feat(nf-tower): add dataset:// FileSystem provider

plugins/nf-tower/build.gradle

@@ -26,7 +26,8 @@ nextflowPlugin {
         'io.seqera.tower.plugin.TowerFactory',
         'io.seqera.tower.plugin.TowerFusionToken',
         'io.seqera.tower.plugin.auth.AuthCommandImpl',
-        'io.seqera.tower.plugin.launch.LaunchCommandImpl'
+        'io.seqera.tower.plugin.launch.LaunchCommandImpl',
+        'io.seqera.tower.plugin.dataset.DatasetPathFactory',
     ]
 }
 

plugins/nf-tower/src/main/io/seqera/tower/plugin/dataset/DatasetFileSystem.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2013-2024, Seqera Labs
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.seqera.tower.plugin.dataset;
+
+import java.io.IOException;
+import java.nio.file.FileStore;
+import java.nio.file.FileSystem;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.WatchService;
+import java.nio.file.attribute.UserPrincipalLookupService;
+import java.nio.file.spi.FileSystemProvider;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Minimal read-only FileSystem for the {@code dataset://} scheme.
+ * <p>
+ * Datasets are single files resolved via the Seqera Platform API,
+ * so most filesystem operations (roots, stores, path matching)
+ * are either trivial or unsupported.
+ *
+ * @author Edmund Miller
+ */
+public class DatasetFileSystem extends FileSystem {
+
+    static final String PATH_SEPARATOR = "/";
+
+    private final DatasetFileSystemProvider provider;
+    private final Map<String, ?> env;
+    private volatile boolean open = true;
+
+    DatasetFileSystem(DatasetFileSystemProvider provider, Map<String, ?> env) {
+        this.provider = provider;
+        this.env = env != null ? env : Collections.emptyMap();
+    }
+
+    @Override
+    public FileSystemProvider provider() {
+        return provider;
+    }
+
+    @Override
+    public void close() throws IOException {
+        open = false;
+    }
+
+    @Override
+    public boolean isOpen() {
+        return open;
+    }
+
+    @Override
+    public boolean isReadOnly() {
+        return true;
+    }
+
+    @Override
+    public String getSeparator() {
+        return PATH_SEPARATOR;
+    }
+
+    @Override
+    public Iterable<Path> getRootDirectories() {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public Iterable<FileStore> getFileStores() {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public Set<String> supportedFileAttributeViews() {
+        return Set.of("basic");
+    }
+
+    @Override
+    public Path getPath(String first, String... more) {
+        // Build a dataset path from string components
+        StringBuilder sb = new StringBuilder(first);
+        for (String part : more) {
+            if (!part.isEmpty()) {
+                sb.append(PATH_SEPARATOR).append(part);
+            }
+        }
+        return new DatasetPath(this, sb.toString());
+    }
+
+    @Override
+    public PathMatcher getPathMatcher(String syntaxAndPattern) {
+        throw new UnsupportedOperationException("Dataset filesystem does not support path matching");
+    }
+
+    @Override
+    public UserPrincipalLookupService getUserPrincipalLookupService() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public WatchService newWatchService() throws IOException {
+        throw new UnsupportedOperationException();
+    }
+
+    Map<String, ?> getEnv() {
+        return env;
+    }
+}