--- /dev/null
+package HTML::CalendarMonth::DateTool::DateCalc;
+
+# Interface to Date::Calc
+
+use strict;
+use Carp;
+
+use vars qw(@ISA $VERSION);
+
+@ISA = qw(HTML::CalendarMonth::DateTool);
+
+$VERSION = '0.03';
+
+use Date::Calc qw(Days_in_Month Day_of_Week Add_Delta_Days
+ Weeks_in_Year Week_of_Year Week_Number Mktime
+ );
+
+sub dow1st_and_lastday {
+ my($self, $month, $year) = @_;
+ $month ||= $self->month;
+ $year ||= $self->year;
+ my $lastday = Days_in_Month($year, $month);
+ # Date::Calc uses 1..7 as indicies in the week, starting with Monday.
+ # Internally, we use 0..6, starting with Sunday. These turn out to be
+ # identical except for Sunday.
+ my $dow1st = $self->dow(1);
+ $dow1st = 0 if $dow1st == 7;
+ ($dow1st, $lastday);
+}
+
+sub day_epoch {
+ my($self, $day, $month, $year) = @_;
+ $month ||= $self->month;
+ $year ||= $self->year;
+ Mktime($year, $month, $day, 0, 0, 0);
+}
+
+sub dow {
+ my($self, $day, $month, $year) = @_;
+ $day || croak "Day required.\n";
+ $month ||= $self->month;
+ $year ||= $self->year;
+ Day_of_Week($year, $month, $day);
+}
+
+sub add_days {
+ my($self, $delta, $day, $month, $year) = @_;
+ defined $delta || croak "Delta (in days) required.\n";
+ $day || croak "Day required.\n";
+ $month ||= $self->month;
+ $year ||= $self->year;
+ my($y, $m, $d) = Add_Delta_Days($year, $month, $day, $delta);
+ ($d, $m, $y);
+}
+
+sub week_of_year {
+ my($self, $day, $month, $year) = @_;
+ $day || croak "Day required.\n";
+ $month ||= $self->month;
+ $year ||= $self->year;
+ my $week;
+ ($week, $year) = Week_of_Year($year, $month, $day);
+ ($year, $week);
+}
+
+1;