initial commit

demo.php

@@ -0,0 +1,20 @@
+<?PHP
+$conf = [
+	'shifts' => array('A','B','C'), //Crew designators in order starting at EPOCH
+	'timeZone' => 'America/New_York', //Local Time Zone
+	'startTime' => '07:30' //Shift start time in 24-hour format
+];
+
+//***********************************************************************************
+
+require 'shiftCycle.php';
+
+$shiftCycle = new shiftCycle($conf);
+
+echo "Local Timestamp: " . $shiftCycle->timestamp . "<br/>";
+echo "Whole days since EPOCH: " . $shiftCycle->daysSince . "<br/>";
+echo "Cycles since EPOCH: " . $shiftCycle->cyclesSince . "<br/>";
+echo "Day in cycle: " . ($shiftCycle->cyclePart + 1) . "<br/>";
+echo "Crew on duty: " . $shiftCycle->currentShift . "<br/>";
+	
+?>

shiftCycle.php

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+<?PHP
+class shiftCycle {
+		
+	public $timestamp;
+	public $daysSince;
+	public $cyclesSince;
+	public $cyclePart;
+	public $currentShift;
+	
+	function __construct($conf){
+
+		$dtz = new DateTimeZone($conf['timeZone']);
+		$dt = new DateTime('now', $dtz); //DateTime object set to defined TZ
+		$this->timestamp = $dt->format('U');
+		
+		$adj = ($this->timestamp - ($this->timeToSeconds($conf['startTime']))); //align shift start change to midnight.
+		$this->daysSince = floor($adj / 86400); //Whole days since EPOCH
+		$this->cyclesSince = floor(($this->daysSince / 3)*10)/10; //Cycles since EPOCH
+		$this->cyclePart = floor(((($this->cyclesSince - floor($this->cyclesSince)) * 10) / count($conf['shifts']))); //Day in cycle
+		$this->currentShift = $conf['shifts'][$this->cyclePart]; //Current Shift
+
+	}
+	
+	private function timeToSeconds($time){ // returns 24-hour time into seconds since midnight 
+		
+		$hm1 = explode(':', $time); // split hours and minutes
+		$hm2 = $hm1[0] + round($hm1[1] / 60, 2); // determine number of hours since midnight
+		$hm3 = $hm2 * 3600; // convert hours to seconds
+		
+		return $hm3;
+		
+	}
+}
+?>