Cancels explosions near permission signs

src/main/java/net/knarcraft/permissionsigns/listener/BlockListener.java

@@ -10,10 +10,13 @@ import org.bukkit.block.BlockFace;
 import org.bukkit.block.Sign;
 import org.bukkit.block.data.type.WallSign;
 import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
 import org.bukkit.event.block.BlockBreakEvent;
+import org.bukkit.event.block.BlockExplodeEvent;
 import org.bukkit.event.block.BlockPhysicsEvent;
+import org.bukkit.event.entity.EntityExplodeEvent;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -33,6 +36,16 @@ public class BlockListener implements Listener {
         }
     }
 
+    @EventHandler
+    public void onBlockExplode(BlockExplodeEvent event) {
+        preventExplosion(event.blockList(), event);
+    }
+
+    @EventHandler
+    public void onEntityExplode(EntityExplodeEvent event) {
+        preventExplosion(event.blockList(), event);
+    }
+
     @EventHandler
     public void onBlockBreak(BlockBreakEvent event) {
         Block block = event.getBlock();
@@ -54,6 +67,26 @@ public class BlockListener implements Listener {
         }
     }
 
+    /**
+     * Prevents explosions from destroying permission signs
+     *
+     * @param blocks <p>The blocks affected by the explosion</p>
+     * @param event  <p>The explosion event to cancel if a permission sign is found</p>
+     */
+    private void preventExplosion(List<Block> blocks, Cancellable event) {
+        for (Block block : blocks) {
+            if (!Tag.SIGNS.isTagged(block.getBlockData().getMaterial())) {
+                continue;
+            }
+            Sign sign = (Sign) block.getState();
+            boolean registered = SignManager.getSign(sign.getLocation()) != null;
+            if (registered) {
+                event.setCancelled(true);
+                break;
+            }
+        }
+    }
+
     /**
      * Protects signs on falling blocks in the given direction
      *