<?
namespace MyApp;

include('config/define.php');

class Init
{
  private $db;
  private $idTag;
  private $name;
  private $connectorIdS = 0;
  private $type;
  private $user_id = 1;

  function __construct()
	{
      $this->db = new MySQL(DB_HOST, DB_PORT, DB_USER, DB_PASS, DB_NAME);
	}

  // Allows us to connect or not
  public function SelectConected($idTag)
	{
    if(isset($idTag) && $idTag != NULL)
    {
      $res = $this->db->row("SELECT * FROM my_charger WHERE idTag = '{$idTag}'  ");

      if($res != NULL && $res['id'] > 0 )
      {
        $this->idTag = $res['idTag'];
        $this->name = $res['name'];

        return true;
      }
    }
    else
      return false;
  }

  //Ping the base my_set_command and if the commands are sent to the station and the command itself is deleted
  public function SetCommand($idTag)
	{
    $res = $this->db->row("SELECT * FROM my_set_command WHERE idTag = '{$idTag}' order by id DESC ");
    if($res != false)
    {
      $us = $this->db->row("SELECT * FROM `my_user` WHERE `mobile` = '{$res['user_id']}' ");
      $res['user_id'] = $us['id'];

      $this->db->query("DELETE FROM `my_set_command` WHERE id = '".$res['id']."'; ");
      return $res;
    }
    else {return false;}
  }

  //We write to the temporary base which connector was launched
  public function UpConnectorCommand($idTag, $connector_id = 0)
	{
    $heartbeat = time();
    $this->db->query(  "DELETE FROM `my_set_command_connector` WHERE  idTag = '{$idTag}' "  );
    $this->db->query(  "INSERT INTO `my_set_command_connector` (`idTag`, `connectorId`, `heartbeat`) VALUES ('{$idTag}', '{$connector_id}', '{$heartbeat}')"   );
  }

  //Write to the temporary base who launched the command
  public function UpUserCommand($idTag, $user_id = 0)
	{
    $heartbeat = time();

    if($user_id > 0)
    {
      $res = $this->db->row("SELECT * FROM my_set_command_buffer WHERE idTag = '{$idTag}' ");
      if($res)
      {
        $id = $res['id'];
        $this->db->query(  "UPDATE `my_set_command_buffer` SET `user_id` = '{$user_id}' WHERE id = '{$id}'; " );
      }
      else {
        $this->db->query(  "INSERT INTO `my_set_command_buffer` (`idTag`, `user_id`, `heartbeat`) VALUES ('{$idTag}', '{$user_id}', '{$heartbeat}')"   );
      }
    }

  }


  //Get the user id who last ran the command on the current station
  public function UserID($idTag)
	{
    $res = $this->db->row("SELECT user_id FROM my_set_command_buffer WHERE idTag = '{$idTag}' ");
    if($res['user_id'] > 0)
    {
        return $res['user_id'];
    }
    else {
      return 1;
    }
  }


  //Get the connector id who last ran the command on the current station
  public function ConnectorSID($idTag)
	{
    $res = $this->db->row("SELECT connectorId FROM my_set_command_connector WHERE idTag = '{$idTag}' ");
    return $res['connectorId'];
  }


//Write the history of commands sent by handles to the database
  public function up_command($data, $idTag)
	{
    $type = json_decode($data);
    $heartbeat = time();

    if(isset($type[2]) && $type[0] == 2)
    {
      $SetType = $this->SetType($type[2]);
      $this->db->query(  "INSERT INTO `my_set_history` (`idTag`, `type`, `typeText`, `text`, `heartbeat`) VALUES ('{$idTag}', '{$SetType}', '{$type[2]}', '{$data}', '{$heartbeat}')"   );
    }
    if($type[0] == 3)
    {
      $search = '[2,"'.$type[1];
      $res = $this->db->row("   SELECT * FROM `my_set_history` WHERE `text` LIKE '%{$search}%' AND idTag = '{$idTag}'  ORDER BY `id` DESC ");
      if($res)
      {
        $this->type = $res['typeText'];
      }

      $SetType = $this->SetType($this->type);
      $this->db->query(  "INSERT INTO `my_set_history` (`idTag`, `type`, `typeText`, `text`, `heartbeat`) VALUES ('{$idTag}', '{$SetType}', '{$this->type}', '{$data}', '{$heartbeat}')"   );
    }
    //If the command is to start a transaction, then assign a connector number
    if($type['2'] == 'RemoteStartTransaction')
    {
      $this->UpConnectorCommand($idTag, $type[3]->connectorId);
    }
  }


