From dd28c78a366032cf5393fbeee709d04b56a0a543 Mon Sep 17 00:00:00 2001
From: Jesse Boyd <jessepaleg@gmail.com>
Date: Sat, 6 Apr 2019 14:45:39 +1100
Subject: [PATCH] trimflatfilter

---
 .../boydti/fawe/command/AnvilCommands.java    | 12 +++
 .../jnbt/anvil/filters/TrimFlatFilter.java    | 73 +++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 core/src/main/java/com/boydti/fawe/jnbt/anvil/filters/TrimFlatFilter.java

diff --git a/core/src/main/java/com/boydti/fawe/command/AnvilCommands.java b/core/src/main/java/com/boydti/fawe/command/AnvilCommands.java
index 1eb6ab67..83fc1e97 100644
--- a/core/src/main/java/com/boydti/fawe/command/AnvilCommands.java
+++ b/core/src/main/java/com/boydti/fawe/command/AnvilCommands.java
@@ -310,6 +310,18 @@ public class AnvilCommands {
     }
 
 
+    @Command(
+            aliases = {"trimallflat", },
+            desc = "Trim all flat chunks"
+    )
+    @CommandPermissions("worldedit.anvil.trimallflat")
+    public void trimAllAir(Player player, String folder, @Switch('u') boolean unsafe) throws WorldEditException {
+        TrimFlatFilter filter = new TrimFlatFilter();
+        TrimFlatFilter result = runWithWorld(player, folder, filter, true, unsafe);
+        if (result != null) player.print(BBC.getPrefix() + BBC.VISITOR_BLOCK.format(result.getTotal()));
+    }
+
+
     @Command(
             aliases = {"debugfixair", },
             desc = "debug - do not use"
diff --git a/core/src/main/java/com/boydti/fawe/jnbt/anvil/filters/TrimFlatFilter.java b/core/src/main/java/com/boydti/fawe/jnbt/anvil/filters/TrimFlatFilter.java
new file mode 100644
index 00000000..c619406d
--- /dev/null
+++ b/core/src/main/java/com/boydti/fawe/jnbt/anvil/filters/TrimFlatFilter.java
@@ -0,0 +1,73 @@
+package com.boydti.fawe.jnbt.anvil.filters;
+
+import com.boydti.fawe.jnbt.anvil.MCAChunk;
+import com.boydti.fawe.jnbt.anvil.MCAFile;
+import com.boydti.fawe.jnbt.anvil.MCAFilterCounter;
+import com.boydti.fawe.object.RunnableVal;
+import com.boydti.fawe.object.number.MutableLong;
+
+public class TrimFlatFilter extends MCAFilterCounter {
+    @Override
+    public MCAChunk applyChunk(MCAChunk chunk, MutableLong cache) {
+        // Check other layers
+        for (int layer = 1; layer < chunk.ids.length; layer++) {
+            byte[] idLayer = chunk.ids[layer];
+            if (idLayer == null) continue;
+            for (int i = 0; i < 4096; i++) {
+                if (idLayer[i] != 0) {
+                    return null;
+                }
+            }
+            { // Possibly dead code depending on the generator
+                chunk.ids[layer] = null;
+                chunk.data[layer] = null;
+                chunk.setModified();
+            }
+        }
+        byte[] layer0 = chunk.ids[0];
+        int index = 0;
+        for (int y = 0; y <= 3; y++) {
+            for (int z = 0; z < 16; z++) {
+                for (int x = 0; x < 16; x++, index++) {
+                    int id = layer0[index] & 0xFF;
+                    switch (id) {
+                        case 2: // grass
+                        case 3: // dirt
+                        case 7: // bedrock
+                            continue;
+                        default:
+                            return;
+                    }
+                }
+            }
+        }
+        for (int y = 4; y < 16; y++) {
+            for (int z = 0; z < 16; z++) {
+                for (int x = 0; x < 16; x++, index++) {
+                    if (layer0[index] != 0) return;
+                }
+            }
+        }
+
+        // Check floor layers
+        cache.add(Character.MAX_VALUE);
+        chunk.setDeleted(true);
+        return null;
+    }
+
+    @Override
+    public void finishFile(MCAFile file, MutableLong cache) {
+        boolean[] deleteFile = { true };
+        file.forEachCachedChunk(new RunnableVal<MCAChunk>() {
+            @Override
+            public void run(MCAChunk value) {
+                if (!value.isDeleted()) {
+                    deleteFile[0] = false;
+                }
+            }
+        });
+        if (deleteFile[0]) {
+            file.setDeleted(true);
+        }
+    }
+}
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