Merge branch 'feature/networking' of github.com-quiqueck:quiqueck/BCLib into feature/networking

src/main/java/ru/bclib/api/dataexchange/Connector.java

@@ -1,16 +1,18 @@
 package ru.bclib.api.dataexchange;
 
+import ru.bclib.api.dataexchange.handler.DataExchange;
+
 import java.util.Set;
 
 abstract class Connector {
-	protected final DataExchangeAPI api;
+	protected final DataExchange api;
 	
-	Connector(DataExchangeAPI api) {
+	Connector(DataExchange api) {
 		this.api = api;
 	}
 	public abstract boolean onClient();
 	
 	protected Set<DataHandlerDescriptor> getDescriptors(){
-		return api.descriptors;
+		return api.getDescriptors();
 	}
 }

src/main/java/ru/bclib/api/dataexchange/ConnectorClientside.java

@@ -8,11 +8,15 @@ import net.minecraft.client.Minecraft;
 import net.minecraft.client.multiplayer.ClientPacketListener;
 import net.minecraft.network.FriendlyByteBuf;
 import ru.bclib.BCLib;
+import ru.bclib.api.dataexchange.handler.DataExchange;
 
+/**
+ * This is an internal class that handles a Clienetside players Connection to a Server
+ */
 @Environment(EnvType.CLIENT)
-class ConnectorClientside extends Connector {
+public class ConnectorClientside extends Connector {
 	private Minecraft client;
-	ConnectorClientside(DataExchangeAPI api) {
+	ConnectorClientside(DataExchange api) {
 		super(api);
 		this.client = null;
 	}
@@ -23,7 +27,7 @@ class ConnectorClientside extends Connector {
 		return true;
 	}
 	
-	protected void onPlayInit(ClientPacketListener handler, Minecraft client){
+	public void onPlayInit(ClientPacketListener handler, Minecraft client){
 		if (this.client!=null && this.client != client){
 			BCLib.LOGGER.warning("Client changed!");
 		}
@@ -34,8 +38,8 @@ class ConnectorClientside extends Connector {
 			});
 		}
 	}
-	
+
-	void onPlayReady(ClientPacketListener handler, PacketSender sender, Minecraft client){
+	public void onPlayReady(ClientPacketListener handler, PacketSender sender, Minecraft client){
 		for(DataHandlerDescriptor desc : getDescriptors()){
 			if (desc.sendOnJoin){
 				DataHandler h = desc.JOIN_INSTANCE.get();
@@ -45,8 +49,8 @@ class ConnectorClientside extends Connector {
 			}
 		}
 	}
-	
+
-	void onPlayDisconnect(ClientPacketListener handler, Minecraft client){
+	public void onPlayDisconnect(ClientPacketListener handler, Minecraft client){
 		for(DataHandlerDescriptor desc : getDescriptors()) {
 			ClientPlayNetworking.unregisterReceiver(desc.IDENTIFIER);
 		}
@@ -57,7 +61,7 @@ class ConnectorClientside extends Connector {
 		h.receiveFromServer(client, handler, buf, responseSender);
 	}
 	
-	void sendToServer(DataHandler h){
+	public void sendToServer(DataHandler h){
 		if (client==null){
 			throw new RuntimeException("[internal error] Client not initialized yet!");
 		}

src/main/java/ru/bclib/api/dataexchange/ConnectorServerside.java

@@ -7,10 +7,14 @@ import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.network.ServerGamePacketListenerImpl;
 import ru.bclib.BCLib;
+import ru.bclib.api.dataexchange.handler.DataExchange;
 
-class ConnectorServerside extends Connector {
+/**
+ * This is an internal class that handles a Serverside Connection to a Client-Player
+ */
+public class ConnectorServerside extends Connector {
 	private MinecraftServer server;
-	ConnectorServerside(DataExchangeAPI api) {
+	ConnectorServerside(DataExchange api) {
 		super(api);
 		server = null;
 	}
@@ -20,7 +24,7 @@ class ConnectorServerside extends Connector {
 		return false;
 	}
 	
-	protected void onPlayInit(ServerGamePacketListenerImpl handler, MinecraftServer server){
+	public void onPlayInit(ServerGamePacketListenerImpl handler, MinecraftServer server){
 		if (this.server!=null && this.server != server){
 			BCLib.LOGGER.warning("Server changed!");
 		}
@@ -31,8 +35,8 @@ class ConnectorServerside extends Connector {
 			});
 		}
 	}
-	
+
-	void onPlayReady(ServerGamePacketListenerImpl handler, PacketSender sender, MinecraftServer server){
+	public void onPlayReady(ServerGamePacketListenerImpl handler, PacketSender sender, MinecraftServer server){
 		for(DataHandlerDescriptor desc : getDescriptors()){
 			if (desc.sendOnJoin){
 				DataHandler h = desc.JOIN_INSTANCE.get();
@@ -42,8 +46,8 @@ class ConnectorServerside extends Connector {
 			}
 		}
 	}
-	
+
-	void onPlayDisconnect(ServerGamePacketListenerImpl handler, MinecraftServer server){
+	public void onPlayDisconnect(ServerGamePacketListenerImpl handler, MinecraftServer server){
 		for(DataHandlerDescriptor desc : getDescriptors()){
 			ServerPlayNetworking.unregisterReceiver(handler, desc.IDENTIFIER);
 		}
@@ -54,7 +58,7 @@ class ConnectorServerside extends Connector {
 		h.receiveFromClient(server, player, handler, buf, responseSender);
 	}
 	
-	void sendToClient(DataHandler h){
+	public void sendToClient(DataHandler h){
 		if (server==null){
 			throw new RuntimeException("[internal error] Server not initialized yet!");
 		}

src/main/java/ru/bclib/api/dataexchange/DataExchangeAPI.java

@@ -6,56 +6,33 @@ import net.fabricmc.api.Environment;
 import net.fabricmc.fabric.api.client.networking.v1.ClientLoginConnectionEvents;
 import net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents;
 import net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents;
-import net.minecraft.client.Minecraft;
 import net.minecraft.network.FriendlyByteBuf;
+import ru.bclib.BCLib;
+import ru.bclib.api.dataexchange.handler.DataExchange;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Function;
+import java.util.function.Predicate;
 
