implemented MultiblockListener

src/main/java/org/kapelle/multiblock/MultiblockListener.java

@@ -0,0 +1,36 @@
+package org.kapelle.multiblock;
+
+import org.bukkit.Location;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.block.BlockPlaceEvent;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.util.BlockVector;
+
+public abstract class MultiblockListener implements Listener {
+    private final BlockComponent coreBlock;
+    private final BlockVector coreBlockOffset;
+    private final MultiblockStructure structure;
+
+    public MultiblockListener(JavaPlugin plugin, MultiblockStructure structure, BlockVector coreBlockOffset){
+        this.structure = structure;
+        this.coreBlockOffset = coreBlockOffset;
+
+        this.coreBlock = structure.getComponent(coreBlockOffset);
+
+        plugin.getServer().getPluginManager().registerEvents(this, plugin);
+    }
+
+    @EventHandler
+    public void onBlockPlaced(BlockPlaceEvent event){
+        Location placedLocation = event.getBlockPlaced().getLocation();
+        if(!event.isCancelled() && this.coreBlock.isValidBlock(placedLocation)){
+            if(this.structure.isValid(placedLocation,this.coreBlockOffset)){
+                callback(placedLocation);
+            }
+        }
+    }
+
+    abstract void callback(Location coreBlockLocation);
+
+}