diff --git a/lib/NGCP/Panel/Controller/API/CFTimeSets.pm b/lib/NGCP/Panel/Controller/API/CFTimeSets.pm
index cabb6533c5..4c8c9137ae 100644
--- a/lib/NGCP/Panel/Controller/API/CFTimeSets.pm
+++ b/lib/NGCP/Panel/Controller/API/CFTimeSets.pm
@@ -155,12 +155,15 @@ sub POST :Allow {
             $self->error($c, HTTP_UNPROCESSABLE_ENTITY, "Invalid field 'times'. Must be an array.");
             last;
         }
+        my $times = $resource->{times};
+        # enable tz and use_owner_tz params for POST:
+        #$times = $self->apply_owner_timezone($c,$b_subscriber,$resource->{times},'deflate');
         try {
             $tset = $schema->resultset('voip_cf_time_sets')->create({
                     name => $resource->{name},
                     subscriber_id => $subscriber->id,
                 });
-            for my $t ( @{$resource->{times}} ) {
+            for my $t ( @$times ) {
                 delete $t->{time_set_id};
                 $tset->create_related("voip_cf_periods", $t);
             }
@@ -169,7 +172,7 @@ sub POST :Allow {
             $self->error($c, HTTP_INTERNAL_SERVER_ERROR, "Failed to create cftimeset.");
             last;
         }
-        
+
         last unless $self->add_create_journal_item_hal($c,sub {
             my $self = shift;
             my ($c) = @_;
diff --git a/lib/NGCP/Panel/Role/API/CFTimeSets.pm b/lib/NGCP/Panel/Role/API/CFTimeSets.pm
index f2ee5a7685..ae38f4588b 100644
--- a/lib/NGCP/Panel/Role/API/CFTimeSets.pm
+++ b/lib/NGCP/Panel/Role/API/CFTimeSets.pm
@@ -15,6 +15,8 @@ use NGCP::Panel::Utils::Subscriber;
 
 use NGCP::Panel::Form;
 
+use NGCP::Panel::Utils::DateTime qw();
+
 sub get_form {
     my ($self, $c) = @_;
     if($c->user->roles eq "subscriber" || $c->user->roles eq "subscriberadmin") {
@@ -24,6 +26,279 @@ sub get_form {
     }
 }
 
+sub apply_owner_timezone {
+
+    my ($self, $c, $subscriber, $times, $mode) = @_;
+
+    my $tz_name;
+    if($c->req->param('tz')) {
+        if (DateTime::TimeZone->is_valid_name($c->req->param('tz'))) {
+            $tz_name = $c->req->param('tz');
+        } else {
+            $self->error($c, HTTP_UNPROCESSABLE_ENTITY, "Query parameter 'tz' value is not a valid time zone");
+            return;
+        }
+    } elsif ($subscriber and $c->req->param('use_owner_tz')) {
+        my $tz = $c->model('DB')->resultset('voip_subscriber_timezone')->search_rs({
+            subscriber_id => $subscriber->id
+        })->first;
+        $tz_name = NGCP::Panel::Utils::DateTime::normalize_db_tz_name($tz->name) if $tz;
+    }
+    $times //= [];
+    my $tz_local = DateTime::TimeZone->new(name => 'local');
+    my ($tz,$offset);
+    if ($tz_name
+        and ($tz = DateTime::TimeZone->new(name => $tz_name))
+        and abs($offset = $tz->offset_for_datetime(DateTime->now()) - $tz_local->offset_for_datetime(DateTime->now())) > 0) {
+
+        my $offset_hrs = int($offset / 3600.0);
+        if ($offset_hrs * 3600 != $offset) {
+            $self->error($c, HTTP_UNPROCESSABLE_ENTITY, "only full hours supported for timezone offset ($tz_name: $offset seconds = $offset_hrs hours)");
+            return;
+        }
+
+        #foreach my $time (@$times) {
+        #    foreach $field (qw(year month mday) {
+        #        if (exists $time->{$field} and $time->{$field}) {
+        #            $self->error($c, HTTP_UNPROCESSABLE_ENTITY, "cannot apply a timezone offset for time with '$field' field ($time->{$field})");
+        #            return;
+        #        }
+        #    }
+        #}
+
+        my $merge = 0;
+        if ('deflate' eq $mode) { #for writing to db
+            $offset_hrs = $offset_hrs * -1;
+            $c->log->debug("cf timeset $mode for timezone $tz_name: offset $offset_hrs hours");
+        } elsif ('inflate' eq $mode) { #for reading from db
+            $merge = 1;
+            $c->log->debug("cf timeset $mode for timezone $tz_name: offset $offset_hrs hours");
+        } else {
+            die("invalid mode $mode");
+        }
+
+        my ($yearmonthmday_map,$yearmonthmdays) = array_to_map($times,sub { my $time = shift;
+            return (length($time->{year}) > 0 ? $time->{year} : '*') .