-public class DataExchangeAPI {
+public class DataExchangeAPI extends DataExchange {
 	private final static List<String> MODS = Lists.newArrayList();
-	private static DataExchangeAPI instance;
+
-	private ConnectorServerside server;
+	/**
-	private ConnectorClientside client;
+	 * You should never need to create a custom instance of this Object.
-	protected final Set<DataHandlerDescriptor> descriptors;
+	 */
-	
+	public DataExchangeAPI() {
-	
+		super((api) -> new ConnectorClientside(api), (api) -> new ConnectorServerside(api));
-	private DataExchangeAPI(){
-		descriptors = new HashSet<>();
 	}
-	
+
-	static DataExchangeAPI getInstance(){
+
-		if (instance==null){
-			instance = new DataExchangeAPI();
-		}
-		return instance;
-	}
-	
-	@Environment(EnvType.CLIENT)
-	private void initClientside(){
-		if (client!=null) return;
-		client = new ConnectorClientside(this);
-		ClientLoginConnectionEvents.INIT.register((a, b) ->{
-			System.out.println("INIT");
-		});
-		ClientLoginConnectionEvents.QUERY_START.register((a, b) ->{
-			System.out.println("INIT");
-		});
-		ClientPlayConnectionEvents.INIT.register(client::onPlayInit);
-		ClientPlayConnectionEvents.JOIN.register(client::onPlayReady);
-		ClientPlayConnectionEvents.DISCONNECT.register(client::onPlayDisconnect);
-	}
-	
-	private void initServerSide(){
-		if (server!=null) return;
-		server = new ConnectorServerside(this);
-		
-		ServerPlayConnectionEvents.INIT.register(server::onPlayInit);
-		ServerPlayConnectionEvents.JOIN.register(server::onPlayReady);
-		ServerPlayConnectionEvents.DISCONNECT.register(server::onPlayDisconnect);
-	}
-	
 	/**
 	 * Register a mod to participate in the DataExchange.
 	 *
@@ -78,34 +55,10 @@ public class DataExchangeAPI {
 	 * @param desc The Descriptor you want to add.
 	 */
 	public static void registerDescriptor(DataHandlerDescriptor desc){
-		DataExchangeAPI api = DataExchangeAPI.getInstance();
+		DataExchange api = DataExchange.getInstance();
-		api.descriptors.add(desc);
+		api.getDescriptors().add(desc);
 	}
-	
+
-	
-	/**
-	 * Initializes all datastructures that need to exist in the client component.
-	 * <p>
-	 * This is automatically called by BCLib. You can register {@link DataHandler}-Objects before this Method is called
-	 */
-	@Environment(EnvType.CLIENT)
-	public static void prepareClientside(){
-		DataExchangeAPI api = DataExchangeAPI.getInstance();
-		api.initClientside();
-		
-	}
-	
-	/**
-	 * Initializes all datastructures that need to exist in the server component.
-	 * <p>
-	 * This is automatically called by BCLib. You can register {@link DataHandler}-Objects before this Method is called
-	 */
-	public static void prepareServerside(){
-		DataExchangeAPI api = DataExchangeAPI.getInstance();
-		api.initServerSide();
-	}
-	
-	
 	/**
 	 * Sends the Handler.
 	 * <p>
@@ -123,22 +76,62 @@ public class DataExchangeAPI {
 			DataExchangeAPI.getInstance().client.sendToServer(h);
 		}
 	}
-	
+
 	/**
-	 * Automatically called before the player enters the world.
+	 * Registers a File for automatic client syncing.
-	 * <p>
+	 *
-	 * This will send all {@link DataHandler}-Objects that have {@link DataHandlerDescriptor#sendBeforeEnter} set to*
+	 * @param modID The ID of the calling Mod
-	 * {@Code true},
+	 * @param fileName The name of the File
 	 */
-	@Environment(EnvType.CLIENT)
+	public static void addAutoSyncFile(String modID, File fileName){
-	public static void sendOnEnter(){
+		getInstance().addAutoSyncFileData(modID, fileName, false, FileHash.NEED_TRANSFER);
-		getInstance().descriptors.forEach((desc)-> {
+	}
-			if (desc.sendBeforeEnter){
+
-				DataHandler h = desc.JOIN_INSTANCE.get();
+	/**
-				if (!h.getOriginatesOnServer()) {
+	 * Registers a File for automatic client syncing.
-					getInstance().client.sendToServer(h);
+	 *
-				}
+	 * @param modID The ID of the calling Mod
-			}
+	 * @param uniqueID A unique Identifier for the File. (see {@link ru.bclib.api.dataexchange.FileHash#uniqueID} for
-		});
+	 *                 Details
+	 * @param fileName The name of the File
+	 */
+	public static void addAutoSyncFile(String modID, String uniqueID, File fileName){
+		getInstance().addAutoSyncFileData(modID, uniqueID, fileName, false, FileHash.NEED_TRANSFER);
+	}
+
+	/**
+	 * Registers a File for automatic client syncing.
+	 *
+	 * @param modID The ID of the calling Mod
+	 * @param fileName The name of the File
+	 * @param requestContent When {@code true} the content of the file is requested for comparison. This will copy the
+	 *                       entire file from the client to the server.
+	 *                       <p>
+	 *                       You should only use this option, if you need to compare parts of the file in order to decide
+	 *                       If the File needs to be copied. Normally using the {@link ru.bclib.api.dataexchange.FileHash}
+	 *                       for comparison is sufficient.
+	 * @param needTransfer If the predicate returns true, the file needs to get copied to the server.
+	 */
+	public static void addAutoSyncFile(String modID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer){
+		getInstance().addAutoSyncFileData(modID, fileName, requestContent, needTransfer);
+	}
+
+	/**
+	 * Registers a File for automatic client syncing.
+	 *
+	 * @param modID The ID of the calling Mod
+	 * @param uniqueID A unique Identifier for the File. (see {@link ru.bclib.api.dataexchange.FileHash#uniqueID} for
+	 *                 Details
+	 * @param fileName The name of the File
+	 * @param requestContent When {@code true} the content of the file is requested for comparison. This will copy the
+	 *                       entire file from the client to the server.
+	 *                       <p>
+	 *                       You should only use this option, if you need to compare parts of the file in order to decide
+	 *                       If the File needs to be copied. Normally using the {@link ru.bclib.api.dataexchange.FileHash}
+	 *                       for comparison is sufficient.
+	 * @param needTransfer If the predicate returns true, the file needs to get copied to the server.
+	 */
+	public static void addAutoSyncFile(String modID, String uniqueID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer){
+		getInstance().addAutoSyncFileData(modID, uniqueID, fileName, requestContent, needTransfer);
 	}
 }

