diff --git a/ext/admin/attendance/api/AttendanceAdminManager.php b/ext/admin/attendance/api/AttendanceAdminManager.php
index 51ff1893..ab49ff1e 100644
--- a/ext/admin/attendance/api/AttendanceAdminManager.php
+++ b/ext/admin/attendance/api/AttendanceAdminManager.php
@@ -211,4 +211,220 @@ if (!class_exists('AttendanceStatus')) {
             return array("element","save","delete");
         }
     }
-}
\ No newline at end of file
+}
+
+
+if (!class_exists('BasicOvertimeCalculator')) {
+
+    class BasicOvertimeCalculator{
+
+        public function createAttendanceSummary($atts){
+
+            $atTimeByDay = array();
+
+            foreach($atts as $atEntry){
+                if($atEntry->out_time == "0000-00-00 00:00:00" || empty($atEntry->out_time)){
+                    continue;
+                }
+
+                $atDate = date("Y-m-d",strtotime($atEntry->in_time));
+
+                if(!isset($atTimeByDay[$atDate])){
+                    $atTimeByDay[$atDate]   = 0;
+                }
+
+                $diff = strtotime($atEntry->out_time) - strtotime($atEntry->in_time);
+                if($diff < 0){
+                    $diff = 0;
+                }
+
+                $atTimeByDay[$atDate] += $diff;
+
+            }
+
+            return $atTimeByDay;
+        }
+
+        public function calculateOvertime($atTimeByDay){
+            $overtimeStarts = SettingsManager::getInstance()->getSetting('Attendance: Overtime Start Hour');
+            $doubletimeStarts = SettingsManager::getInstance()->getSetting('Attendance: Double time Start Hour');
+
+            $overtimeStarts = (is_numeric($overtimeStarts))?floatval($overtimeStarts)*60*60:0;
+            $doubletimeStarts = (is_numeric($doubletimeStarts))?floatval($doubletimeStarts)*60*60:0;
+
+            $atTimeByDayNew = array();
+            foreach($atTimeByDay as $k=>$v){
+                $atTimeByDayNewEntry = array("t"=>$v,"r"=>0,"o"=>0,"d"=>0);
+                if($overtimeStarts > 0 && $v > $overtimeStarts){
+                    $atTimeByDayNewEntry["r"] = $overtimeStarts;
+                    if($doubletimeStarts > 0 && $doubletimeStarts > $overtimeStarts){
+                        //calculate double time
+                        if($v > $doubletimeStarts){
+                            $atTimeByDayNewEntry['d'] =  $v - $doubletimeStarts;
+                            $atTimeByDayNewEntry['o'] = $doubletimeStarts - $overtimeStarts;
+                        }else{
+                            $atTimeByDayNewEntry['d'] = 0 ;
+                            $atTimeByDayNewEntry['o'] = $v - $overtimeStarts;
+                        }
+
+                    }else{
+                        //ignore double time
+                        $atTimeByDayNewEntry['o'] = $v - $overtimeStarts;
+                    }
+                }else{
+                    //ignore overtime
+                    $atTimeByDayNewEntry['r'] = $v;
+                }
+
+                $atTimeByDayNew[$k] = $atTimeByDayNewEntry;
+            }
+
+            return $atTimeByDayNew;
+        }
+
+        protected function removeAdditionalDays($atSummary, $actualStartDate){
+            $newAtSummary = array();
+            foreach($atSummary as $k => $v){
+                if(strtotime($k) >= strtotime($actualStartDate)){
+                    $newAtSummary[$k] = $v;
+                }
+            }
+
+            return $newAtSummary;
+        }
+
+        public function getData($atts, $actualStartDate, $aggregate = false){
+            $atSummary = $this->createAttendanceSummary($atts);
+            $overtime = $this->calculateOvertime($this->removeAdditionalDays($atSummary, $actualStartDate));
+            if($aggregate){
+                $overtime = $this->aggregateData($overtime);
+                return $this->convertToHoursAggregated($overtime);
+            }else{
+                return $this->convertToHours($overtime);
+            }
+
+        }
+
+
+
+        public function convertToHours($overtime){
+            foreach($overtime as $k=>$v){