+            '_' . ($time->{month} || '*') . '_' . ($time->{mday} || '*');
+        },undef,'group');
+
+        $times = [];
+        foreach my $yearmonthmday (@$yearmonthmdays) {
+            if ($offset_hrs > 0) {
+                push(@$times,@{_add($yearmonthmday_map->{$yearmonthmday},$offset_hrs,$merge)});
+            } else {
+                push(@$times,@{_subtract($yearmonthmday_map->{$yearmonthmday},$offset_hrs,$merge)});
+            }
+        }
+
+    } else {
+        $c->log->debug("no timezone to convert to, or zero tz offset");
+    }
+    return $times;
+
+}
+
+sub _add {
+    my ($times,$offset_hrs,$merge) = @_;
+
+    my @result = ();
+    foreach my $time (@$times) {
+        my $p1 = { %$time };
+        unless (length($time->{hour}) > 0) {
+            #nothing to do if there is no hour defined:
+            push(@result,$p1);
+            next;
+        }
+        my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+        my $hour_range;
+        if (defined $hour_end) {
+            $hour_range = 1;
+        } else {
+            $hour_end = $hour_start;
+            $hour_range = 0;
+        }
+        $hour_start += abs($offset_hrs);
+        $hour_end += abs($offset_hrs);
+        if ($hour_start < 24 and $hour_end < 24) {
+            $p1->{hour} = ($hour_range ? $hour_start . '-' . $hour_end : $hour_start);
+            push(@result,$p1);
+            next;
+        }
+        my ($wday_start, $wday_end) = split(/\-/, $time->{wday} || '1-7');
+        my $wday_range;
+        if (defined $wday_end) {
+            $wday_range = 1;
+        } else {
+            $wday_end = $wday_start;
+            $wday_range = 0;
+        }
+        my @nums = ();
+        if ($wday_start <= $wday_end) {
+            push(@nums,$wday_start .. $wday_end);
+        } else {
+            push(@nums,$wday_start .. 7);
+            push(@nums,1 .. $wday_end);
+        }
+        my ($p2,$p_shift_wday);
+        if ($hour_start > 23 and $hour_end > 23) { #26-28
+            $p1->{hour} = ($hour_range ? ($hour_start % 24) . '-' . ($hour_end % 24) : ($hour_start % 24)); #2-4
+            $p_shift_wday = $p1;
+        } elsif ($hour_start < $hour_end) {
+            if ($hour_end > 23) { #17-23 +3-> 20-26
+                $p1->{hour} = $hour_start . '-23'; #20-0
+                $p2 = { %$time };
+                $p2->{hour} = '0-' . ($hour_end % 24); #0-2
+                $p_shift_wday = $p2;
+            }
+        } else {
+            if ($hour_start > 23) { #23-17 +3-> 26-20
+                $p1->{hour} = ($hour_start % 24) . '-' . $hour_end; #2-20
+                $p_shift_wday = $p1;
+            }
+        }
+        if ($p_shift_wday and (scalar @nums) < 7) {
+            $p_shift_wday->{wday} = ($wday_range ? (($wday_start) % 7 + 1) . '-' . (($wday_end) % 7 + 1) : (($wday_start) % 7 + 1));
+        }
+        push(@result,$p1);
+        push(@result,$p2) if $p2;
+    }
+    return ($merge ? merge_adjacent(\@result) : \@result);
+
+}
+
+sub _subtract {
+    my ($times,$offset_hrs,$merge) = @_;
+
+    my @result = ();
+    foreach my $time (@$times) {
+        my $p1 = { %$time };
+        unless (length($time->{hour}) > 0) {
+            #nothing to do if there is no hour defined:
+            push(@result,$p1);
+            next;
+        }
+        my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+        my $hour_range;
+        if (defined $hour_end) {
+            $hour_range = 1;
+        } else {
+            $hour_end = $hour_start;
+            $hour_range = 0;
+        }
+        $hour_start -= abs($offset_hrs);
+        $hour_end -= abs($offset_hrs);
+        if ($hour_start >= 0 and $hour_end >= 0) {
+            $p1->{hour} = ($hour_range ? $hour_start . '-' . $hour_end : $hour_start);
+            push(@result,$p1);
+            next;
+        }
+        my ($wday_start, $wday_end) = split(/\-/, $time->{wday} || '1-7');
+        my $wday_range;
+        if (defined $wday_end) {
+            $wday_range = 1;
+        } else {
+            $wday_end = $wday_start;
+            $wday_range = 0;
+        }
+        my @nums = ();
+        if ($wday_start <= $wday_end) {
+            push(@nums,$wday_start .. $wday_end);
+        } else {
+            push(@nums,$wday_start .. 7);
