"""Computed-style snapshot regression for ``static/style.css``.

The stylesheet is one 51k-line file whose result depends on source order, so an
extraction that "looks fine" can still change which declaration wins. These
tests capture ``getComputedStyle`` over a fixed element inventory across pages,
viewports, themes and density modes, and compare the hash against
``tests/css_snapshot/baseline.json``.

Run ``python scripts/css_snapshot.py --write-baseline`` to re-record the
baseline, and only after confirming the change is intended - see
``tests/css_snapshot/README.md``.
"""
import os

import pytest

from tests.helpers.cli_loader import load_script

snapshot = load_script("css_snapshot.py")

_HAS_BROWSER = snapshot.playwright_available()
_requires_browser = pytest.mark.skipif(
    not _HAS_BROWSER,
    reason="node with the playwright package is required (npm ci)",
)

# The session static server publishes its ephemeral origin here. The literal
# fallback is the fixed port the fixture used before it moved to an ephemeral
# one, so this module works on either revision.
STATIC_ORIGIN = os.environ.get("ODYSSEUS_TEST_STATIC_ORIGIN", "http://127.0.0.1:7011")

# One conflicting selector used to prove the harness is actually sensitive to
# source order. `.attach-strip` is declared three times at the top level of
# style.css with different margin, min-height and padding, so swapping the
# first two changes which declaration wins without changing a single byte of
# any individual rule.
CONFLICTING_SELECTOR = ".attach-strip"


def test_baseline_covers_every_inventory_entry():
    """The committed baseline and the inventory describe the same surface.

    Cheap and browserless: it catches an inventory entry added without
    re-recording the baseline, which would otherwise look like a pass because
    nothing compares an absent key.
    """
    inventory = snapshot.load_inventory()
    baseline = snapshot.load_baseline()

    variant_names = {variant["name"] for variant in inventory["variants"]}
    for page in inventory["pages"]:
        name = page["name"]
        assert name in baseline["elements"], f"{name} missing from the baseline"
        expected_keys = {entry["key"] for entry in page.get("elements", [])}
        expected_keys |= set(page.get("bench", []))
        assert set(baseline["elements"][name]) == expected_keys, (
            f"{name}: baseline elements differ from the inventory; "
            "re-record with scripts/css_snapshot.py --write-baseline"
        )
        assert set(baseline["variants"][name]) == variant_names


@_requires_browser
def test_computed_styles_match_the_committed_baseline():
    captured = snapshot.capture(STATIC_ORIGIN)

    assert captured["missing"] == {}, (
        "inventory entries matched no element - the markup moved under the "
        f"harness: {captured['missing']}"
    )

    summary = snapshot.summarize(captured["snapshot"])
    drift = snapshot.compare(snapshot.load_baseline(), summary)
    assert not drift["elements"] and not drift["variants"] and not drift["digest_changed"], (
        "computed styles moved against tests/css_snapshot/baseline.json.\n"
        f"elements: {drift['elements']}\n"
        f"variants: {drift['variants']}\n"
        "If the change is intended, re-record with "
        "`python scripts/css_snapshot.py --write-baseline`; if it is not, the "
        "restructuring changed which declaration wins."
    )


@_requires_browser
def test_reordering_two_conflicting_declarations_moves_the_digest():
    """The harness has to fail when the cascade changes, or it proves nothing.

    Captures one variant twice - once normally, once with the first two
    top-level `.attach-strip` blocks swapped - and asserts the digest moves and
    points at the affected element.
    """
    variants = ["desktop-dark-comfortable"]
    unchanged = snapshot.summarize(
        snapshot.capture(STATIC_ORIGIN, variants=variants)["snapshot"]
    )
    reordered = snapshot.summarize(
        snapshot.capture(STATIC_ORIGIN, variants=variants,
                         swap_rule=CONFLICTING_SELECTOR)["snapshot"]
    )

    assert unchanged["digest"] != reordered["digest"]
    drift = snapshot.compare(unchanged, reordered)
    assert "app-shell/attach-strip" in drift["elements"]
    assert "bench/.attach-strip" in drift["elements"]