PHP Decode

<?php 
/** 
* Manage date and time conversion from and to UTC and local time. 
* The application expects the timezone set in index.php to be 
* local time and time from database be in UTC. 
* Date from user input MUST be local time 
* 
* 
* @author Methu Mwangi <[email protected]> 
*/ 
class TimeUtilities 
{ 
  const format = "d-M,Y h:i:s A"; 
  const sformat = "Y-m-d H:i:s.v"; 
  /** 
  * @var int|string 
  */ 
  private static $sessionTimeZone; 
 
  /** 
  * Convert local time to UTC time. 
  * @param String $datetime date time to convert to UTC 
  * @return String | null UTC date time in format Y-m-d H:i:s.v 
  */ 
  public static function toUTC($datetime) 
  { 
    try { 
      return self::convertToUTC($datetime, true)->format(self::sformat); 
    } catch (Exception $exc) { 
      return "Invalid Date"; 
    } 
  } 
 
  /** 
  * Convert UTC to local time time. 
  * @param String $datetime UTC date time 
  * @return String | null local date time in format Y-m-d h:i:s.v A GMT+/-HH:MM 
  */ 
  public static function fromUTC($datetime) 
  { 
    try { 
      $datetime = self::convertToLocal($datetime, true); 
      $offset = $datetime->format("P"); 
      return $datetime->format(self::format) . " GMT" . $offset; 
    } catch (Exception $exc) { 
      return "Invalid Date"; 
    } 
  } 
 
  private static function convertToUTC($date, $throw = false) 
  { 
    return self::convert($date, date_default_timezone_get(), "UTC", $throw); 
  } 
 
  private static function convertToLocal($date, $throw = false) 
  { 
    $timezone = self::getSessionTimeZone(); 
    return self::convert($date, "UTC", $timezone, $throw); 
  } 
 
  private static function convert($date, $from, $to, $throw = false) 
  { 
    try { 
      $datetime = new DateTime($date, new DateTimeZone($from)); 
      $timezone = new DateTimeZone($to); 
      $datetime->setTimezone($timezone); 
      return $datetime; 
    } catch (Exception $e) { 
      CoreUtils::flog2( 
        "ERROR", 
        "Error passing date: " . $e->getMessage(), 
        __CLASS__, 
        __FUNCTION__, 
        __LINE__ 
      ); 
      if ($throw) { 
        throw $e; 
      } 
      return "Invalid date provided"; 
    } 
  } 
 
  private static function getSessionTimeZone() 
  { 
    if (self::$sessionTimeZone !== null) { 
      return self::$sessionTimeZone; 
    } 
    $clientCodeTimeZones = [ 
      "ADMIN" => "Africa/Maputo", 
      "BBMZ" => "Africa/Maputo", 
    ]; 
 
    if (isset($_SESSION) && is_array($_SESSION)) { 
      foreach ($_SESSION as $key => $value) { 
        if ( 
          strpos($key, "applications") !== false && 
          isset($value["userData"]["clientCode"]) 
        ) { 
          self::$sessionTimeZone = self::getTimeZoneForClientCode( 
            $value["userData"]["clientCode"], 
            $clientCodeTimeZones 
          ); 
          CoreUtils::flog2( 
            "INFO", 
            $value["userData"]["clientCode"], 
            " uses : " . self::$sessionTimeZone, 
            __CLASS__, 
            __FUNCTION__, 
            __LINE__ 
          ); 
          break; 
        } 
      } 
    } 
    return self::$sessionTimeZone ?? date_default_timezone_get(); 
  } 
 
  public static function getTimeZoneForClientCode( 
    $clientCode, 
    $clientTimeZones 
  ) { 
    foreach ($clientTimeZones as $client => $timeZone) { 
      if ($client === $clientCode) { 
        return $timeZone; 
      } 
    } 
    return date_default_timezone_get(); 
  } 
} ?>