NAME

Date::Manip::Config - Date::Manip configuration

=head1 SYNOPSIS

This documents the configuration information which is stored in
each L<Date::Manip::Base> object, how to modify this information,
and how the information is used in the other Date::Manip modules.

=head1 DESCRIPTION

Date::Manip is a very configurable bundle of modules. Many of it's
behaviors can be modified to change how date operations are done.  To
do this, a list of configuration variables may be set which define
many Date::Manip behaviors.

There are three ways to set config variables. The first two are to
pass them in when creating an object, or to pass them to the config
method after the object is created. All of the main Date::Manip
modules (L<Date::Manip::Base>, L<Date::Manip::TZ>, L<Date::Manip::Date>,
L<Date::Manip::Delta>, and L<Date::Manip::Recur>) have the config method.

As an example, you can create and configure a
L<Date::Manip::Date> object using the commands:

   $date = new Date::Manip::Date;
   $date->config($var1,$val1,$var2,$val2,...);

This can be shortened to:

   $date = new Date::Manip::Date [$var1,$val1,...];

The values of the config variables are stored in the L<Date::Manip::Base>
object. So, if you have a L<Date::Manip::Date> object, it has a
L<Date::Manip::Base> object associated with it, and the configuration
information is stored there. The same L<Date::Manip::Base> object may be
used by any number of higher objects, and all will share the same
configuration. If multiple L<Date::Manip::Date> objects share the same
L<Date::Manip::Base> object, setting a configuration variable on any of
them affects all of the L<Date::Manip::Date> objects. If you need to work
with different configurations simultaneously, it is necessary to work
with multiple L<Date::Manip::Base> objects. This is covered in the
L<Date::Manip::Objects> document.

An alternate method exists if you are using one of the functional
interfaces.  To set a variable using the functional interface, use the
call:

   Date_Init("$var1=$val1");

The third way to set config variables is to store them in a config
file. The config file is read in by passing the appropriate values to
the config method as described below.  A config file is a good way to
easily change a large number of settings. They are also necessary for
other purposes (such as events and holidays which are covered
in the L<Date::Manip::Holidays> document).

=head1 CONFIG FILES

One of the variables that can be passed to the config method is
"ConfigFile". The value of this variable is the path to a config
file.

When any Date::Manip::* object is configured, any number of config
files may be read (and the config files can specify additional files
to read).

The starting section of a config file contains general configuration
variables. A list of all config variables is given below.

Following this, any number of special sections may be included in
the config file. The special sections are used to specify other
types of information, such as a list of holidays or special events.
These special sections are described elsewhere in the documentation.

The syntax of the config file is very simple. Every line is of
the form:

   VAR = VAL

or

   *SECTION

Blank lines and lines beginning with a pound sign (#) are ignored.
All whitespace is optional. Variables names in the main section and
section names are case insensitive (though values in the main section
are typically case sensitive). Strings in other sections (both variables
and values) are case sensitive.

The following is a sample config file:

   DateFormat = US
   Language   = English

   *Holidays

   Dec 25 =  Christmas
   Jan 1  =  New Year's

All config variables that may appear in the main part of a config file
are described in the next section. Other sections are described elsewhere.
The *Holidays and *Events sections are both described in the
L<Date::Manip::Holidays> documentation.

A sample config file is included with the Date::Manip distribution.
Modify it as appropriate and copy it to some appropriate directory and
use the ConfigFile variable to access it. For example, if a config
file is stored in F</home/foo/Manip.cnf>, you can load it by:

   $date->config("ConfigFile","/home/foo/Manip.cnf");

or (if using a functional interface):

   Date_Init("ConfigFile=/home/foo/Manip.cnf");

NOTE: if you use business mode calculations, you must have a config
file since this is the only place where you can define holidays.

In the top section, only variables described below may be used. In
other sections, checking (if any) is done in the module that uses
the data from that section.

=head1 BASIC CONFIGURATION VARIABLES

This section describes the basic Date::Manip configuration variables
which can be used in a config file, or which may be passed in using
the appropriate functions for each module.

Variable names are case insensitive, both as arguments to the config
function and in the config file. The values are case sensitive except
where specified otherwise.

=over 4

=item B<Defaults>

The value for this config variable is ignored. Whenever the Defaults
config variable is encountered, the defaults for all config variables
are restored, overriding ALL changes that have been made.

