feat: implement removal of entities if they would be in a block after the edit (#2311)

- Includes some refactoring to EditSessionBuilder to prevent doubling-up of processors that are also extents
 - Better ordering of the EditSessionBuilder process/extent code to match where extents actually end up in the stack
 - Fixes #1941

worldedit-core/src/main/java/com/fastasyncworldedit/core/configuration/Settings.java

@@ -622,10 +622,11 @@ public class Settings extends Config {
         public boolean PERSISTENT_BRUSHES = true;
 
         @Comment({
-                "[SAFE] Keep entities that are positioned in non-air blocks when editing an area",
+                "[SAFE] Keep entities that are positioned in non-air blocks when editing an area (default: true)",
-                "Might cause client-side FPS lag in some situations"
+                " - Might cause client-side FPS lag in some situations",
+                " - Requires fast-placement to be true"
         })
-        public boolean KEEP_ENTITIES_IN_BLOCKS = false;
+        public boolean KEEP_ENTITIES_IN_BLOCKS = true;
 
         @Comment({
                 "[SAFE] Attempt to remove entities from the world if they were not present in the expected chunk (default: true)",

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/EntityInBlockRemovingProcessor.java

@@ -0,0 +1,57 @@
+package com.fastasyncworldedit.core.extent.processor;
+
+import com.fastasyncworldedit.core.queue.IBatchProcessor;
+import com.fastasyncworldedit.core.queue.IChunk;
+import com.fastasyncworldedit.core.queue.IChunkGet;
+import com.fastasyncworldedit.core.queue.IChunkSet;
+import com.sk89q.jnbt.CompoundTag;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Processor that removes existing entities that would not be in air after the edit
+ *
+ * @since TODO
+ */
+public class EntityInBlockRemovingProcessor implements IBatchProcessor {
+
+    @Override
+    public IChunkSet processSet(final IChunk chunk, final IChunkGet get, final IChunkSet set) {
+        for (CompoundTag tag : get.getEntities()) {
+            // Empty tags for seemingly non-existent entities can exist?
+            if (tag.getList("Pos").size() == 0) {
+                continue;
+            }
+            BlockVector3 pos = tag.getEntityPosition().toBlockPoint();
+            int x = pos.getX() & 15;
+            int y = pos.getY();
+            int z = pos.getZ() & 15;
+            if (!set.hasSection(y >> 4)) {
+                continue;
+            }
+            if (set.getBlock(x, y, z).getBlockType() != BlockTypes.__RESERVED__ && !set
+                    .getBlock(x, y, z)
+                    .getBlockType()
+                    .getMaterial()
+                    .isAir()) {
+                set.removeEntity(tag.getUUID());
+            }
+        }
+        return set;
+    }
+
+    @Nullable
+    @Override
+    public Extent construct(final Extent child) {
+        throw new UnsupportedOperationException("Processing only");
+    }
+
+    @Override
+    public ProcessorScope getScope() {
+        // After block removal but before history
+        return ProcessorScope.CUSTOM;
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/ProcessorScope.java

@@ -7,7 +7,8 @@ package com.fastasyncworldedit.core.extent.processor;
  * - CHANGING_BLOCKS (processors that may ADD or CHANGE blocks being set)
  * - REMOVING_BLOCKS (processors that may ADD, CHANGE or REMOVE blocks being set)
  * - CUSTOM (processors that do not specify a SCOPE)
- * - READING_SET_BLOCKS (processors that do not alter blocks at all, and read the blocks that are actually going to set, e.g. history processors)
+ * - READING_SET_BLOCKS (processors that do not alter blocks at all, and read the blocks that are actually going to set, e.g.
+ * history processors). There is no guarantee that changes made here will be stored in history.
  */
 public enum ProcessorScope {
     ADDING_BLOCKS(0),

