Now vertically auto-extending claims on creation.

Should effectively protect basements and other underground bits of
surface-level structures from the moment of creation, provided the
underground bits connect to the above ground bits via player block types
(those which don't abundantly generate in the world).

src/me/ryanhamshire/GriefPrevention/AutoExtendClaimTask.java

@@ -0,0 +1,95 @@
+package me.ryanhamshire.GriefPrevention;
+
+import java.util.ArrayList;
+
+import org.bukkit.Bukkit;
+import org.bukkit.ChunkSnapshot;
+import org.bukkit.World.Environment;
+import org.bukkit.block.Biome;
+
+//automatically extends a claim downward based on block types detected
+class AutoExtendClaimTask implements Runnable
+{
+    private Claim claim;
+    private ArrayList<ChunkSnapshot> chunks;
+    private Environment worldType;
+
+    public AutoExtendClaimTask(Claim claim, ArrayList<ChunkSnapshot> chunks, Environment worldType)
+    {
+        this.claim = claim;
+        this.chunks = chunks;
+        this.worldType = worldType;
+    }
+
+    @Override
+    public void run()
+    {
+        int newY = this.getLowestBuiltY();
+        if(newY < this.claim.getLesserBoundaryCorner().getBlockY())
+        {
+            Bukkit.getScheduler().runTask(GriefPrevention.instance, new ExecuteExtendClaimTask(claim, newY));
+        }
+    }
+
+    private int getLowestBuiltY()
+    {
+        int y = this.claim.getLesserBoundaryCorner().getBlockY();
+        
+        if(this.yTooSmall(y)) return y;
+        
+        for(ChunkSnapshot chunk : this.chunks)
+        {
+            Biome biome = chunk.getBiome(0,  0);
+            ArrayList<Integer> playerBlockIDs = RestoreNatureProcessingTask.getPlayerBlocks(this.worldType, biome);
+            
+            boolean ychanged = true;
+            while(!this.yTooSmall(y) && ychanged)
+            {
+                ychanged = false;
+                for(int x = 0; x < 16; x++)
+                {
+                    for(int z = 0; z < 16; z++)
+                    {
+                        int blockType = chunk.getBlockTypeId(x, y, z);
+                        while(!this.yTooSmall(y) && playerBlockIDs.contains(blockType))
+                        {
+                            ychanged = true;
+                            blockType = chunk.getBlockTypeId(x, --y, z);
+                        }
+                        
+                        if(this.yTooSmall(y)) return y;
+                    }
+                }
+            }
+            
+            if(this.yTooSmall(y)) return y;
+        }
+        
+        return y;
+    }
+
+    private boolean yTooSmall(int y)
+    {
+        return y == 0 || y <= GriefPrevention.instance.config_claims_maxDepth;
+    }
+    
+    //runs in the main execution thread, where it can safely change claims and save those changes
+    private class ExecuteExtendClaimTask implements Runnable
+    {
+        private Claim claim;
+        private int newY;
+
+        public ExecuteExtendClaimTask(Claim claim, int newY)
+        {
+            this.claim = claim;
+            this.newY = newY;
+        }
+
+        @Override
+        public void run()
+        {
+            GriefPrevention.instance.dataStore.extendClaim(claim, newY);
+        }
+    }
+
+}

src/me/ryanhamshire/GriefPrevention/PlayerEventHandler.java

@@ -36,12 +36,14 @@ import org.bukkit.BanList;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.Chunk;
+import org.bukkit.ChunkSnapshot;
 import org.bukkit.GameMode;
 import org.bukkit.Location;
 import org.bukkit.Material;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.TravelAgent;
 import org.bukkit.BanList.Type;
+import org.bukkit.World;
 import org.bukkit.World.Environment;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
@@ -2493,6 +2495,25 @@ class PlayerEventHandler implements Listener
 		                GriefPrevention.sendMessage(player, TextMode.Info, Messages.BecomeMayor, 200L);
 		                GriefPrevention.sendMessage(player, TextMode.Instr, Messages.SubdivisionVideo2, 201L, DataStore.SUBDIVISION_VIDEO_URL);
 		            }
+					
+					//auto-extend it downward to cover anything already built underground
+					Claim newClaim = result.claim;
+					Location lesserCorner = newClaim.getLesserBoundaryCorner();
+					Location greaterCorner = newClaim.getGreaterBoundaryCorner();
+					World world = lesserCorner.getWorld();
+					ArrayList<ChunkSnapshot> snapshots = new ArrayList<ChunkSnapshot>();
+					for(int chunkx = lesserCorner.getBlockX() / 16; chunkx <= greaterCorner.getBlockX() / 16; chunkx++)
+					{
+					    for(int chunkz = lesserCorner.getBlockZ() / 16; chunkz <= greaterCorner.getBlockZ() / 16; chunkz++)
+					    {
+					        if(world.isChunkLoaded(chunkx, chunkz))
+					        {
+					            snapshots.add(world.getChunkAt(chunkx, chunkz).getChunkSnapshot(true, true, true));
+					        }
+					    }
+					}
+					
+					Bukkit.getScheduler().runTaskAsynchronously(GriefPrevention.instance, new AutoExtendClaimTask(newClaim, snapshots, world.getEnvironment()));
 				}
 			}
 		}