=head1	NAME

Time::Interval - Converts time intervals of days, hours, minutes, and seconds

This is a rather simple perl module for dealing with time intervals. Among other things, 
this module can tell you the number of hours, minutes, and seconds elapsed between two 
dates.

NOTE: this module does not handle resolutions < 1 second. Please see the Time::HiRes 
module for high resolution time operations. This module will round fractional second
values to the nearest whole number.


=head1	SYNOPSIS

	use Time::Interval;
	
	$data = getInterval(
		"1/25/03 12:34:32 EDT 2003",
		"4/25/03 11:24:00 EDT 2003"
	);
	
	$string = getInterval(
		"1/25/03 12:34:32 EDT 2003",
		"4/25/03 11:24:00 EDT 2003",
		"string"
	);
	
	$number_of_minutes = convertInterval(
		days		=> 5,
		hours		=> 23,
		minutes		=> 10,
		ConvertTo	=> "minutes"
	);
	
	$data = parseInterval(seconds => 14295872);

	$string = parseInterval(
		seconds => 14295872,
		String	=> 1
	);
	
	$string = parseInterval(
		seconds => 14295872,
		Small	=> 1
	);
	
	$min_intervals = coalesce([ 
			[ '1/25/03 12:34:32 EDT 2003', '1/25/03 15:34:32 EDT 2003' ],
			[ '1/25/03 14:34:32 EDT 2003', '1/25/03 16:34:32 EDT 2003' ],
			[ '1/25/03 09:10:18 EDT 2003', '1/25/03 12:32:15 EDT 2003' ]
	]);
	


=head1	getInterval

this will take two date strings in any of the formats recognized by Date::Parse, and return
the number of days, hours, minutes, and seconds elapsed between the two times. 

=head2	Returned Data format

getInterval returns a hash reference in the same format as parseInterval.

=head2	Catching exceptions

upon failure this routine will return the undef value, and an error string will be 
warn'd to stdout.

=head2	Arguments

=over

=item argument 1 (required)

this should be a date string in any of the formats available to Date::Parse.

=item argument 2 (required)

this should be a date string in any of the formats available to Date::Parse.

=item argument 3 (optional)

this argument controls how the interval will be returned.
If not defined, the inerval will be returned as a hash reference containing the number of 
days, hourse, minutes and seconds between the two dates. If the following values are specified
the interval will be returned as a string:

=over

=item	'small'

if this value is specified, a string containing abbreviated values will be returned (dhms format)
for instance 1d 2h 3m 0s (one day, two hours, three minutes and 0 seconds)

=item	'string'

if this value (or any value other than 'short') is specified a string containing the interval
will be returned for instance: '1 day, 2 hours, 3 minutes, 0 seconds'

=back

=back


=head1	convertInterval

this will convert a given number of days, hours, minutes, or seconds, or any combination
thereof to the format specified by the ConverrtTo option.

=head2	Returned data

is a number, of time units that you specify on the ConvertTo option

=head2	Options

=over

=item	ConvertTo	'days'|'hours'|'minutes'|'seconds'

convert the given time interval to this unit of time measurement, if not specified, the default
value is 'seconds'

=item	days

specify number of days

=item	hours

specify number of hours

=item	minutes

specify number of minutes

=item	seconds

specify number of seconds

=back


=head1	parseInterval

this will convert the given time interval to the number of days, hours, minutes and seconds.

=head2	Returned Data Format

unless the 'String' option is specified, this routine returns a has reference containing the 
following data:

\%data	= (
	'days'		=> $number_of_days,
	'hours'		=> $number_of_hours,
	'minutes'	=> $number_of_minutes,
	'seconds'	=> $number_of_seconds
);

=head2	Options

=over

=item	days

specify number of days

=item	hours

specify number of hours

=item	minutes

specify number of minutes

=item	seconds

specify number of seconds

=item	String

if this option is specified as a non-zero value a string containing the number of days, hours,
minutes, and seconds is returned, for example:

"70 days, 16 hours, 56 minutes, 18 seconds"

=item	Small

if this option is specified as a non-zero value a string containing the number of days, hours,
minutes, and seconds is returned in abbreviated form (dhms format), for example:

"70d 16h 56m 18s"

=back


=head1	coalesce

given a set of time intervals (start and end time pairs), this method will return the minimum set
based on overlapping time spans. That is, this method will return a list of unique contiguous time
intervals from the given list. As with the other methods in this package, time strings may be 
submitted in any of the formats supported by Date::Parse. Data is returned as it was passed in, as
a reference to an array of array references (see below).

=head2	Arguments

coalesce takes only one argument, an array reference. The reference should be to an array of array 
references, each of which contains a start and an end time. For a quick example, take a look at the
SYNOPSIS section.


=head1	Author: 

    Andrew N. Hicox	<ahicox@hicox.com>
    http://www.hicox.com