Container

package net.asdfowkw.tech.blocks.windgenerator;

import net.asdfowkw.tech.Tech;
import net.asdfowkw.tech.network.MessageSetEnergy;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.player.EntityPlayerMP;
import net.minecraft.inventory.Container;
import net.minecraft.inventory.IInventory;
import net.minecraft.inventory.Slot;
import net.minecraft.item.ItemStack;
import net.minecraftforge.items.CapabilityItemHandler;
import net.minecraftforge.items.IItemHandler;
import net.minecraftforge.items.SlotItemHandler;

public class ContainerWindGenerator extends Container {

    private TileEntityWindGenerator te;
    private int[] prevFields;

    public ContainerWindGenerator(IInventory playerInventory, TileEntityWindGenerator te){
        this.te = te;

        addOwnSlots();
        addPlayerSlots(playerInventory);
    }

    private void addPlayerSlots(IInventory playerInventory) {
        //Slots for main inventory
        for (int row = 0; row < 3; ++row){
            for (int col = 0; col < 9; ++col){
                int x = 9 + col * 18;
                int y = row * 18 + 70;
                this.addSlotToContainer(new Slot(playerInventory, col + row * 9 + 10, x, y));
            }
        }
        //Slots for actionbar
        for (int row = 0; row < 9; ++row){
            int x = 9 + row * 18;
            int y = 58 + 70;
            this.addSlotToContainer(new Slot(playerInventory, row, x, y));
        }
    }

    private void addOwnSlots(){
        IItemHandler itemHandler = this.te.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, null);
        int x = 9;
        int y = 6;

        // Add our own slots
        int slotIndex = 0;
        for (int i = 0; i < itemHandler.getSlots(); i++) {
            addSlotToContainer(new SlotItemHandler(itemHandler, slotIndex, x, y));
            slotIndex++;
            x += 18;
        }
    }

    @Override
    public ItemStack transferStackInSlot(EntityPlayer playerIn, int index) {
        ItemStack itemstack = null;
        Slot slot = this.inventorySlots.get(index);

        if (slot != null && slot.getHasStack()) {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();

            if (index < TileEntityWindGenerator.SLOT_COUNT) {
                if (!this.mergeItemStack(itemstack1, TileEntityWindGenerator.SLOT_COUNT, this.inventorySlots.size(), true)) {
                    return null;
                }
            } else if (!this.mergeItemStack(itemstack1, 0, TileEntityWindGenerator.SLOT_COUNT, false)) {
                return null;
            }

            if (itemstack1.stackSize == 0) {
                slot.putStack(null);
            } else {
                slot.onSlotChanged();
            }
        }

        return itemstack;
    }

    @Override
    public boolean canInteractWith(EntityPlayer playerIn) {
        return te.isUseableByPlayer(playerIn);
    }

    @Override
    public void detectAndSendChanges(){
        super.detectAndSendChanges();

        boolean needUpdate = false;

        int[] fields = this.te.getFields();
        for (int i = 0; i < prevFields.length; i++){
            if(prevFields[i] != fields[i]){
                prevFields[i] = fields[i];
                needUpdate = true;
            }
        }

        if(needUpdate){
            this.listeners.stream().filter(watcher -> watcher instanceof EntityPlayerMP).forEach(watcher -> Tech.channel.sendTo(new MessageSetEnergy(te.getPos(), te.buffer.getEnergyStored()), (EntityPlayerMP) watcher));
        }
    }
}