from __future__ import annotations

import ast
import unittest
from pathlib import Path


class PostboxModuleBoundaryTests(unittest.TestCase):
    def test_backend_does_not_import_sibling_module_implementations(self) -> None:
        root = Path(__file__).parents[1] / "src" / "govoplan_postbox"
        forbidden = (
            "govoplan_access",
            "govoplan_campaign",
            "govoplan_files",
            "govoplan_identity",
            "govoplan_idm",
            "govoplan_mail",
            "govoplan_organizations",
            "govoplan_portal",
        )
        violations: list[str] = []
        for path in root.rglob("*.py"):
            tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
            for node in ast.walk(tree):
                names: list[str] = []
                if isinstance(node, ast.Import):
                    names.extend(alias.name for alias in node.names)
                elif isinstance(node, ast.ImportFrom) and node.module:
                    names.append(node.module)
                for name in names:
                    if name.startswith(forbidden):
                        violations.append(f"{path.relative_to(root)}: {name}")
        self.assertEqual([], violations)


if __name__ == "__main__":
    unittest.main()