api/src/main/java/com/lishid/openinv/internal/ISpecialInventory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2021 lishid. All rights reserved.
+ * Copyright (C) 2011-2022 lishid. All rights reserved.
  *
  * 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
@@ -43,11 +43,13 @@ public interface ISpecialInventory {
     void setPlayerOffline();
 
     /**
-     * Gets whether or not this ISpecialInventory is in use.
+     * Gets whether this ISpecialInventory is in use.
      *
      * @return true if the ISpecialInventory is in use
      */
-    boolean isInUse();
+    default boolean isInUse() {
+        return !getBukkitInventory().getViewers().isEmpty();
+    }
 
     /**
      * Gets the Player associated with this ISpecialInventory.

api/src/main/java/com/lishid/openinv/internal/ISpecialPlayerInventory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2021 lishid. All rights reserved.
+ * Copyright (C) 2011-2022 lishid. All rights reserved.
  *
  * 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
@@ -16,6 +16,35 @@
 
 package com.lishid.openinv.internal;
 
+import java.util.List;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.inventory.Inventory;
+
+/**
+ * Interface defining behavior specific to a player inventory.
+ */
 public interface ISpecialPlayerInventory extends ISpecialInventory {
 
+    /*
+     * Player inventory usage varies from all other inventories - as the inventory is technically open at all times,
+     * if the player is online or has been online while the inventory is open, they are in the viewer list.
+     */
+    @Override
+    default boolean isInUse() {
+        Inventory inventory = getBukkitInventory();
+        List<HumanEntity> viewers = inventory.getViewers();
+
+        if (viewers.size() != 1) {
+            return !viewers.isEmpty();
+        }
+
+        HumanEntity viewer = viewers.get(0);
+
+        if (!viewer.getUniqueId().equals(getPlayer().getUniqueId())) {
+            return true;
+        }
+
+        return viewer.getOpenInventory().getTopInventory().equals(inventory);
+    }
+
 }

internal/v1_17_R1/src/main/java/com/lishid/openinv/internal/v1_17_R1/SpecialEnderChest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2021 lishid. All rights reserved.
+ * Copyright (C) 2011-2022 lishid. All rights reserved.
  *
  * 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
@@ -60,11 +60,6 @@ public class SpecialEnderChest extends PlayerEnderChestContainer implements ISpe
         return inventory;
     }
 
-    @Override
-    public boolean isInUse() {
-        return !this.getViewers().isEmpty();
-    }
-
     @Override
     public void setPlayerOffline() {
         this.playerOnline = false;

internal/v1_17_R1/src/main/java/com/lishid/openinv/internal/v1_17_R1/SpecialPlayerInventory.java

@@ -103,12 +103,6 @@ public class SpecialPlayerInventory extends Inventory implements ISpecialPlayerI
         this.playerOnline = false;
     }
 
-    @Override
-    public boolean isInUse() {
-        List<HumanEntity> viewers = this.getViewers();
-        return viewers.size() > 1 || !viewers.isEmpty() && !viewers.get(0).getUniqueId().equals(this.player.getUUID());
-    }
-
     @Override
     public @NotNull HumanEntity getPlayer() {
         return this.player.getBukkitEntity();

internal/v1_18_R1/src/main/java/com/lishid/openinv/internal/v1_18_R1/SpecialEnderChest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2021 lishid. All rights reserved.
+ * Copyright (C) 2011-2022 lishid. All rights reserved.
  *
  * 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
@@ -60,11 +60,6 @@ public class SpecialEnderChest extends PlayerEnderChestContainer implements ISpe
         return inventory;
     }
 
-    @Override
-    public boolean isInUse() {
-        return !this.getViewers().isEmpty();
-    }
-
     @Override
     public void setPlayerOffline() {
         this.playerOnline = false;

internal/v1_18_R1/src/main/java/com/lishid/openinv/internal/v1_18_R1/SpecialPlayerInventory.java

@@ -103,12 +103,6 @@ public class SpecialPlayerInventory extends Inventory implements ISpecialPlayerI
         this.playerOnline = false;
     }
 
-    @Override
-    public boolean isInUse() {
-        List<HumanEntity> viewers = this.getViewers();
-        return viewers.size() > 1 || !viewers.isEmpty() && !viewers.get(0).getUniqueId().equals(this.player.getUUID());
-    }
-
     @Override
     public @NotNull HumanEntity getPlayer() {
         return this.player.getBukkitEntity();

internal/v1_18_R2/src/main/java/com/lishid/openinv/internal/v1_18_R2/SpecialEnderChest.java

@@ -60,11 +60,6 @@ public class SpecialEnderChest extends PlayerEnderChestContainer implements ISpe
         return inventory;
     }
 
-    @Override
-    public boolean isInUse() {
-        return !this.getViewers().isEmpty();
-    }
-
     @Override
     public void setPlayerOffline() {
         this.playerOnline = false;

internal/v1_18_R2/src/main/java/com/lishid/openinv/internal/v1_18_R2/SpecialPlayerInventory.java

@@ -103,12 +103,6 @@ public class SpecialPlayerInventory extends Inventory implements ISpecialPlayerI
         this.playerOnline = false;
     }
 
-    @Override
-    public boolean isInUse() {
-        List<HumanEntity> viewers = this.getViewers();
-        return viewers.size() > 1 || !viewers.isEmpty() && !viewers.get(0).getUniqueId().equals(this.player.getUUID());
-    }
-
     @Override
     public @NotNull HumanEntity getPlayer() {
         return this.player.getBukkitEntity();