Added stack merging, RMB actions, Sticks and fixed an unholy bug

- Added Test:Stick
- When left-clicking, stacks that can merge will
- Added right-clicking behavior straight from Minecraft
- hooooooly sh*t man StatefulObject.equals was totally broken omfg how
tf i did notice :o

src/main/java/ru/windcorp/progressia/common/state/StatefulObject.java

@@ -235,7 +235,7 @@ public abstract class StatefulObject extends Namespaced implements Encodable {
 
 		StatefulObject statefulObj = (StatefulObject) obj;
 
-		if (statefulObj.getId().equals(this.getId()))
+		if (!statefulObj.getId().equals(this.getId()))
 			return false;
 
 		return true;

src/main/java/ru/windcorp/progressia/common/world/item/ItemSlot.java

@@ -94,6 +94,21 @@ public class ItemSlot implements Encodable {
 		return amount == 0;
 	}
 	
+	public synchronized boolean canInsert(ItemData contents, int amount) {
+		
+		// Ignore amount
+		
+		if (this.contents == null) {
+			return true;
+		}
+		
+		return this.contents.equals(contents);
+	}
+	
+	public synchronized boolean canRemove(int amount) {
+		return this.amount >= amount;
+	}
+	
 	private synchronized void checkState() {
 		if ((contents == null) != (amount == 0)) {
 			if (contents == null) {

src/main/java/ru/windcorp/progressia/common/world/item/Items.java

@@ -0,0 +1,118 @@
+/*
+ * Progressia
+ * Copyright (C)  2020-2021  Wind Corporation and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package ru.windcorp.progressia.common.world.item;
+
+public class Items {
+
+	/**
+	 * Attempts to transfer as many items as possible, but no more than
+	 * {@code max}, between two slots. The origin of the items is {@code from},
+	 * the destination is {@code into}. This method does nothing if the items
+	 * could not be removed from origin or could not be inserted into
+	 * destination, such as when {@code into} contains different items.
+	 * 
+	 * @param from the slot to transfer item from
+	 * @param into the destination of the items
+	 * @param max  the maximum amount of items to transfer. Use
+	 *             {@code Integer.MAX_VALUE} to remove the limit
+	 * @return the actual amount of items moved between slots
+	 */
+	public static int pour(ItemSlot from, ItemSlot into, int max) {
+		synchronized (from) {
+			synchronized (into) {
+
+				ItemData item = from.getContents();
+
+				int originalAmount = from.getAmount();
+				int transferAmount = Math.min(originalAmount, max);
+
+				while (transferAmount > 0 && !into.canInsert(item, transferAmount)) {
+					transferAmount--;
+				}
+				
+				if (transferAmount == 0) {
+					return 0;
+				}
+
+				if (!from.canRemove(transferAmount)) {
+					return 0;
+				}
+
+				into.setContents(item, into.getAmount() + transferAmount);
+				from.setAmount(originalAmount - transferAmount);
+
+				return transferAmount;
+
+			}
+		}
+	}
+
+	/**
+	 * Attempts to transfer as many items as possible between two slots. The
+	 * origin of the items is {@code from}, the destination is {@code into}.
+	 * This method does nothing if the items could not be removed from origin or
+	 * could not be inserted into destination, such as when {@code into}
+	 * contains different items.
+	 * 
+	 * @param from the slot to transfer item from
+	 * @param into the destination of the items
+	 * @return the actual amount of items moved between slots
+	 */
+	public static int pour(ItemSlot from, ItemSlot into) {
+		return pour(from, into, Integer.MAX_VALUE);
+	}
+	
+	/**
+	 * Attempts to swap the contents of the two slots.
+	 * 
+	 * @param a one of the slots
+	 * @param b the other slot
+	 * 
+	 * @return whether the swap succeeded
+	 */
+	public static boolean swap(ItemSlot a, ItemSlot b) {
+		synchronized (a) {
+			synchronized (b) {
+
+				ItemData aItem = a.getContents();
+				int aAmount = a.getAmount();
+				
+				ItemData bItem = b.getContents();
+				int bAmount = b.getAmount();
+				
+				a.clear();
+				b.clear();
+				
+				if (a.canInsert(bItem, bAmount) && b.canInsert(aItem, aAmount)) {
+					a.setContents(bItem, bAmount);
+					b.setContents(aItem, aAmount);
+					return true;
+				} else {
+					a.setContents(aItem, aAmount);
+					b.setContents(bItem, bAmount);
+					return false;
+				}
+				
+			}
+		}
+	}
+
+	private Items() {
+	}
+
+}

src/main/java/ru/windcorp/progressia/server/PlayerManager.java

@@ -65,7 +65,8 @@ public class PlayerManager {
 		
 		player.getInventory().addSlots(10);
 		
