Fix police can drop essential items

src/main/java/net/tiagofar78/prisonescape/Events.java

@@ -166,7 +166,9 @@ public void playerClickInventory(InventoryClickEvent e) {
 
             if (e.getAction() == InventoryAction.DROP_ALL_SLOT || e.getAction() == InventoryAction.DROP_ONE_SLOT) {
                 int slot = e.getSlot();
-                game.playerDropItem(player.getName(), slot);
+                if (game.playerDropItem(player.getName(), slot) == -1) {
+                    e.setCancelled(true);
+                }
                 return;
             }
 
@@ -317,7 +319,10 @@ public void onPlayerDropItem(PlayerDropItemEvent e) {
         Player player = e.getPlayer();
         int slot = player.getInventory().getHeldItemSlot();
 
-        game.playerDropItem(player.getName(), slot);
+        int return_code = game.playerDropItem(player.getName(), slot);
+        if (return_code == -1) {
+            e.setCancelled(true);
+        }
     }
 
 }

src/main/java/net/tiagofar78/prisonescape/game/PrisonEscapeGame.java

@@ -154,7 +154,6 @@ public int playerRejoin(String playerName) {
             );
         }
 
-
         return 0;
     }
 
@@ -698,9 +697,20 @@ private void playerOpenVault(PrisonEscapePlayer player, int vaultIndex, Item ite
         vault.open(player);
     }
 
-    public void playerDropItem(String playerName, int slot) {
+    /**
+     * @return 0 if success<br>
+     *         -1 if cannot drop that item
+     */
+    public int playerDropItem(String playerName, int slot) {
         PrisonEscapePlayer player = getPrisonEscapePlayer(playerName);
-        player.removeItem(slot);
+
+        int return_code = player.removeItem(slot);
+        if (return_code == -1) {
+            MessageLanguageManager messages = MessageLanguageManager.getInstanceByPlayer(playerName);
+            BukkitMessageSender.sendChatMessage(player, messages.getCannotDropThatItemMessage());
+        }
+
+        return return_code;
     }
 
     private void policeSearchVault(PrisonEscapePlayer player, Vault vault, MessageLanguageManager messagesPolice) {

src/main/java/net/tiagofar78/prisonescape/game/PrisonEscapePlayer.java

@@ -122,13 +122,19 @@ public void setItem(int index, Item item) {
         BukkitMenu.setItem(_name, index, item);
     }
 
-    public void removeItem(int slot) {
+
+    /**
+     * @return 0 if success<br>
+     *         -1 if cannot remove item
+     */
+    public int removeItem(int slot) {
         int index = BukkitMenu.convertToIndexPlayerInventory(slot);
         if (index == -1) {
-            return;
+            return -1;
         }
 
         _inventory.set(index, new NullItem());
+        return 0;
     }
 
     public boolean hasIllegalItems() {

src/main/java/net/tiagofar78/prisonescape/managers/MessageLanguageManager.java

@@ -107,6 +107,7 @@ private static String getPlayerLanguage(String playerName) {
     private String _reachedItemLimitMessage;
     private String _notEnoughMoneyMessage;
     private String _successfullyBoughtItemMessage;
+    private String _cannotDropThatItemMessage;
 
 //	########################################
 //	#             Announcements            #
@@ -230,6 +231,7 @@ private MessageLanguageManager(String language) {
         _reachedItemLimitMessage = createMessage(messages.getString(warningPath + "ReachedItemLimit"));
         _notEnoughMoneyMessage = createMessage(messages.getString(warningPath + "NotEnoughMoney"));
         _successfullyBoughtItemMessage = createMessage(messages.getString(warningPath + "SuccessfullyBoughtItem"));
+        _cannotDropThatItemMessage = createMessage(messages.getString(warningPath + "CannotDropThatItem"));
 
         String announcementPath = messagePath + "Announcements.";
         _gameStartingAnnouncementMessage = createMessage(messages.getStringList(announcementPath + "GameStarting"));
@@ -462,6 +464,10 @@ public String getSuccessfullyBoughtItemMessage(int balance) {
         return _successfullyBoughtItemMessage.replace("{BALANCE}", Integer.toString(balance));
     }
 
+    public String getCannotDropThatItemMessage() {
+        return _cannotDropThatItemMessage;
+    }
+
 //	########################################
 //	#             Announcements            #
 //	########################################

src/main/resources/languages/english.yml

@@ -108,6 +108,7 @@ Messages:
     ReachedItemLimit: "&cSorry, you've already reached the maximum limit for this item."
     NotEnoughMoney: "&cYou do not have enough money to buy this item."
     SuccessfullyBoughtItem: "&aSuccessfully bought item. Your current balance is: {BALANCE}."
+    CannotDropThatItem: "&cYou cannot drop that item."
   Announcements:
     GameStarting:
     - "&6==================================="