  //We receive some data from the station and process them through switch - we answer
  public function Status($data, $idTag = '')
	{
    $this->idTag = $idTag;

    $t = explode(" ",microtime());
    $currentTime = date("Y-m-d\TH:i:s",time()).substr((string)$t[0],1,4).'Z';

    if(!is_object($data[2]))
    {
      $this->type = $data[2];
    }

    switch ($data[2])
    {
      case 'BootNotification':
        $boot = new \stdClass();
        $this->SetBootNotification($data);
        $boot->currentTime = $currentTime;
        $boot->interval = 60;
        $boot->status = 'Accepted';
        $BootNotification = json_encode(  array(0 =>3,1 => $data[1], $boot ));
        return $BootNotification;
      break;

      case 'StatusNotification':
        $this->SetStatus($data);
        $StatusNotification = json_encode(  array(0 =>3,1 => $data[1], new \stdClass() ));
        return $StatusNotification;
      break;

      case 'Heartbeat':
        $head = new \stdClass();
        $head->currentTime = $currentTime;
        $Heartbeat = json_encode(  array(0 =>3,1 => $data[1], $head ));
        $this->SetHeartbeat($idTag, $data);
        return $Heartbeat;
      break;

      case 'StartTransaction':
          //Создаем номер транзакции из случайного числа
          $rand = rand(1, 999999999);

          $set = new \stdClass();
          $set->parentIdTag = '';
          $set->status = $this->StartTransactionStatus($idTag, $data);
          $StartTransaction = json_encode(  array(0 => 3, 1 =>  $data[1], array('idTagInfo' => $set, 'transactionId' => $rand ) ));
          $times = time();

          $user_id = $this->UserID($idTag);
          if($set->status == 'Accepted')
          {
            //Записываем в базу my_user_start_transaction кто и когда запустил транзакцию
            $this->db->query("INSERT INTO `my_user_start_transaction` (`user_id`, `transactionId`, `TimeCompletion`) VALUES ('{$user_id}', '{$rand}', '{$times}')");
            //Записываем фальший 0, MeterValues, а так же далее шлем уведомление
            $this->SetFalseMeterValues($idTag, $user_id, $rand);
            return $StartTransaction;
          }
          else {
            $StopTransaction = json_encode(  array(0 => 2, 1 => ''.rand(1000000,9999999).'', 2 => 'RemoteStopTransaction', array('transactionId' => $rand) ));
            $times = time();
            $this->db->row("INSERT INTO `my_set_command` (`idTag`, `user_id`, `type`, `text`, `heartbeat`) VALUES ('{$idTag}', '{$user_id}', 'RemoteStopTransaction', '{$StopTransaction}', '{$times}')");
          }
      break;

      case 'MeterValues':
        $this->MeterValues($idTag, $data);
        $this->SetHeartbeat($idTag, $data);
        $MeterValues = json_encode(  array(0 => 3, 1 => $data[1], new \stdClass() ));
        return $MeterValues;
      break;

      case 'StopTransaction':
          $set = new \stdClass();
          $set->parentIdTag = '';
          $set->status = 'Accepted';
          $StopTransaction = json_encode(  array(0 => 3, 1 =>  $data[1], array('idTagInfo' => $set) ));
          $this->user_id = 1;
          return $StopTransaction;
      break;

      case 'Authorize':
        $Auth = new \stdClass();
        $Auth->status =  $this->AuthorizeStatus($idTag, $data);;
        $Authorize = json_encode(  array(0 => 3, 1 =>  $data[1], array('idTagInfo' => $Auth ) ));
        return $Authorize;
      break;

      default:
        //print_r($data);
      break;
    }
  }


  public function StartTransactionStatus($idTag, $data)
	{
    $res = $this->db->row("SELECT * FROM `my_charger` WHERE idTag = '".$data[3]->idTag."'  ");
    if($res)
    {
      return 'Accepted';
    }
    else
    {
      return 'Blocked';
    }
  }


  public function AuthorizeStatus($idTag, $data)
	{
    $res = $this->db->row("SELECT * FROM `my_charger_authorize` WHERE idTag = '{$idTag}' AND idTag_Authorize = '".$data[3]->idTag."'  ");
    if($res)
    {
      return 'Accepted';
    }
    else
    {
      return 'Blocked';
    }
  }


