Add API to display relative dates

lang/en

@@ -438,6 +438,36 @@ file_truncated_message=fetched $1 of data, truncated $2 out of $3
 file_truncated_message_head=fetched beginning $1 of data, truncated $2 out of $3
 file_truncated_message_tail=fetched ending $1 of data, truncated $2 out of $3
 
+time_ago_year=$1 year ago
+time_ago_years=$1 years ago
+time_ago_month=$1 month ago
+time_ago_months=$1 months ago
+time_ago_week=$1 week ago
+time_ago_weeks=$1 weeks ago
+time_ago_day=$1 day ago
+time_ago_days=$1 days ago
+time_ago_hour=$1 hour ago
+time_ago_hours=$1 hours ago
+time_ago_min=$1 minute ago
+time_ago_mins=$1 minutes ago
+time_ago_sec=$1 second ago
+time_ago_secs=$1 seconds ago
+time_in_year=In $1 year
+time_in_years=In $1 years
+time_in_month=In $1 month
+time_in_months=In $1 months
+time_in_week=In $1 week
+time_in_weeks=In $1 weeks
+time_in_day=In $1 day
+time_in_days=In $1 days
+time_in_hour=In $1 hour
+time_in_hours=In $1 hours
+time_in_min=In $1 minute
+time_in_mins=In $1 minutes
+time_in_sec=In $1 second
+time_in_secs=In $1 seconds
+time_now=Just now
+
 defcert_error=Default $1 bundled SSL certificate is being used. It is highly advised to update default <tt>$2</tt> certificate before proceeding with login.
 
 main_error_details=Error details

web-lib-funcs.pl

@@ -2409,6 +2409,47 @@ if (ref($only) || !$only) {
 return $date;
 }
 
+# make_date_relative(timestamp)
+# Return localized relative time from now or to the future
+# for a given timestamp, or undef if not a valid timestamp
+sub make_date_relative
+{
+my $ts = shift;
+return undef unless(defined($ts) && $ts =~ /^-?\d+(?:\.\d+)?$/);
+$ts = 0 + $ts;
+my $last_login;
+my $now = time();
+my $diff = $ts - $now; # >0 future, <0 past
+my $abs = abs($diff);
+return $text{'time_now'} if ($abs < 10); # within ±10 seconds is now
+my @units = (
+    [ 31536000, 'year',  'years'  ],
+    [ 2592000,  'month', 'months' ],
+    [ 604800,   'week',  'weeks'  ],
+    [ 86400,    'day',   'days'   ],
+    [ 3600,     'hour',  'hours'  ],
+    [ 60,       'min',   'mins'   ],
+    [ 1,        'sec',   'secs'   ],
+);
+my ($val, $sing, $plur);
+foreach my $unit (@units) {
+	my ($secs, $s, $p) = @$unit;
+	next if ($abs < $secs);
+	$val = int($abs / $secs);
+	($sing, $plur) = ($s, $p);
+	last;
+	}
+if (defined($val) && $val > 0) {
+	my $key = ($diff > 0 ? 'time_in_' : 'time_ago_').
+		  ($val == 1 ? $sing : $plur);
+	$last_login = &text($key, $val);
+	}
+else {
+	$last_login = $text{'time_now'};
+	}
+return $last_login;
+}
+
 =head2 file_chooser_button(input, type, [form], [chroot], [addmode])
 
 Return HTML for a button that pops up a file chooser when clicked, and places