#!/usr/bin/env python3
# /// script
# requires-python = ">=3.11"
# ///
"""stamp `/static/<file>?v=<hash>` references in static/index.html with each file's content hash.

cloudflare hands browsers a 4 hour cache lifetime for /static/*.js regardless of the
origin header, so a changed script is invisible until its url changes. index.html is
not edge cached, so a stamped url takes effect within its own 5 minute max-age.

    uv run scripts/stamp_static.py          rewrite stale stamps
    uv run scripts/stamp_static.py --check  exit 1 if any stamp is stale
"""

import hashlib
import re
import sys
from pathlib import Path

STATIC = Path(__file__).resolve().parent.parent / "static"
REF = re.compile(r'(/static/([A-Za-z0-9._\'-]+)\?v=)([0-9a-f]*)')


def digest(name: str) -> str:
    return hashlib.sha256((STATIC / name).read_bytes()).hexdigest()[:10]


def stamped(html: str) -> str:
    return REF.sub(lambda m: m.group(1) + digest(m.group(2)), html)


def main() -> int:
    index = STATIC / "index.html"
    html = index.read_text()
    fresh = stamped(html)
    if fresh == html:
        return 0
    if "--check" in sys.argv[1:]:
        print("static/index.html has stale ?v= stamps; run: uv run scripts/stamp_static.py", file=sys.stderr)
        return 1
    index.write_text(fresh)
    print("stamped static/index.html")
    return 0


if __name__ == "__main__":
    sys.exit(main())