+            push(@nums,1 .. $wday_end);
+        }
+        my ($p2,$p_shift_wday);
+        if ($hour_start < 0 and $hour_end < 0) { #-4 - -2
+            $p1->{hour} = ($hour_range ? ($hour_start % 24) . '-' . ($hour_end % 24) : ($hour_start % 24)); #20-22
+            $p_shift_wday = $p1;
+        } elsif ($hour_start < $hour_end) { #-4 - 3
+            if ($hour_start < 0) { #0-7 -4-> -4 - 3
+                $p1->{hour} = ($hour_start % 24) . '-23'; #20-0
+                $p2 = { %$time };
+                $p2->{hour} = '0-' . $hour_end; #0-3
+                $p_shift_wday = $p1;
+            }
+        } else {
+            if ($hour_end < 0) { #22 - 2 -6-> 16 - -4
+                $p1->{hour} = $hour_start . '-' . ($hour_end % 24); #16-20
+                $p_shift_wday = $p1;
+            }
+        }
+        if ($p_shift_wday and (scalar @nums) < 7) {
+            $p_shift_wday->{wday} = ($wday_range ? (($wday_start - 2) % 7 + 1) . '-' . (($wday_end - 2) % 7 + 1) : (($wday_start - 2) % 7 + 1));
+        }
+        push(@result,$p1);
+        push(@result,$p2) if $p2;
+    }
+    return ($merge ? _merge_adjacent(\@result) : \@result);
+
+}
+
+sub _merge_adjacent {
+    my ($times) = @_;
+
+    my ($wday_map,$wdays) = array_to_map($times,sub { my $time = shift;
+        my $wday = $time->{wday} || '1-7';
+        $wday = '1-7' if $time->{wday} eq '7-1';
+        $wday .= '_' . (defined $time->{minute} ? $time->{minute} : '*');
+        return $wday;
+    },undef,'group');
+
+    my @result = ();
+    my $idx = 0;
+    foreach my $wday (@$wdays) {
+        my %hour_start_map = ();
+        my %hour_end_map = ();
+        my %skip_map = ();
+        my $old_idx = $idx;
+        foreach my $time (@{$wday_map->{$wday}}) {
+            if (length($time->{hour}) > 0) {
+                my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+                $hour_end //= $hour_start;
+                if ($hour_end >= $hour_start) { #we do not create any adjacent roll-over hours, so we also skip such when merging
+                    if (not defined $hour_start_map{$hour_start}
+                        or $hour_end > $hour_start_map{$hour_start}->{hour_end}) {
+                        $hour_start_map{$hour_start} = { hour_end => $hour_end, idx => $idx, };
+                    } else {
+                        $skip_map{$idx} = 0;
+                    }
+                    if (not defined $hour_end_map{$hour_end}
+                        or $hour_start < $hour_end_map{$hour_end}->{hour_start}) {
+                        $hour_end_map{$hour_end} = { hour_start => $hour_start, }; #, idx => $idx,
+                    } else {
+                        $skip_map{$idx} = 0;
+                    }
+                } else {
+                    $skip_map{$idx} = 1;
+                }
+            } else {
+                $skip_map{$idx} = 1;
+            }
+            $idx++;
+        }
+        $idx = $old_idx;
+        foreach my $time (@{$wday_map->{$wday}}) {
+            my $p = { %$time };
+            if (exists $skip_map{$idx}) {
+                push(@result,$p) if $skip_map{$idx};
+            } else {
+                my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+                $hour_end //= $hour_start;
+                #if ($hour_end_map{$hour_end}->{idx} == $idx) {
+                    my $adjacent_start = $hour_end + 1;
+                    if (exists $hour_start_map{$adjacent_start}) {
+                        $p->{hour} = $hour_start . '-' . $hour_start_map{$adjacent_start}->{hour_end};
+                        $skip_map{$hour_start_map{$adjacent_start}->{idx}} = 0;
+                    }
+                    push(@result,$p);
+                #}
+            }
+            $idx++;
+        }
+    }
+    return \@result;
+}
+
 sub hal_from_item {
     my ($self, $c, $item, $type) = @_;
     my $form;
@@ -36,6 +311,8 @@ sub hal_from_item {
         push @times, $timeelem;
     }
     $resource{times} = \@times;
+    # enable tz and use_owner_tz params for GET:
+    #$resource{times} = $self->apply_owner_timezone($c,$item->subscriber->voip_subscriber,\@times,'inflate');
 
     my $b_subs_id = $item->subscriber->voip_subscriber->id;
     $resource{subscriber_id} = $b_subs_id;