+                $overtime[$k]['t'] =  $this->convertToHoursAndMinutes($overtime[$k]['t']);
+                $overtime[$k]['r'] =  $this->convertToHoursAndMinutes($overtime[$k]['r']);
+                $overtime[$k]['o'] =  $this->convertToHoursAndMinutes($overtime[$k]['o']);
+                $overtime[$k]['d'] =  $this->convertToHoursAndMinutes($overtime[$k]['d']);
+            }
+
+            return $overtime;
+        }
+
+        public function convertToHoursAggregated($overtime){
+            $overtime['t'] =  $this->convertToHoursAndMinutes($overtime['t']);
+            $overtime['r'] =  $this->convertToHoursAndMinutes($overtime['r']);
+            $overtime['o'] =  $this->convertToHoursAndMinutes($overtime['o']);
+            $overtime['d'] =  $this->convertToHoursAndMinutes($overtime['d']);
+
+            return $overtime;
+        }
+
+        protected function aggregateData($overtime){
+            $ag = array("t"=>0,"r"=>0,"o"=>0,"d"=>0);
+            foreach($overtime as $k=>$v){
+                $ag['t'] += $v['t'];
+                $ag['r'] += $v['r'];
+                $ag['o'] += $v['o'];
+                $ag['d'] += $v['d'];
+            }
+
+            return $ag;
+        }
+
+        public function convertToHoursAndMinutes($val){
+            $sec = $val % 60;
+            $minutesTot = ($val - $sec)/60;
+
+            $minutes = $minutesTot % 60;
+            $hours = ($minutesTot - $minutes)/60;
+
+            if($hours < 10){
+                $hours = "0".$hours;
+            }
+            if($minutes < 10){
+                $minutes = "0".$minutes;
+            }
+
+            return $hours.":".$minutes;
+
+        }
+
+    }
+
+}
+
+
+if (!class_exists('CaliforniaOvertimeCalculator')) {
+
+    class CaliforniaOvertimeCalculator extends BasicOvertimeCalculator{
+
+        public function getData($atts, $actualStartDate, $aggregate = false){
+
+            if(count($atts) == 0){
+                return array();
+            }
+
+            $atSummary = $this->createAttendanceSummary($atts);
+            $overtime = $this->calculateOvertime($atSummary);
+
+            $workWeekStartDate = SettingsManager::getInstance()->getSetting('Attendance: Work Week Start Day');
+
+            //TODO - just assume a work week from Sunday to Saturday
+
+            //Find first Sunday in array
+            $firstDate = null;
+            //Find double time days (7th work day of a week without a break)
+            $doubleTimeDates = array();
+            $prvDate = null;
+            $consecutiveWorkDays = 1;
+            foreach($overtime as $k=>$v){
+                if($firstDate == null) {
+                    $dw = date("w", strtotime($k));
+                    if ($dw == $workWeekStartDate) {
+                        $firstDate = $k;
+                    }
+                }
+
+                if($firstDate != null){
+                    if($prvDate != null && date('Y-m-d', strtotime('-1 day',strtotime($k))) == $prvDate){
+
+                        $consecutiveWorkDays++;
+                        if($consecutiveWorkDays == 7){
+                            //This is a double time day
+                            $overtime[$k]['d'] = $overtime[$k]['d'] + $overtime[$k]['o'];
+                            $overtime[$k]['o'] = 0;
+                        }
+                    }
+
+                    //Resetting $consecutiveWorkDays at the start of the work week
+                    if($prvDate != null && date( "w", strtotime($k)) == $workWeekStartDate){
+                        $consecutiveWorkDays = 1;
+                        $prvDate = null;
+                    }
+
+                    $prvDate = $k;
+                }
+            }
+
+            $overtime = $this->removeAdditionalDays($overtime, $actualStartDate);
+            if($aggregate){
+                $overtime = $this->aggregateData($overtime);
+                return $this->convertToHoursAggregated($overtime);
+            }else{
+                return $this->convertToHours($overtime);
+            }
+
+
+        }
+
+    }
+
+}