#3 Scrollbar functional on GUI and feels pretty good. Added in some picture assets, shop system still not functional yet

src/client/java/jesse/keeblarcraft/gui/FactionBlockGUI/FactionBlockScreen.java

@@ -25,18 +25,23 @@ public class FactionBlockScreen extends HandledScreen<FactionBlockScreenHandler>
         super.init();
         titleY = 1000; //begone from screen
         playerInventoryTitleY = 1000; //begone from screen
+
+        this.backgroundWidth = 256;
+        this.backgroundHeight = 256;
+        this.x = (width - backgroundWidth) / 2;
+        this.y = (height - backgroundHeight) / 2;
     }
 
     @Override
     protected void drawBackground(DrawContext context, float delta, int mouseX, int mouseY) {
-        RenderSystem.setShader(GameRenderer::getPositionTexProgram);
-        RenderSystem.setShaderColor(1f, 1f, 1f, 1f);
-        RenderSystem.setShaderTexture(0, TEXTURE);
+//        RenderSystem.setShader(GameRenderer::getPositionTexProgram);
+//        RenderSystem.setShaderColor(1f, 1f, 1f, 1f);
+//        RenderSystem.setShaderTexture(0, TEXTURE);
+
+        context.drawTexture(TEXTURE, this.x, this.y, 0, 0, this.backgroundWidth, this.backgroundHeight, this.backgroundWidth, this.backgroundHeight);
 
         this.backgroundHeight = 256;
         this.backgroundWidth = 256;
-
-
     }
 
     @Override

src/client/java/jesse/keeblarcraft/gui/Generics/ClickableLayer.java

@@ -27,6 +27,16 @@ abstract public class ClickableLayer extends ClickableWidget {
         this.layerName = layerName;
     }
 
+    protected void ResizeLayer(int width, int height) {
+        this.setWidth(width);
+        this.setHeight(height);
+    }
+
+    protected void MoveLayer(int startX, int startY) {
+        this.setX(startX);
+        this.setY(startY);
+    }
+
     protected void AddSubLayer(ClickableLayer newLayer) {
         subLayers.add(newLayer);
     }
@@ -59,7 +69,6 @@ abstract public class ClickableLayer extends ClickableWidget {
     @Override
     public void renderButton(DrawContext context, int mouseX, int mouseY, float delta) {
         context.drawTexture(this.GetTexture(), this.getX(), this.getY(), 0, 0, this.getWidth(), this.getHeight(), this.getWidth(), this.getHeight());
-
     }
 
     public Identifier GetTexture() {

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/DrawableStoreItem.java

@@ -0,0 +1,48 @@
+package jesse.keeblarcraft.gui.ShopKeeperGUI;
+
+import jesse.keeblarcraft.Keeblarcraft;
+import jesse.keeblarcraft.gui.Generics.ClickableLayer;
+import net.minecraft.client.gui.screen.narration.NarrationMessageBuilder;
+import net.minecraft.text.Text;
+import net.minecraft.util.Identifier;
+
+// All the custom content that a store item will have. Handled by @see MerchandiseScroller.java
+public class DrawableStoreItem extends ClickableLayer {
+    private static final Identifier ITEM_ICON = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_item_slot.png");
+    private Integer itemCost;
+    private String itemName;
+    private Integer amountSelected = 0;
+
+    public DrawableStoreItem(String itemName, Integer itemCost) {
+        this(itemName, itemCost, Text.of(""), 0, 0, 0, 0);
+
+    }
+
+    public DrawableStoreItem(String itemName, Integer itemCost, Text layerName, int width, int height, int startX, int startY) {
+        super(ITEM_ICON, layerName, width, height, startX, startY);
+        this.itemCost = itemCost;
+        this.itemName = itemName;
+    }
+
+    public void Add() {
+        ++this.amountSelected;
+        System.out.println("Current buy amount: " + this.amountSelected);
+    }
+
+    public void Subtract() {
+        --this.amountSelected;
+        System.out.println("Current buy amount: " + this.amountSelected);
+    }
+
+    public Integer GetTotal() {
+        return this.amountSelected * itemCost;
+    }
+
+    @Override
+    public void onClick(double x, double y) {
+        System.out.println("User clicked the following coordinates: [" + x + ", " + y + "]");
+    }
+
+    @Override
+    protected void appendClickableNarrations(NarrationMessageBuilder builder) {}
+}