  //Write the firmware version
  public function SetBootNotification($data)
	{
    $this->db->query("UPDATE my_charger SET firmwareVersion = '{$data[3]->firmwareVersion}' WHERE idTag = '{$this->idTag}';  ");
  }

  //Record heartbeat time
  public function SetHeartbeat($idTag, $data)
	{
    $time = time();
    $this->db->row("UPDATE `my_charger` SET `heartbeat` = '{$time}' WHERE idTag = '{$idTag}';  ");
  }


  //Write the status of the stations in the StatusNotification method
  public function SetStatus($data)
	{
    //Проверяем базу если такие конектора
    $res = $this->db->row("SELECT * FROM `my_charger_connectorId` WHERE `idTag` LIKE '{$this->idTag}'  ");
    if($res == false)
    {
      $this->connectorId($data);
    }
    else
    {
      $osp = $this->db->row("SELECT * FROM `my_charger_connectorId` WHERE `idTag` LIKE '{$this->idTag}'  AND connectorId = '{$data[3]->connectorId}' ");
      if($osp == false)
      {
        $this->connectorId($data);
      }
      else
      {
        $this->db->query("UPDATE my_charger_connectorId SET status = '{$data[3]->status}', errorCode = '{$data[3]->errorCode}'  WHERE idTag = '{$this->idTag}' AND connectorId = '{$data[3]->connectorId}'  ;  ");
      }
    }
  }


  //Write a fake 0, MeterValues
  public function SetFalseMeterValues($idTag, $user_id, $rand)
  {
    $times = time();
    $user_id = $this->UserID($idTag);
    $connector_id = $this->ConnectorSID($idTag);

    $this->db->query(  "INSERT INTO `my_charger_meter` (`userId`, `idTag`, `connectorId`, `transactionId`, `timestamp`) VALUES ('{$user_id}', '{$idTag}', '{$connector_id}', '{$rand}', '{$times}' )"   );
    $parentId = $this->db->lastInsertId();

    $this->db->query(  "INSERT INTO `my_charger_meter_type` (`idTag`, `transactionId`, `parentId`, `value`, `measurand`, `phase`, `unit`) VALUES ('{$idTag}', '{$rand}', '{$parentId}', 0, 'Energy.Active.Import.Register', NULL, 'Wh')"   );
  }

  //Updating information about the connector
  public function connectorId($data)
  {
    $this->db->query(  "INSERT INTO `my_charger_connectorId` (`idTag`, `connectorId`, `status`, `errorCode`) VALUES ('{$this->idTag}', '{$data[3]->connectorId}', '{$data[3]->status}', '{$data[3]->errorCode}')"   );
  }

  //Get the id of the user who started the transaction
  public function UserTransactionId($transaction = 0)
  {
    if($transaction > 0)
    {
      $user = $this->db->row(" SELECT user_id FROM `my_user_start_transaction` WHERE `transactionId` = '{$transaction}' ");

      if($user['user_id'] > 0)
      {
        return $user['user_id'];
      }
      else {
        return $user['user_id'];
      }
    }
    else {
      return 1;
    }
  }


  public function MeterStartZero($idTag, $transactionId)
  {
    $zero_2 = $this->db->row("SELECT text FROM my_set_history WHERE idTag = '".$idTag."' AND type = 4  AND `text` LIKE '%[3%'  AND text LIKE '%".$transactionId."%' order by id DESC ");
    $type = json_decode($zero_2['text']);

    $zero_3 = $this->db->row("SELECT text FROM my_set_history WHERE idTag = '".$idTag."' AND type = 4  AND `text` LIKE '%[2%'  AND text LIKE '%".$type[1]."%' order by id DESC ");
    $Rtype = json_decode($zero_3['text']);

    return $Rtype[3]->meterStart;
  }


  //write data from counters
  public function MeterValues($idTag, $data)
  {
    if($data[2] == 'MeterValues')
    {
      if($data[3]->transactionId > 0)
      {
        $zero = $this->MeterStartZero($idTag, $data[3]->transactionId);
        if($zero > 0)
        {
          $this->NotStandardAlgorithm($data, $idTag, $zero);
        }
        else
        {
          $this->StandardAlgorithm($data, $idTag);
        }
      }

