Prevent unauthorized sign edits.

Since Minecraft 1.20, players can edit signs by right-clicking on them,
and that poses a problem for the sign-centric portions of the plugin,
such as class selection signs and the various types of arena signs.

This commit refactors the PlayerInteractEvent handler in ArenaListener
in order to break open the possibility of handling non-lobby players as
well. We're a little more strict with lobby players, and we still want
to handle class sign clicks and iron block clicks here. For players who
aren't in the lobby, we're really just blocking the event according to
the regular protection rules (block is inside region, protect is on, and
arena is not in edit mode).

It also blanket cancels events in the HandlesSignClicks event handler,
because there is no meaningful way to edit an arena sign, since their
contents come from the template file and not from what is written on
them by the sign renderer.

Ideally, we'd refactor some of this event handler logic, because it's a
lot easier to take care of the individual responsibilities in separate
event handlers.

Fixes #765

src/main/java/com/garbagemule/MobArena/ArenaListener.java

@@ -44,6 +44,7 @@
 import org.bukkit.entity.ThrownPotion;
 import org.bukkit.entity.Vehicle;
 import org.bukkit.event.Event.Result;
+import org.bukkit.event.block.Action;
 import org.bukkit.event.block.BlockBreakEvent;
 import org.bukkit.event.block.BlockBurnEvent;
 import org.bukkit.event.block.BlockEvent;
@@ -1089,26 +1090,58 @@ public void onPlayerBucketEmpty(PlayerBucketEmptyEvent event) {
     }
 
     public void onPlayerInteract(PlayerInteractEvent event) {
-        Player p = event.getPlayer();
-        if (!arena.inLobby(p)) return;
+        if (arena.inLobby(event.getPlayer())) {
+            onLobbyPlayerInteract(event);
+        } else {
+            onNonLobbyPlayerInteract(event);
+        }
+    }
 
-        // Prevent placing blocks and using held items
+    private void onLobbyPlayerInteract(PlayerInteractEvent event) {
         if (event.hasItem()) {
             event.setUseItemInHand(Result.DENY);
         }
 
-        // Bail if off-hand or if there's no block involved.
-        if (event.getHand() == EquipmentSlot.OFF_HAND || !event.hasBlock())
+        if (event.getHand() == EquipmentSlot.OFF_HAND) {
             return;
+        }
 
-        // Iron block
-        if (event.getClickedBlock().getType() == Material.IRON_BLOCK) {
-            handleReadyBlock(p);
+        Block block = event.getClickedBlock();
+        if (block == null) {
+            return;
         }
-        // Sign
-        else if (event.getClickedBlock().getState() instanceof Sign) {
+
+        if (block.getType() == Material.IRON_BLOCK) {
+            handleReadyBlock(event.getPlayer());
+        } else if (block.getState() instanceof Sign) {
+            if (event.getAction() == Action.RIGHT_CLICK_BLOCK) {
+                event.setCancelled(true);
+            }
             Sign sign = (Sign) event.getClickedBlock().getState();
-            handleSign(sign, p);
+            handleSign(sign, event.getPlayer());
+        }
+    }
+
+    private void onNonLobbyPlayerInteract(PlayerInteractEvent event) {
+        if (!protect) {
+            return;
+        }
+
+        Block block = event.getClickedBlock();
+        if (block == null) {
+            return;
+        }
+        if (!region.contains(block.getLocation())) {
+            return;
+        }
+        if (arena.inEditMode()) {
+            return;
+        }
+
+        if (block.getState() instanceof Sign) {
+            if (event.getAction() == Action.RIGHT_CLICK_BLOCK) {
+                event.setCancelled(true);
+            }
         }
     }
 

src/main/java/com/garbagemule/MobArena/signs/HandlesSignClicks.java

@@ -41,6 +41,7 @@ public void on(PlayerInteractEvent event) {
 
         ArenaSign sign = signStore.findByLocation(block.getLocation());
         if (sign != null) {
+            event.setCancelled(true);
             purgeAndInvoke(sign, event.getPlayer());
         }
     }