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/MerchandiseScroller.java

@@ -0,0 +1,40 @@
+package jesse.keeblarcraft.gui.ShopKeeperGUI;
+
+import jesse.keeblarcraft.GuiMgr.ShopKeeper.ShopKeeperInventory;
+import jesse.keeblarcraft.GuiMgr.ShopKeeper.StoreItem;
+import jesse.keeblarcraft.gui.Generics.ClickableLayer;
+import net.minecraft.client.gui.screen.narration.NarrationMessageBuilder;
+import net.minecraft.text.Text;
+import net.minecraft.util.Identifier;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+// This is the main section in the GUI that will display the stores "merchandise" -- all the items on sale.
+public class MerchandiseScroller {
+    private final ShopKeeperInventory storeInventory;
+
+    // Key = item name
+    // Value = the drawable slot for it
+    // The KVP keeps it so duplicate items don't take up more than 1 store slot
+    private final HashMap<String, DrawableStoreItem> drawableInventory;
+
+    public MerchandiseScroller(ShopKeeperInventory storeInventory) {
+        this.storeInventory = storeInventory;
+        drawableInventory = new HashMap<>();
+    }
+
+    public Integer Size() {
+        return storeInventory.Size();
+    }
+
+    public void Add(StoreItem item) {
+        storeInventory.Add(item);
+        drawableInventory.put(item.GetUPC(), new DrawableStoreItem(item.GetName(), item.GetCost()));
+    }
+
+    public void Remove(String upc) {
+        storeInventory.Remove(upc);
+    }
+}

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/NewItemButton.java

@@ -7,7 +7,7 @@ import net.minecraft.text.Text;
 import net.minecraft.util.Identifier;
 
 public class NewItemButton extends ClickableLayer {
-    private static final Identifier NEW_ITEM_MENU = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_item_slot.jpeg");
+    private static final Identifier NEW_ITEM_MENU = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_item_slot.jpeg"); /// TODO: Does not exist
     private static NewItemMenu newItemMenu;
 
     public NewItemButton(Identifier texture, Text layerName, int width, int height, int startX, int startY) {

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/NewItemMenu.java

@@ -25,6 +25,10 @@ public class NewItemMenu extends ClickableLayer {
         this.AddDrawableSlotByName("add_item_slot", true);
     }
 
+    public void AddItem() {
+
+    }
+
     public boolean IsOpen() {
         return this.isOpen;
     }