src/main/java/ru/bclib/api/dataexchange/DataHandler.java

@@ -48,16 +48,16 @@ public abstract class DataHandler {
 		deserializeFromIncomingData(buf, responseSender, false);
 		server.execute(() -> runOnGameThread(null, server, false));
 	}
-	
+
+	protected void serializeData(FriendlyByteBuf buf) {
+	}
+
 	protected void deserializeFromIncomingData(FriendlyByteBuf buf, PacketSender responseSender, boolean isClient){
 	}
 	
 	protected void runOnGameThread(Minecraft client, MinecraftServer server, boolean isClient){
 	}
-	
+
-	protected void serializeData(FriendlyByteBuf buf) {
-	}
-	
 	final protected boolean reply(DataHandler message, MinecraftServer server){
 		if (lastMessageSender==null) return false;
 		message.sendToClient(server, lastMessageSender);

src/main/java/ru/bclib/api/dataexchange/FileHash.java

@@ -0,0 +1,212 @@
+package ru.bclib.api.dataexchange;
+
+import net.minecraft.network.FriendlyByteBuf;
+import org.jetbrains.annotations.NotNull;
+import ru.bclib.BCLib;
+import ru.bclib.api.dataexchange.handler.DataExchange;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.function.Predicate;
+
+/**
+ * Calculates a hash based on the contents of a File.
+ * <p>
+ * A File-Hash contains the md5-sum of the File, as well as its size and byte-values from defined positions
+ * <p>
+ * You can compare instances using {@link #equals(Object)} to determine if two files are
+ * identical.
+ */
+public class FileHash {
+    /**
+     * The md5-hash of the file
+     */
+    @NotNull
+    public final byte[] md5;
+
+    /**
+     * The size (in bytes) of the input.
+     */
+    public final int size;
+
+    /**
+     * a value that is directly calculated from defined byte positions.
+     */
+    public final int value;
+
+    /**
+     * A Unique ID for the referenced File.
+     * <p>
+     * Files with the same {@link #modID} need to have a unique IDs. Normally the filename from {@link #FileHash(String, File, byte[], int, int)}
+     * is used to generated that ID, but you can directly specify one using {@link #FileHash(String, String, byte[], int, int)}.
+     */
+    @NotNull
+    public final String uniqueID;
+
+    /**
+     * The ID of the Mod that is registering the File
+     */
+    @NotNull
+    public final String modID;
+
+    FileHash(String modID, File file, byte[] md5, int size, int value) {
+        this(modID, file.getName(), md5, size, value);
+    }
+
+    FileHash(String modID, String uniqueID, byte[] md5, int size, int value) {
+        Objects.nonNull(modID);
+        Objects.nonNull(uniqueID);
+        Objects.nonNull(md5);
+
+        this.md5 = md5;
+        this.size = size;
+        this.value = value;
+        this.modID = modID;
+        this.uniqueID = uniqueID;
+    }
+
+    private static int ERR_DOES_NOT_EXIST = -10;
+    private static int ERR_IO_ERROR = -20;
+    static FileHash createForEmpty(String modID, String uniqueID, int errCode){
+        return new FileHash(modID, uniqueID, new byte[0], 0, errCode);
+    }
+
+    final static DataExchange.NeedTransferPredicate NEED_TRANSFER = (clientHash, serverHash, content)-> !clientHash.equals(serverHash);
+
+    public boolean noFile() {
+        return md5.length == 0;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("%08x", size)
+            + "-"
+            + String.format("%08x", value)
+            + "-"
+            + getMd5String();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        FileHash fileHash = (FileHash) o;
+        return size == fileHash.size && value == fileHash.value && Arrays.equals(md5, fileHash.md5) && uniqueID.equals(fileHash.uniqueID) && modID.equals(fileHash.modID);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = Objects.hash(size, value, uniqueID, modID);
+        result = 31 * result + Arrays.hashCode(md5);
+        return result;
+    }
+
+    /**
+     * Convert the md5-hash to a human readable string
+     * @return The converted String
+     */
+    public String getMd5String(){
+        return toHexString(md5);
+    }
+
+    /**
+     * Serializes the Object to a buffer
+     * @param buf The buffer to write to
+     */
+    public void serialize(FriendlyByteBuf buf) {
+        buf.writeInt(size);
+        buf.writeInt(value);
+        buf.writeByteArray(md5);
+        DataHandler.writeString(buf, modID);
+        DataHandler.writeString(buf, uniqueID);
+    }
+
+    /**
+     *Deserialize a Buffer to a new {@link FileHash}-Object
+     * @param buf Thea buffer to read from
+     * @return The received String
+     */
+    public static FileHash deserialize(FriendlyByteBuf buf){
+        final int size = buf.readInt();
+        final int value = buf.readInt();
+        final byte[] md5 = buf.readByteArray();
+        final String modID = DataHandler.readString(buf);
+        final String uniqueID = DataHandler.readString(buf);
+
+        return new FileHash(modID, uniqueID, md5, size, value);
+    }
+
+    /**
+     * Converts a byte-array to a hex-string representation
+     * @param bytes The source array
+     * @return The resulting string, or an empty String if the input was {@code null}
+     */
+    public static String toHexString(byte[] bytes) {
+        if (bytes==null) return "";
+
+        StringBuilder sb = new StringBuilder();
+        for (byte b : bytes) {
+            sb.append(String.format("%02x", b));
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Create a new {@link FileHash}.
+     * <p>
+     * Will call {@link #create(String, File, String)} using the name of the File as {@code uniqueID}.
+     * @param modID ID of the calling Mod
+     * @param file The input file
+     *
+     * @return A new Instance. You can compare instances using {@link #equals(Object)} to determine if two files are
+     * identical. Will return {@code null} when an error occurs or the File does not exist
+     */
+    public static FileHash create(String modID, File file){
+        return create(modID, file, file.getName());
+    }
+
+    /**
+     * Create a new {@link FileHash}.
+     * @param modID ID of the calling Mod
+     * @param file The input file
+     * @param uniqueID The unique ID that is used for this File (see {@link FileHash#uniqueID} for Details.
+     * @return A new Instance. You can compare instances using {@link #equals(Object)} to determine if two files are
+     * identical. Will return {@code null} when an error occurs or the File does not exist
+     */
+    public static FileHash create(String modID, File file, String uniqueID){
+        if (!file.exists()) return createForEmpty(modID, uniqueID, ERR_DOES_NOT_EXIST);
+        final Path path = file.toPath();
+
+        int size = 0;
+        byte[] md5 = new byte[0];
+        int value = 0;
+
+        try {
+            byte[] data = Files.readAllBytes(path);
+
+            size = data.length;
+
+            value = size>0 ? (data[size/3] | (data [size/2]<<8) | (data [size/5]<<16)) : -1;
+            if (size>20) value |= data[20]<<24;
+
+            MessageDigest md = MessageDigest.getInstance("MD5");
+            md.update(data);
+            md5 = md.digest();
+
+            return new FileHash(modID, uniqueID, md5, size, value);
+        } catch (IOException e) {
+            BCLib.LOGGER.error("Failed to read file: " + file);
+            return null;
+        } catch (NoSuchAlgorithmException e) {
+            BCLib.LOGGER.error("Unable to build hash for file: " + file);
+        }
+
+        return createForEmpty(modID, uniqueID,  ERR_IO_ERROR);
+    }
+}

