public class CelestialPowerPedestalTileEntity extends TileEntity {

    public static final int                         slots                  = 1;
    private static      Capability <IItemHandler>   capability             = CapabilityItemHandler.ITEM_HANDLER_CAPABILITY;
    public              IItemHandler                inv                    = capability.getDefaultInstance();
    private final       LazyOptional <IItemHandler> capabilityLazyOptional = LazyOptional.of(() -> inv);

    public CelestialPowerPedestalTileEntity() {
        super(ModTileEntities.CELESTIAL_POWER_PEDESTAL_TILE_ENTITY.get());
    }

    public boolean isFillable() {
        return inv.getStackInSlot(0)
                  .getItem() != ModItems.CELESTIAL_POWER_EYE.get();
    }

    public void read(
        BlockState state,
        CompoundNBT nbt) {
        super.read(state, nbt);

        capability.readNBT(inv, null, nbt);
    }

    @Nonnull
    @Override
    public CompoundNBT write(
        CompoundNBT compound) {
        super.write(compound);
        capability.writeNBT(inv, null);
        return compound;
    }

    @Nonnull
    @Override
    public <T> LazyOptional <T> getCapability(
        Capability <T> cap,
        Direction side) {
        if (cap == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY) {
            return capabilityLazyOptional.cast();
        }
        return super.getCapability(cap, side);
    }

    @Override
    protected void invalidateCaps() {
        super.invalidateCaps();
        capabilityLazyOptional.invalidate();
    }

    @Nullable
    @Override
    public SUpdateTileEntityPacket getUpdatePacket() {
        CompoundNBT nbt = new CompoundNBT();
        this.write(nbt);
        return new SUpdateTileEntityPacket(this.pos, -1, nbt);
    }

    @Override
    public void onDataPacket(
        NetworkManager net,
        SUpdateTileEntityPacket pkt) {
        this.read(world.getBlockState(pkt.getPos()), pkt.getNbtCompound());
    }

    @Override
    public CompoundNBT getUpdateTag() {
        return this.write(new CompoundNBT());
    }

    @Override
    public void handleUpdateTag(
        BlockState state,
        CompoundNBT tag) {
        this.read(state, tag);
    }
}