[Zurich] Factor out working days calculator.

1 files changed, 78 insertions, 0 deletions

diff --git a/perllib/FixMyStreet/WorkingDays.pm b/perllib/FixMyStreet/WorkingDays.pm
new file mode 100644
index 000000000..615b226c6
--- /dev/null
+++ b/perllib/FixMyStreet/WorkingDays.pm
@@ -0,0 +1,78 @@
+package FixMyStreet::WorkingDays;
+
+use Moo;
+
+=head1 FixMyStreet::WorkingDays
+
+Given a list of public holiday dates, creates an object that can be used to
+add/subtract days from a date, only counting working days (excluding public
+holidays and weekends).
+
+=over
+
+=cut
+
+has public_holidays => (
+    is => 'ro',
+    coerce => sub {
+        return { map { $_ => 1 } @{$_[0]} };
+    },
+);
+
+=item add_days
+
+Given a DateTime object and a number of days, returns a new DateTime object
+that many working days (excluding public holidays and weekends) later.
+
+=cut
+
+sub add_days {
+    my ( $self, $dt, $days, $subtract ) = @_;
+    $dt = $dt->clone;
+    while ( $days > 0 ) {
+        $dt->add ( days => $subtract ? -1 : 1 );
+        next if $self->is_public_holiday($dt);
+        next if $self->is_weekend($dt);
+        $days--;
+    }
+    return $dt;
+}
+
+=item sub_days
+
+Given a DateTime object and a number of days, returns a new DateTime object
+that many working days (excluding public holidays and weekends) earlier.
+
+=cut
+
+sub sub_days {
+    my $self = shift;
+    return $self->add_days(@_, 1);
+}
+
+=item is_public_holiday
+
+Given a DateTime object, return true if it is a public holiday.
+
+=cut
+
+sub is_public_holiday {
+    my ($self, $dt) = @_;
+    return $self->public_holidays->{$dt->ymd};
+}
+
+=item is_weekend
+
+Given a DateTime object, return true if it is a weekend.
+
+=cut
+
+sub is_weekend {
+    my ($self, $dt) = @_;
+    return $dt->dow > 5;
+}
+
+1;
+
+=back
+