PHP - Subtracting Time

Good morning. I need to subtract stock levels from oldest stock first then to the next date.

It is allowed to move into negative values.

example

01-10  stock in 10  stock out 5 - stock count 5

02-10 stock in 10 stock out 7 stock count ... here we need to subtract the 7 from previous days 5 til it reches 0  then stock in subtraction

 01-10 stock =0

02-10 stock = 8 --- as 7 -5 gives me -2 in incoming stock is 10 leaving me with stock count of 8.

03-10 stock in 8 stock out 21 

02-10 stck level must be    0

03-10 stock lever now is 8-14 = -6 and so on

below is my code. 

    $lq_in = new ListQuery('stock_audit5f5795042f369');
    $lq_in->addSimpleFilter('name', '%PEPPER yellow%', 'LIKE' );
    //$lq_in->addSimpleFilter('product_id', $product_id, '=');
    $lq_in->setOrderBy('date_entered');
    $res_in = $lq_in->fetchAll();
$StockArray = [];
foreach($res_in as $out_rec) {
    /*$upd_out = array();
    $upd_out['stock_out_done'] = 0;

    $out_rec_u = ListQuery::quick_fetch('stock_audit5f5795042f369', $out_rec->getField('id'));
    $aud_upd_out = RowUpdate::for_result($out_rec_u);
    $aud_upd_out->set($upd_out);
    $aud_upd_out->save();
    continue;
    */
    $stock_out = $out_rec->getField('stock_out');
    $stock_out_done = $out_rec->getField('stock_out_done');
    $date_entered = $out_rec->getField('date_entered');
    $product_id = $out_rec->getField('product_id');

    
    //echo '<pre>';
   // print_r($out_rec->row);
    $StockItems[] = $out_rec->row;

    //$stock_done = 0;
    /*
    foreach($res_in as $in_rec) {
        $upd = array();
        if($stock_out_new > $in_rec->getField('stock_level')) {
            $upd['stock_level'] = 0;
            $stock_out_new = $stock_out_new-$in_rec->getField('stock_level');
            $stock_done = $in_rec->getField('stock_level');
        } elseif ($stock_out_new == $in_rec->getField('stock_level')) {
            $upd['stock_level'] = 0;
            $stock_out_new = 0;
            $stock_done = $stock_out;
        } elseif($stock_out_new < $in_rec->getField('stock_level')) {
            $upd['stock_level'] = $in_rec->getField('stock_level')-$stock_out_new;
            $stock_out_new = 0;
            $stock_done = $stock_out;
        } else {
            continue;
        }

        $in_rec_u = ListQuery::quick_fetch('stock_audit5f5795042f369', $in_rec->getField('id'));
        $aud_upd = RowUpdate::for_result($in_rec_u);
        $aud_upd->set($upd);
        $aud_upd->save();

        if($stock_out_new == $stock_done)
            break;
    }
    
    $upd_out = array();
    $upd_out['stock_out_done'] = $stock_done;

    $out_rec_u = ListQuery::quick_fetch('stock_audit5f5795042f369', $out_rec->getField('id'));
    $aud_upd_out = RowUpdate::for_result($out_rec_u);
    $aud_upd_out->set($upd_out);
    $aud_upd_out->save();
    */
}
function GetFirstItemWithStockKey($StockItemsarrayk = null){
    if($StockItemsarrayk != null){
        foreach($StockItemsarrayk as $key => $value){
            if(((int) $StockItemsarrayk[$key]['stock_level']) > 0){
                return $key;
            }
        }
    }
}

function SetFirstItemWithStock($StockItemsarray = null){
    if($StockItemsarray != null){
        foreach($StockItemsarray as $key => $value){
            if(((int) $StockItemsarray[$key]['stock_level']) > 0){
                return $StockItemsarray[$key];
            }
        }
    }
}
$remainder = 0;
$pkey = "";
$StockLevelKey = 0;
$StockIn = [];
$StockOut = [];
$InStock = [];

