diff --git a/includes/helper/error_helper.php b/includes/helper/error_helper.php
index b4b4f248..58d0ac86 100644
--- a/includes/helper/error_helper.php
+++ b/includes/helper/error_helper.php
@@ -6,7 +6,7 @@
  * @param string $message
  */
 function engelsystem_error($message) {
-  die($message);
+  raw_output($message);
 }
 
 ?>
\ No newline at end of file
diff --git a/includes/pages/user_ical.php b/includes/pages/user_ical.php
index 2f3d5cd5..c38a336c 100644
--- a/includes/pages/user_ical.php
+++ b/includes/pages/user_ical.php
@@ -1,54 +1,82 @@
 <?php
 
-
-// Öffentlich zugängliche Funktion zum Abrufen von iCal-Exports der eigenen Schichten
+/**
+ * Controller for ical output of users own shifts or any user_shifts filter.
+ */
 function user_ical() {
-  global $ical_shifts, $user;
-
-  if (isset ($_REQUEST['key']) && preg_match("/^[0-9a-f]{32}$/", $_REQUEST['key']))
-    $key = $_REQUEST['key'];
-  else
-    die("Missing key.");
-
+  global $user;
+  
+  if (! isset($_REQUEST['key']) || ! preg_match("/^[0-9a-f]{32}$/", $_REQUEST['key'])) {
+    engelsystem_error("Missing key.");
+  }
+  $key = $_REQUEST['key'];
+  
   $user = User_by_api_key($key);
-  if($user === false)
-    die("Unable to find user.");
-  if($user == null)
-    die("Key invalid.");
-  if(!in_array('ical', privileges_for_user($user['UID'])))
-    die("No privilege for ical.");
+  if ($user === false) {
+    engelsystem_error("Unable to find user.");
+  }
+  if ($user == null) {
+    engelsystem_error("Key invalid.");
+  }
+  
+  if (! in_array('ical', privileges_for_user($user['UID'])))
+    engelsystem_error("No privilege for ical.");
+  
+  $ical_shifts = load_ical_shifts();
+  
+  send_ical_from_shifts($ical_shifts);
+}
 
-  if (isset ($_REQUEST['export']) && $_REQUEST['export'] == 'user_shifts') {
+/**
+ * Returns shifts to export.
+ * Users shifts or user_shifts filter based shifts if export=user_shifts is given as param.
+ */
+function load_ical_shifts() {
+  global $user, $ical_shifts;
+  
+  if (isset($_REQUEST['export']) && $_REQUEST['export'] == 'user_shifts') {
     require_once realpath(__DIR__ . '/user_shifts.php');
     view_user_shifts();
-  } else {
-    $ical_shifts = sql_select("
-        SELECT `ShiftTypes`.`name`, `Shifts`.*, `Room`.`Name` as `room_name`
-        FROM `ShiftEntry`
-        INNER JOIN `Shifts` ON (`ShiftEntry`.`SID` = `Shifts`.`SID`)
-        JOIN `ShiftTypes` ON (`ShiftTypes`.`id` = `Shifts`.`shifttype_id`)
-        INNER JOIN `Room` ON (`Shifts`.`RID` = `Room`.`RID`)
-        WHERE `UID`='" . sql_escape($user['UID']) . "'
-        ORDER BY `start`");
+    
+    return $ical_shifts;
   }
+  
+  return Shifts_by_user($user);
+}
 
+/**
+ * Renders an ical calender from given shifts array.
+ *
+ * @param array<Shift> $shifts          
+ */
+function send_ical_from_shifts($shifts) {
   header("Content-Type: text/calendar; charset=utf-8");
-  $html = "BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//-//Engelsystem//DE\r\nCALSCALE:GREGORIAN\r\n";
+  $output = "BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//-//Engelsystem//DE\r\nCALSCALE:GREGORIAN\r\n";
   foreach ($ical_shifts as $shift) {
-    $html .= "BEGIN:VEVENT\r\n";
-    $html .= "UID:" . md5($shift['start'] . $shift['end'] . $shift['name']) . "\r\n";
-    $html .= "SUMMARY:" . str_replace("\n", "\\n", $shift['name']) . " (" . str_replace("\n", "\\n", $shift['title']) . ")\r\n";
-    if(isset($shift['Comment']))
-      $html .= "DESCRIPTION:" . str_replace("\n", "\\n", $shift['Comment']) . "\r\n";
-    $html .= "DTSTART;TZID=Europe/Berlin:" . date("Ymd\THis", $shift['start']) . "\r\n";
-    $html .= "DTEND;TZID=Europe/Berlin:" . date("Ymd\THis", $shift['end']) . "\r\n";
-    $html .= "LOCATION:" . $shift['room_name'] . "\r\n";
-    $html .= "END:VEVENT\r\n";
+    $output .= make_ical_entry_from_shift($shift);
+  }
+  $output .= "END:VCALENDAR\r\n";
+  $output = trim($output, "\x0A");
+  header("Content-Length: " . strlen($output));
+  raw_output($output);
+}
+
+/**
+ * Renders an ical vevent from given shift.
+ *
+ * @param Shift $shift          
+ */
+function make_ical_entry_from_shift($shift) {
+  $output = "BEGIN:VEVENT\r\n";
+  $output .= "UID:" . md5($shift['start'] . $shift['end'] . $shift['name']) . "\r\n";
+  $output .= "SUMMARY:" . str_replace("\n", "\\n", $shift['name']) . " (" . str_replace("\n", "\\n", $shift['title']) . ")\r\n";
+  if (isset($shift['Comment'])) {
+    $output .= "DESCRIPTION:" . str_replace("\n", "\\n", $shift['Comment']) . "\r\n";
   }
-  $html .= "END:VCALENDAR\r\n";
-  $html = trim($html, "\x0A");
-  header("Content-Length: " . strlen($html));
-  echo $html;
-  die();
+  $output .= "DTSTART;TZID=Europe/Berlin:" . date("Ymd\THis", $shift['start']) . "\r\n";
+  $output .= "DTEND;TZID=Europe/Berlin:" . date("Ymd\THis", $shift['end']) . "\r\n";
+  $output .= "LOCATION:" . $shift['Name'] . "\r\n";
+  $output .= "END:VEVENT\r\n";
+  return $output;
 }
 ?>
diff --git a/includes/sys_page.php b/includes/sys_page.php
index 967a0172..52cffb26 100644
--- a/includes/sys_page.php
+++ b/includes/sys_page.php
@@ -8,6 +8,16 @@ function redirect($to) {
   die();
 }
 
+/**
+ * Echoes given output and dies.
+ * 
+ * @param String $output          
+ */
+function raw_output($output) {
+  echo $output;
+  die();
+}
+
 /**
  * Gibt den gefilterten REQUEST Wert ohne Zeilenumbrüche zurück
  */