-		player.getInventory().getSlot(3).setContents(ItemDataRegistry.getInstance().create("Test:MoonTypeIceCream"), 5);
+		player.getInventory().getSlot(3).setContents(ItemDataRegistry.getInstance().create("Test:Stick"), 5);
+		player.getInventory().getSlot(5).setContents(ItemDataRegistry.getInstance().create("Test:Stick"), 4);
 		player.getInventory().getSlot(6).setContents(ItemDataRegistry.getInstance().create("Test:MoonTypeIceCream"), 1);
 
 		player.setPosition(getServer().getWorld().getGenerator().suggestSpawnLocation());

src/main/java/ru/windcorp/progressia/test/TestContent.java

@@ -244,6 +244,7 @@ public class TestContent {
 	
 	private static void registerItems() {
 		registerSimplestItem("MoonTypeIceCream", Units.get("200 g"), Units.get("1 L"));
+		registerSimplestItem("Stick", Units.get("260 g"), Units.get("0.5 L"));
 	}
 
 	private static void registerSimplestBlock(String name) {

src/main/java/ru/windcorp/progressia/test/inv/InventoryScreen.java

@@ -18,6 +18,7 @@
 package ru.windcorp.progressia.test.inv;
 
 import java.util.function.Consumer;
+import java.util.function.Supplier;
 
 import org.lwjgl.glfw.GLFW;
 
@@ -33,11 +34,13 @@ import ru.windcorp.progressia.client.graphics.gui.Layout;
 import ru.windcorp.progressia.client.graphics.gui.Panel;
 import ru.windcorp.progressia.client.graphics.gui.layout.LayoutAlign;
 import ru.windcorp.progressia.client.graphics.gui.layout.LayoutFill;
+import ru.windcorp.progressia.client.graphics.input.KeyEvent;
+import ru.windcorp.progressia.client.graphics.input.bus.InputListener;
 import ru.windcorp.progressia.client.graphics.model.Renderable;
 import ru.windcorp.progressia.common.world.entity.EntityDataPlayer;
 import ru.windcorp.progressia.common.world.item.ItemContainer;
-import ru.windcorp.progressia.common.world.item.ItemData;
 import ru.windcorp.progressia.common.world.item.ItemSlot;
+import ru.windcorp.progressia.common.world.item.Items;
 
 public class InventoryScreen extends Component {
 
@@ -131,34 +134,72 @@ public class InventoryScreen extends Component {
 	}
 
 	private void addListeners(InventoryComponent mainInventory) {
-		Consumer<BasicButton> pickIntoLeft = createPickAction(leftHand.getSlot(0), rightHand.getSlot(0));
 		
-		for (DecoratedSlotComponent component : mainInventory.getSlots()) {
-			component.addAction(pickIntoLeft);
-		}
-	}
-
-	private Consumer<BasicButton> createPickAction(ItemSlot toWithoutCtrl, ItemSlot toWithCtrl) {
-		return button -> {
+		ItemSlot left = leftHand.getSlot(0);
+		ItemSlot right = rightHand.getSlot(0);
 		
+		Supplier<ItemSlot> handSlot = () -> {
 			boolean hasCtrl = InputTracker.isKeyPressed(GLFW.GLFW_KEY_LEFT_CONTROL)
 				|| InputTracker.isKeyPressed(GLFW.GLFW_KEY_RIGHT_CONTROL);
 			
-			ItemSlot to = hasCtrl ? toWithCtrl : toWithoutCtrl;
-			ItemSlot from = ((DecoratedSlotComponent) button).getSlot();
+			return hasCtrl ? left : right;
+		};
 		
-			ItemData fromData = from.getContents();
-			int fromAmount = from.getAmount();
+		Consumer<BasicButton> pickAll = createPickAllAction(handSlot);
 
-			ItemData toData = to.getContents();
-			int toAmount = to.getAmount();
+		for (DecoratedSlotComponent component : mainInventory.getSlots()) {
+			component.addAction(pickAll);
+			component.addListener(KeyEvent.class, createRMBAction(component.getSlot(), handSlot));
+		}
+	}
 
-			from.setContents(toData, toAmount);
-			to.setContents(fromData, fromAmount);
+	private Consumer<BasicButton> createPickAllAction(Supplier<ItemSlot> handSlotChooser) {
+		return button -> {
+			
+			ItemSlot handSlot = handSlotChooser.get();
+			ItemSlot invSlot = ((DecoratedSlotComponent) button).getSlot();
+
+			if (Items.pour(handSlot, invSlot) == 0) {
+				if (!Items.swap(handSlot, invSlot)) {
+					return;
+				}
+			}
 
 			requestReassembly();
 
 		};
 	}
 
+	private InputListener<KeyEvent> createRMBAction(ItemSlot invSlot, Supplier<ItemSlot> handSlotChooser) {
+		return input -> {
+			
+			if (input.isPress() && input.isRightMouseButton()) {
+				ItemSlot handSlot = handSlotChooser.get();
+
+				boolean success = false;
+				
+				if (handSlot.isEmpty()) {
+					success = Items.pour(invSlot, handSlot, invSlot.getAmount() / 2) != 0;
+				}
+				
+				if (!success) {
+					success = Items.pour(handSlot, invSlot, 1) != 0;
+				}
+				
+				if (!success) {
+					success = Items.swap(handSlot, invSlot);
+				}
+
+				if (success) {
+					requestReassembly();
+				}
+				
+				return true;
+			}
+			
+			return false;
+			
+		};
+	}
+
 }