Support GNU package indexing

Signed-off-by: Keshav Priyadarshi <git@keshav.space>

Author: keshav-space

minecode/visitors/gnu.py

@@ -0,0 +1,41 @@
+#
+# Copyright (c) nexB Inc. and others. All rights reserved.
+# purldb is a trademark of nexB Inc.
+# SPDX-License-Identifier: Apache-2.0
+# See http://www.apache.org/licenses/LICENSE-2.0 for the license text.
+# See https://github.com/nexB/purldb for support or download.
+# See https://aboutcode.org for more information about nexB OSS projects.
+#
+
+
+import logging
+
+from packageurl import PackageURL
+
+from minecode import priority_router
+from minecode.visitors.generic import map_directory_listed_package
+
+logger = logging.getLogger(__name__)
+handler = logging.StreamHandler()
+logger.addHandler(handler)
+logger.setLevel(logging.INFO)
+
+
+@priority_router.route("pkg:gnu/.*")
+def process_request(purl_str):
+    """
+    Process `priority_resource_uri` containing a GNU Package URL (PURL) as a
+    URI.
+
+    This involves obtaining Package information for the PURL using
+    https://github.com/nexB/fetchcode and using it to create a new
+    PackageDB entry. The package is then added to the scan queue afterwards.
+    """
+    package_url = PackageURL.from_string(purl_str)
+    if not package_url.version:
+        return
+
+    error_msg = map_directory_listed_package(package_url)
+
+    if error_msg:
+        return error_msg