Add option to keep files during world regen

src/main/java/org/mvplugins/multiverse/core/commands/DeleteCommand.java

@@ -29,6 +29,7 @@
 import org.mvplugins.multiverse.core.world.MultiverseWorld;
 import org.mvplugins.multiverse.core.world.WorldManager;
 import org.mvplugins.multiverse.core.world.helpers.PlayerWorldTeleporter;
+import org.mvplugins.multiverse.core.world.options.DeleteWorldOptions;
 
 @Service
 class DeleteCommand extends CoreCommand {
@@ -94,7 +95,7 @@ private void runDeleteCommand(MVCommandIssuer issuer, MultiverseWorld world, Par
     }
 
     private void doWorldDeleting(MVCommandIssuer issuer, MultiverseWorld world) {
-        worldManager.deleteWorld(world)
+        worldManager.deleteWorld(DeleteWorldOptions.world(world))
                 .onSuccess(deletedWorldName -> {
                     Logging.fine("World delete success: " + deletedWorldName);
                     issuer.sendInfo(MVCorei18n.DELETE_SUCCESS, Replace.WORLD.with(deletedWorldName));

src/main/java/org/mvplugins/multiverse/core/commands/RegenCommand.java

@@ -19,7 +19,6 @@
 
 import org.mvplugins.multiverse.core.command.LegacyAliasCommand;
 import org.mvplugins.multiverse.core.command.MVCommandIssuer;
-import org.mvplugins.multiverse.core.command.MVCommandManager;
 import org.mvplugins.multiverse.core.command.flag.CommandFlag;
 import org.mvplugins.multiverse.core.command.flag.CommandFlagsManager;
 import org.mvplugins.multiverse.core.command.flag.CommandValueFlag;
@@ -30,6 +29,7 @@
 import org.mvplugins.multiverse.core.locale.MVCorei18n;
 import org.mvplugins.multiverse.core.locale.message.Message;
 import org.mvplugins.multiverse.core.locale.message.MessageReplacement.Replace;
+import org.mvplugins.multiverse.core.utils.REPatterns;
 import org.mvplugins.multiverse.core.utils.WorldTickDeferrer;
 import org.mvplugins.multiverse.core.utils.result.AsyncAttemptsAggregate;
 import org.mvplugins.multiverse.core.world.LoadedMultiverseWorld;
@@ -112,7 +112,8 @@ private void doWorldRegening(
                 .seed(parsedFlags.flagValue(flags.seed))
                 .keepWorldConfig(!parsedFlags.hasFlag(flags.resetWorldConfig))
                 .keepGameRule(!parsedFlags.hasFlag(flags.resetGamerules))
-                .keepWorldBorder(!parsedFlags.hasFlag(flags.resetWorldBorder));
+                .keepWorldBorder(!parsedFlags.hasFlag(flags.resetWorldBorder))
+                .keepFiles(parsedFlags.flagValue(flags.keepFiles));
 
         worldManager.regenWorld(regenWorldOptions).onSuccess(newWorld -> {
             Logging.fine("World regen success: " + newWorld);
@@ -153,6 +154,13 @@ private Flags(@NotNull CommandFlagsManager flagsManager) {
         private final CommandFlag resetWorldBorder = flag(CommandFlag.builder("--reset-world-border")
                 .addAlias("-wb")
                 .build());
+
+        private final CommandValueFlag<List> keepFiles = flag(CommandValueFlag.builder("--keep-files", List.class)
+                .addAlias("-f")
+                .completion(input -> List.of("paper-world.yml"))
+                .defaultValue(Collections.emptyList())
+                .context(input -> List.of(REPatterns.COMMA.split(input)))
+                .build());
     }
 
     @Service

src/main/java/org/mvplugins/multiverse/core/utils/FileUtils.java

@@ -9,9 +9,12 @@
 
 import java.io.File;
 import java.io.IOException;
-import java.lang.management.ManagementFactory;
-import java.nio.file.*;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
@@ -20,7 +23,6 @@
 import com.dumptruckman.minecraft.util.Logging;
 import io.vavr.control.Try;
 import jakarta.inject.Inject;
-import org.bukkit.Bukkit;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jvnet.hk2.annotations.Service;
@@ -102,7 +104,11 @@ public File getServerFolder() {
      *         the folder could not be deleted.
      */
     public Try<Void> deleteFolder(File file) {
-        return deleteFolder(file.toPath());
+        return deleteFolder(file, Collections.emptyList());
+    }
+
+    public Try<Void> deleteFolder(File file, Collection<String> keepFiles) {
+        return deleteFolder(file.toPath(), keepFiles);
     }
 
