1 files changed, 60 insertions, 0 deletions
diff --git a/pre_commit_hooks/check_vcs_permalinks.py b/pre_commit_hooks/check_vcs_permalinks.py
new file mode 100644
index 0000000..1c77b9a
--- /dev/null
+++ b/pre_commit_hooks/check_vcs_permalinks.py
@@ -0,0 +1,60 @@
+import argparse
+import re
+import sys
+from typing import List
+from typing import Optional
+from typing import Pattern
+from typing import Sequence
+
+
+def _get_pattern(domain: str) -> Pattern[bytes]:
+    regex = (
+        rf'https://{domain}/[^/ ]+/[^/ ]+/blob/'
+        r'(?![a-fA-F0-9]{4,64}/)([^/. ]+)/[^# ]+#L\d+'
+    )
+    return re.compile(regex.encode())
+
+
+def _check_filename(filename: str, patterns: List[Pattern[bytes]]) -> int:
+    retv = 0
+    with open(filename, 'rb') as f:
+        for i, line in enumerate(f, 1):
+            for pattern in patterns:
+                if pattern.search(line):
+                    sys.stdout.write(f'{filename}:{i}:')
+                    sys.stdout.flush()
+                    sys.stdout.buffer.write(line)
+                    retv = 1
+    return retv
+
+
+def main(argv: Optional[Sequence[str]] = None) -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*')
+    parser.add_argument(
+        '--additional-github-domain',
+        dest='additional_github_domains',
+        action='append',
+        default=['github.com'],
+    )
+    args = parser.parse_args(argv)
+
+    patterns = [
+        _get_pattern(domain)
+        for domain in args.additional_github_domains
+    ]
+
+    retv = 0
+
+    for filename in args.filenames:
+        retv |= _check_filename(filename, patterns)
+
+    if retv:
+        print()
+        print('Non-permanent github link detected.')
+        print('On any page on github press [y] to load a permalink.')
+    return retv
+
+
+if __name__ == '__main__':
+    raise SystemExit(main())