#!/usr/bin/env python3
"""layout-probe — find controls that render but cannot be clicked.

WHY THIS EXISTS. On 2026-09-21 the operator reported "release button covers
delete button". Both controls were `position:absolute` on the same corner of a
kept card, and `release` was the later sibling, so it painted over the × with
30x22 px of overlap on a 30px button. `elementFromPoint` at the ×'s centre
returned the release form: the × was 100% unclickable from the day it shipped.

Nothing in the test suite could have caught it. The markup was correct, the
route was correct, the CSS was individually valid. OCCLUSION IS A PROPERTY OF
THE RENDERED LAYOUT, and the only instrument that sees it is a browser.

This is the second control shipped inert in two days — the first was a reveal
button whose handler Jinja discarded. Both were reported by the operator, both
would have taken ten seconds to catch by looking at the page.

USAGE
    <a python with playwright> scripts/layout-probe.py [URL ...]

Exits 0 if every control is hittable, 1 if any is occluded. No arguments
probes the booth index and every booth linked from it.
"""
import sys
from playwright.sync_api import sync_playwright

DEFAULT = "http://10.100.10.50:8090/"

# Does a click at this element's centre actually reach it?
HIT = """(el) => {
  // ⚠ Use getClientRects()[0], NOT getBoundingClientRect(). For an INLINE
  // element that WRAPS, the bounding rect is the union of its line boxes and
  // its geometric centre can land in the gutter between lines — on the parent,
  // not on the element. The third version of this probe reported three zip
  // links as OCCLUDED for exactly that reason: long booth names wrapped the
  // link, and `elementFromPoint` correctly returned the parent .sub div. Real
  // geometry, wrong question. Per-line rects ask the right one.
  const rects = el.getClientRects();
  const r = rects.length ? rects[0] : el.getBoundingClientRect();
  if (r.width === 0 || r.height === 0) return 'ZERO-SIZE';
  const x = r.x + r.width / 2, y = r.y + r.height / 2;
  if (x < 0 || y < 0 || x > innerWidth || y > innerHeight) return 'OFF-SCREEN';
  const top = document.elementFromPoint(x, y);
  if (!top) return 'OFF-SCREEN';
  // `top.contains(el)` is NOT a hit and must never be added back. An ANCESTOR
  // receiving the click is precisely what occlusion looks like when the
  // overlay is a parent or a parent's ::after, and an ancestor trivially
  // contains its descendant — that clause made version one report OK for a
  // real overlay. A DESCENDANT receiving it is fine: <a><img> resolves to the
  // img and the anchor still gets the click.
  return (el === top || el.contains(top)) ? 'OK' : 'OCCLUDED';
}"""


def probe(page, url: str) -> list[str]:
    bad = []
    page.goto(url, wait_until="networkidle")
    # Hover every card first: these UIs reveal controls on hover, and an
    # opacity-0 control still occupies layout and still occludes.
    for card in page.locator("article.card").all():
        try:
            card.hover(timeout=1500)
        except Exception:
            pass
    for el in page.locator("button, a.dl-link, a.thumb").all():
        try:
            # ⚠ elementFromPoint is VIEWPORT-relative. Without scrolling first,
            # every control below the fold reports OCCLUDED and the probe
            # drowns its real findings in noise — which is what the second
            # version did on a page with sixteen kept booths.
            el.scroll_into_view_if_needed(timeout=1500)
            verdict = el.evaluate(HIT)
        except Exception:
            continue
        if verdict in ("OCCLUDED", "ZERO-SIZE"):
            label = (el.get_attribute("aria-label")
                     or el.get_attribute("title")
                     or (el.text_content() or "").strip()[:30] or "?")
            bad.append(f"{url}  {verdict:<10} {label}")
    return bad


def main(argv: list[str]) -> int:
    urls = argv[1:] or [DEFAULT]
    failures = []
    with sync_playwright() as pw:
        b = pw.chromium.launch()
        pg = b.new_page(viewport={"width": 1400, "height": 900})
        for u in urls:
            failures += probe(pg, u)
        b.close()
    if failures:
        print("UNCLICKABLE CONTROLS:")
        for f in failures:
            print(" ", f)
        return 1
    print(f"all controls hittable across {len(urls)} page(s)")
    return 0


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