     /**
@@ -112,11 +118,19 @@ public Try<Void> deleteFolder(File file) {
      * @return A {@link Try} that will contain {@code null} if the folder was deleted successfully, or an exception if
      *         the folder could not be deleted.
      */
-    public Try<Void> deleteFolder(Path path) {
+    public Try<Void> deleteFolder(Path path, Collection<String> keepFiles) {
         try (Stream<Path> files = Files.walk(path)) {
             files.sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(file -> {
+                if (!isDirectoryEmpty(file)) {
+                    Logging.finest("Cannot delete folder as it is not empty: " + file);
+                    return;
+                }
+                if (file.isFile() && keepFiles.contains(file.getName())) {
+                    Logging.finest("Keeping file: " + file);
+                    return;
+                }
                 if (!file.delete()) {
-                    Logging.warning("Failed to delete file: " + file);
+                    throw new IllegalStateException("Failed to delete file: " + file);
                 }
             });
             return Try.success(null);
@@ -127,6 +141,17 @@ public Try<Void> deleteFolder(Path path) {
         }
     }
 
+    private boolean isDirectoryEmpty(File file) {
+        if (!file.isDirectory()) {
+            return true;
+        }
+        try (Stream<Path> entries = Files.list(file.toPath())) {
+            return entries.findFirst().isEmpty();
+        } catch (IOException e) {
+            return true;
+        }
+    }
+
     /**
      * Copies all the content of the given folder to the given target folder.
      *

src/main/java/org/mvplugins/multiverse/core/world/WorldManager.java

@@ -55,6 +55,7 @@
 import org.mvplugins.multiverse.core.world.helpers.WorldNameChecker;
 import org.mvplugins.multiverse.core.world.options.CloneWorldOptions;
 import org.mvplugins.multiverse.core.world.options.CreateWorldOptions;
+import org.mvplugins.multiverse.core.world.options.DeleteWorldOptions;
 import org.mvplugins.multiverse.core.world.options.ImportWorldOptions;
 import org.mvplugins.multiverse.core.world.options.KeepWorldSettingsOptions;
 import org.mvplugins.multiverse.core.world.options.RegenWorldOptions;
@@ -211,7 +212,7 @@ private Attempt<CreateWorldOptions, CreateFailureReason> validateCreateWorldOpti
             return worldActionResult(CreateFailureReason.WORLD_EXIST_LOADED, options.worldName());
         } else if (getWorld(options.worldName()).isDefined()) {
             return worldActionResult(CreateFailureReason.WORLD_EXIST_UNLOADED, options.worldName());
-        } else if (worldNameChecker.hasWorldFolder(options.worldName())) {
+        } else if (options.doFolderCheck() && worldNameChecker.hasWorldFolder(options.worldName())) {
             return worldActionResult(CreateFailureReason.WORLD_EXIST_FOLDER, options.worldName());
         }
         return worldActionResult(options);
@@ -506,28 +507,15 @@ private Attempt<String, RemoveFailureReason> removeWorldFromConfig(@NotNull Mult
      * Deletes an existing multiverse world entirely. World will be loaded if it is not already loaded.
      * Warning: This will delete all world files.
      *
-     * @param worldName The name of the world to delete.
+     * @param options The options for customizing the deletion of a world.
      * @return The result of the delete action.
      */
-    public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull String worldName) {
-        return getWorld(worldName)
-                .map(this::deleteWorld)
-                .getOrElse(() -> worldActionResult(DeleteFailureReason.WORLD_NON_EXISTENT, worldName));
-    }
-
-    /**
-     * Deletes an existing multiverse world entirely. World will be loaded if it is not already loaded.
-     * Warning: This will delete all world files.
-     *
-     * @param world The world to delete.
-     * @return The result of the delete action.
-     */
-    public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull MultiverseWorld world) {
-        return getLoadedWorld(world).fold(
-                () -> loadWorld(world)
+    public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull DeleteWorldOptions options) {
+        return getLoadedWorld(options.world()).fold(
+                () -> loadWorld(options.world())
                         .transform(DeleteFailureReason.LOAD_FAILED)
-                        .mapAttempt(this::deleteWorld),
-                this::deleteWorld);
+                        .mapAttempt(world -> doDeleteWorld(world, options)),
+                world -> doDeleteWorld(world, options));
     }
 