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/Scrollbar.java

@@ -0,0 +1,77 @@
+package jesse.keeblarcraft.gui.ShopKeeperGUI;
+
+import jesse.keeblarcraft.gui.Generics.ClickableLayer;
+import net.minecraft.client.gui.screen.narration.NarrationMessageBuilder;
+
+import net.minecraft.text.Text;
+import net.minecraft.util.Identifier;
+
+public class Scrollbar extends ClickableLayer {
+    private boolean isDragging = false;
+    private int scrollbarStart = 0;
+    private int scrollbarEnd = 0;
+
+    public Scrollbar(Identifier texture, Text layerName, int width, int height, int startX, int startY, int scrollbarStart, int scrollbarMaxLength) {
+        super(texture, layerName, width, height, startX, startY);
+        this.scrollbarStart = scrollbarStart;
+        this.scrollbarEnd = startY + scrollbarMaxLength;
+    }
+
+    @Override
+    protected void onDrag(double mX, double mY, double dX, double dY) {
+        // We only want to enable dragging if this feature is being toggled
+        if (dY > 0) {
+           dY = 1.0;
+        } else {
+            dY = -1.0;
+        }
+
+        if (isDragging && mY >= this.scrollbarStart && mY <= this.scrollbarEnd) {
+            this.MoveLayer(this.getX(), (int)mY - (this.getHeight() / 2));
+        }
+    }
+
+    @Override
+    public boolean mouseScrolled(double mouseX, double mouseY, double horizontalAmount, double verticalAmount) {
+        // We intentionally switch the scroll direction since it is backwards
+        // The number set to is the speed of scrolling
+        if (verticalAmount > 0) {
+            verticalAmount = -3;
+        } else {
+            verticalAmount = 3;
+        }
+
+
+        int newY = this.getY() + (int) verticalAmount;
+        System.out.println("Mouse move. newY: " + newY + " -> this.getY()=" + this.getY());
+        if (newY >= this.scrollbarStart-12 && newY <= this.scrollbarEnd-9) {
+            this.MoveLayer(this.getX(), newY);
+        }
+
+        return true;
+    }
+
+    @Override
+    public boolean mouseClicked(double mouseX, double mouseY, int button) {
+        SetDragging(true);
+        return true;
+    }
+
+    @Override
+    public boolean mouseReleased(double mouseX, double mouseY, int button) {
+        SetDragging(false);
+        return true;
+    }
+
+    public Boolean IsDragging() {
+        return this.isDragging;
+    }
+
+    public void SetDragging(boolean b) {
+        System.out.println("Toggling dragging mode on scrollbar");
+        this.isDragging = b;
+    }
+
+    @Override
+    protected void appendClickableNarrations(NarrationMessageBuilder builder) {}
+}

src/client/java/jesse/keeblarcraft/gui/ShopKeeperGUI/ShopKeeperMenu.java

@@ -1,12 +1,16 @@
 package jesse.keeblarcraft.gui.ShopKeeperGUI;
 
+import jesse.keeblarcraft.Entities.ShopKeeper;
 import jesse.keeblarcraft.GuiMgr.ShopKeeper.ShopKeeperHandler;
+import jesse.keeblarcraft.GuiMgr.ShopKeeper.ShopKeeperInventory;
 import jesse.keeblarcraft.Keeblarcraft;
 import jesse.keeblarcraft.ClientHelpers.Helper;
 import jesse.keeblarcraft.gui.Generics.ClickableLayer;
 import net.minecraft.client.gui.DrawContext;
 import net.minecraft.client.gui.screen.ingame.HandledScreen;
 import net.minecraft.entity.player.PlayerInventory;
+import net.minecraft.item.ItemStack;
+import net.minecraft.item.Items;
 import net.minecraft.text.Text;
 import net.minecraft.util.Identifier;
 
@@ -15,12 +19,15 @@ import java.util.List;
 import java.util.Map;
 
 public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
-    private static final Identifier MENU_TEXTURE = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_gui.jpeg");
-    private static final Identifier ADD_BUTTON = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_add_icon.jpeg");
-    private static final Identifier NEW_ITEM_MENU = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_item_slot.jpeg");
+    private static final Identifier MENU_TEXTURE = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/shopkeeper_gui.png");
+    private static final Identifier ADD_BUTTON = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/plus.png");
+    private static final Identifier SCROLLBAR = new Identifier(Keeblarcraft.MOD_ID, "textures/gui/scrollbar.png");
     private int x = 0;
     private int y = 0;
     private final List<ClickableLayer> layers = new ArrayList<>();
+    private MerchandiseScroller catalogue;
+    private ShopKeeperInventory serverInventory;
+    Scrollbar scrollbar;
 
     public ShopKeeperMenu(ShopKeeperHandler handler, PlayerInventory inventory, Text title) {
         super(handler, inventory, title);
@@ -37,9 +44,14 @@ public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
         this.backgroundHeight = 256;
         this.x = (width - backgroundWidth) / 2;
         this.y = (height - backgroundHeight) / 2;
+        scrollbar = new Scrollbar(SCROLLBAR, Text.of("scrollbar"), 15, 28, x+243, y+40, y+50, 163);
 