In other words, in the following call:

   $date->config("Language","Russian",
                 "Defaults","1");

the first option will end up being ignored since the Defaults config
variable will set the language back to it's default value which is
English.

When using a functional interface, use:

   Date_Init("Defaults=1");

=item B<ConfigFile>

The ConfigFile variable defines a config file which will be parsed for
configuration information. It may be included any number of times, each
one including the path to a single config file. The value of this
variable is a full path to a file.

An example call to the config function might be:

   $date->config("ConfigFile","/tmp/file1",
                 'Language',$val);

Config files are parsed immediately when encountered. So in this example,
the file F</tmp/file1> will be parsed before the next variable ('Language').
In addition, if a config file contains a ConfigFile variable, that file
will immediately be parsed before continuing with the original file.

The path to the file may be specified in any way valid for the
operating system. If a file is not found, a warning will be issued,
but execution will continue.

Multiple config files are safe, and a section may safely be split
across multiple files.

When using a functional interface, use:

   Date_Init("ConfigFile=/tmp/file1");

=item B<Language>

Date::Manip can be used to parse dates in many different languages.
A list of the languages is given in the L<Date::Manip::Lang> document.

To parse dates in a different language, just use the Language config
variable with the name of the language as the value. Language names
are case insensitive.

Additional languages may be added with the help of someone fluent in
English and the other language.  If you are interested in providing a
translation for a new language, please refer to the L<Date::Manip::Lang>
document for instructions.

=item B<Encoding>

Date::Manip has some support for handling date strings encoded in
alternate character encodings.

By default, input strings may be tested using multiple encodings that
are commonly used for the specific languages, as well as using
standard perl escape sequences, and output is done in UTF-8.

The input, output, or both can be overridden using the Encoding
variable.

Setting Encoding to the name of a single encoding (a name supported
by the Encoding perl module), will force all input and output to be
done in that encoding.

So, setting:

   Encoding = iso-8859-1

means that all input and output will be in that encoding. The
encoding 'perl' has the special meaning of storing the string in
perl escape sequences.

Encoding can also be set to the name of two encoding (separated
by a comma).

   Encoding = iso-8859-1,utf-16

which means that all input is in iso-8859-1 encoding, but all output
will be utf-16.

Encoding may also be set as follows:

   Encoding = iso-8859-1,

meaning that input is in iso-8859-1 and output is in the default (i.e.
UTF-8) encoding.

   Encoding = ,utf-16

means to check the input in all of the encodings, but all output will
be in utf-16 encoding.

Note that any time you change languages, it will reset the encodings,
so you should set this config variable AFTER setting the language.

=item B<FirstDay>

It is sometimes necessary to know what day of week is regarded as
first.  By default, this is set to Monday as that conforms to ISO
8601, but many countries and people will prefer Sunday (and in a few
cases, a different day may be desired).  Set the FirstDay variable to
be the first day of the week (1=Monday, 7=Sunday).

=item B<Jan1Week1>

ISO 8601 states that the first week of the year is the one which contains
Jan 4 (i.e. it is the first week in which most of the days in that week
fall in that year).  This means that the first 3 days of the year may
be treated as belonging to the last week of the previous year.  If this
is set to non-nil, the ISO 8601 standard will be ignored and the first
week of the year contains Jan 1.

=item B<Printable>

Some commands may produce a printable version of a date. By default,
the printable version of the date is of the format:

   YYYYMMDDHH:MN:SS

Two other simple versions have been created. If the Printable variable is
set to 1, the format is:

   YYYYMMDDHHMNSS

If Printable is set to 2, the format is:

   YYYY-MM-DD-HH:MN:SS

This config variable is present in order to maintain backward
compatibility, and may actually be deprecated at some point. As such,
additional formats will not be added. Instead, use the printf method
in the L<Date::Manip::Date> module to extract information with complete
flexibility.

=back

=head1 DATE PARSING CONFIGURATION VARIABLES

=over 4

=item B<DateFormat>

Different countries look at the date 12/10 as Dec 10 or Oct 12.  In
the United States, the first is most common, but this certainly
doesn't hold true for other countries.  Setting DateFormat to "US"
(case insensitive) forces the first behavior (Dec 10).  Setting
DateFormat to anything else forces the second behavior (Oct 12).  The
"US" setting is the default (sorry about that...  I live in the US).

