How do I make it so when a player types a command and looks at an cauldron......

My plugin is a trash plugin and I want to make it so you type a command and it saves the cauldron as a trash can.

What is the code(s) for; when a player types /trash create and is looking at a cauldron, it saves the cauldron as a trash can and I will put my code for when a player hits the cauldron the item in their hand "goes away".

 

get the Event
this will remove the item from there hand when they left click it
its up to you to fill in the rest

Code:

 @EventHandler
public void OnPlayerClickEvent(PlayerInteractEvent event) {
    Material type = event.getClickedBlock().getType();
    Action ac = event.getAction();
    Player p = event.getPlayer();
    if(type == Material.CAULDRON)&&
        (ac == ac.LEFT_CLICK_BLOCK){
        ItemStack item =  p.getItemInHand();
        item.setAmount(0);
    }