#!/usr/bin/env python3
"""Validate the user guide PDF generated by l3build."""
from pathlib import Path
import re

root = Path(__file__).resolve().parents[1]
pdf = root / "calendar-grid-doc.pdf"
if not pdf.is_file() or pdf.stat().st_size < 10_000:
    raise SystemExit("calendar-grid-doc.pdf is missing or unexpectedly small")
if pdf.read_bytes()[:5] != b"%PDF-":
    raise SystemExit("calendar-grid-doc.pdf has no PDF signature")
logs = [root / "calendar-grid-doc.log", *root.glob("build/**/calendar-grid-doc.log")]
log = next((candidate for candidate in logs if candidate.is_file()), None)
if log is None:
    raise SystemExit("calendar-grid-doc.log is missing; cannot verify the generated page count")
match = re.search(r"Output written on .*?\((\d+) pages?\)\.", log.read_text(errors="replace"))
if not match:
    raise SystemExit("The XeLaTeX transcript has no successful PDF page-count record")
pages = int(match.group(1))
if not 3 <= pages <= 40:
    raise SystemExit(f"Unexpected documentation page count: {pages}")
print(f"Documentation PDF valid: {pdf.stat().st_size} bytes, {pages} pages")