"""Il server non importa VisionSuite, e questo lo verifica.

Senza qualcuno che lo controlli, il confine si perde in silenzio: basta un
import comodo perché l'immagine dell'API torni da cinque gigabyte e il motivo
per cui il worker esiste svanisca senza che nessuna prova diventi rossa.
"""
import ast
from pathlib import Path

BACKEND = Path(__file__).resolve().parents[1]

# Full dotted prefixes, not bare roots: "src" alone would forbid every import
# the backend legitimately makes of itself (src.backend.*), so the entries
# for the vision tree are multi-segment ("src.vision", "src.vision_worker")
# while VisionSuite's own top-level packages stay single-segment.
#
# M2: "Acquire" used to sit here as a stand-in for vs-camera, but it is a
# class/SDK name (Balluff's "mvIMPACT Acquire" SDK), never an import root -
# it could never match. vs-camera imports under the same `visionsuite`
# namespace as vs-core (see
# vendor/visionsuite/packages/vs-camera/pyproject.toml: "il codice si importa
# come visionsuite.camera...."), which "visionsuite" below already forbids,
# so there is nothing separate to add for it.
FORBIDDEN = {
    "visionsuite", "pm2d", "dxf_compare", "torch",
    "src.vision", "src.vision_worker",
}


def _imported_modules(source: Path) -> set[str]:
    """Full dotted module paths this file imports - not just their first
    segment. `from src.vision.runner import ...` must be checked against
    "src.vision.runner" (inside the forbidden "src.vision"), not against
    "src" alone, which is never forbidden since the backend imports itself
    constantly.
    """
    tree = ast.parse(source.read_text(encoding="utf-8"), filename=str(source))
    modules: set[str] = set()
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            modules.update(alias.name for alias in node.names)
        elif isinstance(node, ast.ImportFrom) and node.module and node.level == 0:
            modules.add(node.module)
    return modules


def _forbidden_hits(modules: set[str]) -> set[str]:
    """Which FORBIDDEN entries a set of imported module paths triggers.

    A module counts as forbidden if it equals a forbidden entry exactly, or
    lives inside it ("src.vision.runner" is inside "src.vision").
    """
    hits: set[str] = set()
    for module in modules:
        for entry in FORBIDDEN:
            if module == entry or module.startswith(entry + "."):
                hits.add(entry)
    return hits


def test_the_server_never_imports_visionsuite():
    offenders = []
    for source in BACKEND.rglob("*.py"):
        if "tests" in source.parts or "migrations" in source.parts:
            continue
        forbidden = _forbidden_hits(_imported_modules(source))
        if forbidden:
            offenders.append(f"{source.relative_to(BACKEND)}: {sorted(forbidden)}")

    assert offenders == [], (
        "il server deve restare cieco alla visione; usa il worker via HTTP:\n"
        + "\n".join(offenders)
    )


def test_the_submodule_is_pinned():
    """Server e stazione devono montare lo stesso commit: qui c'è la fonte."""
    gitmodules = Path(__file__).resolve().parents[3] / ".gitmodules"
    assert gitmodules.exists(), "vendor/visionsuite non è un sottomodulo"
    assert "vendor/visionsuite" in gitmodules.read_text(encoding="utf-8")


def test_a_full_module_path_import_is_caught_not_just_its_root(tmp_path):
    """M2: `from src.vision.runner import ...` inside src/backend/** must be
    caught. Checking only the first dotted segment ("src") would miss it -
    "src" itself is never forbidden, the backend imports itself all the time.
    This is the blind spot the reviewer found: same repository, no install
    needed, the most tempting shortcut of all.
    """
    offender = tmp_path / "sneaky.py"
    offender.write_text("from src.vision.runner import run_graph\n")
    assert _forbidden_hits(_imported_modules(offender)) == {"src.vision"}


def test_a_vision_worker_import_is_also_caught(tmp_path):
    offender = tmp_path / "sneaky.py"
    offender.write_text("import src.vision_worker.main\n")
    assert _forbidden_hits(_imported_modules(offender)) == {"src.vision_worker"}


def test_an_unrelated_src_backend_import_is_not_caught(tmp_path):
    """The fix must not turn every self-import of the backend into an
    offender - only the vision subtrees are forbidden."""
    innocent = tmp_path / "innocent.py"
    innocent.write_text("from src.backend.config import settings\n")
    assert _forbidden_hits(_imported_modules(innocent)) == set()