src/main/java/ru/bclib/api/dataexchange/handler/DataExchange.java

@@ -0,0 +1,247 @@
+package ru.bclib.api.dataexchange.handler;
+
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+import net.fabricmc.fabric.api.client.networking.v1.ClientLoginConnectionEvents;
+import net.fabricmc.fabric.api.client.networking.v1.ClientPlayConnectionEvents;
+import net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents;
+import net.minecraft.network.FriendlyByteBuf;
+import ru.bclib.api.dataexchange.ConnectorClientside;
+import ru.bclib.api.dataexchange.ConnectorServerside;
+import ru.bclib.api.dataexchange.DataExchangeAPI;
+import ru.bclib.api.dataexchange.DataHandler;
+import ru.bclib.api.dataexchange.DataHandlerDescriptor;
+import ru.bclib.api.dataexchange.FileHash;
+import ru.bclib.util.Pair;
+import ru.bclib.util.Triple;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+abstract public class DataExchange {
+    @FunctionalInterface
+    public interface NeedTransferPredicate  {
+        public boolean test(FileHash clientHash, FileHash serverHash, byte[] content);
+    }
+
+    final static class AutoSyncTriple extends Triple<FileHash, byte[], DataExchange.AutoFileSyncEntry>{
+        public AutoSyncTriple(FileHash first, byte[] second, AutoFileSyncEntry third) {
+            super(first, second, third);
+        }
+    }
+    static class AutoFileSyncEntry {
+        public final NeedTransferPredicate needTransfer;
+        public final File fileName;
+        public final String modID;
+        public final String uniqueID;
+        public final boolean requestContent;
+        private FileHash hash;
+
+        AutoFileSyncEntry(String modID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer) {
+            this(modID, fileName.getName(), fileName, requestContent, needTransfer);
+        }
+
+        AutoFileSyncEntry(String modID, String uniqueID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer) {
+            this.needTransfer = needTransfer;
+            this.fileName = fileName;
+            this.modID = modID;
+            this.uniqueID = uniqueID;
+            this.requestContent = requestContent;
+        }
+
+        public FileHash getFileHash(){
+            if (hash == null) {
+                hash = FileHash.create(modID, fileName, uniqueID);
+            }
+            return hash;
+        }
+
+        public byte[] getContent(){
+            if (!fileName.exists()) return new byte[0];
+            final Path path = fileName.toPath();
+
+            try {
+                return Files.readAllBytes(path);
+            } catch (IOException e) {
+
+            }
+            return new byte[0];
+        }
+
+
+        public void serialize(FriendlyByteBuf buf){
+            getFileHash().serialize(buf);
+            buf.writeBoolean(requestContent);
+
+            if (requestContent) {
+                byte[] content = getContent();
+                buf.writeInt(content.length);
+                buf.writeByteArray(content);
+            }
+        }
+
+        public static AutoSyncTriple deserializeAndMatch(FriendlyByteBuf buf){
+            Pair<FileHash, byte[]> e = deserialize(buf);
+            AutoFileSyncEntry match = findMatching(e.first);
+            return new AutoSyncTriple(e.first, e.second, match);
+        }
+
+        public static Pair<FileHash, byte[]> deserialize(FriendlyByteBuf buf){
+            FileHash hash = FileHash.deserialize(buf);
+            boolean withContent = buf.readBoolean();
+            byte[] data = null;
+            if (withContent) {
+                int size = buf.readInt();
+                data = buf.readByteArray(size);
+            }
+
+            return new Pair(hash, data);
+        }
+
+        public static AutoFileSyncEntry findMatching(FileHash hash){
+            return DataExchange
+                    .getInstance()
+                    .autoSyncFiles
+                    .stream()
+                    .filter(asf -> asf.modID.equals(hash.modID) && asf.uniqueID.equals(hash.uniqueID))
+                    .findFirst()
+                    .orElse(null);
+        }
+    }
+
+    private static DataExchangeAPI instance;
+    protected static DataExchangeAPI getInstance(){
+        if (instance==null){
+            instance = new DataExchangeAPI();
+        }
+        return instance;
+    }
+
+    protected ConnectorServerside server;
+    protected ConnectorClientside client;
+    protected final Set<DataHandlerDescriptor> descriptors;
+    protected final List<AutoFileSyncEntry> autoSyncFiles = new ArrayList<>(4);
+
+    private final Function<DataExchange, ConnectorClientside> clientSupplier;
+    private final Function<DataExchange, ConnectorServerside> serverSupplier;
+
+    protected DataExchange(Function<DataExchange, ConnectorClientside> client, Function<DataExchange, ConnectorServerside> server){
+        descriptors = new HashSet<>();
+        this.clientSupplier = client;
+        this.serverSupplier = server;
+    }
+
+    public Set<DataHandlerDescriptor> getDescriptors() { return descriptors; }
+
+    @Environment(EnvType.CLIENT)
+    protected void initClientside(){
+        if (client!=null) return;
+        client = clientSupplier.apply(this);
+        ClientLoginConnectionEvents.INIT.register((a, b) ->{
+            System.out.println("INIT");
+        });
