- my $issueno = 0;
-
- if($unit) {
- my ($year, $month, $day) = split /-/, $publisheddate;
- my ($fa_year, $fa_month, $fa_day) = split /-/, $subscription->{'firstacquidate'};
- my $wkno;
- my $delta;
-
- if($unit eq 'day') {
- $delta = Delta_Days($fa_year, $fa_month, $fa_day, $year, $month, $day);
- } elsif($unit eq 'week') {
- ($wkno, $year) = Week_of_Year($year, $month, $day);
- my ($fa_wkno, $fa_yr) = Week_of_Year($fa_year, $fa_month, $fa_day);
- $delta = ($fa_yr == $year) ? ($wkno - $fa_wkno) : ( ($year-$fa_yr-1)*52 + (52-$fa_wkno+$wkno) );
- } elsif($unit eq 'month') {
- $delta = ($fa_year == $year)
- ? ($month - $fa_month)
- : ( ($year-$fa_year-1)*12 + (12-$fa_month+$month) );
- } elsif($unit eq 'year') {
- $delta = $year - $fa_year;
- }
- if($frequency->{'unitsperissue'} == 1) {
- $issueno = $delta * $frequency->{'issuesperunit'} + $subscription->{'countissuesperunit'};
- } else {
- # Assuming issuesperunit == 1
- $issueno = int( ($delta + $frequency->{'unitsperissue'}) / $frequency->{'unitsperissue'} );
- }
+ return if !$unit;
+ my $issueno;
+
+ my ( $year, $month, $day ) = split /-/, $publisheddate;
+ my ( $fa_year, $fa_month, $fa_day ) = split /-/, $subscription->{'firstacquidate'};
+ my $delta = _delta_units( [$fa_year, $fa_month, $fa_day], [$year, $month, $day], $unit );
+
+ if( $frequency->{'unitsperissue'} == 1 ) {
+ $issueno = $delta * $frequency->{'issuesperunit'} + $subscription->{'countissuesperunit'};
+ } else { # issuesperunit == 1
+ $issueno = 1 + int( $delta / $frequency->{'unitsperissue'} );