Log::Parallel::Durations - parse duration specifications

 Log::Parallel::Durations - parse duration specifications

 use Log::Parallel::Durations;

 my $job = {
	frequency => 'daily',
	timespan => '30 days',
 };
 my $jd = Time::JulianDay::julian_day(2008, 10, 22);
 my $jd_from_limit = Time::JulianDay::julian_day(2008, 8, 22);
 my $jd_to_limit = Time::JulianDay::julian_day(2008, 12, 14);

 ($timespec, @jd_range) = frequency_and_span($job, $jd, $jd_from_limit, $jd_to_limit);

 daily
 every 3 days
 every week
 each month on the 13th
 on the 1st each month
 on the 1st of each month
 every Tuesday
 on the 3rd Wednesday of each month

 3 days
 1 quarter
 2 years

package Log::Parallel::Durations;

use strict;
use warnings;
require Exporter;
use List::EvenMoreUtils qw(keys_to_regex);
use Lingua::EN::Inflect qw(PL);
use Time::JulianDay;

our @ISA = qw(Exporter);
our @EXPORT = qw(frequency_and_span);

my %span = (
	#	   days months
	day	=> [ 1,  0 ],
	week	=> [ 7,  0 ],
	month	=> [ 0,  1 ],
	quarter	=> [ 0,  3 ],
	year	=> [ 0, 12 ],
);

my %translations = qw(
	daily		day
	weekly		week
	monthly		month
	yearly		year
	quarterly	quarter
);

my %weekdays = qw(
	sun 0		sunday 0
	mon 1		monday 1
	tue 2		tuesday 2
	wed 3		wednesday 3
	thu 4		thursday 4
	fri 5		friday 5
	sat 6		saturday 6
);


my %spans = map { PL($_) => $span{$_} } keys %span;
my %singular = map { PL($_) => $_ } keys %span;
my $re_trans = keys_to_regex(%translations);
my $re_span = keys_to_regex(%span);
my $re_spans = keys_to_regex(%spans);
my $re_wday = keys_to_regex(%weekdays);

my %timely = map { $translations{$_} => $_ } keys %translations;

my $re_nth = qr/(?:((?:[23]?1(?=st))|(?:2?2(?=nd))|(2?3(?=rd))|(?:(?:1\d|2?[04-9]|30)(?=th)))..)/;
my $re_small_nth = qr/(?:((?:1(?=st))|(?:2(?=nd))|(3(?=rd))|(?:4(?=th)))..)/;

sub match_span
{
	my ($jd, $from, $count, $type) = @_;
	my ($sd, $sm) = @{$span{$type}};
	die if $sd && $sm;
	if ($sd) {
		return 1 if ($jd - $from) % ($count * $sd) == 0;
		return 0;
	}
	my ($y, $m, $d) = inverse_julian_day($jd);
	my ($fy, $fm, $fd) = inverse_julian_day($from);
	return 0 unless $d == $fd;
	my $md = $m - $fm + $y*12 - $fy*12;
	return 1 if $md % ($count * $sm) == 0;
	return 0;
}


#use Tie::Function::Examples;
#tie my %yyyymmdd, 'Tie::Function::Examples',
#	sub {
#		my ($y, $m, $d) = inverse_julian_day($_[0]);
#		return sprintf("%d-%02d-%02d", $y, $m, $d);
#	};

sub frequency_and_span
{
	my ($job, $jd, $jd_from_limit, $jd_to_limit) = @_;

#print "F&S: $job->{name} $yyyymmdd{$jd} $yyyymmdd{$jd_from_limit} $yyyymmdd{$jd_to_limit} $job->{frequency}\n";

#if $job->{frequency} && $job->{frequency} ne 'daily';

	return unless $jd >= $jd_from_limit && $jd <= $jd_to_limit;

	my $frequency = $job->{frequency} || 'daily';

