"""A stylesheet shared by `<style src>` must sit at the same block index in
every component that loads it that way.

plugin-vue caches one SFC descriptor per `src` file and resolves a request for
`moments-shared.css?vue&type=style&index=N` against whichever component last
registered it. When two components carry the same src at different indexes,
the lookup can land on a component with fewer style blocks, and the production
build dies with "Cannot read properties of undefined (reading 'scoped')". It
depends on transform order, so an unrelated change, such as a new import in a
view, is enough to flip it. vue-tsc cannot see it; only `vite build` can, and
that runs at image-build time, after every test has passed.
"""
from __future__ import annotations

import pathlib
import re
from collections import defaultdict

ROOT = pathlib.Path(__file__).resolve().parents[1] / "frontend" / "src"
STYLE_TAG = re.compile(r"<style\b([^>]*)>")
SRC_ATTR = re.compile(r'\bsrc="([^"]+)"')


def src_indexes(sources: dict[str, str]) -> dict[str, dict[int, list[str]]]:
    """{src: {block index: [component, ...]}} over a set of SFC sources."""
    seen: dict[str, dict[int, list[str]]] = defaultdict(lambda: defaultdict(list))
    for name, text in sources.items():
        for index, attrs in enumerate(STYLE_TAG.findall(text)):
            match = SRC_ATTR.search(attrs)
            if match:
                seen[match.group(1)][index].append(name)
    return seen


def disagreements(sources: dict[str, str]) -> dict[str, dict[int, list[str]]]:
    return {src: dict(at) for src, at in src_indexes(sources).items() if len(at) > 1}


def test_every_shared_style_src_sits_at_one_block_index():
    sources = {str(p.relative_to(ROOT)): p.read_text() for p in ROOT.rglob("*.vue")}
    assert sources, f"no .vue files under {ROOT}"
    assert disagreements(sources) == {}, (
        "a <style src> sheet sits at different block indexes across components — "
        "load it with @import in the odd one out"
    )


def test_the_guard_can_fail():
    sources = {
        "A.vue": '<style scoped></style>\n<style src="@/x.css" />',
        "B.vue": '<style scoped></style>\n<style src="@/y.css" />\n<style src="@/x.css" />',
    }
    assert disagreements(sources) == {"@/x.css": {1: ["A.vue"], 2: ["B.vue"]}}