=item B<YYtoYYYY>

When parsing a date containing a 2-digit year, the year must be converted
to 4 digits. This config variable determines how this is done.

By default, a 2 digit year is treated as falling in the 100 year period of
CURR-89 to CURR+10. So in the year 2005, a two digit year will be somewhere
in the range 1916 to 2015.

YYtoYYYY may be set to any integer N to force a 2 digit year into the
period CURR-N to CURR+(99-N).  A value of 0 forces the year to be the
current year or later.  A value of 99 forces the year to be the
current year or earlier.  Although the most common choice of values
will be somewhere between 0 and 99, there is no restriction on N that
forces it to be so. It can actually be any positive or negative number
you want to force it into any 100 year period desired.

YYtoYYYY can also be set to "C" to force it into the current century, or
to "C##" to force it into a specific century.  So, in 1998, "C" forces
2 digit years to be 1900-1999.  "C18" would always force a 2 digit year to
be in the range 1800-1899. Note: I'm aware that the actual definitions of
century are 1901-2000, NOT 1900-1999, so for purists, treat this as
the way to supply the first two digits rather than as supplying a
century.

It can also be set to the form "C####" to force it into a specific 100
year period.  C1950 refers to 1950-2049.

=item B<DefaultTime>

When a date is parsed from one of the formats listed in the "Common date formats"
or "Less common formats" sections of the L<Date::Manip::Date> document, and no time
is explicitly included, the default time can be determined by the value of this
variable. The two possible values are:

   midnight   the default time is 00:00:00
   curr       the default time is the current time

"midnight" is the default value.

NOTE: this only applies to dates parsed with the parse method. Dates parsed
using the parse_date method always default to 00:00:00.

=item B<PeriodTimeSep>

By default, the time separator (i.e. the character that separates
hours from minutes and minutes from seconds) is specified in the
language translations and in most cases it does not include a period.
In English, the only defined time separator is a colon (:), so the time
can be written as 12:15:30 .

If you want to use a period (.) as a time separator as well, set this
to 1.  Then you can write the time as 12.15.30 .

By default, a period is used as a date separator, so 12.15.30 would be
interpreted as Dec 15 1930 (or 2030), so if you use the period as a
date separator, it should not be used as a time separator too.

=item B<Format_MMMYYYY>

By default, when parsing a string like 'Jun 1925', it will be interpreted
as 'Jun 19, 2025' (i.e. MMM DDYY).  Also, the string '1925 Jun' is not allowed.

This variable can be set to either 'first' or 'last', and in that case,
both 'Jun 1925' and '1925 Jun' will be allowed, and will refer to either
the first or last day of June in 1925.

=back

=head1 BUSINESS CONFIGURATION VARIABLES

These are configuration variables used to define work days and
holidays used in business mode calculations. Refer to the
L<Date::Manip::Calc> documentation for details on these calculations.

=over 4

=item B<WorkWeekBeg>

=item B<WorkWeekEnd>

The first and last days of the work week.  These default to Monday and
Friday.  Days are numbered from 1 (Monday) to 7 (Sunday).  WorkWeekBeg
must come before WorkWeekEnd numerically so there is no way to handle
a work week of Sunday to Thursday using these variables.

There is also no way to handle an odd work schedule such as 10 days
on, 4 days off.

However, both of these situations can be handled using a fairly simple
workaround.

To handle a work week of Sunday to Thursday, just set WorkWeekBeg=1
and WorkWeekEnd=7 and defined a holiday that occurs every Friday and
Saturday.

To handle a 10 days on, 4 days off schedule, do something similar
but defined a holiday that occurs on all of the 4 days off.

Both of these can be done using recurrences. Refer to the L<Date::Manip::Recur>
documentation for details.

=item B<WorkDay24Hr>

=item B<WorkDayBeg>

=item B<WorkDayEnd>

If WorkDay24Hr is non-zero, a work day is treated as usually being 24
hours long (daylight saving time changes ARE taken into account).  The
WorkDayBeg and WorkDayEnd variables are ignored in this case.

By default, WorkDay24Hr is zero, and the work day is defined by the
WorkDayBeg and WorkDayEnd variables. These are the times when the work
day starts and ends respectively. WorkDayBeg must come before
WorkDayEnd (i.e. there is no way to handle the night shift where the
work day starts one day and ends another).

