added fill capabilities

src/main/java/me/touchie771/minecraftGUI/api/Menu.java

@@ -2,6 +2,7 @@
 
 import net.kyori.adventure.text.Component;
 import org.bukkit.Bukkit;
+import org.bukkit.Material;
 import org.bukkit.plugin.Plugin;
 import org.bukkit.event.inventory.InventoryCloseEvent;
 import org.bukkit.inventory.Inventory;
@@ -352,6 +353,98 @@ public MenuBuilder items(SlotItem @NotNull ... items) {
             return this;
         }
 
+        /**
+         * Fills all empty slots in the inventory with the specified material.
+         *
+         * @param material the material to fill with
+         * @return this builder instance
+         * @throws IllegalStateException if inventory size is not set
+         */
+        public MenuBuilder fillEmptyWith(@NotNull Material material) {
+            return fillEmptyWith(material, null);
+        }
+
+        /**
+         * Fills all empty slots in the inventory with the specified material and display name.
+         *
+         * @param material the material to fill with
+         * @param name the display name for the filler items, or null to keep default name
+         * @return this builder instance
+         * @throws IllegalStateException if inventory size is not set
+         */
+        public MenuBuilder fillEmptyWith(@NotNull Material material, @Nullable Component name) {
+            if (inventorySize <= 0) {
+                throw new IllegalStateException("Inventory size must be set before filling empty slots");
+            }
+
+            for (int i = 0; i < inventorySize; i++) {
+                if (isSlotFree(i)) {
+                    items.add(SlotItem.builder(i)
+                        .material(material)
+                        .itemName(name)
+                        .build());
+                }
+            }
+            return this;
+        }
+
+        /**
+         * Fills all empty slots except the specified ones with the given material.
+         *
+         * @param material the material to fill with
+         * @param excludedSlots the slots to exclude from filling
+         * @return this builder instance
+         * @throws IllegalStateException if inventory size is not set
+         */
+        public MenuBuilder fillExcept(@NotNull Material material, int... excludedSlots) {
+            if (inventorySize <= 0) {
+                throw new IllegalStateException("Inventory size must be set before filling empty slots");
+            }
+
+            Set<Integer> excluded = new HashSet<>();
+            for (int slot : excludedSlots) {
+                excluded.add(slot);
+            }
+
+            for (int i = 0; i < inventorySize; i++) {
+                if (!excluded.contains(i) && isSlotFree(i)) {
+                    items.add(SlotItem.builder(i)
+                        .material(material)
+                        .build());
+                }
+            }
+            return this;
+        }
+
+        /**
+         * Fills a range of slots with the specified material.
+         * The range is from start (inclusive) to end (exclusive).
+         *
+         * @param start the starting slot (inclusive)
+         * @param end the ending slot (exclusive)
+         * @param material the material to fill with
+         * @return this builder instance
+         * @throws IllegalArgumentException if start or end are invalid
+         */
+        public MenuBuilder fillRange(int start, int end, @NotNull Material material) {
+            if (start < 0 || end > 54 || start >= end) {
+                throw new IllegalArgumentException("Invalid range: " + start + " to " + end);
+            }
+
+            for (int i = start; i < end; i++) {
+                if (isSlotFree(i)) {
+                    items.add(SlotItem.builder(i)
+                        .material(material)
+                        .build());
+                }
+            }
+            return this;
+        }
+
+        private boolean isSlotFree(int slot) {
+            return items.stream().noneMatch(item -> item.itemSlot() == slot);
+        }
+
         /**
          * Builds and returns a new Menu instance with the configured properties.
          * This method validates all parameters before creating the menu.

src/test/java/me/touchie771/minecraftGUI/api/MenuTest.java

@@ -1,24 +1,24 @@
 package me.touchie771.minecraftGUI.api;
 
 import be.seeseemelk.mockbukkit.MockBukkit;
-import be.seeseemelk.mockbukkit.ServerMock;
 import net.kyori.adventure.text.Component;
 import org.bukkit.Material;
 import org.bukkit.plugin.Plugin;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import java.util.Objects;
+
 import static org.junit.jupiter.api.Assertions.*;
 
 class MenuTest {
 
-    private ServerMock server;
     private Plugin plugin;
 
