Introduce preChecks to the DataFixer

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

@@ -139,12 +139,12 @@ public class DataFixerAPI {
 	/**
 	 * Initializes the DataStorage for this world. If the world is new, the patch registry is initialized to the
 	 * current versions of the plugins.
-	 * @param levelPath Folder of the world
+	 * @param levelBaseDir Folder of the world
 	 * @param newWorld {@code true} if this is a fresh world
 	 *
 	 */
-	public static void initializeWorldData(File levelPath, boolean newWorld){
+	public static void initializeWorldData(File levelBaseDir, boolean newWorld){
-		WorldDataAPI.load(new File(levelPath, "data"));
+		WorldDataAPI.load(new File(levelBaseDir, "data"));
 		
 		if (newWorld){
 			getMigrationProfile().markApplied();
@@ -153,7 +153,7 @@ public class DataFixerAPI {
 	}
 	
 	private static boolean fixData(File dir, String levelID, boolean showUI, Consumer<Boolean> onResume) {
-		MigrationProfile profile = loadProfileIfNeeded();
+		MigrationProfile profile = loadProfileIfNeeded(dir);
 		
 		Consumer<Boolean> runFixes = (applyFixes) -> {
 			if (applyFixes) {
@@ -203,13 +203,14 @@ public class DataFixerAPI {
 		return false;
 	}
 	
-	private static MigrationProfile loadProfileIfNeeded(){
+	private static MigrationProfile loadProfileIfNeeded(File levelBaseDir){
 		if (!Configs.MAIN_CONFIG.getBoolean(Configs.MAIN_PATCH_CATEGORY, "applyPatches", true)) {
 			LOGGER.info("World Patches are disabled");
 			return null;
 		}
 		
 		MigrationProfile profile = getMigrationProfile();
+		profile.runPrePatches(levelBaseDir);
 		
 		if (!profile.hasAnyFixes()) {
 			LOGGER.info("Everything up to date");
@@ -254,7 +255,7 @@ public class DataFixerAPI {
 		List<File> players = getAllPlayers(dir);
 		players.parallelStream().forEach((file) -> fixPlayer(profile, state, file));
 
-		fixLevel(profile, state, new File(dir, "level.dat"));
+		fixLevel(profile, state, dir);
 
 		try {
 			profile.patchWorldData();
@@ -269,30 +270,29 @@ public class DataFixerAPI {
 		}
 	}
 	
-	private static void fixLevel(MigrationProfile data, State state, File file) {
+	private static void fixLevel(MigrationProfile profile, State state, File levelBaseDir) {
 		try {
-			LOGGER.info("Inspecting " + file);
+			LOGGER.info("Inspecting level.dat in " + levelBaseDir);
-			CompoundTag level = NbtIo.readCompressed(file);
+			
-			boolean[] changed = { false };
+			//load the level (could already contain patches applied by patchLevelDat)
+			CompoundTag level = profile.getLevelDat(levelBaseDir);
+			boolean[] changed = { profile.isLevelDatChanged() };
+			
+			if (profile.getPrePatchException()!=null){
+				throw profile.getPrePatchException();
+			}
 			
 			if (level.contains("Data")) {
 				CompoundTag dataTag = (CompoundTag)level.get("Data");
 				if (dataTag.contains("Player")) {
 					CompoundTag player = (CompoundTag)dataTag.get("Player");
-					fixPlayerNbt(player, changed, data);
+					fixPlayerNbt(player, changed, profile);
 				}
 			}
 
-			try {
-				changed[0] |= data.patchLevelDat(level);
-			} catch (PatchDidiFailException e){
-				state.didFail = true;
-				BCLib.LOGGER.error(e.getMessage());
-			}
-
 			if (changed[0]) {
-				LOGGER.warning("Writing '{}'", file);
+				LOGGER.warning("Writing '{}'", profile.getLevelDatFile());
-				NbtIo.writeCompressed(level, file);
+				NbtIo.writeCompressed(level, profile.getLevelDatFile());
 			}
 		}
 		catch (Exception e) {