      //Stop charging function if the user's balance is less than 0
      $transaction_user = $this->db->row("SELECT user_id FROM `my_user_start_transaction` WHERE transactionId = '{$data[3]->transactionId}' ");
      $user = $this->db->row("SELECT * FROM `my_user` WHERE id = '".$transaction_user['user_id']."' AND stop = 0 ");
      if($user)
      {
        if($user['balanse'] <= 0)
        {
          //If there is no stop command in the database, write the stop command to the database :)
          $row = $this->db->row("SELECT * FROM `my_set_command` WHERE idTag = '".$idTag."' AND type = 'RemoteStopTransaction' ");
          if($row === false)
          {
            $StopTransaction = json_encode(  array(0 => 2, 1 => ''.rand(1000000,9999999).'', 2 => 'RemoteStopTransaction', array('transactionId' => $data[3]->transactionId) ));
            $mobile = $user['mobile'];    $times = time();

            $this->db->row("INSERT INTO `my_set_command` (`idTag`, `user_id`, `type`, `text`, `heartbeat`) VALUES ('{$idTag}', '{$mobile}', 'RemoteStopTransaction', '{$StopTransaction}', '{$times}')");

          }
        }
      }//if($user)


    }
  }


  public function NotStandardAlgorithm($data, $idTag, $zero)
  {
      //Первым делом удаляем фальшивый MeterValues
      $this->db->query(" DELETE FROM `my_charger_meter_type` WHERE idTag ='".$idTag."' AND `transactionId` LIKE '".$data[3]->transactionId."' AND value = '0.00' AND `measurand` LIKE 'Energy.Active.Import.Register';  ");
      //Первым делом удоляем фальшивый MeterValues

      $times = time();

      //Определяем кому принадлежит сессия
      $user = $this->UserTransactionId($data[3]->transactionId);

      $this->db->query(  "INSERT INTO `my_charger_meter` (`userId`, `idTag`, `connectorId`, `transactionId`, `timestamp`) VALUES ('{$user}', '{$idTag}', '{$data[3]->connectorId}', '{$data[3]->transactionId}', '{$times}')"   );

      $parentId = $this->db->lastInsertId();

      $eair = $this->searchForId('Energy.Active.Import.Register', $data[3]->meterValue[0]->sampledValue);

      if($eair === NULL)
      {
        //Шнайдер
        if(count($data[3]->meterValue[0]->sampledValue) == 1)
        {
          foreach ($data[3]->meterValue[0]->sampledValue as $key => $value)
          {
            $measurandS = 'Energy.Active.Import.Register';
            $unitS = 'Wh';
            $value = $value->value;

            $this->db->query( "INSERT INTO `my_charger_meter_type`(`idTag`,`transactionId`, `parentId`, `value`, `measurand`, `unit`)  VALUES  ('{$idTag}', '{$data[3]->transactionId}', '{$parentId}', '{$value}', '{$measurandS}', '{$unitS}')"   );

            $this->SetMoney($this->db->lastInsertId());
          }
        }//Похожие станции с отсутствующим значением measurand = Energy.Active.Import.Register в масииве sampledValue
        else
        {
          foreach ($data[3]->meterValue[0]->sampledValue as $key => $value)
          {
            if(isset($value->phase)) {$phase = $value->phase;} else { $phase = NULL;}
            if(isset($value->unit)) {$unit = $value->unit;} else { $unit = NULL;}

            if(isset($value->measurand))
            {
              $measurand = $value->measurand;
              $value = $value->value;
            }
            else
            {
              $measurand = 'Energy.Active.Import.Register';
              $unit = 'Wh';
              $value = $value->value - $zero;
            }

            $this->db->query(  "INSERT INTO `my_charger_meter_type`(`idTag`,`transactionId`, `parentId`, `value`, `measurand`, `phase`, `unit`)  VALUES  ('{$idTag}', '{$data[3]->transactionId}', '{$parentId}', '{$value}', '{$measurand}', '{$phase}', '{$unit}')"   );