         // Add all layers below
-        AddNewButton(ADD_BUTTON, Text.of("ADD ITEM BUTTON"), x, y, 64, 64);
+        AddNewButton(ADD_BUTTON, Text.of("ADD ITEM BUTTON"), x+20, y+20, 8, 8);
+        AddNewLayer(scrollbar);
+
+        catalogue = new MerchandiseScroller(this.getScreenHandler().GetInventory());
+        System.out.println("This store catalogue has size " + catalogue.Size());
     }
 
     @Override
@@ -50,17 +62,25 @@ public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
 //        context.drawTexture(NEW_ITEM_MENU, this.x, this.y, 0, 0, 32, 24);
 //        context.drawTexture(NEW_ITEM_MENU, this.x, this.y, 0, 0, 32, 24, 32, 24);
 
-//        this.getScreenHandler().showSlot("new_item", "add_item_slot");
+        this.getScreenHandler().showSlot("add_item_menu", "add_item_slot");
 
+        //  TODO: Temporary to just prove a point that we can draw item icons in the menu
+        ItemStack tempStack = Items.ACACIA_DOOR.getDefaultStack();
+
+
+        // Draws primary layers first
         for (ClickableLayer layer : layers) {
             layer.renderButton(context, mouseX, mouseY, delta);
             ToggleSlots(layer.GetLayerName().getString(), layer.GetDrawableSlots());
 
+            // If a primary layer happens to want sub-layers in itself; we draw those here
             for (ClickableLayer subLayer : layer.GetSubLayers()) {
                 subLayer.renderButton(context, mouseX, mouseY, delta);
                 ToggleSlots(subLayer.GetLayerName().getString(), subLayer.GetDrawableSlots());
             }
 
+            // TODO: HACK to see if this works
+            context.drawItem(tempStack, this.x, this.y); // TODO: REMOVE
             // We only notify the parent to update sub layers. It must manage its own sub layers
             layer.UpdateSubLayers();
         }
@@ -69,10 +89,10 @@ public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
     private void ToggleSlots(String menuName, Map<String, Boolean> slotNames) {
         for (Map.Entry<String, Boolean> slot : slotNames.entrySet()) {
             if (slot.getValue()) {
-                System.out.println("Attempting to turn slot " + slot.getKey() + " to value " + slot.getValue());
+//                System.out.println("Attempting to turn slot " + slot.getKey() + " to value " + slot.getValue());
                 this.getScreenHandler().showSlot(menuName, slot.getKey());
             } else {
-                System.out.println("Attempting to turn slot " + slot.getKey() + " to value " + slot.getValue());
+//                System.out.println("Attempting to turn slot " + slot.getKey() + " to value " + slot.getValue());
                 this.getScreenHandler().hideSlot(menuName, slot.getKey());
             }
         }
@@ -83,6 +103,10 @@ public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
         layers.add(new NewItemButton(iconId, layerName, imgWidth, imgHeight, drawX, drawY));
     }
 
+    private void AddNewLayer(ClickableLayer layer) {
+        layers.add(layer);
+    }
+
     @Override
      public void drawForeground(DrawContext context, int mouseX, int mouseY) {
          // We override this function to intentionally do nothing
@@ -108,6 +132,69 @@ public class ShopKeeperMenu extends HandledScreen<ShopKeeperHandler> {
         return true;
     }
 