+        ClientLoginConnectionEvents.QUERY_START.register((a, b) ->{
+            System.out.println("INIT");
+        });
+        ClientPlayConnectionEvents.INIT.register(client::onPlayInit);
+        ClientPlayConnectionEvents.JOIN.register(client::onPlayReady);
+        ClientPlayConnectionEvents.DISCONNECT.register(client::onPlayDisconnect);
+    }
+
+    protected void initServerSide(){
+        if (server!=null) return;
+        server = serverSupplier.apply(this);
+
+        ServerPlayConnectionEvents.INIT.register(server::onPlayInit);
+        ServerPlayConnectionEvents.JOIN.register(server::onPlayReady);
+        ServerPlayConnectionEvents.DISCONNECT.register(server::onPlayDisconnect);
+    }
+
+    /**
+     * Initializes all datastructures that need to exist in the client component.
+     * <p>
+     * This is automatically called by BCLib. You can register {@link DataHandler}-Objects before this Method is called
+     */
+    @Environment(EnvType.CLIENT)
+    public static void prepareClientside(){
+        DataExchange api = DataExchange.getInstance();
+        api.initClientside();
+
+    }
+
+    /**
+     * Initializes all datastructures that need to exist in the server component.
+     * <p>
+     * This is automatically called by BCLib. You can register {@link DataHandler}-Objects before this Method is called
+     */
+    public static void prepareServerside(){
+        DataExchange api = DataExchange.getInstance();
+        api.initServerSide();
+    }
+
+
+
+    /**
+     * Automatically called before the player enters the world.
+     * <p>
+     * This is automatically called by BCLib. It will send all {@link DataHandler}-Objects that have {@link DataHandlerDescriptor#sendBeforeEnter} set to*
+     * {@Code true},
+     */
+    @Environment(EnvType.CLIENT)
+    public static void sendOnEnter(){
+        getInstance().descriptors.forEach((desc)-> {
+            if (desc.sendBeforeEnter){
+                DataHandler h = desc.JOIN_INSTANCE.get();
+                if (!h.getOriginatesOnServer()) {
+                    getInstance().client.sendToServer(h);
+                }
+            }
+        });
+    }
+
+    /**
+     * Registers a File for automatic client syncing.
+     *
+     * @param modID The ID of the calling Mod
+     * @param needTransfer If the predicate returns true, the file needs to get copied to the server.
+     * @param fileName The name of the File
+     * @param requestContent When {@code true} the content of the file is requested for comparison. This will copy the
+     *                       entire file from the client to the server.
+     *                       <p>
+     *                       You should only use this option, if you need to compare parts of the file in order to decide
+     *                       If the File needs to be copied. Normally using the {@link ru.bclib.api.dataexchange.FileHash}
+     *                       for comparison is sufficient.
+     */
+    protected void addAutoSyncFileData(String modID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer){
+        autoSyncFiles.add(new AutoFileSyncEntry(modID, fileName, requestContent, needTransfer));
+    }
+
+    /**
+     * Registers a File for automatic client syncing.
+     *
+     * @param modID The ID of the calling Mod
+     * @param uniqueID A unique Identifier for the File. (see {@link ru.bclib.api.dataexchange.FileHash#uniqueID} for
+     *                 Details
+     * @param needTransfer If the predicate returns true, the file needs to get copied to the server.
+     * @param fileName The name of the File
+     * @param requestContent When {@code true} the content of the file is requested for comparison. This will copy the
+     *                       entire file from the client to the server.
+     *                       <p>
+     *                       You should only use this option, if you need to compare parts of the file in order to decide
+     *                       If the File needs to be copied. Normally using the {@link ru.bclib.api.dataexchange.FileHash}
+     *                       for comparison is sufficient.
+     */
+    protected void addAutoSyncFileData(String modID, String uniqueID, File fileName, boolean requestContent, NeedTransferPredicate needTransfer){
+       autoSyncFiles.add(new AutoFileSyncEntry(modID, uniqueID, fileName, requestContent, needTransfer));
+    }
+}

src/main/java/ru/bclib/api/dataexchange/handler/HelloClient.java

@@ -7,7 +7,6 @@ import net.fabricmc.loader.api.FabricLoader;
 import net.fabricmc.loader.api.ModContainer;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.gui.screens.Screen;
-import net.minecraft.client.gui.screens.worldselection.EditWorldScreen;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.MinecraftServer;
@@ -15,10 +14,12 @@ import ru.bclib.BCLib;
 import ru.bclib.api.dataexchange.DataExchangeAPI;
 import ru.bclib.api.dataexchange.DataHandler;
 import ru.bclib.api.dataexchange.DataHandlerDescriptor;
+import ru.bclib.api.dataexchange.FileHash;
 import ru.bclib.api.datafixer.DataFixerAPI;
-import ru.bclib.gui.screens.ConfirmFixScreen;
 import ru.bclib.gui.screens.WarnBCLibVersionMismatch;
+import ru.bclib.util.Triple;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -26,6 +27,11 @@ import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.function.Consumer;
 