     /**
@@ -536,7 +524,7 @@ public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull MultiverseWorld
      * @param world The multiverse world to delete.
      * @return The result of the delete action.
      */
-    public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull LoadedMultiverseWorld world) {
+    private Attempt<String, DeleteFailureReason> doDeleteWorld(@NotNull LoadedMultiverseWorld world, @NotNull DeleteWorldOptions options) {
         AtomicReference<File> worldFolder = new AtomicReference<>();
         return validateWorldToDelete(world)
                 .peek(worldFolder::set)
@@ -548,7 +536,7 @@ public Attempt<String, DeleteFailureReason> deleteWorld(@NotNull LoadedMultivers
                             : Attempt.success(null);
                 })
                 .mapAttempt(() -> removeWorld(world).transform(DeleteFailureReason.REMOVE_FAILED))
-                .mapAttempt(() -> fileUtils.deleteFolder(worldFolder.get()).fold(
+                .mapAttempt(() -> fileUtils.deleteFolder(worldFolder.get(), options.keepFiles()).fold(
                         exception -> worldActionResult(DeleteFailureReason.FAILED_TO_DELETE_FOLDER,
                                 world.getName(), exception),
                         success -> worldActionResult(world.getName())));
@@ -665,9 +653,10 @@ public Attempt<LoadedMultiverseWorld, RegenFailureReason> regenWorld(@NotNull Re
                 .generator(world.getGenerator())
                 .seed(options.seed())
                 .useSpawnAdjust(!shouldKeepSpawnLocation && world.getAdjustSpawn())
-                .worldType(world.getWorldType().getOrElse(WorldType.NORMAL));
+                .worldType(world.getWorldType().getOrElse(WorldType.NORMAL))
+                .doFolderCheck(options.keepFiles().isEmpty());
 
-        return deleteWorld(world)
+        return deleteWorld(DeleteWorldOptions.world(world).keepFiles(options.keepFiles()))
                 .transform(RegenFailureReason.DELETE_FAILED)
                 .mapAttempt(() -> createWorld(createWorldOptions).transform(RegenFailureReason.CREATE_FAILED))
                 .onSuccess(newWorld -> {

src/main/java/org/mvplugins/multiverse/core/world/options/CreateWorldOptions.java

@@ -30,6 +30,7 @@ public final class CreateWorldOptions {
     private long seed;
     private boolean useSpawnAdjust = true;
     private WorldType worldType = WorldType.NORMAL;
+    private boolean doFolderCheck = true;
 
     /**
      * Creates a new {@link CreateWorldOptions} instance with the given world name.
@@ -239,4 +240,24 @@ public boolean useSpawnAdjust() {
     public @NotNull WorldType worldType() {
         return worldType;
     }
+
+    /**
+     * Sets whether to ensure folder does not exist before creating the world.
+     *
+     * @param doFolderCheckInput Whether to do the folder check
+     * @return This {@link CreateWorldOptions} instance
+     */
+    public @NotNull CreateWorldOptions doFolderCheck(boolean doFolderCheckInput) {
+        this.doFolderCheck = doFolderCheckInput;
+        return this;
+    }
+
+    /**
+     * Gets whether to ensure folder does not exist before creating the world.
+     *
+     * @return Whether to do the folder check
+     */
+    public boolean doFolderCheck() {
+        return doFolderCheck;
+    }
 }

src/main/java/org/mvplugins/multiverse/core/world/options/DeleteWorldOptions.java

