Add seqera:// data-links support to nf-tower filesystem

plugins/nf-tower/src/main/io/seqera/tower/plugin/datalink/PagedDataLinkContent.groovy

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2013-2026, 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.datalink
+
+import groovy.transform.CompileStatic
+import io.seqera.tower.model.DataLinkItem
+
+/**
+ * Lazy, paginated view over a data-link's content.
+ *
+ * The first page is fetched eagerly by the producer so callers can inspect
+ * {@link #getOriginalPath()} and {@link #getFirstPage()} without triggering
+ * additional HTTP calls. Iterating yields items from the first page followed
+ * by subsequent pages fetched on demand via the injected page fetcher.
+ */
+@CompileStatic
+class PagedDataLinkContent implements Iterable<DataLinkItem> {
+
+    /**
+     * Opaque page fetcher. Given a {@code nextPageToken}, returns the next page
+     * as a map with keys {@code objects} ({@code List<DataLinkItem>}) and
+     * {@code nextPageToken} ({@code String}, null if no more pages).
+     */
+    static interface PageFetcher {
+        Map<String, Object> fetch(String nextPageToken) throws IOException
+    }
+
+    private final String originalPath
+    private final List<DataLinkItem> firstPage
+    private final String firstPageNextToken
+    private final PageFetcher pageFetcher
+
+    PagedDataLinkContent(String originalPath,
+                         List<DataLinkItem> firstPage,
+                         String firstPageNextToken,
+                         PageFetcher pageFetcher) {
+        this.originalPath = originalPath
+        this.firstPage = firstPage ?: Collections.<DataLinkItem>emptyList()
+        this.firstPageNextToken = firstPageNextToken
+        this.pageFetcher = pageFetcher
+    }
+
+    String getOriginalPath() { originalPath }
+
+    /** First page, loaded eagerly — bounded in size by the server's page size. */
+    List<DataLinkItem> getFirstPage() { Collections.unmodifiableList(firstPage) }
+
+    boolean isEmpty() { firstPage.isEmpty() && !firstPageNextToken }
+
+    @Override
+    Iterator<DataLinkItem> iterator() {
+        return new PagedIterator(firstPage, firstPageNextToken, pageFetcher)
+    }
+
+    /** Lazy iterator that paginates on demand. */
+    @CompileStatic
+    private static class PagedIterator implements Iterator<DataLinkItem> {
+        private Iterator<DataLinkItem> current
+        private String nextToken
+        private final PageFetcher fetcher
+
+        PagedIterator(List<DataLinkItem> firstPage, String firstPageNextToken, PageFetcher fetcher) {
+            this.current = firstPage.iterator()
+            this.nextToken = firstPageNextToken
+            this.fetcher = fetcher
+        }
+
+        @Override
+        boolean hasNext() {
+            while (!current.hasNext()) {
+                if (!nextToken) return false
+                try {
+                    final page = fetcher.fetch(nextToken)
+                    final items = (page?.objects ?: []) as List<DataLinkItem>
+                    current = items.iterator()
+                    nextToken = page?.nextPageToken as String
+                } catch (IOException e) {
+                    throw new UncheckedIOException(e)
+                }
+            }
+            return true
+        }
+
+        @Override
+        DataLinkItem next() {
+            if (!hasNext()) throw new NoSuchElementException()
+            return current.next()
+        }
+    }
+}