            $this->SetMoney($this->db->lastInsertId());
          }
        }
      }
      else
      {
        //Все остальные станции
        foreach ($data[3]->meterValue[0]->sampledValue as $key => $value)
        {
          if(isset($value->phase)) {$phase = $value->phase;} else { $phase = NULL;}
          if(isset($value->unit)) {$unit = $value->unit;} else { $unit = NULL;}

          if(isset($value->measurand))
          {
            if($value->measurand == 'Energy.Active.Import.Register')
            {
                $measurand = $value->measurand;
                $value = $value->value - $zero;
            }
            else
            {
              $measurand = $value->measurand;
              $value = $value->value;
            }
          } else { $measurand = NULL;  $value = $value->value;}

          $this->db->query(  "INSERT INTO `my_charger_meter_type`(`idTag`,`transactionId`, `parentId`, `value`, `measurand`, `phase`, `unit`)  VALUES  ('{$idTag}', '{$data[3]->transactionId}', '{$parentId}', '{$value}', '{$measurand}', '{$phase}', '{$unit}')"   );

          $this->SetMoney($this->db->lastInsertId());
        }
      }


  }

  public function StandardAlgorithm($data, $idTag)
  {
    $times = time();

    //Определяем кому принадлежит сессия
    $user = $this->UserTransactionId($data[3]->transactionId);

    $this->db->query(  "INSERT INTO `my_charger_meter` (`userId`, `idTag`, `connectorId`, `transactionId`, `timestamp`) VALUES ('{$user}', '{$idTag}', '{$data[3]->connectorId}', '{$data[3]->transactionId}', '{$times}')"   );

    $parentId = $this->db->lastInsertId();


    $eair = $this->searchForId('Energy.Active.Import.Register', $data[3]->meterValue[0]->sampledValue);


    if($eair === NULL)
    {
      //Шнайдер
      foreach ($data[3]->meterValue[0]->sampledValue as $key => $value)
      {
        $measurandS = 'Energy.Active.Import.Register';
        $unitS = 'Wh';
        $value = $value->value;

        $this->db->query( "INSERT INTO `my_charger_meter_type`(`idTag`,`transactionId`, `parentId`, `value`, `measurand`, `unit`)  VALUES  ('{$idTag}', '{$data[3]->transactionId}', '{$parentId}', '{$value}', '{$measurandS}', '{$unitS}')"   );

        $this->SetMoney($this->db->lastInsertId());
      }
    }
    else
    {

        //Все остальные станции
        foreach ($data[3]->meterValue[0]->sampledValue as $key => $value)
        {
          if(isset($value->phase)) {$phase = $value->phase;} else { $phase = NULL;}
          if(isset($value->unit)) {$unit = $value->unit;} else { $unit = NULL;}
          if(isset($value->measurand)) {$measurand = $value->measurand;} else { $measurand = NULL;}
          if(isset($value->value)) {$value = $value->value;} else { $value = NULL;}

          $this->db->query(  "INSERT INTO `my_charger_meter_type`(`idTag`,`transactionId`, `parentId`, `value`, `measurand`, `phase`, `unit`)  VALUES  ('{$idTag}', '{$data[3]->transactionId}', '{$parentId}', '{$value}', '{$measurand}', '{$phase}', '{$unit}')"   );

          $this->SetMoney($this->db->lastInsertId());
        }

    }
  }


  // Ticketing
  public function SetMoney($parent_id)
	{
      //Если где то сработал MeterValues
      if($parent_id > 0)
      {
        //Получаем информаци о текщей операции
        $res = $this->db->row("SELECT * FROM `my_charger_meter_type` WHERE id = '{$parent_id}' ");

        //Если в масиве есть значение Energy.Active.Import.Register
        if($res['measurand'] == 'Energy.Active.Import.Register')
        {
          $times = time();

          $parentId = $res['parentId'];

          //Получаем информацию о текущей операции
          $parent_id = $this->db->row("SELECT * FROM `my_charger_meter` WHERE id = '{$parentId}' ");
          //Устанавливаем переменные
          $transactionId = $parent_id['transactionId'];
          $idTag = $parent_id['idTag'];
          $connectorId = $parent_id['connectorId'];


          //Получаем предыдущию информацию о значения счетчика
          $old_t = $this->db->row("SELECT * FROM `my_charger_meter_type` WHERE transactionId = '{$transactionId}' AND idTag = '{$idTag}' AND measurand = 'Energy.Active.Import.Register' ORDER BY id DESC LIMIT 1, 1; ");

