"""Unit tests for the A5 purity guard (phase 02 task 01).

Proves the shipped `sim/` package imports nothing forbidden, and — just as
important — that the guard actually catches a violation when one exists.
"""

from __future__ import annotations

from pathlib import Path

import pytest

from undercooked.sim.purity import (
    FORBIDDEN_ROOTS,
    PurityError,
    assert_pure_imports,
    find_violations,
)

pytestmark = pytest.mark.unit


def test_forbidden_roots_are_the_plan_a5_list() -> None:
    assert frozenset({"asyncio", "fastapi", "socket", "time", "uvicorn"}) == FORBIDDEN_ROOTS


def test_shipped_sim_package_is_pure() -> None:
    assert find_violations() == []
    assert_pure_imports()  # must not raise


def test_clean_module_with_stdlib_sibling_and_relative_imports(tmp_path: Path) -> None:
    (tmp_path / "ok.py").write_text(
        "import math\n"
        "from hashlib import sha256\n"
        "from undercooked.sim.model import Vec2\n"
        "from . import model\n",
        encoding="utf-8",
    )
    assert find_violations(tmp_path) == []


def test_comments_and_strings_are_not_imports(tmp_path: Path) -> None:
    (tmp_path / "prose.py").write_text(
        '# we must never "import asyncio" here\nDOC = "import time is forbidden"\n',
        encoding="utf-8",
    )
    assert find_violations(tmp_path) == []


@pytest.mark.parametrize(
    ("statement", "root"),
    [
        ("import asyncio", "asyncio"),
        ("import time", "time"),
        ("from time import monotonic", "time"),
        ("import socket", "socket"),
        ("from socket import socket", "socket"),
        ("from fastapi import FastAPI", "fastapi"),
        ("import uvicorn", "uvicorn"),
        ("import uvicorn.protocols", "uvicorn"),
    ],
)
def test_find_violations_detects_each_forbidden_import(
    tmp_path: Path, statement: str, root: str
) -> None:
    (tmp_path / "bad.py").write_text(f"{statement}\n", encoding="utf-8")
    assert find_violations(tmp_path) == [f"bad.py: imports {root}"]


def test_find_violations_scans_subpackages(tmp_path: Path) -> None:
    sub = tmp_path / "deep"
    sub.mkdir()
    (sub / "leak.py").write_text("import asyncio\n", encoding="utf-8")
    assert find_violations(tmp_path) == ["deep/leak.py: imports asyncio"]


def test_assert_pure_imports_raises_with_the_violation_list(tmp_path: Path) -> None:
    (tmp_path / "bad.py").write_text("import time\nimport socket\n", encoding="utf-8")
    with pytest.raises(PurityError, match=r"bad\.py: imports socket"):
        assert_pure_imports(tmp_path)