From bb461c8daa97358e8bcce923a21eba0abd6ea3dc Mon Sep 17 00:00:00 2001
From: Oleg Pudeyev <oleg@bsdpower.com>
Date: Thu, 10 Mar 2011 19:14:53 -0500
Subject: [PATCH] [feature/new-tz-handling] Sort timezones in selector by
 offset.

Since the list of timezones is very long, and users are likely
to know their current offset but not necessarily which city
that is nearby is in the timezone database, sort the list of
timezones by offset.

UTC is specially handled to show up before other GMT+0 timezones.

PHPBB3-9558
---
 phpBB/feed.php               | 10 +----
 phpBB/includes/functions.php | 71 +++++++++++++++++++++++++++++++++++-
 2 files changed, 71 insertions(+), 10 deletions(-)

diff --git a/phpBB/feed.php b/phpBB/feed.php
index d7092d6758..025904e682 100644
--- a/phpBB/feed.php
+++ b/phpBB/feed.php
@@ -256,15 +256,7 @@ function feed_format_date($time)
 		global $user;
 
 		$zone_offset = $user->create_datetime()->getOffset();
-
-		$sign = ($zone_offset < 0) ? '-' : '+';
-		$time_offset = abs($zone_offset);
-
-		$offset_seconds	= $time_offset % 3600;
-		$offset_minutes	= $offset_seconds / 60;
-		$offset_hours	= ($time_offset - $offset_seconds) / 3600;
-
-		$offset_string	= sprintf("%s%02d:%02d", $sign, $offset_hours, $offset_minutes);
+		$offset_string = phpbb_format_timezone_offset($zone_offset);
 	}
 
 	return gmdate("Y-m-d\TH:i:s", $time + $zone_offset) . $offset_string;
diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 69bfe3e090..31a191b513 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -1069,6 +1069,65 @@ function style_select($default = '', $all = false)
 	return $style_options;
 }
 
+function phpbb_format_timezone_offset($tz_offset)
+{
+	$sign = ($tz_offset < 0) ? '-' : '+';
+	$time_offset = abs($tz_offset);
+
+	$offset_seconds	= $time_offset % 3600;
+	$offset_minutes	= $offset_seconds / 60;
+	$offset_hours	= ($time_offset - $offset_seconds) / 3600;
+
+	$offset_string	= sprintf("%s%02d:%02d", $sign, $offset_hours, $offset_minutes);
+	return $offset_string;
+}
+
+// Compares two time zone labels.
+// Arranges them in increasing order by timezone offset.
+// Places UTC before other timezones in the same offset.
+function tz_select_compare($a, $b)
+{
+	$a_sign = $a[3];
+	$b_sign = $b[3];
+	if ($a_sign != $b_sign)
+	{
+		return $a_sign == '-' ? -1 : 1;
+	}
+
+	$a_offset = substr($a, 4, 5);
+	$b_offset = substr($b, 4, 5);
+	if ($a_offset == $b_offset)
+	{
+		$a_name = substr($a, 12);
+		$b_name = substr($b, 12);
+		if ($a_name == $b_name)
+		{
+			return 0;
+		} else if ($a_name == 'UTC')
+		{
+			return -1;
+		} else if ($b_name == 'UTC')
+		{
+			return 1;
+		}
+		else
+		{
+			return $a_name < $b_name ? -1 : 1;
+		}
+	}
+	else
+	{
+		if ($a_sign == '-')
+		{
+			return $a_offset > $b_offset ? -1 : 1;
+		}
+		else
+		{
+			return $a_offset < $b_offset ? -1 : 1;
+		}
+	}
+}
+
 /**
 * Pick a timezone
 * @todo Possible HTML escaping
@@ -1083,7 +1142,17 @@ function tz_select($default = '', $truncate = false)
 	{
 		$timezones = DateTimeZone::listIdentifiers();
 
-		sort($timezones);
+		foreach ($timezones as &$timezone)
+		{
+			$tz = new DateTimeZone($timezone);
+			$dt = new phpbb_datetime('now', $tz);
+			$offset = $dt->getOffset();
+			$offset_string = phpbb_format_timezone_offset($offset);
+			$timezone = 'GMT' . $offset_string . ' - ' . $timezone;
+		}
+		unset($timezone);
+
+		usort($timezones, 'tz_select_compare');
 	}
 
 	$tz_select = '';