Adds some code for generating item icons

pom.xml

@@ -84,5 +84,11 @@
             <version>1.19.3-R0.1-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains</groupId>
+            <artifactId>annotations</artifactId>
+            <version>19.0.0</version>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
 </project>

src/main/java/net/knarcraft/knargui/AbstractGUI.java

@@ -11,11 +11,15 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.UUID;
 
+/**
+ * An abstract GUI used for creating specific GUIs
+ */
+@SuppressWarnings("unused")
 public abstract class AbstractGUI {
 
-    private final UUID uuid;
+    private UUID uuid;
-    private final Inventory inventory;
+    private Inventory inventory;
-    private final Map<Integer, Map<ClickType, GUIAction>> actions;
+    private Map<Integer, Map<ClickType, GUIAction>> actions;
 
     /**
      * Instantiates a new abstract GUI
@@ -25,12 +29,27 @@ public abstract class AbstractGUI {
      * @param inventoryType <p>The type of inventory to use for the GUI, or null for a variable chest GUI</p>
      */
     public AbstractGUI(int inventorySize, String inventoryName, InventoryType inventoryType) {
-        this.uuid = UUID.randomUUID();
+        Inventory inventory;
         if (inventoryType == null) {
-            this.inventory = Bukkit.createInventory(null, inventorySize, inventoryName);
+            inventory = Bukkit.createInventory(null, inventorySize, inventoryName);
         } else {
-            this.inventory = Bukkit.createInventory(null, inventoryType, inventoryName);
+            inventory = Bukkit.createInventory(null, inventoryType, inventoryName);
         }
+        instantiate(inventory);
+    }
+
+    /**
+     * Instantiates a new abstract GUI
+     *
+     * @param inventory <p>The inventory to use for the GUI</p>
+     */
+    public AbstractGUI(Inventory inventory) {
+        instantiate(inventory);
+    }
+
+    private void instantiate(Inventory inventory) {
+        this.uuid = UUID.randomUUID();
+        this.inventory = inventory;
         this.actions = new HashMap<>();
         GUIRegistry.registerGUI(this);
     }

src/main/java/net/knarcraft/knargui/AnvilGUI.java

@@ -9,6 +9,7 @@ import java.util.function.BiConsumer;
 /**
  * A user-interface using an anvil GUI
  */
+@SuppressWarnings("unused")
 public abstract class AnvilGUI extends AbstractGUI {
 
     private BiConsumer<String, Player> action;

src/main/java/net/knarcraft/knargui/GUIListener.java

@@ -11,6 +11,7 @@ import org.bukkit.event.player.PlayerQuitEvent;
 /**
  * A listener for tracking GUI interaction
  */
+@SuppressWarnings("unused")
 public class GUIListener implements Listener {
 
     private final boolean autoDelete;