@@ -135,13 +412,17 @@ sub update_item {
         last;
     }
 
+    my $times = $resource->{times};
+    # enable tz and use_owner_tz params for PUT/PATCH/POST:
+    #$times = $self->apply_owner_timezone($c,$b_subscriber,$resource->{times},'deflate');
+
     try {
         $item->update({
                 name => $resource->{name},
                 subscriber_id => $subscriber->id,
             })->discard_changes;
         $item->voip_cf_periods->delete;
-        for my $t ( @{$resource->{times}} ) {
+        for my $t ( @$times ) {
             delete $t->{time_set_id};
             $item->create_related("voip_cf_periods", $t);
         }
diff --git a/lib/NGCP/Panel/Utils/Generic.pm b/lib/NGCP/Panel/Utils/Generic.pm
index 10b0d2797e..45021aa984 100644
--- a/lib/NGCP/Panel/Utils/Generic.pm
+++ b/lib/NGCP/Panel/Utils/Generic.pm
@@ -17,7 +17,7 @@ use Data::Compare qw//;
 my $MIME_TYPES = {
     #first extension is default, others are for extension 2 mime_type detection
     'audio/x-wav' => ['wav'],
-    'audio/mpeg'  => ['mp3'], 
+    'audio/mpeg'  => ['mp3'],
     'audio/ogg'   => ['ogg'],
 };
 
@@ -168,4 +168,48 @@ sub extension_to_mime_type {
     return $mime_type;
 }
 
+sub array_to_map {
+
+    my ($array_ptr,$get_key_code,$get_value_code,$mode) = @_;
+    my $map = {};
+    my @keys = ();
+    my @values = ();
+    if (defined $array_ptr and ref $array_ptr eq 'ARRAY') {
+        if (defined $get_key_code and ref $get_key_code eq 'CODE') {
+            if (not (defined $get_value_code and ref $get_value_code eq 'CODE')) {
+                $get_value_code = sub { return shift; };
+            }
+            $mode = lc($mode);
+            if (not ($mode eq 'group' or $mode eq 'first' or $mode eq 'last')) {
+                $mode = 'group';
+            }
+            foreach my $item (@$array_ptr) {
+                my $key = &$get_key_code($item);
+                if (defined $key) {
+                    my $value = &$get_value_code($item);
+                    if (defined $value) {
+                        if (not exists $map->{$key}) {
+                            if ($mode eq 'group') {
+                                $map->{$key} = [ $value ];
+                            } else {
+                                $map->{$key} = $value;
+                            }
+                            push(@keys,$key);
+                        } else {
+                            if ($mode eq 'group') {
+                                push(@{$map->{$key}}, $value);
+                            } elsif ($mode eq 'last') {
+                                $map->{$key} = $value;
+                            }
+                        }
+                        push(@values,$value);
+                    }
+                }
+            }
+        }
+    }
+    return ($map,\@keys,\@values);
+
+}
+
 1;
diff --git a/sandbox/cftimeset_time_tz_conversion.t b/sandbox/cftimeset_time_tz_conversion.t
new file mode 100644
index 0000000000..b43f068d0c
--- /dev/null
+++ b/sandbox/cftimeset_time_tz_conversion.t
@@ -0,0 +1,421 @@
+use strict;
+
+use Test::More;
+
+{
+    use DateTime;
+    use DateTime::TimeZone;
+    my $tz = DateTime::TimeZone->new(name => 'America/Chicago'); #'Europe/Dublin');
+    my $dt = DateTime->now();
+    my $offset = $tz->offset_for_datetime($dt);
+    diag($dt .' - offset: ' . $offset);
+}
+
+#goto SKIP;
+### add
+{
+    # single day, no roll-over hours:
+    is_deeply(_add([{wday => '7',hour => '2-3',},],3), [{wday => '7',hour => '5-6',
+    },], "single day add, hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '7',hour => '20-23',},],3), [{wday => '7',hour => '23-23',},{wday => '1',hour => '0-2',
+    }], "single day add, hour to shifted to next day");
+    is_deeply(_add([{wday => '7',hour => '22-23',},],3), [{wday => '1',hour => '1-2',
+    },], "single day add, hour from and hour to shifted to next day");
+
+    # single day, roll over hours:
+    is_deeply(_add([{wday => '7',hour => '3-2',},],3), [{wday => '7',hour => '6-5',
+    },], "single day add, roll-over hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '7',hour => '22-3',},],3), [{wday => '1',hour => '1-6',
+    },], "single day add, roll-over hour from shifted to next day");