	$frequency =~ s/\b($re_trans)\b/every $translations{$1}/g;

	my ($yyyy, $mm, $dd) = inverse_julian_day($jd);
	my ($name, $count, $default_span);

	if ($frequency =~ /^\s*(?:every\s+)?(\d+)\s+($re_spans)$/i) {
		$count = $1;
		$name = $singular{$2};
		$default_span = "$count $name";
		return unless match_span($jd, $jd_from_limit, $count, $name);
	} elsif ($frequency =~ /^\s*every\s+($re_span)/i) {
		$count = 1;
		$name = $1;
		$default_span = "$count $name";
		return unless match_span($jd, $jd_from_limit, $count, $name);
	} elsif ($frequency =~ /^\s*every\s+$re_nth\s+day\s+each\s+month\s*$/i) {
		$name = "month";
		$count = 1;
		return unless $dd == $1;
		$default_span = "1 month";
	} elsif ($frequency =~ /^\s*(?:each\s+month,?\s+)?on\s+the\s+$re_nth(?:\s+(?:of\s+)?each\s+month)?\s*$/i) {
		$name = "month";
		$count = 1;
		return unless $dd == $1;
		$default_span = "1 month";
	} elsif ($frequency =~ /^\s*every\s+($re_wday)\s*$/i) {
		my $dow = $weekdays{lc($2)};
		return unless $dow = day_of_week($jd);
		$name = "week";
		$count = 1;
		$default_span = "1 week";
	} elsif ($frequency =~ /^\s*(?:every|on\s+the)\s$re_small_nth\s+($re_wday)(?:\s+(?:of\s+)?each\s+month)?\s*$/i) {
		$name = "month";
		$count = 1;
		$default_span = "1 month";
		my $nth = $1;
		my $dow = $weekdays{lc($2)};
		return unless $dow = day_of_week($jd);
		my $weeknum = int(($dd - 1)/ 7) + 1;
		return unless $weeknum == $nth;
	} elsif ($frequency =~ /^\s*range\s*$/) {
		return unless $jd == $jd_to_limit;
		my ($from_yyyy, $from_mm, $from_dd) = inverse_julian_day($jd_from_limit);
		my ($yyyy, $mm, $dd) = inverse_julian_day($jd_to_limit);
		return ({
			YYYY		=> $yyyy,
			FROM_YYYY	=> $from_yyyy,
			MM		=> $mm,
			FROM_MM		=> $from_mm,
			DD		=> $dd,
			FROM_DD		=> $from_dd,
			DURATION	=> 'range',
			FROM_JD		=> $jd_from_limit,
			JD		=> $jd,
		}, $jd_from_limit .. $jd_to_limit);
	} else {
		require Carp;
		Carp::confess "could not parse frequency '$frequency'";
	}

	my $timespan = $job->{timespan} || $default_span;

	my $duration;
	my $spancount;
	my $spanname;
	if ($timespan =~ /^(\d+)\s+($re_spans)$/) {
		$spancount = $singular{$1};
		$spanname = $2;
	} elsif ($timespan =~ /^(\d+)\s+($re_span)$/) {
		$spancount = $1;
		$spanname = $2;
	} elsif ($timespan =~ /^\s*all ?time\s*$/) {
		return unless $jd == $jd_to_limit;
		$spancount = 0;
	} else {
		die "can't parse timespan '$timespan'";
	}

	my ($spand, $spanm) = @{$span{$spanname}};
	my $fy = $yyyy;
	my $fm = $mm - $spanm * $spancount;
	while ($fm < 1) {
		$fy -= 1;
		$fm += 12;
	}
	my $fromjd = julian_day($fy, $fm, $dd);
	$fromjd -= $spand * $spancount;
	$fromjd += 1;		# don't overlap

	if ($count == 1) {
		$duration ||= $timely{$name};
	} else {
		$duration ||= "$count$name";
	}
	my ($from_yyyy, $from_mm, $from_dd) = inverse_julian_day($fromjd);

	return ({
		YYYY		=> $yyyy,
		FROM_YYYY	=> $from_yyyy,
		MM		=> $mm,
		FROM_MM		=> $from_mm,
		DD		=> $dd,
		FROM_DD		=> $from_dd,
		DURATION	=> $duration,
		FROM_JD		=> $fromjd,
		JD		=> julian_day($yyyy, $mm, $dd),
	}, $fromjd .. $jd);
}

1;

__END__