The time in both should be a valid time format (H, H:M, or H:M:S).

Note that setting WorkDay24Hr to a non-zero value automatically sets
WorkDayBeg and WorkDayEnd to "00:00:00" and "24:00:00" respectively,
so to switch back to a non-24 hour day, you will need to reset both
of those config variables.

Similarly, setting either the WorkDayBeg or WorkDayEnd variables
automatically turns off WorkDay24Hr.

=item B<TomorrowFirst>

Periodically, if a day is not a business day, we need to find the
nearest business day to it.  By default, we'll look to "tomorrow"
first, but if this variable is set to 0, we'll look to "yesterday"
first.  This is only used in the
C<Date::Manip::Date::nearest_business_day> method (and the
C<Date_NearestWorkDay> function) and is easily overridden (see
documentation for the nearest_business_day method).

=item B<EraseHolidays>

=item B<EraseEvents>

If these variables are used (a value must be passed in, but is
ignored), the current list of defined holidays or events is erased.  A
new set will be set the next time a config file is read in.

Although these variables are supported, the best way to have multiple
holiday or events lists will be to create multiple L<Date::Manip::Base>
objects based on separate config files.

=back

=head1 RECURRENCE CONFIGURATION VARIABLES

The following config variables help in the handling of recurrences.

=over 4

=item B<RecurRange>

When a recurrence is created, it begins with a default range (start
and end date). The range selected depends on the value of this
variable, and can be set to any of the following:

   none     no default range supplied
   year     the current year
   month    the current month
   week     the current week
   day      the current day
   all      Jan 2, 0001 to Dec 30, 9999

The default value is "none".

=item B<MaxRecurAttempts>

Occasionally, a recurrence is invalid (though it cannot be easily determined
in advance).

When searching for dates that match the recurrence, this is the maximum number
of attempts that will be done.  If none are found, the recurrence will be
assumed to be invalid.

=back

=head1 TIME ZONE RELATED CONFIGURATION VARIABLES

The following configuration variables may alter the current
time zone. As such, they are only available once the L<Date::Manip::TZ>
module is available. An easy way to handle this is to only pass them
to the config method of a L<Date::Manip::TZ> object or one of the high
level objects (L<Date::Manip::Date>, L<Date::Manip::Delta>, or
L<Date::Manip::Recur>).

Many of Date::Manip's operations rely on knowing what time it is
now. This consists of three things: knowing what date and time it is,
knowing what time zone it is, and knowing whether it is daylight
saving or not. All of this is necessary in order to correctly handle
every possible date.

The daylight saving time information is only used for a couple hours
each year during daylight saving time changes (at all other times, the
date, time, and time zone are sufficient information), so it is
optional, and defaults to standard time if omitted.

The default behavior of Date::Manip is to use the system localtime
function to determine the date, time, and daylight saving time
information, and to use various methods (see
L<Date::Manip::TZ/"DETERMINING THE SYSTEM TIME ZONE">) to determine what
time zone the computer is in.

=over 4

=item B<TZ>

This variable is deprecated, but will be supported for several
releases. The SetDate or ForceDate variables (described next) should be
used instead.

The following are equivalent:

    $date->config("tz","Europe/Rome");
    $date->config("setdate","now,Europe/Rome");

or in the functional interface:

    Date_Init("tz=Europe/Rome");
    Date_Init("setdate=now,Europe/Rome");

=item B<SetDate>

The SetDate config variable is used to set the current date, time, or
time zone, but then allow it to change over time using the rules of
that time zone.

There are several cases where this may be useful.

Often, you may want to use the system time to get the date and time, but
you want to work in another time zone. For this, use the call:

   $date->config("setdate","now,ZONE");

or in the function interface:

   Date_Init("setdate=now,ZONE");

If it is currently

   Jun 6, 2009 12:00:00 in the America/New_York time zone

and you call:

   $date->config("setdate","now,Europe/Rome");

the Date::Manip will treat that exact instant as

   Jun 6, 2009 12:00:00 in the Europe/Rome time zone

At that precise moment, looking at the system time and parsing the
date "now" in Date::Manip will give the same date and time.

