Add block placing midair

src/main/java/net/thenextlvl/utilities/UtilitiesPlugin.java

@@ -111,6 +111,7 @@ public void onDisable() {
 
     private void registerListeners() {
         getServer().getPluginManager().registerEvents(new AdvancedFlyListener(this), this);
+        getServer().getPluginManager().registerEvents(new AirPlacingListener(this), this);
         getServer().getPluginManager().registerEvents(new BlockBreakListener(this), this);
         getServer().getPluginManager().registerEvents(new BlockPhysicsListener(this), this);
         getServer().getPluginManager().registerEvents(new ConnectionListener(this), this);

src/main/java/net/thenextlvl/utilities/listener/AirPlacingListener.java

@@ -0,0 +1,75 @@
+package net.thenextlvl.utilities.listener;
+
+import lombok.RequiredArgsConstructor;
+import net.thenextlvl.utilities.UtilitiesPlugin;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.attribute.Attribute;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.block.data.Waterlogged;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerMoveEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+@RequiredArgsConstructor
+public class AirPlacingListener implements Listener {
+    static final Map<Player, Location> targetBlocks = new WeakHashMap<>();
+    private final BlockData blockData = Material.BARRIER.createBlockData();
+    private final BlockData waterlogged = Material.BARRIER.createBlockData(data ->
+            ((Waterlogged) data).setWaterlogged(true));
+    private final UtilitiesPlugin plugin;
+
+    @EventHandler(priority = EventPriority.MONITOR)
+    public void onPlayerQuit(PlayerQuitEvent event) {
+        targetBlocks.remove(event.getPlayer());
+    }
+
+    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
+    public void onPlayerMove(PlayerMoveEvent event) {
+        var player = event.getPlayer();
+
+        if (!plugin.settingsController().isAirPlacing(player)) {
+            hideBlock(player);
+            return;
+        }
+
+        if (player.getInventory().getItemInMainHand().isEmpty()
+            && player.getInventory().getItemInOffHand().isEmpty()) {
+            hideBlock(player);
+            return;
+        }
+
+        var range = player.getAttribute(Attribute.PLAYER_BLOCK_INTERACTION_RANGE);
+        if (range == null || player.getTargetBlockExact((int) range.getValue()) != null) {
+            hideBlock(player);
+            return;
+        }
+
+        var eyeLocation = player.getEyeLocation();
+        var targetBlock = eyeLocation.add(eyeLocation.getDirection().multiply(range.getValue()));
+
+        var lastTarget = targetBlocks.put(player, targetBlock);
+
+        var isWater = targetBlock.getBlock().getType().equals(Material.WATER);
+        if ((!isWater && !targetBlock.getBlock().isEmpty()) || targetBlock.equals(lastTarget)) return;
+
+        if (lastTarget != null) player.sendBlockChange(lastTarget, lastTarget.getBlock().getBlockData());
+
+        if (event.getFrom().distanceSquared(event.getTo()) > 0.5) return;
+
+        player.sendBlockChange(targetBlock, isWater ? waterlogged : blockData);
+    }
+
+    private void hideBlock(Player player) {
+        targetBlocks.computeIfPresent(player, (entry, location) -> {
+            entry.sendBlockChange(location, location.getBlock().getBlockData());
+            return null;
+        });
+    }
+}

src/main/java/net/thenextlvl/utilities/listener/ConnectionListener.java

@@ -48,6 +48,7 @@ public void onPlayerQuit(PlayerQuitEvent event) {
         AdvancedFlyListener.lastVelocity.remove(event.getPlayer());
         AdvancedFlyListener.slower1.remove(event.getPlayer());
         AdvancedFlyListener.slower2.remove(event.getPlayer());
+        AirPlacingListener.targetBlocks.remove(event.getPlayer());
         plugin.settingsController().purge(event.getPlayer());
     }
 }