+    @Override
+    public boolean mouseReleased(double mouseX, double mouseY, int button) {
+        scrollbar.SetDragging(false);
+
+        for (ClickableLayer layer : layers) {
+            // Scrollbar gets special handling above this. Ignore in loop
+            if (layer.GetLayerName().getString().equals("scrollbar")) {
+                continue;
+            }
+            // Check main layer first
+            if (Helper.WithinBounds(layer.getX(), layer.getY(), layer.getWidth(), layer.getHeight(), mouseX, mouseY)) {
+                layer.mouseReleased(mouseX, mouseY, button);
+            }
+
+            for (ClickableLayer subLayer : layer.GetSubLayers()) {
+
+                if (subLayer.visible && Helper.WithinBounds(subLayer.getX(), subLayer.getY(), subLayer.getWidth(), subLayer.getHeight(), mouseX, mouseY)) {
+                    subLayer.mouseReleased(mouseX, mouseY, button);
+                }
+            }
+        }
+
+        return true;
+    }
+
+    @Override
+    public boolean mouseScrolled(double mouseX, double mouseY, double horizontalAmount, double verticalAmount) {
+        System.out.println("Mouse scrolled. Vert amount is: " + verticalAmount);
+        scrollbar.mouseScrolled(mouseX, mouseY, horizontalAmount, verticalAmount);
+        return true;
+    }
+
+
+
+    @Override
+    public boolean mouseDragged(double mouseX, double mouseY, int button, double deltaX, double deltaY) {
+//        super.mouseDragged(mouseX, mouseY, button, deltaX, deltaY);
+        if (scrollbar.IsDragging()) {
+            scrollbar.mouseDragged(mouseX, mouseY, button, deltaX, deltaY);
+        }
+
+        for (ClickableLayer layer : layers) {
+            // Scrollbar layer gets special handling above this for loop. Skip here
+            if (layer.GetLayerName().getString().equals("scrollbar")) {
+                continue;
+            }
+
+            // Check main layer first
+            if (Helper.WithinBounds(layer.getX(), layer.getY(), layer.getWidth(), layer.getHeight(), mouseX, mouseY)) {
+                layer.mouseDragged(mouseX, mouseY, button, deltaX, deltaY);
+            }
+
+            for (ClickableLayer subLayer : layer.GetSubLayers()) {
+
+                if (subLayer.visible && Helper.WithinBounds(subLayer.getX(), subLayer.getY(), subLayer.getWidth(), subLayer.getHeight(), mouseX, mouseY)) {
+                    subLayer.mouseDragged(mouseX, mouseY, button, deltaX, deltaY);
+                }
+            }
+        }
+
+        return true;
+    }
+
     // Check if a click point is within the context of a square (square = x, y, w, h)
 //    public static boolean WithinBounds(double x, double y, double w, double h, double clickX, double clickY) {
 ////        System.out.println("Mouse click X Y: " + clickX + " " + clickY);

src/main/java/jesse/keeblarcraft/Entities/ShopKeeper.java

@@ -26,6 +26,7 @@ public class ShopKeeper extends VillagerEntity {
     }
 
     private void BeginTrades(PlayerEntity player) {
+        System.out.println("Beginning trades with player");
         super.setCustomer(player);
         this.sendOffers(player, this.getDisplayName(), this.getVillagerData().getLevel());
     }

src/main/java/jesse/keeblarcraft/GuiMgr/Factions/FactionBlockScreenHandler.java

@@ -79,7 +79,6 @@ public class FactionBlockScreenHandler extends ScreenHandler {
         return newStack;
     }
 
-    // From Kaupenjoe video
     private void addPlayerInventory(PlayerInventory playerInventory) {
         int spacing = -8;
         for (int i = 0; i < 3; ++i) { // Rows
@@ -92,7 +91,6 @@ public class FactionBlockScreenHandler extends ScreenHandler {
         }
     }
 
-    // From Kaupenjoe video
     private void addPlayerHotbar(PlayerInventory playerInventory) {
         int spacing = -8;
         for (int i = 0; i < 9; ++i) {

src/main/java/jesse/keeblarcraft/GuiMgr/ShopKeeper/ShopKeeperHandler.java

@@ -1,5 +1,6 @@
 package jesse.keeblarcraft.GuiMgr.ShopKeeper;
 
