"""``PostgresTaskStore`` 的惰性导入契约——**不需要数据库**。

钉住两条承诺：

1. 取到 ``chongming_task.PostgresTaskStore`` 之前，iss 不导入 psycopg——核心包保持
   零第三方运行时依赖（``import chongming_task`` 不会因为没装驱动而变慢或失败）；
2. 没装可选依赖时，报错必须**可操作**：给出安装命令，而不是一个光秃秃的
   ``ModuleNotFoundError``。

真正的行为测试在 ``tests/integration/test_postgres_store.py``（需要 DSN）。
"""

from __future__ import annotations

import os
import subprocess
import sys

import pytest

import chongming_task


def _run(script: str) -> subprocess.CompletedProcess[str]:
    environment = {**os.environ}
    return subprocess.run(
        [sys.executable, "-c", script],
        capture_output=True,
        text=True,
        env=environment,
        timeout=60,
    )


def test_star_import_does_not_pull_the_driver() -> None:
    """``from chongming_task import *`` 不该要求安装数据库驱动。"""
    assert "PostgresTaskStore" not in chongming_task.__all__

    script = (
        "import sys\n"
        "from chongming_task import *\n"
        "assert 'psycopg' not in sys.modules, '星号导入拉起了 psycopg'\n"
        "assert 'PostgresTaskStore' not in dir(), '它不该出现在星号导入里'\n"
        "print('ok')\n"
    )
    completed = _run(script)
    assert completed.returncode == 0, completed.stderr
    assert completed.stdout.strip() == "ok"


def test_lazy_attribute_does_not_import_the_driver_until_used() -> None:
    script = (
        "import sys\n"
        "import chongming_task\n"
        "assert 'psycopg' not in sys.modules, '导入核心包就拉起了 psycopg'\n"
        "print('ok')\n"
    )
    completed = _run(script)
    assert completed.returncode == 0, completed.stderr
    assert completed.stdout.strip() == "ok"


def test_missing_driver_gives_an_actionable_error() -> None:
    """把 psycopg 屏蔽成"未安装"，取 ``PostgresTaskStore`` 必须报出安装指引。"""
    script = (
        "import sys\n"
        "sys.modules['psycopg'] = None\n"
        "sys.modules['psycopg_pool'] = None\n"
        "import chongming_task\n"
        "try:\n"
        "    chongming_task.PostgresTaskStore\n"
        "except ImportError as exc:\n"
        "    text = str(exc)\n"
        "    assert 'chongming-task[postgres]' in text, text\n"
        "    print('ok')\n"
        "else:\n"
        "    raise SystemExit('没有抛出 ImportError')\n"
    )
    completed = _run(script)
    assert completed.returncode == 0, completed.stderr
    assert completed.stdout.strip() == "ok"


def test_unknown_attribute_still_raises_attribute_error() -> None:
    """``__getattr__`` 只放行已知的可选导出，其余照常抛 AttributeError。"""
    with pytest.raises(AttributeError, match="no attribute"):
        _ = chongming_task.NoSuchThing  # type: ignore[attr-defined]


def test_postgres_store_resolves_when_the_extra_is_installed() -> None:
    """装了可选依赖时必须能取到——并在 stores 包与顶层给出同一个类。"""
    pytest.importorskip("psycopg")

    from chongming_task.stores import PostgresTaskStore as FromStores
    from chongming_task.stores.postgres import PostgresTaskStore as FromModule

    assert chongming_task.PostgresTaskStore is FromModule
    assert FromStores is FromModule