src/main/java/net/knarcraft/knargui/item/AbstractGUIItemFactory.java

@@ -0,0 +1,132 @@
+package net.knarcraft.knargui.item;
+
+import org.bukkit.enchantments.Enchantment;
+import org.bukkit.inventory.ItemFlag;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.ItemMeta;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+import java.util.function.Consumer;
+
+/**
+ * An abstract factory for creating GUI items
+ *
+ * @param <B> <p>A child class implementing this class</p>
+ */
+@SuppressWarnings("unused")
+public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>> {
+
+    private final ItemStack itemStack;
+    private B child;
+
+    /**
+     * Instantiates a new abstract GUI item factory
+     *
+     * @param itemStack <p>The item stack to use for this factory</p>
+     */
+    protected AbstractGUIItemFactory(@NotNull ItemStack itemStack) {
+        this.itemStack = itemStack;
+    }
+
+    /**
+     * Sets the instance of the child class extending this class
+     *
+     * <p>This makes the factory return the given object. Setting this allows the factory to return a specific
+     * implementation every time, without using an unsafe cast.</p>
+     *
+     * @param child <p>The child class extending this</p>
+     */
+    protected void setChild(B child) {
+        this.child = child;
+    }
+
+    /**
+     * Builds the item as described in previous calls
+     *
+     * @return <p>The output of this factory</p>
+     */
+    public ItemStack build() {
+        return this.itemStack;
+    }
+
+    /**
+     * Sets the name of this factory's item
+     *
+     * @param name <p>The new item name</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public B setName(String name) {
+        return changeItemMeta((meta) -> meta.setDisplayName(name));
+    }
+
+    /**
+     * Sets the lore for this factory's item
+     *
+     * @param lore <p>The new lore</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public B setLore(List<String> lore) {
+        return changeItemMeta((meta) -> meta.setLore(lore));
+    }
+
+    /**
+     * Sets whether this factory's item should look enchanted
+     *
+     * @param enchanted <p>True if the item should look enchanted</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public B setEnchanted(boolean enchanted) {
+        if (enchanted) {
+            changeItemMeta((meta) -> meta.addEnchant(Enchantment.MENDING, 1, true));
+            return changeItemMeta((meta) -> meta.addItemFlags(ItemFlag.HIDE_ENCHANTS));
+        } else {
+            //Remove all enchantments
+            changeItemMeta((meta) -> meta.removeEnchant(Enchantment.MENDING));
+            return changeItemMeta((meta) -> meta.removeItemFlags(ItemFlag.HIDE_ENCHANTS));
+        }
+    }
+
+    /**
+     * Changes some metadata for this factory's item
+     *
+     * @param action <p>The action to be run on the metadata</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    protected B changeItemMeta(Consumer<ItemMeta> action) {
+        return changeItemMeta(ItemMeta.class, action);
+    }
+
+    /**
+     * Changes some metadata for this factory's item
+     *
+     * @param metaType <p>The type of metadata to change</p>
+     * @param action   <p>The action to be run on the metadata</p>
+     * @param <M>      <p>The type of the metadata</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    protected <M extends ItemMeta> B changeItemMeta(Class<M> metaType, Consumer<M> action) {
+        M meta = checkForNullMetadata(metaType);
+        action.accept(meta);
+        this.itemStack.setItemMeta(meta);
+        if (child == null) {
+            throw new IllegalStateException("Child class instance is not defined.");
+        }
+        return child;
+    }
+
+    /**
+     * Throws an exception if this factory's item has null metadata
+     *
+     * @return <p>The metadata for this factory's item</p>
+     */
+    protected <M extends ItemMeta> M checkForNullMetadata(Class<M> metaType) {
+        M meta = metaType.cast(this.itemStack.getItemMeta());
+        if (meta == null) {
+            throw new IllegalArgumentException("Cannot change missing metadata");
+        } else {
+            return meta;
+        }
+    }
+
+}

src/main/java/net/knarcraft/knargui/item/GUIItemFactory.java

@@ -0,0 +1,33 @@
+package net.knarcraft.knargui.item;
+
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+
+/**
+ * A class for crating visual items for the GUI
+ */
+@SuppressWarnings("unused")
+public class GUIItemFactory extends AbstractGUIItemFactory<GUIItemFactory> {
+
+    /**
+     * Instantiates a new item factory
+     *
+     * @param material <p>The material to use for the new item</p>
+     */
+    public GUIItemFactory(Material material) {
+        super(new ItemStack(material, 1));
+        setChild(this);
+    }
+
+    /**
+     * Instantiates a new item factory
+     *
+     * @param material <p>The material to use for the new item</p>
+     * @param amount   <p>The number of items to be displayed</p>
+     */
+    public GUIItemFactory(Material material, int amount) {
+        super(new ItemStack(material, amount));
+        setChild(this);
+    }
+
+}

src/main/java/net/knarcraft/knargui/item/PlayerHeadGUIItemFactory.java

@@ -0,0 +1,56 @@
+package net.knarcraft.knargui.item;
+
+import org.bukkit.Bukkit;
+import org.bukkit.Material;
+import org.bukkit.OfflinePlayer;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.SkullMeta;
+import org.bukkit.profile.PlayerProfile;
+
+import java.util.UUID;
+
+/**
+ * An item factory for generating player head-based icons
+ */
+@SuppressWarnings("unused")
+public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadGUIItemFactory> {
+
+    /**
+     * Instantiates a player head gui item factory
+     */
+    public PlayerHeadGUIItemFactory() {
+        super(new ItemStack(Material.PLAYER_HEAD, 1));
+        setChild(this);
+    }
+
+    /**
+     * Uses the head skin from the given player
+     *
+     * @param player <p>The player whose skin should be used</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public PlayerHeadGUIItemFactory useSkin(OfflinePlayer player) {
+        return changeItemMeta(SkullMeta.class, (meta) -> meta.setOwningPlayer(player));
+    }
+
+    /**
+     * Uses the head skin from the given player profile
+     *
+     * @param playerProfile <p>The player profile whose skin should be used</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public PlayerHeadGUIItemFactory useSkin(PlayerProfile playerProfile) {
+        return changeItemMeta(SkullMeta.class, (meta) -> meta.setOwnerProfile(playerProfile));
+    }
+
+    /**
+     * Uses the head skin from the given player UUID
+     *
+     * @param uuid <p>The UUID of the skin to use</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    public PlayerHeadGUIItemFactory useSkin(UUID uuid) {
+        return useSkin(Bukkit.getOfflinePlayer(uuid));
+    }
+
+}