src/lib/pdf_export/fetch_font.py

"""One-shot helper to (re)download the bundled Arabic font.

Run if `src/lib/pdf_export/fonts/NotoNaskhArabic-Regular.ttf` is missing
(e.g. fresh checkout that excluded it from git, or you wiped it).

    python -m src.lib.pdf_export.fetch_font

Pinned to a notofonts.github.io tree on jsdelivr — same upstream source
as Google Fonts, but a stable filename layout and no auth.
"""

from __future__ import annotations

import hashlib
import sys
import urllib.request
from pathlib import Path

URL = (
    "https://cdn.jsdelivr.net/gh/notofonts/notofonts.github.io@main/"
    "fonts/NotoNaskhArabic/full/ttf/NotoNaskhArabic-Regular.ttf"
)
EXPECTED_SIZE = 291980  # bytes; sanity check, not a hard pin
OUT = Path(__file__).resolve().parent / "fonts" / "NotoNaskhArabic-Regular.ttf"


def main() -> int:
    OUT.parent.mkdir(parents=True, exist_ok=True)
    print(f"Fetching {URL}")
    req = urllib.request.Request(URL, headers={"User-Agent": "patristic-arabic-library/0.1"})
    with urllib.request.urlopen(req, timeout=30) as r:
        data = r.read()
    print(f"  {len(data):,} bytes  SHA-256={hashlib.sha256(data).hexdigest()[:16]}…")
    if abs(len(data) - EXPECTED_SIZE) > 50_000:
        print(
            f"WARN: size {len(data):,} drifted from expected {EXPECTED_SIZE:,}. "
            f"The upstream may have changed; verify before relying on it."
        )
    OUT.write_bytes(data)
    print(f"Wrote {OUT}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())