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

@@ -2,10 +2,14 @@ package ru.bclib.api.datafixer;
 
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.ListTag;
+import net.minecraft.nbt.NbtIo;
 import net.minecraft.nbt.Tag;
 import org.jetbrains.annotations.NotNull;
+import ru.bclib.BCLib;
 import ru.bclib.api.WorldDataAPI;
 
+import java.io.File;
+import java.io.IOException;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedList;
@@ -22,6 +26,11 @@ public class MigrationProfile {
 	final Map<String, List<String>> worldDataIDPaths;
 	
 	private final CompoundTag config;
+	private CompoundTag level;
+	private File levelBaseDir;
+	private boolean prePatchChangedLevelDat;
+	private boolean didRunPrePatch;
+	private Exception prePatchException;
 	
 	MigrationProfile(CompoundTag config) {
 		this.config = config;
@@ -64,6 +73,53 @@ public class MigrationProfile {
 		this.worldDataPatchers = Collections.unmodifiableList(worldDataPatches);
 	}
 	
+	final public CompoundTag getLevelDat(File levelBaseDir){
+		if (level == null || this.levelBaseDir==null || !this.levelBaseDir.equals(levelBaseDir)){
+			runPrePatches(levelBaseDir);
+		}
+		return level;
+	}
+	
+	final public boolean isLevelDatChanged(){
+		return prePatchChangedLevelDat;
+	}
+	
+	final public File getLevelDatFile(){
+		return new File(levelBaseDir, "level.dat");
+	}
+	
+	final public Exception getPrePatchException(){
+		return prePatchException;
+	}
+	
+	
+	final public void runPrePatches(File levelBaseDir){
+		if (didRunPrePatch){
+			BCLib.LOGGER.warning("Already did run PrePatches for " + this.levelBaseDir + ".");
+		}
+		BCLib.LOGGER.info("Running Pre Patchers on " + levelBaseDir);
+		
+		this.levelBaseDir = levelBaseDir;
+		this.level = null;
+		this.prePatchException = null;
+		didRunPrePatch = true;
+		
+		this.prePatchChangedLevelDat = runPreLevelPatches(getLevelDatFile());
+	}
+	
+	private boolean runPreLevelPatches(File levelDat){
+		try {
+			level = NbtIo.readCompressed(levelDat);
+			
+			boolean changed = patchLevelDat(level);
+			return changed;
+		}
+		catch (IOException | PatchDidiFailException e) {
+			prePatchException = e;
+			return false;
+		}
+	}
+	
 	final public void markApplied() {
 		for (String modID : mods) {
 			DataFixerAPI.LOGGER.info("Updating Patch-Level for '{}' from {} to {}", modID, currentPatchLevel(modID), Patch.maxPatchLevel(modID));
@@ -81,7 +137,14 @@ public class MigrationProfile {
 	}
 	
 	public boolean hasAnyFixes() {
-		return idReplacements.size() > 0 || levelPatchers.size() > 0 || worldDataPatchers.size() > 0;
+		boolean hasLevelDatPatches;
+		if (didRunPrePatch != false) {
+			hasLevelDatPatches = prePatchChangedLevelDat;
+		} else {
+			hasLevelDatPatches = levelPatchers.size()>0;
+		}
+		
+		return idReplacements.size() > 0 || hasLevelDatPatches || worldDataPatchers.size() > 0;
 	}
 
 	public String replaceStringFromIDs(@NotNull String val) {

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

@@ -3,6 +3,7 @@ package ru.bclib.api.datafixer;
 import net.minecraft.nbt.CompoundTag;
 import org.jetbrains.annotations.NotNull;
 
+import java.io.File;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -151,6 +152,7 @@ public abstract class Patch {
 	 * A {@link #Patch} with a given {@link #level} is only included if the patch-level of the
 	 * world is less
 	 * @param config The current patch-level configuration
+	 * @param levelBaseDir The location of the level
 	 * @return a new {@link MigrationProfile} Object.
 	 */
 	static MigrationProfile createMigrationData(CompoundTag config) {