VirtualInventory serialization

src/main/java/de/studiocode/invgui/InvGui.java

@@ -1,32 +1,37 @@
 package de.studiocode.invgui;
 
-import de.studiocode.invgui.window.WindowManager;
 import org.bukkit.plugin.Plugin;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class InvGui {
     
     private static InvGui instance;
     
+    private final List<Runnable> disableHandlers = new ArrayList<>();
     private Plugin plugin;
     
     public static InvGui getInstance() {
         return instance == null ? instance = new InvGui() : instance;
     }
     
+    public void setPlugin(Plugin plugin) {
+        this.plugin = plugin;
+    }
+    
     public Plugin getPlugin() {
         if (plugin == null)
             throw new IllegalStateException("Please set your plugin using InvGui.getInstance().setPlugin");
         return plugin;
     }
     
-    public void setPlugin(Plugin plugin) {
-        this.plugin = plugin;
+    public void addDisableHandler(Runnable runnable) {
+        disableHandlers.add(runnable);
     }
     
     public void onDisable() {
-        if (WindowManager.hasInstance())
-            WindowManager.getInstance().getWindows()
-                .forEach(w -> w.close(true));
+        disableHandlers.forEach(Runnable::run);
     }
     
 }

src/main/java/de/studiocode/invgui/virtualinventory/VirtualInventory.java

@@ -3,22 +3,29 @@ package de.studiocode.invgui.virtualinventory;
 import de.studiocode.invgui.InvGui;
 import de.studiocode.invgui.window.Window;
 import org.bukkit.Bukkit;
+import org.bukkit.configuration.serialization.ConfigurationSerializable;
 import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
-import java.util.Arrays;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.*;
 
-public class VirtualInventory {
+public class VirtualInventory implements ConfigurationSerializable {
     
-    private transient final Set<Window> windows = new HashSet<>();
+    private final Set<Window> windows = new HashSet<>();
     
+    private final UUID uuid;
     private int size;
     private ItemStack[] items;
     
-    public VirtualInventory(int size) {
+    public VirtualInventory(@Nullable UUID uuid, int size, @NotNull ItemStack[] items) {
+        this.uuid = uuid;
         this.size = size;
-        this.items = new ItemStack[size];
+        this.items = items;
+    }
+    
+    public VirtualInventory(@Nullable UUID uuid, int size) {
+        this(uuid, size, new ItemStack[size]);
     }
     
     public int getSize() {
@@ -125,4 +132,24 @@ public class VirtualInventory {
             windows.forEach(window -> window.handleVirtualInventoryUpdate(this)));
     }
     
+    public UUID getUuid() {
+        return uuid;
+    }
+    
+    @NotNull
+    @Override
+    public Map<String, Object> serialize() {
+        Map<String, Object> result = new LinkedHashMap<>();
+        result.put("uuid", uuid.toString());
+        result.put("size", size);
+        result.put("items", items);
+        return result;
+    }
+    
+    public static VirtualInventory deserialize(@NotNull Map<String, Object> args) {
+        //noinspection unchecked
+        return new VirtualInventory(UUID.fromString((String) args.get("uuid")),
+            (int) args.get("size"), ((ArrayList<ItemStack>) args.get("items")).toArray(new ItemStack[0]));
+    }
+    
 }

src/main/java/de/studiocode/invgui/virtualinventory/VirtualInventoryManager.java

@@ -0,0 +1,82 @@
+package de.studiocode.invgui.virtualinventory;
+
+import de.studiocode.invgui.InvGui;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.configuration.serialization.ConfigurationSerialization;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+/**
+ * Automatically serializes and deserializes {@link VirtualInventory}s
+ * when the server reloads / restarts.
+ */
+public class VirtualInventoryManager {
+    
+    private static final File SAVE_DIR = new File("plugins/InvGui/VirtualInventory/");
+    
+    private static VirtualInventoryManager instance;
+    
+    private final Map<UUID, VirtualInventory> inventories = new HashMap<>();
+    
+    private VirtualInventoryManager() {
+        ConfigurationSerialization.registerClass(VirtualInventory.class);
+        InvGui.getInstance().addDisableHandler(this::serializeAll);
+        deserializeAll();
+    }
+    
+    public static VirtualInventoryManager getInstance() {
+        return instance == null ? instance = new VirtualInventoryManager() : instance;
+    }
+    
+    public VirtualInventory createNew(@NotNull UUID uuid, int size) {
+        if (inventories.containsKey(uuid))
+            throw new IllegalArgumentException("A VirtualInventory with that UUID already exists");
+        
+        VirtualInventory virtualInventory = new VirtualInventory(uuid, size);
+        inventories.put(uuid, virtualInventory);
+        
+        return virtualInventory;
+    }
+    
+    public VirtualInventory getByUuid(@NotNull UUID uuid) {
+        return inventories.get(uuid);
+    }
+    
+    public VirtualInventory getOrCreate(UUID uuid, int size) {
+        VirtualInventory virtualInventory = getByUuid(uuid);
+        return virtualInventory == null ? createNew(uuid, size) : virtualInventory;
+    }
+    
+    private void deserializeAll() {
+        if (SAVE_DIR.exists()) {
+            Arrays.stream(SAVE_DIR.listFiles())
+                .filter(file -> file.getName().endsWith(".vi"))
+                .forEach(file -> {
+                    YamlConfiguration config = YamlConfiguration.loadConfiguration(file);
+                    VirtualInventory virtualInventory = config.getSerializable("vi", VirtualInventory.class);
+                    
+                    inventories.put(virtualInventory.getUuid(), virtualInventory);
+                });
+        }
+    }
+    
+    private void serializeAll() {
+        inventories.values().forEach(virtualInventory -> {
+            try {
+                File file = new File(SAVE_DIR, virtualInventory.getUuid() + ".vi");
+                YamlConfiguration config = new YamlConfiguration();
+                config.set("vi", virtualInventory);
+                config.save(file);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        });
+    }
+    
+}

src/main/java/de/studiocode/invgui/window/WindowManager.java

@@ -24,6 +24,7 @@ public class WindowManager implements Listener {
         Bukkit.getPluginManager().registerEvents(this, InvGui.getInstance().getPlugin());
         Bukkit.getScheduler().scheduleSyncRepeatingTask(InvGui.getInstance().getPlugin(),
             () -> windows.forEach(Window::handleTick), 0, 1);
+        InvGui.getInstance().addDisableHandler(() -> windows.forEach(w -> w.close(true)));
     }
     
     /**
@@ -32,16 +33,7 @@ public class WindowManager implements Listener {
      * @return The {@link WindowManager} instance
      */
     public static WindowManager getInstance() {
-        return !hasInstance() ? instance = new WindowManager() : instance;
-    }
-    
-    /**
-     * Gets if the {@link WindowManager} already has an instance.
-     * 
-     * @return if the {@link WindowManager} already has an instance
-     */
-    public static boolean hasInstance() {
-        return instance != null;
+        return instance == null ? instance = new WindowManager() : instance;
     }
     
     /**