How to create a PHP request to update data in mongoDB with conditions?

This request stopped me).

What the request should do:

1. Find a document by _id or create a new document if not found

2. Change the value of the 'count Operations' field (increment)

3. Calculate the 'sum' field using the incremented value of the 'count Operations' field and the comparison conditions (see block 'pseudocode')

4. Save document with new values

I stopped at the stage of calculating 'sum' ...

PHP 7.3

mongoDB 4.4.6

    $id="123";
    $clientName="Alex Petrov";
    $num=8;
    $price1=10;
    $price2=11;
    $price3=12;
    $price4=13;

    $res= $db->collection->findOneAndUpdate(
        array('_id'=>$id),
        array(
            '$inc' => array('countOperations'=>$num),
            '$setOnInsert' => array(
                'clientname'=>$clientName
            ),
            '$set' => array(
                'sum'=>array(
                    
                    ////////////////////
                    // pseudocode begin
                    ////////////////////
                    
                    if('countOperations'>1 && 'countOperations'<=10)
                    {   'sum'='countOperations'*$price1;
                    }                   
                    else
                    if('countOperations'>10 && 'countOperations'<=20)
                    {   'sum'='countOperations'*$price2;
                    }                   
                    else
                    if('countOperations'>20 && 'countOperations'<=30)
                    {   'sum'='countOperations'*$price3;
                    }                   
                    else
                    {   'sum'='countOperations'*$price4;
                    }                   
                
                    // as an option I planned to use:
                    // switch()
                    // {    case: then:
                    //      defaul:
                    // }
                    
                    ////////////////////
                    // pseudocode end 
                    ////////////////////
                    
                )
            )
        ),
        array('upsert'=>true)
    );