internal: add BaseInventory implementation that saves/loads nbt correct

src/core/scala/mrtjp/projectred/core/inventory/BaseInventory.java

@@ -0,0 +1,54 @@
+package mrtjp.projectred.core.inventory;
+
+import net.minecraft.inventory.Inventory;
+import net.minecraft.item.ItemStack;
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.nbt.ListNBT;
+
+/**
+ * Simple extension of default vanilla Inventory class that allows for proper saving and loading
+ * to a CompoundNBT. Default implementation does not load items back into their original slots.
+ * <p>
+ * Use BaseInventory#save and BaseInventory#load instead of Inventory#createTag and Inventory#fromTag
+ */
+public class BaseInventory extends Inventory {
+
+    private static final String TAG_ITEMS = "items";
+    private static final String TAG_SLOT = "slot";
+    private static final String TAG_ITEM_COUNT = "item_count";
+
+    public BaseInventory(int size) {
+        super(size);
+    }
+
+    public void save(CompoundNBT tag) {
+        ListNBT list = new ListNBT();
+        for (int i = 0; i < getContainerSize(); i++) {
+            ItemStack stack = getItem(i);
+            if (!stack.isEmpty()) {
+                CompoundNBT itemTag = new CompoundNBT();
+                itemTag.putInt(TAG_SLOT, i);
+                stack.save(itemTag);
+                list.add(itemTag);
+            }
+        }
+        tag.put(TAG_ITEMS, list);
+        tag.putInt(TAG_ITEM_COUNT, list.size());
+    }
+
+    public void load(CompoundNBT tag) {
+        clearContent();
+        ListNBT list = tag.getList(TAG_ITEMS, 10);
+        for (int i = 0; i < list.size(); i++) {
+            CompoundNBT itemTag = list.getCompound(i);
+            int slot = itemTag.contains("index") ? itemTag.getInt("index") : itemTag.getInt(TAG_SLOT); //TODO remove legacy support
+            if (slot >= 0 && slot < getContainerSize()) {
+                setItem(slot, ItemStack.of(itemTag));
+            }
+        }
+    }
+
+    public static int getItemCount(CompoundNBT tag) {
+        return tag.contains(TAG_ITEM_COUNT) ? tag.getInt(TAG_ITEM_COUNT) : tag.getList(TAG_ITEMS, 10).size(); //TODO remove legacy support
+    }
+}

src/core/scala/mrtjp/projectred/lib/InventoryLib.java

@@ -1,9 +1,13 @@
 package mrtjp.projectred.lib;
 
+import net.minecraft.entity.player.PlayerInventory;
 import net.minecraft.inventory.IInventory;
+import net.minecraft.inventory.container.Slot;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.NonNullList;
 
+import java.util.function.Consumer;
+
 public class InventoryLib {
 
     public static void injectItemStack(IInventory inventory, ItemStack stack, boolean reverse) {
@@ -66,4 +70,43 @@ private static void injectItemStack(IInventory inventory, ItemStack stack, int s
     public static boolean areStackable(ItemStack a, ItemStack b) {
         return ItemStack.isSame(a, b) && ItemStack.tagMatches(a, b) && a.getMaxStackSize() > 1 && b.getMaxStackSize() > 1;
     }
+
+    public static void addPlayerInventory(PlayerInventory playerInventory, int x, int y, Consumer<Slot> slotConsumer) {
+        addInventory(playerInventory, 9, x, y, 9, 3, slotConsumer); // Inventory (0 - 26)
+        addInventory(playerInventory, 0, x, y + 58, 9, 1, slotConsumer); // Hotbar slots (27 - 35)
+    }
+
+    public static void addPlayerInventory(PlayerInventory playerInventory, int x, int y, SlotFactory slotFactory, Consumer<Slot> slotConsumer) {
+        addInventory(playerInventory, 9, x, y, 9, 3, slotFactory, slotConsumer); // Inventory (0 - 26)
+        addInventory(playerInventory, 0, x, y + 58, 9, 1, slotFactory, slotConsumer); // Hotbar slots (27 - 35)
+    }
+
+    public static void addInventory(IInventory inventory, int i, int x, int y, int columns, int rows, Consumer<Slot> slotConsumer) {
+        addInventory(inventory, i, x, y, columns, rows, Slot::new, slotConsumer);
+    }
+
+    /**
+     * Creates a grid of slots for a container with standard spacing.
+     *
+     * @param inventory The inventory backing the slots
+     * @param i Inventory index of the first slot
+     * @param x X position of the top left slot
+     * @param y Y position of the top left slot
+     * @param columns Number of columns in the grid
+     * @param rows Number of rows in the grid
+     * @param slotFactory Factory for creating the slots
+     * @param slotConsumer Consumer for the slots (typically Container.addSlot(...))
+     */
+    public static void addInventory(IInventory inventory, int i, int x, int y, int columns, int rows, SlotFactory slotFactory, Consumer<Slot> slotConsumer) {
+        for (int c = 0; c < columns; c++) {
+            for (int r = 0; r < rows; r++) {
+                slotConsumer.accept(slotFactory.createSlot(inventory, i + (r * columns + c), x + c * 18, y + r * 18));
+            }
+        }
+    }
+
+    @FunctionalInterface
+    public interface SlotFactory {
+        Slot createSlot(IInventory inventory, int index, int x, int y);
+    }
 }