+import jesse.keeblarcraft.ConfigMgr.ConfigManager;
 import jesse.keeblarcraft.GuiMgr.ScreenHandlerRegistration;
 import jesse.keeblarcraft.Utils.CustomSlot;
 import net.minecraft.entity.player.PlayerEntity;
@@ -18,12 +19,18 @@ import java.util.Map;
 
 public class ShopKeeperHandler extends ScreenHandler {
     private Merchant merchant;
+    private ShopKeeperInventory shopKeeperInventory;
     private MerchantInventory merchantInventory;
+    ConfigManager config = new ConfigManager();
+    String shopName;
+    // 0 size is default to prevent null. Inventory expanded later
+
+//    private final DefaultedList<ItemStack> merchantInventory = DefaultedList.ofSize(0, ItemStack.EMPTY);
     private boolean canRefreshTrades = false;
     private boolean isLeveledMerchant = false;
     private int levelAmount = 0;
     private int merchantExperience = 0;
-    private Map<Text, Integer> slotIdByName = new HashMap<>();
+    private Map<Text, Integer> slotIdByName = new HashMap<>(); ///TODO: Is this deprecated? Seems unused
     ShopKeeperSlots allSlots = new ShopKeeperSlots();
 
     public ShopKeeperHandler(int syncId, PlayerInventory playerInventory) {
@@ -32,12 +39,26 @@ public class ShopKeeperHandler extends ScreenHandler {
 
     public ShopKeeperHandler(int syncId, PlayerInventory playerInventory, Merchant merchant) {
         super(ScreenHandlerRegistration.SHOP_KEEPER_HANDLER_SCREEN_HANDLER_TYPE, syncId);
+        this.shopName = playerInventory.player.getEntityName(); ///TODO: Needs to be pulled from a shop manager
         this.merchant = merchant;
         this.merchantInventory = new MerchantInventory(merchant);
+        merchantInventory.onOpen(playerInventory.player); // not sure if this is doing anything
+        this.shopKeeperInventory = new ShopKeeperInventory(merchantInventory);
+        addPlayerHotbar(playerInventory);
         RegisterSlots();
-        // Add slots below
-//        this.addSlot(new Slot(this.merchantInventory, 0, 136, 37));
-//        this.addSlot(new CustomSlot(this.merchantInventory, 0, 136, 37), Text.of("test"));
+    }
+
+    public ShopKeeperInventory GetInventory() {
+        String name = "shops/" + shopName;
+        if (config.DoesFileExist(name)) {
+            ///  TODO: Add system to pull json shop stuff
+            System.out.println("Shop exists.");
+        } else {
+            System.out.println("[NOWARN]: ShopKeep inventory not found for this shop. Creating one...");
+            config.CreateFile(name);
+        }
+
+        return this.shopKeeperInventory;
     }
 
     public void RegisterSlots() {
@@ -90,14 +111,47 @@ public class ShopKeeperHandler extends ScreenHandler {
         this.canRefreshTrades = isRefreshable;
     }
 
+    // This is just for SHIFT+CLICK moving
     @Override
-    public ItemStack quickMove(PlayerEntity player, int slot) {
-        return null;
+    public ItemStack quickMove(PlayerEntity player, int invSlot) {
+        System.out.println("Is client: " + player.getWorld().isClient());
+        ItemStack newStack = ItemStack.EMPTY;
+        Slot slot = this.slots.get(invSlot);
+        if (slot.hasStack()) {
+            ItemStack originalStack = slot.getStack();
+            newStack = originalStack.copy();
+
+            // TODO: This is from the YT video and it looks atrocious. Refactor this later
+            if ((invSlot < this.merchantInventory.size() && !this.insertItem(originalStack, this.merchantInventory.size(), this.slots.size(), true)) ||
+                    (!this.insertItem(originalStack, 0, this.merchantInventory.size(), false))) {
+                return ItemStack.EMPTY;
+            }
+
+            if (originalStack.isEmpty()) {
+                slot.setStack(ItemStack.EMPTY);
+            } else {
+                slot.markDirty();;
+            }
+        }
+        return newStack;
+    }
+
+    private void addPlayerHotbar(PlayerInventory playerInventory) {
+        int spacing = -8;
+        for (int i = 0; i < 9; ++i) {
+            // int x = (8 + i * 18) + spacing; // Texture draw position
+            int x = i * 22 + spacing; // Texture draw position
+            int y = 162; // Texture draw position
+            this.addSlot(new Slot(playerInventory, i, x, y));
+        }
     }
 
