Find the Item that was used for an Attack?

[FenrisFox86]

So I'm creating a mod that includes a double-wieldable variation of the sworditem. The double wielding itsself works fine. 

But my mod also adds some enchantments to the game. Right now I have the problem that offhand weapons use the mainhand weapons' enchantment information. Here's my enchantment code:

@SubscribeEvent
    public static void OnHitEntity(LivingAttackEvent event) {
        Entity entity = event.getSource().getTrueSource();
        if(entity instanceof LivingEntity) {
            LivingEntity living = (LivingEntity) entity;
            LivingEntity target = event.getEntityLiving();
            Iterable<ItemStack> equipment = living.getEquipmentAndArmor();
            ItemStack stack = living.getHeldItem(living.getActiveHand());

            //Dark Contract
            level = EnchantmentHelper.getEnchantmentLevel(DARK_CONTRACT.get(), stack);
            if(level > 0) {
                target.attackEntityFrom(DamageSource.GENERIC, level*2);
                living.attackEntityFrom(DamageSource.causeIndirectMagicDamage(living, null), level);
            }
        }
    }

As you see, I only apply the effects of the active hand. In my double sword code, I set the active hand to offhand on right click: 

public ActionResult<ItemStack> onItemRightClick(World worldIn, PlayerEntity playerIn, Hand handIn) {
        playerIn.setActiveHand(Hand.OFF_HAND);
        return ActionResult.resultSuccess(playerIn.getHeldItemOffhand());
    }
  
@Override
public ActionResultType itemInteractionForEntity(ItemStack stack, PlayerEntity playerIn, LivingEntity target, Hand hand) {
        playerIn.setActiveHand(Hand.OFF_HAND);
        stack.getItem().hitEntity(stack, target, playerIn);
        return ActionResultType.SUCCESS;
    }

So even though I set the active hand and use this information to apply the effects, it keeps using the wrong hand's enchantments. 

Since the hitEntity() method takes an ItemStack as an argument, I started asking myself if there was a way to get the stack that was used from the event. That would make it much easier. Any Ideas are appreciated. 

[FenrisFox86]

So can you think of any other way to find out which hand was used for an attack?

The problem here is that I want these effects to also work on vanilla swords or even weapons from other mods. Could I create a mixin that fires an event when Item#hitEntity is called to know which stack was used? 

I haven't really worked with mixins yet so I don't know if they are a solution in this situation. 

[FenrisFox86]

My question's if you're able to find the stack that was given as a parameter. Because right now I could also shoot with a bow and then switch to an enchanted sword while the arrow is flying. The effect would be applied since the item that I had in my hand on impact was enchanted. 

I'm trying to trace the itemstack that was used to initiate the attack. 

[Draco18s]

Or deny the enchantment on bows.

[Lily Faerose]

I've been working on a magic mod and had a similar problem my (untested) solution was to use a custom damagesource to store what I needed and send it upstream. 

edit: finally did some testing worked fine. 

Edited June 28, 2021 by Lily Faerose

[FenrisFox86]

Solved:

So I followed @diesieben07's instructions and created a boolean capabbility for players that checks if their last hand used was the offhand. Enchantments that are hand-based will simply check the OffhandUsed capability and only apply the effect if they're in the correct hand when they're used by players. 

Sadly Vanilla enchants won't work on the left hand like this but it's the best I could do for now.