The time will continue to advance, but it will use time change rules
from the Europe/Rome time zone. What that means is that if a daylight
saving time occurs on the computer, but NOT in the Europe/Rome
time zone (or vice versa), the system date and time will no longer
match the results of parsing the date "now" in Date::Manip.

In general (unless the program runs for an extended period of
time), the system date and time WILL match the value of "now", so
this is a good way to simulate placing the computer in another
time zone.

If the current date/time is ambiguous (i.e. it exists in both
standard and daylight saving time in the alternate zone), you
can use the call:

   $date->config("setdate","now,DSTFLAG,ZONE");

to force it to be in one or the other. DSTFLAG can be "std",
"dst", "stdonly", or "dstonly". "std" and "dst" mean that
the date can be in either standard or saving time, but will
try standard first (for "dst") or saving time first (if "dst"),
and will only try the other if the date is not valid. If
"stdonly" or "dstonly" is used, the date will be forced to
be standard or saving time respectively (an error will be
triggered if there is no valid date in that time).

If the current date/time doesn't exist in the alternate zone,
an error will occur.

The other common operation is that you might want to see results
as they would appear on a computer running in a different time zone.

This can be done using the call:

   $date->config("setdate","zone,ZONE");
   $date->config("setdate","zone,DSTFLAG,ZONE");

If it is currently

   Jun 6, 2009 12:00:00 in the America/New_York time zone

and you call:

   $date->config("setdate","zone,America/Chicago");

then parsing "now" at precisely that moment will return "Jun 6, 2009
11:00:00".  This is equivalent to working in the current zone, but
then converting everything to the alternate zone.

Note that DSTFLAG is only used if ZONE is entered as an offset.

The final case where the SetDate config variable is used is to alter
the date and time to some other value (completely independent of
the current date and time) and allow it to advance normally from
that point.

   $date->config("setdate","DATE");
   $date->config("setdate","DATE,ZONE");
   $date->config("setdate","DATE,DSTFLAG,ZONE");

set both the date/time and zone.

If DATE is not valid in the time zone (either the local time zone
or the specified one), and error occurs.

The call:

   $date->config("setdate","now");

resets everything to use the current date/time and zone and lets it
advance normally.

=item B<ForceDate>

The ForceDate config variable is similar to the SetDate variable, except
that once "now" is set, it is not allowed to change. Parsing the date "now"
will not change, regardless of how long the program runs (unless either
the SetDate or ForceDate variables are set to some other value).

   $date->config("forcedate","now,ZONE");
   $date->config("forcedate","now,DSTFLAG,ZONE");
   $date->config("forcedate","zone,ZONE");
   $date->config("forcedate","zone,DSTFLAG,ZONE");
   $date->config("forcedate","DATE");
   $date->config("forcedate","DATE,ZONE");
   $date->config("forcedate","DATE,DSTFLAG,ZONE");
   $date->config("forcedate","now");

all set "now" in the same way as the SetDate variable.  Spaces after commas are
ignored.

=back

ZONE can be any time zone name, alias, abbreviation, or offset, and
the best time zone will be determined from all given information.

It should be noted that setting the SetDate or ForceDate variable
twice will always refer to the system date/time as a starting point.
For example, if a program is running, and calls the method:

   $date->config("forcedate","now");

at Jun 6, 2009 at 12:00, that time will be treated as now from that
point on. If the same call is done an hour later, "now" will then
be Jun 6, 2009 at 13:00 from that moment on.

Since the current date is used in the date parsing routines, no
parsing can be done on the DATE value in any of the calls.  Instead,
DATE must be a date in one of the two formats:

   YYYY-MM-DD-HH:MN:SS
   YYYYMMDDHH:MN:SS

=head1 DEPRECATED CONFIGURATION VARIABLES

The following config variables are currently supported, but are
deprecated.  They will be removed in a future Date::Manip release:

=over 4

=item B<TZ>

This is discussed above. Use SetDate or ForceDate instead.

Scheduled for removal 2016-03-01

=back

=head1 KNOWN BUGS

None known.

=head1 BUGS AND QUESTIONS

Please refer to the L<Date::Manip::Problems> documentation for
information on submitting bug reports or questions to the author.

=head1 SEE ALSO

L<Date::Manip>        - main module documentation

=head1 LICENSE

This script is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

=head1 AUTHOR

Sullivan Beck (sbeck@cpan.org)

=cut