lib: rewrite manifest2po in Python

Extracting translatable strings from manifests is easy enough to do in
pure Python and removes an dependency on node_modules.

The differences in the Python implementation versus the JavaScript
version:
- no longer relies on global state to gather the msgid's
- doesn't encode duplicate filenames for the same msgid

pkg/lib/manifest2po

@@ -0,0 +1,114 @@
+#!/usr/bin/python3
+# This file is part of Cockpit.
+#
+# Copyright (C) 2025 Red Hat, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import argparse
+import collections
+import json
+import pathlib
+import re
+from typing import Any, DefaultDict, Dict, Iterable, List, Set
+
+PO_HEADER = """msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE_VERSION\\n"
+"MIME-Version: 1.0\\n"
+"Content-Type: text/plain; charset=UTF-8\\n"
+"Content-Transfer-Encoding: 8bit\\n"
+"X-Generator: Cockpit manifest2po\\n"
+"""
+
+
+def get_docs_strings(docs: List[Dict[str, str]]) -> Iterable[str]:
+    for doc in docs:
+        assert 'label' in doc, 'doc entry without label'
+        yield doc['label']
+
+
+def get_keyword_strings(keywords: List[Dict[str, List[str]]]) -> Iterable[str]:
+    for keyword in keywords:
+        assert 'matches' in keyword, 'keywords entry without matches'
+        for match in keyword['matches']:
+            yield match
+
+
+def get_menu_strings(menu: Dict[str, Any]) -> Iterable[str]:
+    for _, entry in menu.items():
+        if 'label' in entry:
+            yield entry['label']
+        if 'keywords' in entry:
+            yield from get_keyword_strings(entry['keywords'])
+        if 'docs' in entry:
+            yield from get_docs_strings(entry['docs'])
+
+
+def get_bridges_strings(bridges: List[Dict[str, str]]) -> Iterable[str]:
+    for bridge in bridges:
+        if 'label' in bridge:
+            yield bridge['label']
+
+
+def get_manifest_strings(manifest: Dict[str, Any]) -> Iterable[str]:
+    if 'menu' in manifest:
+        yield from get_menu_strings(manifest['menu'])
+    if 'tools' in manifest:
+        yield from get_menu_strings(manifest['tools'])
+    if 'bridges' in manifest:
+        yield from get_bridges_strings(manifest['bridges'])
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(prog='manifest2po',
+                                     description='Extracts translatable strings from manifest.json files')
+    parser.add_argument('-d', '--directory', help='Base directory for input files')
+    parser.add_argument('-o', '--output', help='Output files', required=True)
+    parser.add_argument('files', nargs='+', help='One or more input files', type=pathlib.Path, metavar='FILE')
+
+    args = parser.parse_args()
+    strings: DefaultDict[str, Set[str]] = collections.defaultdict(set)
+
+    file: pathlib.Path
+    for file in args.files:
+        if file.name != 'manifest.json':
+            continue
+
+        # Qualify the filename if necessary
+        full_path = args.directory / file if args.directory else file
+        with open(full_path, 'r') as fp:
+            data = fp.read()
+
+            # There are variables which when not substituted can cause JSON.parse to fail
+            # Dummy replace them. None variable is going to be translated anyway
+            safe_data = re.sub(r"@.+?@", "1", data)
+            manifest = json.loads(safe_data)
+            for msgid in get_manifest_strings(manifest):
+                strings[msgid].add(str(file))
+
+    # Write PO file
+    with open(args.output, "w") as fp:
+        fp.write(PO_HEADER)
+        for msgid in strings:
+            manifest_filenames = ' '.join([f'{fname}:0' for fname in strings[msgid]])
+            fp.write(f"""
+#: {manifest_filenames}
+msgid "{msgid}"
+msgstr ""
+""")
+
+
+if __name__ == "__main__":
+    main()

po/Makefile.am

@@ -24,9 +24,9 @@ po/cockpit.js.pot:
 		$$( cd $(srcdir) && find pkg/ ! -name 'test-*' -name '*.[jt]s' -o -name '*.[jt]sx') | \
 		sed '/^#/ s/, c-format//' > $@
 
-po/cockpit.manifest.pot: $(srcdir)/package-lock.json
+po/cockpit.manifest.pot:
 	$(AM_V_GEN) mkdir -p $(dir $@) && \
-	$(srcdir)/pkg/lib/manifest2po.js -d $(srcdir) -o $@ \
+	$(srcdir)/pkg/lib/manifest2po -d $(srcdir) -o $@ \
 		$$(cd $(srcdir) && find pkg/ -name 'manifest.json')
 
 po/cockpit.appstream.pot: