//replace

src/main/java/me/youhavetrouble/blockedit/BlockEdit.java

@@ -1,6 +1,7 @@
 package me.youhavetrouble.blockedit;
 
 import me.youhavetrouble.blockedit.api.BlockEditWands;
+import me.youhavetrouble.blockedit.commands.ReplaceCommand;
 import me.youhavetrouble.blockedit.commands.SetCommand;
 import me.youhavetrouble.blockedit.commands.WandCommand;
 import me.youhavetrouble.blockedit.wands.SelectionWand;
@@ -35,6 +36,12 @@ public final class BlockEdit extends JavaPlugin {
             bukkitSetCommand.setExecutor(setCommand);
             bukkitSetCommand.setTabCompleter(setCommand);
         }
+        ReplaceCommand replaceCommand = new ReplaceCommand();
+        PluginCommand bukkitReplaceCommand = getCommand("/replace");
+        if (bukkitReplaceCommand != null) {
+            bukkitReplaceCommand.setExecutor(replaceCommand);
+            bukkitReplaceCommand.setTabCompleter(replaceCommand);
+        }
 
     }
 

src/main/java/me/youhavetrouble/blockedit/commands/ReplaceCommand.java

@@ -0,0 +1,70 @@
+package me.youhavetrouble.blockedit.commands;
+
+import me.youhavetrouble.blockedit.BEPlayer;
+import me.youhavetrouble.blockedit.WorkSplitter;
+import me.youhavetrouble.blockedit.operations.ReplaceOperation;
+import net.kyori.adventure.text.Component;
+import org.bukkit.Material;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabExecutor;
+import org.bukkit.entity.Player;
+import org.bukkit.util.BoundingBox;
+import org.bukkit.util.StringUtil;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ReplaceCommand implements TabExecutor {
+
+    @Override
+    public boolean onCommand(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
+        if (!(sender instanceof Player player)) return true;
+        if (args.length == 0) {
+            player.sendMessage(Component.text("You need to provide block type"));
+            return true;
+        }
+        if (args.length < 2) {
+            player.sendMessage(Component.text("You need to provide block type to replace"));
+            return true;
+        }
+        Material materialToReplace = Material.getMaterial(args[0].toUpperCase());
+        if (materialToReplace == null) {
+            player.sendMessage(Component.text("Provided material does not exist"));
+            return true;
+        }
+        Material material = Material.getMaterial(args[1].toUpperCase());
+        if (material == null) {
+            player.sendMessage(Component.text("Provided material does not exist"));
+            return true;
+        }
+
+        BlockData blockData = material.createBlockData();
+        BlockData blockDataToReplaceWith = materialToReplace.createBlockData();
+        BEPlayer bePlayer = BEPlayer.getByPlayer(player);
+        BoundingBox selection = bePlayer.getSelection();
+        if (selection == null) {
+            player.sendMessage(Component.text("You need to select 2 points to do this"));
+            return true;
+        }
+        new ReplaceOperation(WorkSplitter.getOperatedOnChunks(selection), bePlayer,blockDataToReplaceWith, blockData, 1);
+        return true;
+    }
+
+    @Override
+    public @Nullable List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String alias, @NotNull String[] args) {
+        if (args.length == 1 || args.length == 2) {
+            ArrayList<String> suggestions = new ArrayList<>();
+            for (Material material : Material.values()) {
+                if (material.isBlock())
+                    suggestions.add(material.name().toLowerCase());
+            }
+            return StringUtil.copyPartialMatches(args[args.length-1], suggestions, new ArrayList<>());
+        }
+        return null;
+    }
+
+}

src/main/java/me/youhavetrouble/blockedit/operations/ReplaceOperation.java

@@ -0,0 +1,60 @@
+package me.youhavetrouble.blockedit.operations;
+
+import me.youhavetrouble.blockedit.BEPlayer;
+import me.youhavetrouble.blockedit.BlockEdit;
+import me.youhavetrouble.blockedit.util.ChunkWork;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.block.Block;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.util.BoundingBox;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class ReplaceOperation {
+
+    private final BoundingBox selection;
+    private final BlockData blockToSet, getBlockToReplace;
+    private final List<ChunkWork> chunkwork = new ArrayList<>();
+
+    public ReplaceOperation(HashSet<ChunkWork> chunkWorks, BEPlayer bePlayer,BlockData blockToReplace , BlockData blockToSet, int chunksPerTick) {
+        this.selection = bePlayer.getSelection();
+        this.blockToSet = blockToSet;
+        this.getBlockToReplace = blockToReplace;
+        this.chunkwork.addAll(chunkWorks);
+        AtomicInteger element = new AtomicInteger(chunkwork.size()-1);
+
+        Bukkit.getScheduler().runTaskTimer(BlockEdit.getPlugin(), (task) -> {
+            if (element.get() < 0) {
+                task.cancel();
+                return;
+            }
+            for (int i = 0; i<= chunksPerTick; i++) {
+                processChunkWork(chunkwork.get(element.getAndDecrement()), bePlayer.getSelectionWorld());
+            }
+        }, 0, 1);
+    }
+
+    private void processChunkWork(ChunkWork chunkWork, UUID worldUuid) {
+        World world = Bukkit.getWorld(worldUuid);
+        if (world == null) return;
+        chunkWork.getChunkAsync(world).thenAccept(chunk -> {
+            // skip y levels that are not in the selection
+            for (int y = (int) selection.getMinY(); y <= selection.getMaxY(); y++) {
+                for (int x = 0; x <= 15; x++) {
+                    for (int z = 0; z <= 15; z++) {
+                        Block block = chunk.getBlock(x, y, z);
+                        if (!selection.contains(block.getLocation().toVector())) continue;
+                        if (block.getBlockData().matches(getBlockToReplace))
+                            block.setBlockData(blockToSet);
+                    }
+                }
+            }
+        });
+    }
+
+}

src/main/resources/plugin.yml

@@ -13,4 +13,7 @@ commands:
     description: Gives you a blockedit wand
   /set:
     permission: blockedit.set
-    description: Set selection to chosen block
+    description: Set selection area to chosen block
+  /replace:
+    permission: blockedit.replace
+    description: Replace selected blocks in selection area