          //Переопределяем юзера - берем с текщей сесии
          $user_id = $this->UserTransactionId($transactionId);

          //Что бы узнать за сколько ватт снимать деньги, от текущей операции отнимаем значение предыдущей операции (значения счетчика)
          $wh = $res['value'] - $old_t['value'];


          $special = $this->SpecialMoney($idTag, $connectorId, $user_id);
          if($special > 0)
          {
            $price_c = $special/1000;
          }
          else
          {
            //Получаем стандартную стоимость 1Квт на текущем конекторе
            $connector = $this->db->row("SELECT * FROM `my_charger_connectorId` WHERE idTag = '{$idTag}' AND connectorId = '{$connectorId}' ; ");

            //Переводим Квт В Ватты
            $price_c = $connector['price']/1000;
          }

          //Сумма за затраченную энергию в текущем состоянии
          $price_m = $wh*$price_c;


          //Записываем значения в базу my_user_operations о затраченой энергии и денег
          $this->db->query(  "INSERT INTO `my_user_operations`(`user_id`,`transactionId`, `operationTime`, `MeterValues`, `money`)
          VALUES  ('{$user_id}', '{$transactionId}', '{$times}', '{$wh}', '{$price_m}')"   );

          $parentId = $this->db->lastInsertId();


          //Полученную сумму отнимает от основного счета
          $sum_user = $this->db->row("SELECT * FROM `my_user` WHERE id = '{$user_id}' AND visible = '1' ; ");
          $bals_user = $sum_user['balanse'] - $price_m;

          //Обновляем баланс юзера
          $this->db->row("UPDATE `my_user` SET `balanse` = '{$bals_user}' WHERE id = '{$user_id}';  ");

          //Записываем остаток баланса
          $this->db->row("UPDATE `my_user_operations` SET `user_balanse` = '{$bals_user}' WHERE id = '{$parentId}';  ");
        }

      }
  }

  // Special price for some users
  public function SpecialMoney($idTag, $connectorId, $user_id)
	{
    //Получаем номер пользователя, он же логин
    $mobile = $this->db->row("SELECT mobile FROM `my_user` WHERE id = '{$user_id}'; ");

    //Проверяем если спец цена для юзера на этой станции и конекторе
    $connector = $this->db->row("SELECT * FROM `my_charger_connectorId_special` WHERE idTag = '{$idTag}' AND connectorId = '{$connectorId}' AND user_id = '".$mobile['mobile']."' AND endcdate > '".time()."'  ; ");

    if($connector)
    {
      return $connector['price'];
    }
  }


  //What type is this number
  public function SetType($type)
	{
    switch ($type)
    {
      case 'Heartbeat':
        $int = 1;
      break;

      case 'BootNotification':
        $int = 2;
      break;

      case 'StatusNotification':
        $int = 3;
      break;

      case 'StartTransaction':
        $int = 4;
      break;

      case 'StopTransaction':
        $int = 5;
      break;

      case 'RemoteStartTransaction':
        $int = 6;
      break;

      case 'RemoteStopTransaction':
        $int = 7;
      break;

      case 'MeterValues':
        $int = 8;
      break;

      case 'Authorize':
        $int = 9;
      break;

      case 'Reset':
        $int = 10;
      break;

      case 'UpdateFirmware':
        $int = 11;
      break;

      case 'GetDiagnostics':
        $int = 12;
      break;

      case 'DiagnosticsStatusNotification':
        $int = 13;
      break;

      case 'FirmwareStatusNotification':
        $int = 14;
      break;

      case 'TriggerMessage':
        $int = 15;
      break;

      case 'ChangeConfiguration':
        $int = 16;
      break;

      case 'GetConfiguration':
        $int = 17;
      break;

      case 'ClearCache':
        $int = 18;
      break;

      case 'ReserveNow':
        $int = 19;
      break;

      case 'CancelReservation':
        $int = 20;
      break;

      case 'UnlockConnector':
        $int = 21;
      break;


      case 'DataTransfer':
        $int = 22;
      break;


      default:
        continue;
      break;
    }

    return $int;
  }


  //Search for the Energy.Active.Import.Register value in the array
  public function searchForId($id, $array)
	{
    foreach ($array as $key => $val)
    {
      if(isset($val->measurand))
      {
        if ($val->measurand === $id)
        {
          return $key;
        }
      }
     }
     return null;
  }

}