$NewStockItems = $StockItems;
$ArrayKeys = [];
foreach($StockItems as $key => $value){
  $StockIn[$key] = (int) $StockItems[$key]['stock_in'];
  $StockOut[$key] = (int) $StockItems[$key]['stock_out'];
  $InStock[$key] = (int) $StockItems[$key]['stock_level'];
  $ArrayKeys[] = (int)$key;
  
}
//var_dump($InStock);
foreach($NewStockItems as $key => $value){
    if($key < 1){
        if($StockIn[$key] > 0 && $StockOut[$key] == 0 && $InStock[$key] == 0){
            $StockItems[$key]['stock_level'] = ($InStock[$key] + $StockIn[$key]);     
        }
        if($StockIn[$key] == 0 && $StockOut[$key] > 0 && $InStock[$key] == 0){
            $StockItems[$key]['stock_level'] = ($InStock[$key] - $StockOut[$key]);
         
        }
        if($StockIn[$key] > 0 && $StockOut[$key] > 0 && $InStock[$key] == 0){
            $StockItems[$key]['stock_level'] = ($InStock[$key] - $StockOut[$key] + $StockIn[$key]);
            $StockItems[$key]['stock_out'] = 0;
        }
    }
    if($key > 0){
        $previousWithStockItem = SetFirstItemWithStock($StockItems);
        $previousItemWithStockKey = GetFirstItemWithStockKey($StockItems);
       // echo "<pre>";
      //  print_r($previousWithStockItem);
       // var_dump($StockIn[$key]); echo "&nbsp;&nbsp;&nbsp;&nbsp;--IN";
      //  var_dump($InStock[$key]); echo "&nbsp;&nbsp;&nbsp;&nbsp;--- current";
       // var_dump($StockOut[$key]); echo "&nbsp;&nbsp;&nbsp;&nbsp;--- OUT";
        while($StockOut[$key] > 0){
            if($StockOut[$key] > 0 && $previousWithStockItem['stock_level'] > 0){
                $Counter = 0;
                $maxIteration = 0;
                for($Counter = $previousWithStockItem['stock_level']; $Counter >= 0; $Counter--){
                    $StockItems[$previousItemWithStockKey]['stock_level'] = $Counter;
                    if($Counter == 0){
                         $StockOut[$key] = $StockOut[$key] - $maxIteration;
                    }
                    $maxIteration++;
                }
            }
            if((((int) $StockItems[$key]['stock_level'] < 0) || ((int) $StockItems[$key]['stock_level'] === 0))&& ($StockIn[$key] > 0)){
                $valueTotal = $StockItems[$key]['stock_level'] + $StockIn[$key];
                $StockItems[$key]['stock_level'] = $valueTotal;
            }
            echo "<hr/>";
            echo (int) $StockOut[$key];
            echo "<br/>";
             echo (int) $StockItems[$key]['stock_level'];
            echo "<br/>";
             echo "<hr/>";
            if(((int) $StockOut[$key] > 0) && ((int) $StockItems[$key]['stock_level'] > 0) && ((int) $StockItems[$key]['stock_level'] > $StockOut[$key])){
              
                $newStockLevel = $StockItems[$key]['stock_level'] - $StockOut[$key];
                echo $newStockLevel;
                $StockItems[$key]['stock_level'] = $newStockLevel;
                $StockItems[$key]['stock_out'] = 0;
                $StockOut[$key] = 0;
            }
            if((((int) $StockItems[$key]['stock_level'] < 0) || ((int) $StockItems[$key]['stock_level'] === 0))&& ($StockIn[$key] > 0)){
                $valueTotal = $StockItems[$key]['stock_level'] + $StockIn[$key];
                echo $valueTotal;
                $StockItems[$key]['stock_level'] = $valueTotal;
            }
        }
    }
}
echo "<table><tr><td><pre>";
print_r($NewStockItems);
echo "</pre></td><td><pre>";
print_r($StockItems);
echo "</pre></td></table>";
/*
        if($StockIn[$key] > 0 && $StockOut[$key] >0 && $InStock[$key] == 0){
            $StockItems[$key]['stock_level'] = ($InStock[$key] + ($StockIn[$key] + $StockOut[$key]));
            