+/**
+ * Sent from the Server to the Client.
+ * <p>
+ * For Details refer to {@link HelloServer}
+ */
 public class HelloClient extends DataHandler {
 	public static DataHandlerDescriptor DESCRIPTOR = new DataHandlerDescriptor(new ResourceLocation(BCLib.MOD_ID, "hello_client"), HelloClient::new, false, false);
 	
@@ -45,20 +51,56 @@ public class HelloClient extends DataHandler {
 	static String getBCLibVersion(){
 		return getModVersion(BCLib.MOD_ID);
 	}
+
+	@Override
+	protected void serializeData(FriendlyByteBuf buf) {
+		final List<String> mods = DataExchangeAPI.registeredMods();
+
+		//write BCLibVersion (=protocol version)
+		buf.writeInt(DataFixerAPI.getModVersion(getBCLibVersion()));
+
+		//write Plugin Versions
+		buf.writeInt(mods.size());
+		for (String modID : mods) {
+			writeString(buf, modID);
+			buf.writeInt(DataFixerAPI.getModVersion(getModVersion(modID)));
+		}
+
+		//send config Data
+		final List<DataExchange.AutoFileSyncEntry> autoSyncFiles = DataExchange.getInstance().autoSyncFiles;
+		buf.writeInt(autoSyncFiles.size());
+		for (DataExchange.AutoFileSyncEntry entry : autoSyncFiles) {
+			System.out.println("Serializing " + entry.getFileHash());
+			entry.serialize(buf);
+		}
+	}
 	
 	String bclibVersion ="0.0.0";
 	Map<String, String> modVersion = new HashMap<>();
+	List<DataExchange.AutoSyncTriple> autoSyncedFiles = null;
 	@Override
 	protected void deserializeFromIncomingData(FriendlyByteBuf buf, PacketSender responseSender, boolean fromClient) {
+		//read BCLibVersion (=protocol version)
 		bclibVersion = DataFixerAPI.getModVersion(buf.readInt());
+
+		//read Plugin Versions
 		modVersion = new HashMap<>();
-		
 		int count = buf.readInt();
-		for (int i=0; i< count; i++){
+		for (int i=0; i< count; i++) {
 			String id = readString(buf);
 			String version = DataFixerAPI.getModVersion(buf.readInt());
 			modVersion.put(id, version);
 		}
+
+		//read config Data
+		count = buf.readInt();
+		autoSyncedFiles = new ArrayList<>(count);
+		for (int i=0; i< count; i++) {
+			System.out.println("Deserializing ");
+			DataExchange.AutoSyncTriple t = DataExchange.AutoFileSyncEntry.deserializeAndMatch(buf);
+			autoSyncedFiles.add(t);
+			System.out.println(t.first);
+		}
 	}
 	
 	@Override
@@ -75,17 +117,13 @@ public class HelloClient extends DataHandler {
 			String ver = getModVersion(e.getKey());
 			BCLib.LOGGER.info("    - " + e.getKey() + " (client="+ver+", server="+ver+")");
 		}
-	}
+
-	
+		for (DataExchange.AutoSyncTriple e : autoSyncedFiles) {
-	@Override
+			if (e.third == null) {
-	protected void serializeData(FriendlyByteBuf buf) {
+				BCLib.LOGGER.info("    - File " + e.first.modID + "." + e.first.uniqueID + ": Does not exist on client.");
-		final List<String> mods = DataExchangeAPI.registeredMods();
+			} else if (e.third.needTransfer.test(e.third.getFileHash(), e.first, e.second)) {
-		buf.writeInt(DataFixerAPI.getModVersion(getBCLibVersion()));
+				BCLib.LOGGER.info("    - File " + e.first.modID + "." + e.first.uniqueID + ": Needs Transfer");
-		
+			}
-		buf.writeInt(mods.size());
-		for (String modID : mods) {
-			writeString(buf, modID);
-			buf.writeInt(DataFixerAPI.getModVersion(getModVersion(modID)));
 		}
 	}
 	

src/main/java/ru/bclib/api/dataexchange/handler/HelloServer.java

@@ -12,6 +12,34 @@ import ru.bclib.api.dataexchange.DataHandler;
 import ru.bclib.api.dataexchange.DataHandlerDescriptor;
 import ru.bclib.api.datafixer.DataFixerAPI;
 
+/**
+ * This message is sent once a player enters the world. It initiates a sequence of Messages that will sync files between both
+ * client and server.
+ * <p>
+ * <tab<le>
+ *     <tr>
+ *         <th>Server</th>
+ *         <th></th>
+ *         <th>Client</th>
+ *         <th></th>
+ *     </tr>
+ *     <tr>
+ *         <td colspan="4">Player enters World</td>
+ *     </tr>
+ *     <tr>
+ *         <td></td>
+ *         <td>&lt;--</td>
+ *         <td>{@link HelloServer}</td>
+ *         <td>Sends the current BLib-Version installed on the Client</td>
+ *     </tr>
+ *	   <tr>
+ *         <td>{@link HelloClient}</td>
+ *         <td>--&gt;</td>
+ *         <td></td>
+ *         <td>Sends the current BClIb-Version and the Version of all Plugins on the Server</td>
+ *     </tr>
+ * </table>
+ */
 public class HelloServer extends DataHandler {
 	public static DataHandlerDescriptor DESCRIPTOR = new DataHandlerDescriptor(new ResourceLocation(BCLib.MOD_ID, "hello_server"), HelloServer::new, false, true);
 	