+    is_deeply(_add([{wday => '7',hour => '23-22',},],3), [{wday => '1',hour => '2-1',
+    },], "single day add, roll-over hour from and hour to shifted to next day");
+
+    # range days, no roll-over hours:
+    is_deeply(_add([{wday => '3-7',hour => '2-3',},],3), [{wday => '3-7',hour => '5-6',
+    },], "range days add, hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '3-7',hour => '20-23',},],3), [{wday => '3-7',hour => '23-23',},{wday => '4-1',hour => '0-2',
+    }], "range days add, hour to shifted to next day");
+    is_deeply(_add([{wday => '3-7',hour => '22-23',},],3), [{wday => '4-1',hour => '1-2',
+    },], "range days add, hour from and hour to shifted to next day");
+
+    # range days, roll over hours:
+    is_deeply(_add([{wday => '3-7',hour => '3-2',},],3), [{wday => '3-7',hour => '6-5',
+    },], "range days add, roll-over hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '3-7',hour => '22-3',},],3), [{wday => '4-1',hour => '1-6',
+    },], "range days add, roll-over hour from shifted to next day");
+    is_deeply(_add([{wday => '3-7',hour => '23-22',},],3), [{wday => '4-1',hour => '2-1',
+    },], "range days add, roll-over hour from and hour to shifted to next day");
+
+    # all days, no roll-over hours:
+    is_deeply(_add([{wday => '7-1',hour => '2-3',},],3), [{wday => '7-1',hour => '5-6',
+    },], "any days add, hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '1-7',hour => '20-23',},],3), [{wday => '1-7',hour => '23-23',},{wday => '1-7',hour => '0-2',
+    }], "any days add, hour to shifted to next day");
+    is_deeply(_add([{wday => '',hour => '22-23',},],3), [{wday => '',hour => '1-2',
+    },], "any days add, hour from and hour to shifted to next day");
+
+    # all days, roll over hours:
+    is_deeply(_add([{wday => '7-1',hour => '3-2',},],3), [{wday => '7-1',hour => '6-5',
+    },], "any days add, roll-over hour from and hour to not shifted to next day");
+    is_deeply(_add([{wday => '',hour => '22-3',},],3), [{wday => '',hour => '1-6',
+    },], "any days add, roll-over hour from shifted to next day");
+    is_deeply(_add([{wday => '1-7',hour => '23-22',},],3), [{wday => '1-7',hour => '2-1',
+    },], "any days add, roll-over hour from and hour to shifted to next day");
+
+}
+
+#SKIP:
+### subtract
+{
+    # single day, no roll-over hours:
+    is_deeply(_subtract([{wday => '1',hour => '5-6',},],3), [{wday => '1',hour => '2-3',
+    },], "single day subtract, hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1',hour => '2-4',},],3), [{wday => '7',hour => '23-23',},{wday => '1',hour => '0-1',
+    }], "single day subtract, hour from shifted to previous day");
+    is_deeply(_subtract([{wday => '1',hour => '0-2',},],3), [{wday => '7',hour => '21-23',
+    },], "single day subtract, hour from and hour to shifted to previous day");
+
+    # single day, roll over hours:
+    is_deeply(_subtract([{wday => '1',hour => '6-5',},],3), [{wday => '1',hour => '3-2',
+    },], "single day subtract, roll-over hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1',hour => '6-1',},],3), [{wday => '7',hour => '3-22',
+    },], "single day subtract, roll-over hour to shifted to previous day");
+    is_deeply(_subtract([{wday => '1',hour => '2-1',},],3), [{wday => '7',hour => '23-22',
+    },], "single day subtract, roll-over hour from and hour to shifted to previous day");
+
+    # range days, no roll-over hours:
+    is_deeply(_subtract([{wday => '1-3',hour => '5-6',},],3), [{wday => '1-3',hour => '2-3',
+    },], "range days subtract, hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1-3',hour => '2-4',},],3), [{wday => '7-2',hour => '23-23',},{wday => '1-3',hour => '0-1',
+    }], "range days subtract, hour from shifted to previous day");
+    is_deeply(_subtract([{wday => '1-3',hour => '0-2',},],3), [{wday => '7-2',hour => '21-23',
+    },], "range days subtract, hour from and hour to shifted to previous day");
+
+    # range days, roll over hours:
+    is_deeply(_subtract([{wday => '1-3',hour => '6-5',},],3), [{wday => '1-3',hour => '3-2',
+    },], "range days subtract, roll-over hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1-3',hour => '6-1',},],3), [{wday => '7-2',hour => '3-22',
+    },], "range days subtract, roll-over hour to shifted to previous day");
