[FEATURE] Implement ResourceLayer API

Launcher/src/main/java/pro/gravit/launcher/runtime/backend/LauncherBackendImpl.java

@@ -68,6 +68,7 @@ public class LauncherBackendImpl implements LauncherBackendAPI, TextureUploadExt
     private volatile List<Java> availableJavas;
     private volatile CompletableFuture<List<Java>> availableJavasFuture;
     private volatile CompletableFuture<Void> processHardwareFuture;
+    private volatile Path vfsRootPath;
     private final Map<UUID, CompletableFuture<ServerPingInfo>> pingFutures = new ConcurrentHashMap<>();
 
     @Override
@@ -315,6 +316,14 @@ public boolean isTestMode() {
         }
     }
 
+    @Override
+    public ResourceLayer makeResourceLayer(List<Path> overlayList) {
+        if(vfsRootPath == null) {
+            vfsRootPath = initVfsDirectory();
+        }
+        return new ResourceLayerImpl(vfsRootPath, overlayList);
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public <T extends Extension> T getExtension(Class<T> clazz) {

Launcher/src/main/java/pro/gravit/launcher/runtime/backend/ResourceLayerImpl.java

@@ -0,0 +1,39 @@
+package pro.gravit.launcher.runtime.backend;
+
+import pro.gravit.launcher.base.vfs.Vfs;
+import pro.gravit.launcher.base.vfs.VfsDirectory;
+import pro.gravit.launcher.base.vfs.directory.OverlayVfsDirectory;
+import pro.gravit.launcher.core.backend.LauncherBackendAPI;
+import pro.gravit.utils.helper.SecurityHelper;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+public class ResourceLayerImpl implements LauncherBackendAPI.ResourceLayer {
+    private final Path vfsPath;
+
+    public ResourceLayerImpl(Path basePath, List<Path> overlayList) {
+        if(overlayList == null || overlayList.isEmpty()) {
+            vfsPath = basePath;
+            return;
+        }
+        List<VfsDirectory> overlays = Stream.concat(overlayList.stream(), Stream.of(Path.of("")))
+                .map(basePath::resolve)
+                .map(x -> (VfsDirectory) Vfs.get().resolve(x))
+                .filter(Objects::nonNull)
+                .toList();
+        OverlayVfsDirectory directory = new OverlayVfsDirectory(overlays);
+        String randomName = SecurityHelper.randomStringToken();
+        vfsPath = Path.of(randomName);
+        Vfs.get().put(vfsPath, directory);
+    }
+
+    @Override
+    public URL getURL(Path path) throws IOException {
+        return Vfs.get().getURL(vfsPath.resolve(path));
+    }
+}

LauncherAPI/src/main/java/pro/gravit/launcher/base/vfs/directory/FileVfsDirectory.java

@@ -33,10 +33,10 @@ public VfsEntry find(String name) {
     @Override
     public VfsEntry resolve(Path path) {
         if(path == null) {
-            return null;
+            return this;
         }
 
-        Path target = path.resolve(path);
+        Path target = this.path.resolve(path);
         if(Files.exists(target)) {
             if(Files.isDirectory(target)) {
                 return new FileVfsDirectory(target);

LauncherAPI/src/main/java/pro/gravit/launcher/base/vfs/directory/SimpleVfsDirectory.java

@@ -19,7 +19,7 @@ public VfsEntry find(String name) {
     @Override
     public VfsEntry resolve(Path path)  {
         if(path == null) {
-            return null;
+            return this;
         }
 
         VfsDirectory current = this;
@@ -30,6 +30,9 @@ public VfsEntry resolve(Path path)  {
                 if(entity instanceof SimpleVfsDirectory) {
                     current = newDir;
                 } else {
+                    if (i+1 >= path.getNameCount()) {
+                        return newDir;
+                    }
                     Path newPath = path.subpath(i+1, path.getNameCount());
                     return newDir.resolve(newPath);
                 }

LauncherCore/src/main/java/pro/gravit/launcher/core/backend/LauncherBackendAPI.java

@@ -9,6 +9,8 @@
 import pro.gravit.launcher.core.api.model.UserPermissions;
 import pro.gravit.launcher.core.backend.extensions.Extension;
 
+import java.io.IOException;
+import java.net.URL;
 import java.nio.file.Path;
 import java.util.List;
 import java.util.Set;
@@ -38,6 +40,7 @@ public interface LauncherBackendAPI {
     String getUsername();
     SelfUser getSelfUser();
     boolean isTestMode();
+    ResourceLayer makeResourceLayer(List<Path> overlayList);
     // Extensions
     <T extends Extension> T getExtension(Class<T> clazz);
     void shutdown();
@@ -173,4 +176,8 @@ interface ServerPingInfo {
         int getOnline();
         List<String> getPlayerNames();
     }
+
+    interface ResourceLayer {
+        URL getURL(Path path) throws IOException;
+    }
 }