@@ -19,6 +47,11 @@ public class HelloServer extends DataHandler {
 	public HelloServer() {
 		super(DESCRIPTOR.IDENTIFIER, false);
 	}
+
+	@Override
+	protected void serializeData(FriendlyByteBuf buf) {
+		buf.writeInt(DataFixerAPI.getModVersion(HelloClient.getBCLibVersion()));
+	}
 	
 	@Override
 	protected void deserializeFromIncomingData(FriendlyByteBuf buf, PacketSender responseSender, boolean fromClient) {
@@ -31,9 +64,4 @@ public class HelloServer extends DataHandler {
 		BCLib.LOGGER.info("Received Hello from Client. (server="+localBclibVersion+", client="+bclibVersion+")");
 		reply(new HelloClient(), server);
 	}
-	
-	@Override
-	protected void serializeData(FriendlyByteBuf buf) {
-		buf.writeInt(DataFixerAPI.getModVersion(HelloClient.getBCLibVersion()));
-	}
 }

src/main/java/ru/bclib/api/datafixer/DataFixerAPI.java

@@ -254,6 +254,13 @@ public class DataFixerAPI {
 		players.parallelStream().forEach((file) -> fixPlayer(profile, state, file));
 
 		fixLevel(profile, state, new File(dir, "level.dat"));
+
+		try {
+			profile.patchWorldData();
+		} catch (PatchDidiFailException e){
+			state.didFail = true;
+			BCLib.LOGGER.error(e.getMessage());
+		}
 		
 		if (!state.didFail) {
 			profile.markApplied();

src/main/java/ru/bclib/api/datafixer/MigrationProfile.java

@@ -2,6 +2,7 @@ package ru.bclib.api.datafixer;
 
 import net.minecraft.nbt.CompoundTag;
 import org.jetbrains.annotations.NotNull;
+import ru.bclib.api.WorldDataAPI;
 
 import java.util.Collections;
 import java.util.HashMap;
@@ -11,10 +12,11 @@ import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-class MigrationProfile {
+public class MigrationProfile {
 	final Set<String> mods;
 	final Map<String, String> idReplacements;
 	final List<PatchFunction<CompoundTag, Boolean>> levelPatchers;
+	final List<Patch> worldDataPatchers;
 	
 	private final CompoundTag config;
 	
@@ -28,6 +30,7 @@ class MigrationProfile {
 		
 		HashMap<String, String> replacements = new HashMap<String, String>();
 		List<PatchFunction<CompoundTag, Boolean>> levelPatches = new LinkedList<>();
+		List<Patch> worldDataPatches = new LinkedList<>();
 		for (String modID : mods) {
 			Patch.getALL()
 				 .stream()
@@ -37,6 +40,8 @@ class MigrationProfile {
 						 replacements.putAll(patch.getIDReplacements());
 						 if (patch.getLevelDatPatcher()!=null)
 							 levelPatches.add(patch.getLevelDatPatcher());
+						 if (patch.getWorldDataPatcher()!=null)
+							 worldDataPatches.add(patch);
 						 DataFixerAPI.LOGGER.info("Applying " + patch);
 					 }
 					 else {
@@ -47,6 +52,7 @@ class MigrationProfile {
 		
 		this.idReplacements = Collections.unmodifiableMap(replacements);
 		this.levelPatchers = Collections.unmodifiableList(levelPatches);
+		this.worldDataPatchers = Collections.unmodifiableList(worldDataPatches);
 	}
 	
 	final public void markApplied() {
@@ -66,7 +72,7 @@ class MigrationProfile {
 	}
 	
 	public boolean hasAnyFixes() {
-		return idReplacements.size() > 0 || levelPatchers.size() > 0;
+		return idReplacements.size() > 0 || levelPatchers.size() > 0 || worldDataPatchers.size() > 0;
 	}
 	
 	public boolean replaceStringFromIDs(@NotNull CompoundTag tag, @NotNull String key) {
@@ -87,8 +93,18 @@ class MigrationProfile {
 	public boolean patchLevelDat(@NotNull CompoundTag level) throws PatchDidiFailException {
 		boolean changed = false;
 		for (PatchFunction<CompoundTag, Boolean> f : levelPatchers) {
-			changed |= f.apply(level);
+			changed |= f.apply(level, this);
 		}
 		return changed;
 	}
+
+	public void patchWorldData() throws PatchDidiFailException {
+		for (Patch patch : worldDataPatchers) {
+			CompoundTag root = WorldDataAPI.getRootTag(patch.modID);
+			boolean changed = patch.getWorldDataPatcher().apply(root, this);
+			if (changed) {
+				WorldDataAPI.saveFile(patch.modID);
+			}
+		}
+	}
 }

src/main/java/ru/bclib/api/datafixer/Patch.java

@@ -124,14 +124,25 @@ public abstract class Patch {
 	 * Return a {@link PatchFunction} that is called with the content of <i>level.dat</i>.
 	 * <p>
 	 * The function needs to return {@code true}, if changes were made to the data.
-	 * If an error occurs, the method shoudl throw a {@link PatchDidiFailException}
+	 * If an error occurs, the method should throw a {@link PatchDidiFailException}
 	 *
 	 * The default implementation of this method returns null.
 	 *
-	 * @return The returned function is called a {@code CompoundTag} that contains the
+	 * @return {@code true} if changes were applied and we need to save the data
-	 * contents of <i>level.dat</i>
 	 */
 	public PatchFunction<CompoundTag, Boolean> getLevelDatPatcher() { return null; }
+
+	/**
+	 * Return a {@link PatchFunction} that is called with the content from the
+	 * {@link ru.bclib.api.WorldDataAPI} for this Mod.
+	 * The function needs to return {@code true}, if changes were made to the data.
+	 * If an error occurs, the method should throw a {@link PatchDidiFailException}
+	 *
+	 * The default implementation of this method returns null.
+	 *
+	 * @return {@code true} if changes were applied and we need to save the data
+	 */
+	public PatchFunction<CompoundTag, Boolean> getWorldDataPatcher() { return null; }
 	
