"""请求校验错误信封契约测试（文档 §3.4 / §3.5 / §3.6 `AGENT_INPUT_INVALID`）。

修复前 FastAPI 返回自己的 `{"detail": [...]}` 结构，与业务异常的 `{error, meta}` 信封
不一致，客户端必须为"参数错误"单独兼容一套解析逻辑。本测试锁定修复后的形状：
状态码 422、顶层只有 `error`/`meta`、字段级原因进 `error.field_errors`、
`meta.trace_id` 沿用 `X-Trace-ID` 回显规则，同时保证鉴权仍先于参数校验失败。
"""

from fastapi.testclient import TestClient

from app.api.dependencies.auth import build_request_context
from app.core.contracts import RequestContext
from app.main import create_app

AGENT_RUNS = "/api/v1/agent-runs"


def _authenticated_client() -> TestClient:
    application = create_app()

    async def context() -> RequestContext:
        return RequestContext(
            user_id="1", trace_id="validation-trace", permissions=("agent:run",)
        )

    application.dependency_overrides[build_request_context] = context
    return TestClient(application)


def test_missing_body_fields_use_unified_envelope() -> None:
    with _authenticated_client() as client:
        response = client.post(AGENT_RUNS, json={}, headers={"X-Trace-ID": "val-trace"})

    assert response.status_code == 422
    body = response.json()
    assert set(body) == {"error", "meta"}, "校验错误只允许 error/meta 两个顶层字段"
    error = body["error"]
    assert error["code"] == "AGENT_INPUT_INVALID"
    assert error["retryable"] is False
    assert error["message"] == "请求参数不满足接口约束"
    fields = {item["field"] for item in error["field_errors"]}
    assert {"body.agent_type", "body.message", "body.session_id"} <= fields
    assert all(item["message"] for item in error["field_errors"])
    assert body["meta"] == {"trace_id": "val-trace"}


def test_validation_handler_does_not_hijack_authentication() -> None:
    """未带令牌 + 参数也不合法：必须仍是 401，参数校验不得掩盖鉴权失败。"""
    with TestClient(create_app()) as client:
        response = client.post(AGENT_RUNS, json={})

    assert response.status_code == 401
    assert response.json()["error"]["code"] == "AUTHENTICATION_REQUIRED"