worldedit-core/src/main/java/com/sk89q/worldedit/EditSessionBuilder.java

@@ -32,6 +32,7 @@ import com.fastasyncworldedit.core.extent.NullExtent;
 import com.fastasyncworldedit.core.extent.SingleRegionExtent;
 import com.fastasyncworldedit.core.extent.SlowExtent;
 import com.fastasyncworldedit.core.extent.StripNBTExtent;
+import com.fastasyncworldedit.core.extent.processor.EntityInBlockRemovingProcessor;
 import com.fastasyncworldedit.core.extent.processor.heightmap.HeightmapProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.NullRelighter;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelightMode;
@@ -543,25 +544,6 @@ public final class EditSessionBuilder {
                     }
                 }
             }
-            FaweRegionExtent regionExtent = null;
-            if (disallowedRegions != null) { // Always use MultiRegionExtent if we have blacklist regions
-                regionExtent = new MultiRegionExtent(this.extent, this.limit, allowedRegions, disallowedRegions);
-            } else if (allowedRegions == null) {
-                allowedRegions = new Region[]{RegionWrapper.GLOBAL()};
-            } else {
-                if (allowedRegions.length == 0) {
-                    regionExtent = new NullExtent(this.extent, FaweCache.NO_REGION);
-                } else {
-                    if (allowedRegions.length == 1) {
-                        regionExtent = new SingleRegionExtent(this.extent, this.limit, allowedRegions[0]);
-                    } else {
-                        regionExtent = new MultiRegionExtent(this.extent, this.limit, allowedRegions, null);
-                    }
-                }
-            }
-            if (placeChunks && regionExtent != null) {
-                queue.addProcessor(regionExtent);
-            }
             // There's no need to do the below (and it'll also just be a pain to implement) if we're not placing chunks
             if (placeChunks) {
                 if (((relightMode != null && relightMode != RelightMode.NONE) || (relightMode == null && Settings.settings().LIGHTING.MODE > 0))) {
@@ -571,6 +553,11 @@ public final class EditSessionBuilder {
                     queue.addProcessor(new RelightProcessor(relighter));
                 }
                 queue.addProcessor(new HeightmapProcessor(world.getMinY(), world.getMaxY()));
+
+                if (!Settings.settings().EXPERIMENTAL.KEEP_ENTITIES_IN_BLOCKS) {
+                    queue.addProcessor(new EntityInBlockRemovingProcessor());
+                }
+
                 IBatchProcessor platformProcessor = WorldEdit
                         .getInstance()
                         .getPlatformManager()
@@ -590,24 +577,13 @@ public final class EditSessionBuilder {
             } else {
                 relighter = NullRelighter.INSTANCE;
             }
-            Consumer<Component> onErrorMessage;
-            if (getActor() != null) {
-                onErrorMessage = c -> getActor().print(Caption.of("fawe.error.occurred-continuing", c));
-            } else {
-                onErrorMessage = c -> {
-                };
-            }
-            if (limit != null && !limit.isUnlimited() && regionExtent != null) {
-                this.extent = new LimitExtent(regionExtent, limit, onErrorMessage);
-            } else if (limit != null && !limit.isUnlimited()) {
-                this.extent = new LimitExtent(this.extent, limit, onErrorMessage);
-            } else if (regionExtent != null) {
-                this.extent = regionExtent;
-            }
             if (this.limit != null && this.limit.STRIP_NBT != null && !this.limit.STRIP_NBT.isEmpty()) {
-                this.extent = new StripNBTExtent(this.extent, this.limit.STRIP_NBT);
+                StripNBTExtent ext = new StripNBTExtent(this.extent, this.limit.STRIP_NBT);
                 if (placeChunks) {
-                    queue.addProcessor((IBatchProcessor) this.extent);
+                    queue.addProcessor(ext);
+                }
+                if (!placeChunks || !combineStages) {
+                    this.extent = ext;
                 }
             }
             if (this.limit != null && !this.limit.isUnlimited()) {
@@ -620,12 +596,50 @@ public final class EditSessionBuilder {
                 }
                 Set<PropertyRemap<?>> remaps = this.limit.REMAP_PROPERTIES;
                 if (!limitBlocks.isEmpty() || (remaps != null && !remaps.isEmpty())) {
-                    this.extent = new DisallowedBlocksExtent(this.extent, limitBlocks, remaps);
+                    DisallowedBlocksExtent ext = new DisallowedBlocksExtent(this.extent, limitBlocks, remaps);
                     if (placeChunks) {
-                        queue.addProcessor((IBatchProcessor) this.extent);
+                        queue.addProcessor(ext);
+                    }
+                    if (!placeChunks || !combineStages) {
+                        this.extent = ext;
                     }
                 }
             }
+
+            FaweRegionExtent regionExtent = null;
+            if (disallowedRegions != null) { // Always use MultiRegionExtent if we have blacklist regions
+                regionExtent = new MultiRegionExtent(this.extent, this.limit, allowedRegions, disallowedRegions);
+            } else if (allowedRegions == null) {
+                allowedRegions = new Region[]{RegionWrapper.GLOBAL()};
+            } else {
+                if (allowedRegions.length == 0) {
+                    regionExtent = new NullExtent(this.extent, FaweCache.NO_REGION);
+                } else {
+                    if (allowedRegions.length == 1) {
+                        regionExtent = new SingleRegionExtent(this.extent, this.limit, allowedRegions[0]);
+                    } else {
+                        regionExtent = new MultiRegionExtent(this.extent, this.limit, allowedRegions, null);
+                    }
+                }
+            }
+            if (regionExtent != null) {
+                if (placeChunks) {
+                    queue.addProcessor(regionExtent);
+                }
+                if (!placeChunks || !combineStages) {
+                    this.extent = regionExtent;
+                }
+            }
+            Consumer<Component> onErrorMessage;
+            if (getActor() != null) {
+                onErrorMessage = c -> getActor().print(Caption.of("fawe.error.occurred-continuing", c));
+            } else {
+                onErrorMessage = c -> {
+                };
+            }
+            if (limit != null && !limit.isUnlimited()) {
+                this.extent = new LimitExtent(this.extent, limit, onErrorMessage);
+            }
             this.extent = wrapExtent(this.extent, eventBus, event, EditSession.Stage.BEFORE_HISTORY);
         }
         return this;

worldedit-core/src/main/java/com/sk89q/worldedit/function/entity/ExtentEntityCopy.java

@@ -160,17 +160,7 @@ public class ExtentEntityCopy implements EntityFunction {
             // Remove
             if (isRemoving() && success) {
                 //FAWE start
-                UUID uuid = null;
+                UUID uuid = entity.getState().getNbtData().getUUID();
-                if (tag.containsKey("UUID")) {
-                    int[] arr = tag.getIntArray("UUID");
-                    uuid = new UUID((long) arr[0] << 32 | (arr[1] & 0xFFFFFFFFL), (long) arr[2] << 32 | (arr[3] & 0xFFFFFFFFL));
-                } else if (tag.containsKey("UUIDMost")) {
-                    uuid = new UUID(tag.getLong("UUIDMost"), tag.getLong("UUIDLeast"));
-                } else if (tag.containsKey("WorldUUIDMost")) {
-                    uuid = new UUID(tag.getLong("WorldUUIDMost"), tag.getLong("WorldUUIDLeast"));
-                } else if (tag.containsKey("PersistentIDMSB")) {
-                    uuid = new UUID(tag.getLong("PersistentIDMSB"), tag.getLong("PersistentIDLSB"));
-                }
                 if (uuid != null) {
                     if (source != null) {
                         source.removeEntity(