BlockWoodRailDropper.java

package slimeknights.tconstruct.gadgets.block;

import net.minecraft.entity.item.EntityMinecart;
import net.minecraft.item.ItemStack;
import net.minecraft.tileentity.IHopper;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;
import net.minecraftforge.items.CapabilityItemHandler;
import net.minecraftforge.items.IItemHandler;
import net.minecraftforge.items.ItemHandlerHelper;

public class BlockWoodRailDropper extends BlockWoodRail {

  @Override
  public void onMinecartPass(World world, EntityMinecart cart, BlockPos pos) {
    if(!cart.hasCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, EnumFacing.DOWN) || !(cart instanceof IHopper)) {
      return;
    }
    TileEntity tileEntity = world.getTileEntity(pos.down());
    if(tileEntity == null || !tileEntity.hasCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, EnumFacing.DOWN)) {
      return;
    }

    IItemHandler itemHandlerCart = cart.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, EnumFacing.UP);
    IItemHandler itemHandlerTE = tileEntity.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, EnumFacing.UP);

    for(int i = 0; i < itemHandlerCart.getSlots(); i++) {
      ItemStack itemStack = itemHandlerCart.extractItem(i, 1, true);
      if(ItemHandlerHelper.insertItem(itemHandlerTE, itemStack, true) == null) {
        itemStack = itemHandlerCart.extractItem(i, 1, false);
        ItemHandlerHelper.insertItem(itemHandlerTE, itemStack, false);
        break;
      }
    }
  }
}