"""扫描的通知环节：失败必须能被区分出来。

**背景**：`_create_notifications` 原先失败时 `return 0`，而"无需通知"（没有高风险预警、
通知功能关闭）也返回 0 —— 调用方只拿到一个 `notification_count`，分不清两者。

这不是洁癖：**通知没发出去等于处置链路的第一环断了，而扫描依旧报"完成"**。
风控系统里这种"看起来在工作、其实有一环没跑"的状态最难发现（同一批缺陷里，
"定时扫描重启后不再执行"也是这个性质）。

所以这里锁住契约：返回 `(条数, 失败原因)`，失败原因非空即代表出了问题。
"""

import logging
from types import SimpleNamespace
from typing import Any, cast

import pytest

from app.service.risk_scan_service import HIGH_RISK, RiskScanService


class _FakeNested:
    async def __aenter__(self) -> "_FakeNested":
        return self

    async def __aexit__(self, *exc: object) -> bool:
        return False


class _FakeSession:
    """只提供 `begin_nested()`；被测方法不碰其它会话能力。"""

    def begin_nested(self) -> _FakeNested:
        return _FakeNested()


class _FakeNotificationService:
    def __init__(self, *, fail: bool = False) -> None:
        self.fail = fail
        self.in_app: list[str] = []

    def create_in_app(self, alert: Any, **kwargs: Any) -> None:
        if self.fail:
            raise RuntimeError("通知写库失败")
        self.in_app.append(str(alert.alert_no))

    def create_mail_record(self, alert: Any, **kwargs: Any) -> None:
        if self.fail:
            raise RuntimeError("邮件记录写库失败")


def _alert(level: str, alert_no: str = "ALTEST") -> Any:
    return SimpleNamespace(
        alert_level=level, alert_no=alert_no, alert_type="大额频繁交易",
        evidence_summary="摘要", handler_id=9002,
    )


def _service(*, enabled: bool = True, fail: bool = False,
             email: str | None = None) -> RiskScanService:
    service = object.__new__(RiskScanService)
    service.notification_enabled = enabled
    service.notification_email = email
    service.mail_enabled = False
    service.notification_service = cast(Any, _FakeNotificationService(fail=fail))
    service.session = cast(Any, _FakeSession())
    return service


@pytest.mark.asyncio
async def test_success_reports_count_and_no_failure() -> None:
    service = _service()

    count, failure = await service._create_notifications([_alert(HIGH_RISK)])

    assert count == 1
    assert failure == ""


@pytest.mark.asyncio
async def test_nothing_to_notify_is_not_a_failure() -> None:
    """没有高风险预警，或通知功能关闭——都不算失败，失败原因应为空。"""
    service = _service()
    assert await service._create_notifications([_alert("低")]) == (0, "")

    disabled = _service(enabled=False)
    assert await disabled._create_notifications([_alert(HIGH_RISK)]) == (0, "")


@pytest.mark.asyncio
async def test_failure_is_reported_not_swallowed(caplog: pytest.LogCaptureFixture) -> None:
    """通知创建失败时必须带出原因——这正是原先丢失的信号。"""
    service = _service(fail=True)

    with caplog.at_level(logging.ERROR):
        count, failure = await service._create_notifications([_alert(HIGH_RISK)])

    assert count == 0
    assert "RuntimeError" in failure
    assert "通知写库失败" in failure


@pytest.mark.asyncio
async def test_failure_reason_differs_from_nothing_to_notify() -> None:
    """两种 0 必须可区分——这是本次修复的全部意义。"""
    quiet, _ = await _service()._create_notifications([_alert("低")])
    _count, failure = await _service(fail=True)._create_notifications([_alert(HIGH_RISK)])

    assert quiet == 0
    assert failure != "", "失败必须能与『无需通知』区分开"