 	/**
 	 * Generates ready to use data for all currently registered patches. The list of

src/main/java/ru/bclib/api/datafixer/PatchFunction.java

@@ -2,5 +2,5 @@ package ru.bclib.api.datafixer;
 
 @FunctionalInterface
 public interface PatchFunction<T, R> {
-	R apply(T t) throws PatchDidiFailException;
+	R apply(T t, MigrationProfile profile) throws PatchDidiFailException;
 }

src/main/java/ru/bclib/config/Config.java

@@ -2,6 +2,7 @@ package ru.bclib.config;
 
 import org.jetbrains.annotations.Nullable;
 import ru.bclib.BCLib;
+import ru.bclib.api.dataexchange.DataExchangeAPI;
 import ru.bclib.config.ConfigKeeper.BooleanEntry;
 import ru.bclib.config.ConfigKeeper.Entry;
 import ru.bclib.config.ConfigKeeper.FloatEntry;
@@ -13,16 +14,19 @@ import java.io.File;
 
 public abstract class Config {
 	protected final ConfigKeeper keeper;
-	
+	protected final boolean autoSync;
 	protected abstract void registerEntries();
-	
+
-	public Config(String modID, String group) {
+	protected Config(String modID, String group) {
-		this(modID, group, null);
+		this(modID, group, true);
 	}
 	
-	protected Config(String modID, String group, File path) {
+	protected Config(String modID, String group, boolean autoSync) {
-		this.keeper = new ConfigKeeper(modID, group, path);
+		this.keeper = new ConfigKeeper(modID, group);
 		this.registerEntries();
+		this.autoSync = autoSync;
+
+		DataExchangeAPI.addAutoSyncFile(BCLib.MOD_ID, "CONFIG_"+modID+"_"+group, keeper.getConfigFile());
 	}
 	
 	public void saveChanges() {

src/main/java/ru/bclib/config/ConfigKeeper.java

@@ -22,13 +22,13 @@ public final class ConfigKeeper {
 	private boolean changed = false;
 	
 	public ConfigKeeper(String modID, String group) {
-		this(modID, group, null);
+		this.writer = new ConfigWriter(modID, group);
-	}
-	
-	protected ConfigKeeper(String modID, String group, File path) {
-		this.writer = new ConfigWriter(modID, group, path);
 		this.configObject = writer.load();
 	}
+
+	File getConfigFile(){
+		return this.writer.getConfigFile();
+	}
 	
 	public void save() {
 		if (!changed) return;

src/main/java/ru/bclib/config/ConfigWriter.java

@@ -15,20 +15,17 @@ public class ConfigWriter {
 	private JsonObject configObject;
 	
 	public ConfigWriter(String modID, String configFile) {
-		this(modID, configFile, null);
+		this.configFile = new File(GAME_CONFIG_DIR.resolve(modID).toFile() , configFile + ".json");
-	}
-	
-	public ConfigWriter(String modID, String configFile, File configFolder) {
-		this.configFile = new File((configFolder == null ? GAME_CONFIG_DIR.resolve(modID).toFile() : new File(
-			configFolder,
-			modID
-		)), configFile + ".json");
 		File parent = this.configFile.getParentFile();
 		if (!parent.exists()) {
 			parent.mkdirs();
 		}
 		this.load();
 	}
+
+	File getConfigFile(){
+		return this.configFile;
+	}
 	
 	public JsonObject getConfig() {
 		return configObject;

src/main/java/ru/bclib/config/PathConfig.java

@@ -8,13 +8,13 @@ import ru.bclib.config.ConfigKeeper.IntegerRange;
 import java.io.File;
 
 public class PathConfig extends Config {
-	
+
-	public PathConfig(String modID, String group) {
+	public PathConfig(String modID, String group, boolean autoSync) {
-		this(modID, group, null);
+		super(modID, group, autoSync);
 	}
 	
-	protected PathConfig(String modID, String group, File path) {
+	public PathConfig(String modID, String group) {
-		super(modID, group, path);
+		super(modID, group);
 	}
 	
 	@Override

src/main/java/ru/bclib/config/SessionConfig.java

@@ -1,25 +0,0 @@
-package ru.bclib.config;
-
-import net.minecraft.server.level.ServerLevel;
-import net.minecraft.world.level.storage.LevelStorageSource;
-import ru.bclib.BCLib;
-
-import java.io.File;
-
-public class SessionConfig extends PathConfig {
-	private static File getWorldFolder(LevelStorageSource.LevelStorageAccess session, ServerLevel world) {
-		File dir = session.getDimensionPath(world.dimension());
-		if (!new File(dir, "level.dat").exists()) {
-			dir = dir.getParentFile();
-		}
-		return dir;
-	}
-	
-	public final File levelFolder;
-	
-	public SessionConfig(String modID, String group, LevelStorageSource.LevelStorageAccess session, ServerLevel world) {
-		super(modID, group, new File(getWorldFolder(session, world), BCLib.MOD_ID+"-config"));
-		
-		this.levelFolder = new File(getWorldFolder(session, world), BCLib.MOD_ID+"-config");
-	}
-}

src/main/java/ru/bclib/mixin/client/GameMixin.java

@@ -13,6 +13,6 @@ public class GameMixin {
 	
 	@Inject(method="onStartGameSession", at=@At("TAIL"))
 	public void bcliv_onStart(CallbackInfo ci){
-		DataExchangeAPI.send(new HelloServer());
+		DataExchangeAPI.sendOnEnter();
 	}
 }

src/main/java/ru/bclib/util/Pair.java

@@ -0,0 +1,11 @@
+package ru.bclib.util;
+
+public class Pair <A, B>{
+    public final A first;
+    public final B second;
+
+    public Pair(A first, B second) {
+        this.first = first;
+        this.second = second;
+    }
+}

src/main/java/ru/bclib/util/Triple.java

@@ -0,0 +1,10 @@
+package ru.bclib.util;
+
+public class Triple <A, B, C> extends Pair<A, B>{
+    public final C third;
+
+    public Triple(A first, B second, C third) {
+        super(first, second);
+        this.third = third;
+    }
+}