Add world persistence because I can

This is terribly inefficient both storage- and TPS-wise.
Enable/disable with ru.windcorp.progressia.test.TestWorldDiskIO.ENABLE

src/main/java/ru/windcorp/progressia/server/ChunkManager.java

@@ -12,6 +12,7 @@ import ru.windcorp.progressia.common.world.WorldData;
 import ru.windcorp.progressia.common.world.generic.ChunkSet;
 import ru.windcorp.progressia.common.world.generic.ChunkSets;
 import ru.windcorp.progressia.test.TestContent;
+import ru.windcorp.progressia.test.TestWorldDiskIO;
 
 public class ChunkManager {
 	
@@ -120,8 +121,12 @@ public class ChunkManager {
 
 		WorldData world = getServer().getWorld().getData();
 		
-		ChunkData chunk = new ChunkData(chunkPos, world);
+		ChunkData chunk = TestWorldDiskIO.tryToLoad(chunkPos, world);
-		TestContent.generateChunk(chunk);
+		if (chunk == null) {
+			chunk = new ChunkData(chunkPos, world);
+			TestContent.generateChunk(chunk);
+		}
+		
 		world.addChunk(chunk);
 		
 	}
@@ -137,8 +142,11 @@ public class ChunkManager {
 					chunkPos.x, chunkPos.y, chunkPos.z
 			));
 		}
+		
 		world.removeChunk(chunk);
 		
+		TestWorldDiskIO.saveChunk(chunk);
+		
 	}
 
 	public void sendChunk(Player player, Vec3i chunkPos) {

src/main/java/ru/windcorp/progressia/test/TestWorldDiskIO.java

@@ -0,0 +1,96 @@
+package ru.windcorp.progressia.test;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.zip.DeflaterOutputStream;
+import java.util.zip.InflaterInputStream;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import glm.vec._3.i.Vec3i;
+import ru.windcorp.progressia.common.io.ChunkIO;
+import ru.windcorp.progressia.common.world.ChunkData;
+import ru.windcorp.progressia.common.world.DecodingException;
+import ru.windcorp.progressia.common.world.WorldData;
+
+public class TestWorldDiskIO {
+	
+	private static final Path SAVE_DIR = Paths.get("tmp_world");
+	private static final Logger LOG = LogManager.getLogger("TestWorldDiskIO");
+	
+	private static final boolean ENABLE = true;
+
+	public static void saveChunk(ChunkData chunk) {
+		if (!ENABLE) return;
+		
+		try {
+			LOG.debug(
+					"Saving {} {} {}",
+					chunk.getPosition().x, chunk.getPosition().y, chunk.getPosition().z
+			);
+			
+			Files.createDirectories(SAVE_DIR);
+			
+			Path path = SAVE_DIR.resolve(String.format(
+					"chunk_%+d_%+d_%+d.progressia_chunk",
+					chunk.getPosition().x, chunk.getPosition().y, chunk.getPosition().z
+			));
+			
+			try (OutputStream output = new DeflaterOutputStream(new BufferedOutputStream(Files.newOutputStream(path)))) {
+				ChunkIO.save(chunk, output);
+			}
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+	
+	public static ChunkData tryToLoad(Vec3i chunkPos, WorldData world) {
+		if (!ENABLE) return null;
+		
+		Path path = SAVE_DIR.resolve(String.format(
+				"chunk_%+d_%+d_%+d.progressia_chunk",
+				chunkPos.x, chunkPos.y, chunkPos.z
+		));
+		
+		if (!Files.exists(path)) {
+			LOG.debug(
+					"Not found {} {} {}",
+					chunkPos.x, chunkPos.y, chunkPos.z
+			);
+			
+			return null;
+		}
+		
+		try {
+			ChunkData result = load(path, chunkPos, world);
+			
+			LOG.debug(
+					"Loaded {} {} {}",
+					chunkPos.x, chunkPos.y, chunkPos.z
+			);
+			
+			return result;
+		} catch (Exception e) {
+			e.printStackTrace();
+			LOG.debug(
+					"Could not load {} {} {}",
+					chunkPos.x, chunkPos.y, chunkPos.z
+			);
+			return null;
+		}
+	}
+
+	private static ChunkData load(Path path, Vec3i chunkPos, WorldData world) throws IOException, DecodingException {
+		try (InputStream input = new InflaterInputStream(new BufferedInputStream(Files.newInputStream(path)))) {
+			return ChunkIO.load(world, chunkPos, input);
+		}
+	}
+
+}