            $StockOut[$key] = 0;
            $StockItems[$key]['stock_out'] = 0;
        }
        if($StockIn[$key] != 0 && $StockOut[$key] != 0 && $InStock[$key] != 0){
            $StockItems[$key]['stock_level'] = ($InStock[$key] - ($StockOut[$key] + $StockIn[$key]));
            
            $StockOut[$key] = 0;
            $StockItems[$key]['stock_out'] = 0;
        }*/
/**
 @Rule 1 
 # Stockin has value and stock_out = 0 and stock_level = 0 and stock_out_done = null, actualstock to show actual stock level;
 # 
 
 */

/*if($StockCalculation[$Skey]['stock_out'] >= $StockItems[$key]['stock_level']){
                           $StockItems[$key]['stock_out'] = ($StockItems[$key] - 1);
                           $StockItems[$key]['stock_level'] = ($StockItems[$key]['stock_level'] - 1);
                           // If StockOut == 0 next StockOutItem
                           if($StockCalculation[$Skey]['stock_out'] == 0){
                               $remainder = 0;
                                continue;
                           }elseif($StockItems[$key]['stock_level'] == 0){
                               //CurrentInStock == 0 then continue to next CurrentItem
                                $remainder = $StockItems[$key]['stock_out'];
                                continue(2);
                           }
                       }
 $CurrentStockIn = $StockItems[$key]['stock_in'];
   $CurrentStockOut = $StockItems[$key]['stock_out'];
   $CurrentInStock = $StockItems[$key]['stock_level'];
   if($key == 0){
       if($CurrentStockIn > 0 && $CurrentStockOut === 0 && $CurrentInStock == 0){
           $CurrentInStock = $CurrentStockIn;
           //Query update stock level set = stock_in 
           //"UPDATE STOCK SET stock_level = {$CurrentStockIn} where id = {$StockItems[$key]['id']}";
           $StockItems[$key]['stock_level'] = $CurrentStockIn;
       }
       if($CurrentStockIn != 0 && $CurrentStockOut != 0 && $CurrentInStock == 0){
           //Query Update Stocklevel if stock_out > 0 and stock_level = 0
           //"UPDATE STOCK SET stock_level = "+($CurrentStockIn - $CurrentStockOut) + "where id = {$StockItems[$key]['id']}";
           if($CurrentStockIn > $CurrentStockOut && $CurrentStockOut == 0){
               $StockItems[$key]['stock_out'] = 0;
               $StockItems[$key]['stock_level'] = $CurrentInStock = $CurrentStockIn - $CurrentStockOut;
           }
           if($CurrentStockOut > $CurrentStockIn){
               $StockItems[$key]['stock_level'] = $CurrentInStock = $CurrentInStock - $CurrentStockOut;
           }
       }
       if($CurrentInStock != 0 && $CurrentStockOut > 0){
            //If Current in stock below 0 and stock out > 0 then negative more
           //"UPDATE STOCK SET stock_level = "+($CurrentInStock - $CurrentStockOut) + "where id = {$StockItems[$key]['id']}";
           $StockItems[$key]['stock_level'] = $CurrentInStock = ($CurrentInStock - $CurrentStockOut);
           $StockItems[$key]['stock_out'] = 0;
       }
        if($CurrentInStock != 0 && $CurrentStockIn > 0){
            