@@ -0,0 +1,54 @@
+package org.mvplugins.multiverse.core.world.options;
+
+import org.jetbrains.annotations.NotNull;
+import org.mvplugins.multiverse.core.world.MultiverseWorld;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Options for customizing the deletion of a world.
+ */
+public final class DeleteWorldOptions {
+
+    /**
+     * Creates a new {@link DeleteWorldOptions} instance with the given world.
+     *
+     * @param world The world to delete.
+     * @return A new {@link DeleteWorldOptions} instance.
+     */
+    public static @NotNull DeleteWorldOptions world(@NotNull MultiverseWorld world) {
+        return new DeleteWorldOptions(world);
+    }
+
+    private final MultiverseWorld world;
+    private List<String> keepFiles = Collections.emptyList();
+
+    DeleteWorldOptions(MultiverseWorld world) {
+        this.world = world;
+    }
+
+    public MultiverseWorld world() {
+        return world;
+    }
+
+    /**
+     * Sets the files to keep during deletion.
+     *
+     * @param keepFilesInput The files to keep during deletion.
+     * @return This {@link DeleteWorldOptions} instance.
+     */
+    public @NotNull DeleteWorldOptions keepFiles(List<String> keepFilesInput) {
+        this.keepFiles = keepFilesInput == null ? Collections.emptyList() : keepFilesInput.stream().toList();
+        return this;
+    }
+
+    /**
+     * Gets the files to keep during deletion. Note: The list is unmodifiable.
+     *
+     * @return The files to keep during deletion.
+     */
+    public List<String> keepFiles() {
+        return keepFiles;
+    }
+}

src/main/java/org/mvplugins/multiverse/core/world/options/RegenWorldOptions.java

@@ -7,6 +7,9 @@
 
 import org.mvplugins.multiverse.core.world.LoadedMultiverseWorld;
 
+import java.util.Collections;
+import java.util.List;
+
 /**
  * Options for customizing the regeneration of a world.
  */
@@ -31,6 +34,7 @@ public final class RegenWorldOptions implements KeepWorldSettingsOptions {
     private boolean keepWorldBorder = true;
     private boolean randomSeed = false;
     private long seed = UNINITIALIZED_SEED_VALUE;
+    private List<String> keepFiles = Collections.emptyList();
 
     RegenWorldOptions(@NotNull LoadedMultiverseWorld world) {
         this.world = world;
@@ -211,4 +215,24 @@ public long seed() {
         }
         return world.getSeed();
     }
+
+    /**
+     * Sets the files to keep during regeneration.
+     *
+     * @param keepFilesInput The files to keep during regeneration.
+     * @return This {@link RegenWorldOptions} instance.
+     */
+    public @NotNull RegenWorldOptions keepFiles(@Nullable List<String> keepFilesInput) {
+        this.keepFiles = keepFilesInput == null ? Collections.emptyList() : keepFilesInput.stream().toList();
+        return this;
+    }
+
+    /**
+     * Gets the files to keep during regeneration. Note: The list is unmodifiable.
+     *
+     * @return The files to keep during regeneration.
+     */
+    public @NotNull List<String> keepFiles() {
+        return keepFiles;
+    }
 }

src/test/java/org/mvplugins/multiverse/core/world/WorldManagerTest.kt

@@ -9,6 +9,7 @@ import org.mvplugins.multiverse.core.TestWithMockBukkit
 import org.mvplugins.multiverse.core.event.world.*
 import org.mvplugins.multiverse.core.world.options.CloneWorldOptions
 import org.mvplugins.multiverse.core.world.options.CreateWorldOptions
+import org.mvplugins.multiverse.core.world.options.DeleteWorldOptions
 import org.mvplugins.multiverse.core.world.options.RegenWorldOptions
 import org.mvplugins.multiverse.core.world.options.UnloadWorldOptions
 import org.mvplugins.multiverse.core.world.reasons.CloneFailureReason
@@ -112,8 +113,10 @@ class WorldManagerTest : TestWithMockBukkit() {
 
     @Test
     fun `Delete world`() {
-        assertTrue(worldManager.deleteWorld(world).isSuccess)
+        assertTrue(File(Bukkit.getWorldContainer(), "world").isDirectory)
+        assertTrue(worldManager.deleteWorld(DeleteWorldOptions.world(world)).isSuccess)
         assertFalse(worldManager.getLoadedWorld("world").isDefined)
+        assertFalse(File(Bukkit.getWorldContainer(), "world").isDirectory)
 
         assertThat(server.pluginManager, hasFiredEventInstance(MVWorldDeleteEvent::class.java))
         assertThat(server.pluginManager, hasFiredEventInstance(MVWorldUnloadedEvent::class.java))