upgrade amor

how to upgrade amor by killing players ?
1. full leather -> full chain
please help me

PHP:

    public function onPlayerDeathEvent(PlayerDeathEvent $event)
     {
       $player = $event->getEntity();
     
       if ($player instanceof Player)
       {
         $cause = $player->getLastDamageCause();
     
         if($cause instanceof EntityDamageByEntityEvent)
         {
           $damager = $cause->getDamager();
           
           if($damager instanceof Player)
           {
  $damager->sendMessage(Color::GREEN."test");
   
             $this->money->addMoney($damager, 5);
           
             $this->money->reduceMoney($player, 5);

https://github.com/PocketMine/Pocke...pocketmine/inventory/PlayerInventory.php#L193
https://github.com/PocketMine/Pocke...pocketmine/inventory/PlayerInventory.php#L197
https://github.com/PocketMine/Pocke...pocketmine/inventory/PlayerInventory.php#L201
https://github.com/PocketMine/Pocke...pocketmine/inventory/PlayerInventory.php#L205

i dont understand it :/

You would call that function on inventory object.
$player->getInventory()->setHelmet($item);

PHP:

    public function getHelmet(){
        return $this->getItem($this->getSize());
    }
    public function getChestplate(){
        return $this->getItem($this->getSize() + 1);
    }
    public function getLeggings(){
        return $this->getItem($this->getSize() + 2);
    }
    public function getBoots(){
        return $this->getItem($this->getSize() + 3);
    }
    public function setHelmet(Item $helmet){
        return $this->setItem($this->getSize(), $helmet);
    }
    public function setChestplate(Item $chestplate){
        return $this->setItem($this->getSize() + 1, $chestplate);
    }
    public function setLeggings(Item $leggings){
        return $this->setItem($this->getSize() + 2, $leggings);
    }
    public function setBoots(Item $boots){
        return $this->setItem($this->getSize() + 3, $boots);
    }

// What you do not understand?
// Just add leather armor id and here you goes

PHP:

if($player->getInventory()->getHelmet(Item::get(298, 0, 1)) and $player->getInventory()->getChestplate(Item::get(299, 0, 1)) and $player->getInventory()->getLeggings(Item::get(300, 0, 1)) and $player->getInventory()->getBoots(Item::get(301, 0, 1))) {
$player->getInventory()->setHelmet(Item::get(302, 0,1));
$player->getInventory()->setChestplate(Item::get(303, 0, 1));
$player->getInventory()->setLeggings(Item::get(304, 0, 1));
$player->getInventory()->setBoots(Item::get(305, 0,1));
}
// Leather armor to chainmail armor
// You could edit all $player to $damager like in your code

omg it works THANK YOU SOOOOOOOO MUCH YOUR THE BEST !

@PaulchenHD I can't skype. How about Privat conversation?