     // Called every tick
     @Override
     public boolean canUse(PlayerEntity player) {
+//        System.out.println("canUse called on screen handler");
+//        System.out.println("Can player use? " + this.merchantInventory.canPlayerUse(player));
+//        System.out.println("Current customer is : " + this.merchantInventory.);
         return true;
     }
 }

src/main/java/jesse/keeblarcraft/GuiMgr/ShopKeeper/ShopKeeperInventory.java

@@ -0,0 +1,35 @@
+package jesse.keeblarcraft.GuiMgr.ShopKeeper;
+
+import net.minecraft.village.MerchantInventory;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ShopKeeperInventory {
+    private final List<StoreItem> items;
+    private final MerchantInventory merchantInventory;
+
+    public ShopKeeperInventory(MerchantInventory merchantInventory) {
+        items = new ArrayList<StoreItem>();
+        // This is temporary to see if this stuff works client->server->client etc
+        items.add(new StoreItem("Among Us Statue", "$$$$$$$$$$", 10000));
+        this.merchantInventory = merchantInventory;
+    }
+
+    public List<StoreItem> GetItems() {
+        return this.items;
+    }
+
+    public Integer Size() {
+        System.out.println("Size called...");
+        return this.items.size();
+    }
+
+    public void Add(StoreItem item) {
+        this.items.add(item);
+    }
+
+    public void Remove(String upc) {
+        this.items.removeIf(item -> item.equals(upc));
+    }
+}

src/main/java/jesse/keeblarcraft/GuiMgr/ShopKeeper/ShopKeeperSlots.java

@@ -3,13 +3,14 @@ package jesse.keeblarcraft.GuiMgr.ShopKeeper;
 import jesse.keeblarcraft.Utils.CustomSlot;
 
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 // Until I find the will and way to mixin slots to be able to be removed (i.e: not backed by an Inventory) I am patching
 // slots in its own registration class (like ShopKeeperSlots). The time to do the mixin stuff far exceeds what is worth
 // it for the time being.
 public class ShopKeeperSlots {
+    // Key = The GUI menu the slot belongs to. Helpful in parsing
+    // Value = Map Key = Name of slot; Value = Slot itself. Name of slot is helpful for parsing if set
     private final Map<String, HashMap<String, CustomSlot>> shopKeeperSlots = new HashMap<>();
 
     public ShopKeeperSlots() {}

src/main/java/jesse/keeblarcraft/GuiMgr/ShopKeeper/StoreItem.java

@@ -0,0 +1,30 @@
+package jesse.keeblarcraft.GuiMgr.ShopKeeper;
+
+// All the custom content that a store item will have. Handled by @see MerchandiseScroller.java
+public class StoreItem {
+    private Integer itemCost;
+    private String itemName;
+    private String upc;
+
+    public StoreItem(String itemName, String upc, Integer cost) {
+        this.itemName = itemName;
+        this.upc = upc;
+        this.itemCost = cost;
+    }
+
+    public String GetName() {
+        return itemName;
+    }
+
+    public String GetUPC() {
+        return this.upc;
+    }
+
+    public Integer GetCost() {
+        return this.itemCost;
+    }
+
+    public boolean equals(String other) {
+        return upc.equals(other);
+    }
+}