"""`ApiTransactionService` 的输入契约与 `digest` 测试。

`Idempotency-Key` 是所有公共写接口的强制头，它的长度与字符集校验必须在**开启事务之前**
完成——否则非法请求也会占用一次事务和一次 `INSERT ... ON DUPLICATE KEY` 抢占，把本该
零成本的拒绝变成一次真实的库写入尝试。本文件用"创建会话即报错"的替身来证明这个顺序。

抢占、命中回放、哈希冲突的完整路径需要 `PlatformRepository.table()` 反射真实表，
那部分由集成测试覆盖（`tests/integration/`），这里不重复造表。
"""

from typing import Any

import pytest

from app.core.contracts import RequestContext
from app.core.errors import ValidationAgentError
from app.service.api_transaction_service import ApiTransactionService, digest

CONTEXT = RequestContext(user_id="9001", trace_id="trace-1")


async def never_called(_session: Any) -> dict[str, Any]:  # pragma: no cover - 不应被调用
    raise AssertionError("非法请求不应执行 action")


def exploding_factory() -> None:
    raise AssertionError("非法请求不应创建数据库会话")


@pytest.mark.parametrize(
    "key",
    [
        None,
        "",  # 空
        "x" * 15,  # 短于 16
        "x" * 129,  # 长于 128
        "稳健型稳健型稳健型稳健型",  # 长度够但不是 ASCII
    ],
)
async def test_invalid_key_is_rejected_before_any_database_work(
    key: str | None, monkeypatch: pytest.MonkeyPatch
) -> None:
    monkeypatch.setattr(
        "app.service.api_transaction_service.SessionFactory", exploding_factory
    )

    with pytest.raises(ValidationAgentError):
        await ApiTransactionService().execute(CONTEXT, "conversations", key, {}, never_called)


async def test_valid_key_passes_the_guard(monkeypatch: pytest.MonkeyPatch) -> None:
    """合法 key 不应被前置校验拦下：用一个立即失败的替身证明校验已通过、进入数据库阶段。"""
    monkeypatch.setattr(
        "app.service.api_transaction_service.SessionFactory", exploding_factory
    )

    with pytest.raises(AssertionError, match="不应创建数据库会话"):
        await ApiTransactionService().execute(CONTEXT, "conversations", "a" * 16, {}, never_called)


def test_digest_is_order_independent() -> None:
    assert digest({"a": 1, "b": 2}) == digest({"b": 2, "a": 1})


def test_digest_changes_with_content() -> None:
    assert digest({"a": 1}) != digest({"a": 2})


def test_digest_is_stable_for_non_ascii() -> None:
    value = {"text": "稳健型"}
    assert digest(value) == digest({"text": "稳健型"})
    assert len(digest(value)) == 64