"""IMP-45 (#74) u6 — subprocess smoke for the slide-level CSS override axis.

End-to-end guard that the ``slide_overrides.css`` frontmatter axis added
in u2 propagates through the pipeline (u4) and lands in ``final.html``
via :func:`src.slide_css_injector.inject_slide_css` (u3).

The fixture is the new ``slide_overrides.css`` frontmatter block in
``samples/mdx_batch/04.mdx`` (u6 migration of the legacy frontend-only
``MDX04_DEFAULT_OVERRIDE_CSS`` constant). The pipeline is spawned via
``python -m src.phase_z2_pipeline 04.mdx <run_id>`` so the assertion
applies to the on-disk artifact CI / CLI / regression all observe, not
to a live iframe view.

The subprocess returncode is intentionally NOT asserted: mdx04 has known
downstream issues (see ``test_pipeline_smoke_imp85.py`` —
``test_mdx04_no_longer_emits_imp85_crash_signature``) that are tracked
on a separate axis. Step 13 runs before the downstream failure surface,
so ``final.html`` is written with the injected slide CSS marker
regardless. The test asserts ``final.html`` exists and contains both
the IMP-45 sentinel marker and a distinctive CSS substring from the
migrated frontmatter block.
"""
from __future__ import annotations

import subprocess
import sys
import uuid
from pathlib import Path

REPO_ROOT = Path(__file__).resolve().parents[1]
SAMPLES_DIR = REPO_ROOT / "samples" / "mdx_batch"
RUNS_DIR = REPO_ROOT / "data" / "runs"

# IMP-45 (#74) u3 marker sentinel emitted by
# :func:`src.slide_css_injector.inject_slide_css` around the injected
# ``<style>`` block. Match the ``_IMP45_STYLE_MARKER_OPEN`` constant in
# ``src/slide_css_injector.py`` byte-for-byte.
IMP45_OPEN_MARKER = "<!--IMP45-SLIDE-CSS:OPEN-->"
IMP45_CLOSE_MARKER = "<!--IMP45-SLIDE-CSS:CLOSE-->"

# Distinctive substring from the migrated frontmatter block in
# ``samples/mdx_batch/04.mdx``. ``f29b__cell:nth-child(n+3)`` is unique
# to the MDX04 slide-level override CSS and does not appear elsewhere in
# the slide_base / partial templates, so its presence in ``final.html``
# is sufficient evidence that the frontmatter axis fed the injector.
MDX04_DISTINCTIVE_CSS_SUBSTRING = ".f29b__cell:nth-child(n+3)"


def _run_pipeline(mdx_name: str, run_id: str, timeout: int = 240) -> subprocess.CompletedProcess:
    """Spawn ``python -m src.phase_z2_pipeline <mdx> <run_id>``."""
    return subprocess.run(
        [
            sys.executable,
            "-m",
            "src.phase_z2_pipeline",
            str(SAMPLES_DIR / mdx_name),
            run_id,
        ],
        capture_output=True,
        text=True,
        timeout=timeout,
        cwd=str(REPO_ROOT),
    )


def _unique_run_id(prefix: str) -> str:
    return f"{prefix}_imp45_slide_css_smoke_{uuid.uuid4().hex[:8]}"


def test_mdx04_slide_overrides_css_lands_in_final_html() -> None:
    """mdx04 ``slide_overrides.css`` frontmatter must reach ``final.html``.

    Contract pins both the IMP-45 marker sentinel and a distinctive CSS
    substring from the migrated frontmatter block so a regression in
    either the frontmatter extractor (u2), the kwarg forwarding (u4),
    or the injector (u3) is caught by this single smoke.
    """
    run_id = _unique_run_id("mdx04")
    cp = _run_pipeline("04.mdx", run_id)

    final_html_path = RUNS_DIR / run_id / "phase_z2" / "final.html"
    assert final_html_path.is_file(), (
        f"final.html not found at {final_html_path}\n"
        f"--- stderr tail ---\n{cp.stderr[-1500:]}\n"
        f"--- stdout tail ---\n{cp.stdout[-1500:]}"
    )
    html = final_html_path.read_text(encoding="utf-8")

    assert IMP45_OPEN_MARKER in html, (
        f"IMP-45 open marker missing from mdx04 final.html ({final_html_path}).\n"
        f"slide_overrides.css frontmatter axis did not reach the injector."
    )
    assert IMP45_CLOSE_MARKER in html, (
        f"IMP-45 close marker missing from mdx04 final.html ({final_html_path}).\n"
        f"Marker wrap appears unbalanced — check inject_slide_css() output."
    )
    assert MDX04_DISTINCTIVE_CSS_SUBSTRING in html, (
        f"Migrated frontmatter CSS substring "
        f"{MDX04_DISTINCTIVE_CSS_SUBSTRING!r} missing from mdx04 final.html "
        f"({final_html_path}). The slide_overrides.css block did not propagate."
    )