+    is_deeply(_subtract([{wday => '1-3',hour => '2-1',},],3), [{wday => '7-2',hour => '23-22',
+    },], "range days subtract, roll-over hour from and hour to shifted to previous day");
+
+    # all days,  no roll-over hours:
+    is_deeply(_subtract([{wday => '7-1',hour => '5-6',},],3), [{wday => '7-1',hour => '2-3',
+    },], "any day subtract, hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1-7',hour => '2-4',},],3), [{wday => '1-7',hour => '23-23',},{wday => '1-7',hour => '0-1',
+    }], "any day subtract, hour from shifted to previous day");
+    is_deeply(_subtract([{wday => '',hour => '0-2',},],3), [{wday => '',hour => '21-23',
+    },], "any day subtract, hour from and hour to shifted to previous day");
+
+    # all days,  roll over hours:
+    is_deeply(_subtract([{wday => '7-1',hour => '6-5',},],3), [{wday => '7-1',hour => '3-2',
+    },], "any day subtract, roll-over hour from and hour to not shifted to previous day");
+    is_deeply(_subtract([{wday => '1-7',hour => '6-1',},],3), [{wday => '1-7',hour => '3-22',
+    },], "any day subtract, roll-over hour to shifted to previous day");
+    is_deeply(_subtract([{wday => '',hour => '2-1',},],3), [{wday => '',hour => '23-22',
+    },], "any day subtract, roll-over hour from and hour to shifted to previous day");
+}
+
+{
+    is_deeply(_subtract(_add([{wday => '7',hour => '20-23',},],3),3,1), [{wday => '7',hour => '20-23',},],
+    "merge adjacent add->subtract");
+    is_deeply(_add(_subtract([{wday => '1',hour => '2-4',},],3),3,1), [{wday => '1',hour => '2-4',},],
+    "merge adjacent subtract->add");
+}
+
+done_testing;
+
+sub _add {
+    my ($times,$offset_hrs,$merge) = @_;
+
+    my @result = ();
+    foreach my $time (@$times) {
+        my $p1 = { %$time };
+        unless (length($time->{hour}) > 0) {
+            #nothing to do if there is no hour defined:
+            push(@result,$p1);
+            next;
+        }
+        my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+        my $hour_range;
+        if (defined $hour_end) {
+            $hour_range = 1;
+        } else {
+            $hour_end = $hour_start;
+            $hour_range = 0;
+        }
+        $hour_start += abs($offset_hrs);
+        $hour_end += abs($offset_hrs);
+        if ($hour_start < 24 and $hour_end < 24) {
+            $p1->{hour} = ($hour_range ? $hour_start . '-' . $hour_end : $hour_start);
+            push(@result,$p1);
+            next;
+        }
+        my ($wday_start, $wday_end) = split(/\-/, $time->{wday} || '1-7');
+        my $wday_range;
+        if (defined $wday_end) {
+            $wday_range = 1;
+        } else {
+            $wday_end = $wday_start;
+            $wday_range = 0;
+        }
+        my @nums = ();
+        if ($wday_start <= $wday_end) {
+            push(@nums,$wday_start .. $wday_end);
+        } else {
+            push(@nums,$wday_start .. 7);
+            push(@nums,1 .. $wday_end);
+        }
+        my ($p2,$p_shift_wday);
+        if ($hour_start > 23 and $hour_end > 23) { #26-28
+            $p1->{hour} = ($hour_range ? ($hour_start % 24) . '-' . ($hour_end % 24) : ($hour_start % 24)); #2-4
+            $p_shift_wday = $p1;
+        } elsif ($hour_start < $hour_end) {
+            if ($hour_end > 23) { #17-23 +3-> 20-26
+                $p1->{hour} = $hour_start . '-23'; #20-0
+                $p2 = { %$time };
+                $p2->{hour} = '0-' . ($hour_end % 24); #0-2
+                $p_shift_wday = $p2;
+            }
+        } else {
+            if ($hour_start > 23) { #23-17 +3-> 26-20
+                $p1->{hour} = ($hour_start % 24) . '-' . $hour_end; #2-20
+                $p_shift_wday = $p1;
+            }
+        }
+        if ($p_shift_wday and (scalar @nums) < 7) {
+            $p_shift_wday->{wday} = ($wday_range ? (($wday_start) % 7 + 1) . '-' . (($wday_end) % 7 + 1) : (($wday_start) % 7 + 1));
+        }
+        push(@result,$p1);
+        push(@result,$p2) if $p2;
+    }
+    return ($merge ? merge_adjacent(\@result) : \@result);
+
+}
+
+sub _subtract {
+    my ($times,$offset_hrs,$merge) = @_;
+
+    my @result = ();
+    foreach my $time (@$times) {
+        my $p1 = { %$time };
+        unless (length($time->{hour}) > 0) {
+            #nothing to do if there is no hour defined:
+            push(@result,$p1);
+            next;
+        }
+        my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+        my $hour_range;
+        if (defined $hour_end) {
+            $hour_range = 1;
+        } else {
+            $hour_end = $hour_start;
+            $hour_range = 0;
+        }
+        $hour_start -= abs($offset_hrs);
+        $hour_end -= abs($offset_hrs);
+        if ($hour_start >= 0 and $hour_end >= 0) {
+            $p1->{hour} = ($hour_range ? $hour_start . '-' . $hour_end : $hour_start);
+            push(@result,$p1);
+            next;
+        }
+        my ($wday_start, $wday_end) = split(/\-/, $time->{wday} || '1-7');
+        my $wday_range;
+        if (defined $wday_end) {
+            $wday_range = 1;
+        } else {
+            $wday_end = $wday_start;
+            $wday_range = 0;
+        }
+        my @nums = ();
+        if ($wday_start <= $wday_end) {
+            push(@nums,$wday_start .. $wday_end);
+        } else {
+            push(@nums,$wday_start .. 7);
+            push(@nums,1 .. $wday_end);
+        }
+        my ($p2,$p_shift_wday);
+        if ($hour_start < 0 and $hour_end < 0) { #-4 - -2
+            $p1->{hour} = ($hour_range ? ($hour_start % 24) . '-' . ($hour_end % 24) : ($hour_start % 24)); #20-22
+            $p_shift_wday = $p1;
+        } elsif ($hour_start < $hour_end) { #-4 - 3
+            if ($hour_start < 0) { #0-7 -4-> -4 - 3
+                $p1->{hour} = ($hour_start % 24) . '-23'; #20-0
+                $p2 = { %$time };
+                $p2->{hour} = '0-' . $hour_end; #0-3
+                $p_shift_wday = $p1;
+            }
+        } else {
+            if ($hour_end < 0) { #22 - 2 -6-> 16 - -4
+                $p1->{hour} = $hour_start . '-' . ($hour_end % 24); #16-20
+                $p_shift_wday = $p1;
+            }
+        }
+        if ($p_shift_wday and (scalar @nums) < 7) {
+            $p_shift_wday->{wday} = ($wday_range ? (($wday_start - 2) % 7 + 1) . '-' . (($wday_end - 2) % 7 + 1) : (($wday_start - 2) % 7 + 1));
+        }
+        push(@result,$p1);
+        push(@result,$p2) if $p2;
+    }
+    return ($merge ? _merge_adjacent(\@result) : \@result);
+
+}
+
+sub _merge_adjacent {
+    my ($times) = @_;
+
+    my ($wday_map,$wdays) = array_to_map($times,sub { my $time = shift;
+        my $wday = $time->{wday} || '1-7';
+        $wday = '1-7' if $time->{wday} eq '7-1';
+        $wday .= '_' . (defined $time->{minute} ? $time->{minute} : '*');
+        return $wday;
+    },undef,'group');
+
+    my @result = ();
+    my $idx = 0;
+    foreach my $wday (@$wdays) {
+        my %hour_start_map = ();
+        my %hour_end_map = ();
+        my %skip_map = ();
+        my $old_idx = $idx;
+        foreach my $time (@{$wday_map->{$wday}}) {
+            if (length($time->{hour}) > 0) {
+                my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+                $hour_end //= $hour_start;
+                if ($hour_end >= $hour_start) { #we do not create any adjacent roll-over hours, so we also skip such when merging
+                    if (not defined $hour_start_map{$hour_start}
+                        or $hour_end > $hour_start_map{$hour_start}->{hour_end}) {
+                        $hour_start_map{$hour_start} = { hour_end => $hour_end, idx => $idx, };
+                    } else {
+                        $skip_map{$idx} = 0;
+                    }
+                    if (not defined $hour_end_map{$hour_end}
+                        or $hour_start < $hour_end_map{$hour_end}->{hour_start}) {
+                        $hour_end_map{$hour_end} = { hour_start => $hour_start, }; #, idx => $idx,
+                    } else {
+                        $skip_map{$idx} = 0;
+                    }
+                } else {
+                    $skip_map{$idx} = 1;
+                }
+            } else {
+                $skip_map{$idx} = 1;
+            }
+            $idx++;
+        }
+        $idx = $old_idx;
+        foreach my $time (@{$wday_map->{$wday}}) {
+            my $p = { %$time };
+            if (exists $skip_map{$idx}) {
+                push(@result,$p) if $skip_map{$idx};
+            } else {
