added iso8601 handling functions, to avoid ugly nasty conversions

git-svn-id: http://svn.automattic.com/wordpress/trunk@1372 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions-formatting.php

@@ -414,4 +414,35 @@ function get_date_from_gmt($string) {
   return $string_localtime;
 }
 
+// computes an offset in seconds from an iso8601 timezone
+function iso8601_timezone_to_offset($timezone) {
+  // $timezone is either 'Z' or '[+|-]hhmm'
+  if ($timezone == 'Z') {
+    $offset = 0;
+  } else {
+    $sign    = (substr($timezone, 0, 1) == '+') ? 1 : -1;
+    $hours   = intval(substr($timezone, 1, 2));
+    $minutes = intval(substr($timezone, 3, 4)) / 60;
+    $offset  = $sign * 3600 * ($hours + $minutes);
+  }
+  return $offset;
+}
+
+// converts an iso8601 date to MySQL DateTime format used by post_date[_gmt]
+function iso8601_to_datetime($date_string, $timezone = USER) {
+  if ($timezone == GMT) {
+    preg_match('#([0-9]{4})([0-9]{2})([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(Z|[\+|\-][0-9]{2,4}){0,1}#', $date_string, $date_bits);
+    if (!empty($date_bits[7])) { // we have a timezone, so let's compute an offset
+      $offset = iso8601_timezone_to_offset($date_bits[7]);
+    } else { // we don't have a timezone, so we assume user local timezone (not server's!)
+      $offset = 3600 * get_settings('gmt_offset');
+    }
+    $timestamp = gmmktime($date_bits[4], $date_bits[5], $date_bits[6], $date_bits[2], $date_bits[3], $date_bits[1]);
+    $timestamp -= $offset;
+    return gmdate('Y-m-d H:i:s', $timestamp);
+  } elseif ($timezone == USER) {
+    return preg_replace('#([0-9]{4})([0-9]{2})([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})(Z|[\+|\-][0-9]{2,4}){0,1}#', '$1-$2-$3 $4:$5:$6', $date_string);
+  }
+}
+
 ?>