(Untested) Implementation of a full chunk tech hider

Signed-off-by: Lixfel <agga-games@gmx.de>

FightSystem_15/src/de/steamwar/fightsystem/utils/TechHider_15.java

@@ -13,11 +13,13 @@ import de.steamwar.fightsystem.IFightSystem;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.UnpooledByteBufAllocator;
 import net.minecraft.server.v1_15_R1.PacketPlayOutMapChunk;
+import org.bukkit.Bukkit;
 import org.bukkit.craftbukkit.v1_15_R1.CraftChunk;
 import org.bukkit.craftbukkit.v1_15_R1.entity.CraftPlayer;
 import org.bukkit.entity.Player;
 
 import java.util.List;
+import java.util.logging.Level;
 
 import static de.steamwar.fightsystem.utils.ITechHider.bypass;
 
@@ -90,8 +92,8 @@ public class TechHider_15 {
                     if(bitsPerBlock < 4)
                         bitsPerBlock = 4;
                     else if(bitsPerBlock > 8){
+                        Bukkit.getLogger().log(Level.WARNING, "Full chunk! bitsPerBlock: " + bitsPerBlock + " numChunkSections: " + numChunkSections);
                         bitsPerBlock = 14;
-                        buffer.writeByte(data[++i]);
                     }
 
                     if(bitsPerBlock != 14){
@@ -120,12 +122,71 @@ public class TechHider_15 {
                     }else{
                         int dataArrayLength = ITechHider.readVarInt(data, i);
                         int dataArrayLengthLength = ITechHider.readVarIntLength(data, i);
-                        buffer.writeBytes(data, i, dataArrayLength*8 + dataArrayLengthLength);
+                        buffer.writeBytes(data, i, dataArrayLengthLength);
                         i += dataArrayLengthLength;
-                        i += dataArrayLength * 8;
+
+                        int arrayEnd = dataArrayLength * 8 + i;
+                        while(i < arrayEnd){
+                            /*Every blockid is encoded in 14 bits (state id).
+                            * 4 blockIds (in the 16*16*16 Chunk) are encoded in 7 bytes:
+                            *
+                            *   1 2 3 4 5 6 7 8
+                            *  ________________
+                            * |       0        |
+                            * |     0      | 1 |
+                            * |       1        |
+                            * |  1     |   2   |
+                            * |       2        |
+                            * |  2 |      3    |
+                            * |       3        |
+                            *  ----------------
+                            * */
+                            boolean lineChanged = false;
+
+                            //Extract block ids
+                            int blockId0 = (data[i] << 6) | ((data[i+1] & 0xFC) >> 2);
+                            int blockId1 = ((data[i+1] & 0x03) << 12) | (data[i+2] << 4) | ((data[i+3] & 0xF0) >> 4);
+                            int blockId2 = ((data[i+3] & 0x0F) << 10) | (data[i+4] << 2) | ((data[i+5] & 0xC0) >> 6);
+                            int blockId3 = ((data[i+5] & 0x3F) << 8) | data[i+6];
+
+                            //Check for hidden blocks
+                            if(Config.HiddenBlocks.contains(blockId0)){
+                                lineChanged = true;
+                                blockId0 = Config.ObfuscateWith;
+                            }
+                            if(Config.HiddenBlocks.contains(blockId1)){
+                                lineChanged = true;
+                                blockId1 = Config.ObfuscateWith;
+                            }
+                            if(Config.HiddenBlocks.contains(blockId2)){
+                                lineChanged = true;
+                                blockId2 = Config.ObfuscateWith;
+                            }
+                            if(Config.HiddenBlocks.contains(blockId3)){
+                                lineChanged = true;
+                                blockId3 = Config.ObfuscateWith;
+                            }
+
+                            //Write bytes out
+                            if(lineChanged){
+                                changed = true;
+                                buffer.writeByte(blockId0 >> 6);
+                                buffer.writeByte(((blockId0 << 2) & 0xFC) | blockId1 >> 12);
+                                buffer.writeByte((blockId1 >> 4) & 0xFF);
+                                buffer.writeByte(((blockId1 << 4) & 0xF0) | blockId2 >> 10);
+                                buffer.writeByte((blockId2 >> 2) & 0xFF);
+                                buffer.writeByte(((blockId2 << 6) & 0xC0) | blockId3 >> 8);
+                                buffer.writeByte(blockId3 & 0xFF);
+                            }else{
+                                buffer.writeBytes(data, i, 7);
+                            }
+                            i += 7;
+                        }
                     }
                     numChunkSections--;
                 }
+                if(data.length - i != 0)
+                    Bukkit.getLogger().log(Level.WARNING, "There should be no more data. i: " + i + " data.length: " + data.length);
                 buffer.writeBytes(data, i, data.length - i);
 
                 if(changed){