     @BeforeEach
     void setUp() {
-        server = MockBukkit.mock();
+        MockBukkit.mock();
         plugin = MockBukkit.createMockPlugin();
     }
 
@@ -60,11 +60,75 @@ void testAddItem() {
             .plugin(plugin)
             .build();
 
-        SlotItem item = new SlotItem(Component.text("Diamond"), (short) 0, Material.DIAMOND, 1);
+        SlotItem item = SlotItem.builder(0)
+            .itemName(Component.text("Diamond"))
+            .material(Material.DIAMOND)
+            .build();
         menu.addItems(item);
 
         assertTrue(menu.getItems().contains(item));
         assertNotNull(menu.getInventory().getItem(0));
-        assertEquals(Material.DIAMOND, menu.getInventory().getItem(0).getType());
+        assertEquals(Material.DIAMOND, Objects.requireNonNull(menu.getInventory().getItem(0)).getType());
+    }
+
+    @Test
+    void testFillEmptyWith() {
+        Menu menu = Menu.newBuilder()
+            .size(9)
+            .title(Component.text("Filler Test"))
+            .plugin(plugin)
+            .items(SlotItem.builder(4).material(Material.DIAMOND).build())
+            .fillEmptyWith(Material.GRAY_STAINED_GLASS_PANE)
+            .build();
+
+        // Slot 4 should be Diamond
+        assertEquals(Material.DIAMOND, Objects.requireNonNull(menu.getInventory().getItem(4)).getType());
+
+        // Other slots should be filler
+        assertEquals(Material.GRAY_STAINED_GLASS_PANE, Objects.requireNonNull(menu.getInventory().getItem(0)).getType());
+        assertEquals(Material.GRAY_STAINED_GLASS_PANE, Objects.requireNonNull(menu.getInventory().getItem(8)).getType());
+
+        // Total items should be 9
+        assertEquals(9, menu.getItems().size());
+    }
+
+    @Test
+    void testFillExcept() {
+        Menu menu = Menu.newBuilder()
+            .size(9)
+            .title(Component.text("Fill Except Test"))
+            .plugin(plugin)
+            .fillExcept(Material.STONE, 0, 8)
+            .build();
+
+        // Slots 0 and 8 should be empty (null)
+        assertNull(menu.getInventory().getItem(0));
+        assertNull(menu.getInventory().getItem(8));
+
+        // Middle slot should be filled
+        assertEquals(Material.STONE, Objects.requireNonNull(menu.getInventory().getItem(4)).getType());
+
+        // Total filled items should be 7
+        assertEquals(7, menu.getItems().size());
+    }
+
+    @Test
+    void testFillRange() {
+        Menu menu = Menu.newBuilder()
+            .size(9)
+            .title(Component.text("Fill Range Test"))
+            .plugin(plugin)
+            .items(SlotItem.builder(4).material(Material.DIAMOND).build())
+            .fillRange(3, 6, Material.DIRT)
+            .build();
+
+        // Range 3-6 (3, 4, 5). 4 is occupied by Diamond.
+        // So 3 and 5 should be DIRT. 4 should be DIAMOND.
+
+        assertNull(menu.getInventory().getItem(2)); // Outside range
+        assertEquals(Material.DIRT, Objects.requireNonNull(menu.getInventory().getItem(3)).getType());
+        assertEquals(Material.DIAMOND, Objects.requireNonNull(menu.getInventory().getItem(4)).getType());
+        assertEquals(Material.DIRT, Objects.requireNonNull(menu.getInventory().getItem(5)).getType());
+        assertNull(menu.getInventory().getItem(6)); // Outside range (end exclusive)
     }
 }