            //If Current in stock below 0 and stock out > 0 then negative more
           //"UPDATE STOCK SET stock_level = "+($CurrentInStock - $CurrentStockOut) + "where id = {$StockItems[$key]['id']}";
           $StockItems[$key]['stock_level'] = $CurrentInStock = ($CurrentInStock + $CurrentStockIn);
       }
       // Run row update for first item
   }else{
       foreach($StockCalculation as $Skey => $Sval){
           $NextStockOut = $Sval['stock_out'];
           $NextStockIn = $Sval['stock_in'];
           $NextStockLevel = $Sval['stock_level'];
           
           if($Skey > 0 && $key > 0){
              // print_r($NextStockOut);
                   for($i = $NextStockOut; $i >= -1; $i--){
                       if($NextStockOut > 0){
                           if($NextStockOut > 0){
                               /* if($StockItems[$StockLevelKey]['stock_level'] != 0){
                                    $StockItems[($StockLevelKey)]['stock_level'] = ($StockItems[($StockLevelKey)]['stock_level'] - 1);
                                    //$StockItems[($Skey-1)]['stock_out'] = ($StockItems[($Skey-1)]['stock_out'] -1);
                                }
                                if($StockItems[($Skey-1)]['stock_level'] != 0){
                                    $StockItems[($Skey-1)]['stock_level'] = ($StockItems[($Skey-1)]['stock_level'] - 1);
                                }
                           }
                       }
                       $NextStockOut = ($NextStockOut -1);
                       if($NextStockOut != 0){
                           $StockItems[$Skey]['stock_out'] = 0;
                           
                           break;
                       }
                       
                   }
               
           }
           unset($StockCalculation[$Skey]);
       }
   }/*
*/

PHP date and time function is not showing correct time on my local system

I have the following php code

date_default_timezone_set("Africa/Lagos");

$date = date('d-m-y h:i:s');

echo "Server Time ".$date ."<br>";

echo "The time is " . date("h:i:sa")."<br>";

$current_datetime = date("Y-m-d") . ' ' . date("H:i:s", STRTOTIME(date('h:i:sa')));

echo "Current time1: ".$current_datetime . "<br>";

Output

Server Time 21-05-21 09:55:39
The time is 09:55:39am
Current time1: 2021-05-21 09:55:39

Expected Output

Server Time 21-05-21 10:55:39
The time is 10:55:39am
Current time1: 2021-05-21 10:55:3

Any help would be appreciated.

What are the differences and implications of UTC time and Zulu time?
  

<?php
function getArr(string $time):array
{
    $dateTime = new \DateTime($time);
    return [
        'time'=>$time,
        'timestamp'=> $dateTime->getTimestamp(),
        'dateTime' => $dateTime
    ];
}
$arr = getArr('2020-08-05');  
$arr_z = getArr('2020-08-05T00:00:00Z');  

print_r($arr);
print_r($arr_z);

echo('equal timestamps: '.($arr['timestamp'] === $arr['timestamp']?'true':'false'));

Array
(
    [time] => 2020-08-05
    [timestamp] => 1596585600
    [dateTime] => DateTime Object
        (
            [date] => 2020-08-05 00:00:00.000000
            [timezone_type] => 3
            [timezone] => UTC
        )

)
Array
(
    [time] => 2020-08-05T00:00:00Z
    [timestamp] => 1596585600
    [dateTime] => DateTime Object
        (
            [date] => 2020-08-05 00:00:00.000000
            [timezone_type] => 2
            [timezone] => Z
        )

)
equal timestamps: true

I have this:

    $sql = mysqli_query($conn, "SELECT ip
                                     , page
                                     , CASE WHEN referrer = ''
                                            THEN 'N/A'
                                            ELSE referrer
                                       END as referrer     
                                     , DATE_FORMAT(date, '%m/%d/%y') as date
                                     , TIME_FORMAT(time, '%T') as time
                                FROM tblTraffic 
                                ORDER BY date DESC, time DESC");

most of my traffic report contains the correct times, my time, which is CST in the USA.  but some records are off by a lot.  Does the time() function capture the time of the actual location from which the visitor is coming from?  if so, what could I do to return my timezone for any visitor?  w3 schools and php.net don't mention this.

Let's say I am buying a share for $10.

If I sell the share on the same day BEFORE 3:30PM, it will be sold for $10, but if I keep the share past 3:30PM, I want the code to automatically add $1 (Taxes and such) once in the the price of the share in database, after that no matter how many days pass by, the price will remain the same.

I've thought about CRON jobs, but I have no idea how to make/use them or set them up.

Any direction or help is appreciated.