AutoSwap/src/main/kotlin/net/shadowfacts/autoswap/AutoSwap.kt

package net.shadowfacts.autoswap

import net.fabricmc.api.ModInitializer
import net.minecraft.client.network.packet.EntityEquipmentUpdateS2CPacket
import net.minecraft.client.network.packet.ItemPickupAnimationS2CPacket
import net.minecraft.entity.EquipmentSlot
import net.minecraft.entity.player.PlayerEntity
import net.minecraft.entity.player.PlayerInventory
import net.minecraft.item.ItemStack
import net.minecraft.server.network.ServerPlayerEntity
import net.minecraft.util.math.BlockPos

/**
 * @author shadowfacts
 */
object AutoSwap: ModInitializer {

	override fun onInitialize() {
	}

	fun endBreakBlock(playerInv: PlayerInventory, heldStackAtBeginningOfBreak: ItemStack) {
		val currentlySelected = playerInv.mainHandStack
		if (currentlySelected.isEmpty && !heldStackAtBeginningOfBreak.isEmpty) {
			val index = playerInv.main.indexOfFirst {
				ItemStack.areItemsEqualIgnoreDamage(heldStackAtBeginningOfBreak, it)
			}
			if (index >= 0) {
				playerInv.swapSlotWithHotbar(index)
			}
		}
	}

	fun onUseOnItem(player: ServerPlayerEntity, playerInv: PlayerInventory, heldStackBeforeUse: ItemStack) {
		val heldStack = playerInv.mainHandStack
		if (!player.isCreative && heldStack.isEmpty) {
			val index = playerInv.main.indexOfFirst {
				ItemStack.areItemsEqualIgnoreDamage(heldStackBeforeUse, it)
			}
			if (index >= 0) {
				playerInv.swapSlotWithHotbar(index)
				val newStack = playerInv.mainHandStack
				player.networkHandler.sendPacket(EntityEquipmentUpdateS2CPacket(player.entityId, EquipmentSlot.MAINHAND, newStack))
			}
		}
	}

	fun afterAttack(playerInv: PlayerInventory, heldStackBeforeAttack: ItemStack) {
		val heldStack = playerInv.mainHandStack
		if (!heldStackBeforeAttack.isEmpty && heldStack.isEmpty) {
			val index = playerInv.main.indexOfFirst {
				ItemStack.areItemsEqualIgnoreDamage(heldStackBeforeAttack, it)
			}
			if (index >= 0) {
				playerInv.swapSlotWithHotbar(index)
			}
		}
	}

}