+                my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+                $hour_end //= $hour_start;
+                #if ($hour_end_map{$hour_end}->{idx} == $idx) {
+                    my $adjacent_start = $hour_end + 1;
+                    if (exists $hour_start_map{$adjacent_start}) {
+                        $p->{hour} = $hour_start . '-' . $hour_start_map{$adjacent_start}->{hour_end};
+                        $skip_map{$hour_start_map{$adjacent_start}->{idx}} = 0;
+                    }
+                    push(@result,$p);
+                #}
+            }
+            $idx++;
+        }
+    }
+    return \@result;
+}
+
+sub _merge {
+    my ($times) = @_;
+
+    my ($wday_map,$wdays,$wday_groups) = array_to_map($times,sub { my $time = shift;
+        my $wday = $time->{wday} || '1-7';
+        $wday = '1-7' if $time->{wday} eq '7-1';
+        $wday .= '_' . (defined $time->{minute} ? $time->{minute} : '*');
+        return $wday;
+    },undef,'group');
+
+    my @result = ();
+    my %ranges = ();
+    foreach my $wday (@$wdays) {
+        foreach my $time (@{$wday_map->{$wday}}) {
+            my $p = { %$time };
+            if (length($time->{hour}) > 0) {
+                my ($hour_start,$hour_end) = split(/\-/, $time->{hour});
+                $hour_end //= $hour_start;
+                if ($hour_end >= $hour_start) {
+                    #https://stackoverflow.com/questions/42928964/finding-and-merging-down-intervalls-in-perl
+                    my $in_range = 0;
+                    foreach my $range (@{$ranges{$wday}} ) {
+                        if (($hour_start >= $range->{start} and $hour_start <= $range->{end})
+                             or ( $hour_end >= $range->{start} and $hour_end <= $range->{end})
+                            ) {
+                            $range->{end} = $hour_end if $hour_end > $range->{end};
+                            $range->{start} = $hour_start if $hour_start < $range->{start};
+                            $in_range++;
+                        }
+                    }
+                    if (not $in_range) {
+                        push(@{$ranges{$wday}},{ start => $hour_start, end => $hour_end, });
+                        $p->{hour} = $hour_start . '-' . $hour_end;
+                        push(@result,$p);
+                    }
+                } else { #splitting by the tz offset add/subtract never produces roll-overs, so we don't merge such
+                    push(@result,$p);
+                }
+            } else {
+                push(@result,$p);
+            }
+        }
+    }
+    return \@result;
+
+}
+
+
+
+
+sub array_to_map {
+
+    my ($array_ptr,$get_key_code,$get_value_code,$mode) = @_;
+    my $map = {};
+    my @keys = ();
+    my @values = ();
+    if (defined $array_ptr and ref $array_ptr eq 'ARRAY') {
+        if (defined $get_key_code and ref $get_key_code eq 'CODE') {
+            if (not (defined $get_value_code and ref $get_value_code eq 'CODE')) {
+                $get_value_code = sub { return shift; };
+            }
+            $mode = lc($mode);
+            if (not ($mode eq 'group' or $mode eq 'first' or $mode eq 'last')) {
+                $mode = 'group';
+            }
+            foreach my $item (@$array_ptr) {
+                my $key = &$get_key_code($item);
+                if (defined $key) {
+                    my $value = &$get_value_code($item);
+                    if (defined $value) {
+                        if (not exists $map->{$key}) {
+                            if ($mode eq 'group') {
+                                $map->{$key} = [ $value ];
+                            } else {
+                                $map->{$key} = $value;
+                            }
+                            push(@keys,$key);
+                        } else {
+                            if ($mode eq 'group') {
+                                push(@{$map->{$key}}, $value);
+                            } elsif ($mode eq 'last') {
+                                $map->{$key} = $value;
+                            }
+                        }
+                        push(@values,$value);
+                    }
+                }
+            }
+        }
+    }
+    return ($map,\@keys,\@values);
+
+}
\ No newline at end of file