"""SSE `Accept` 契约测试（文档 §3.2 请求头表 + §3.5 状态码 + §6.4 主要错误）。

权威规则：`Accept` **非必填**，"默认 `application/json`；SSE 为 `text/event-stream`"，
`SSE_NOT_ACCEPTABLE` 是 SSE 接口的主要错误之一（406）。

覆盖两条容易写错的分支：
1. **未携带** `Accept` 必须放行——把"未携带"当成"不接受"会把所有默认客户端挡在门外；
2. `q=0` 属于显式拒绝，不能被通配符掩盖。

校验顺序另在 `stream_agent_run_events` 中做了断言：可见性（RUN_NOT_FOUND）先行，
否则 406/404 的差异就等于一次运行存在性枚举。
"""

from typing import Any

import pytest
from fastapi.testclient import TestClient

from app.api.controllers.agent_runs import accepts_event_stream
from app.api.dependencies.auth import build_request_context
from app.core.contracts import RequestContext
from app.core.errors import RunNotFoundError
from app.main import create_app
from app.service.run_query_service import RunSnapshot

EVENTS_PATH = "/api/v1/agent-runs/run-1/events"


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


def app_with_query(monkeypatch: pytest.MonkeyPatch, query: Any) -> TestClient:
    application = create_app()
    application.dependency_overrides[build_request_context] = resolve_context
    monkeypatch.setattr("app.api.controllers.agent_runs.RunQueryService", lambda: query)
    return TestClient(application)


class StubQuery:
    """`get` 返回终态快照、`watch` 立即收流，避免测试连接挂住。"""

    def __init__(self, status: str = "succeeded") -> None:
        self.status = status

    async def get(self, run_id: str, _ctx: RequestContext) -> RunSnapshot:
        return RunSnapshot(run_id=run_id, trace_id="trace-1", status=self.status,
                           agent_type="customer_service", session_id="s", result=None,
                           error_code=None, created_at="2026-01-01T00:00:00Z",
                           completed_at="2026-01-01T00:00:01Z")

    async def watch(self, initial: RunSnapshot, _ctx: RequestContext):
        yield initial


class MissingQuery:
    async def get(self, _run_id: str, _ctx: RequestContext) -> RunSnapshot:
        raise RunNotFoundError("运行不存在或不可见")

    async def watch(self, initial: RunSnapshot, _ctx: RequestContext):
        yield initial


@pytest.mark.parametrize(
    "accept",
    [None, "", "*/*", "text/*", "text/event-stream", "text/event-stream;q=0.8",
     "application/json, text/event-stream"],
)
def test_acceptable_or_absent_accept_is_allowed(accept: str | None) -> None:
    assert accepts_event_stream(accept) is True


@pytest.mark.parametrize(
    "accept",
    ["application/json", "text/html", "application/json, text/html",
     "*/*;q=0", "text/event-stream;q=0", "text/*;q=0, application/json"],
)
def test_explicitly_unacceptable_accept_is_rejected(accept: str) -> None:
    assert accepts_event_stream(accept) is False


@pytest.mark.parametrize("accept", [None, "*/*", "text/event-stream"])
def test_missing_wildcard_and_exact_accept_are_allowed_by_endpoint(
    monkeypatch: pytest.MonkeyPatch, accept: str | None
) -> None:
    headers = {} if accept is None else {"Accept": accept}
    with app_with_query(monkeypatch, StubQuery()) as client:
        response = client.get(EVENTS_PATH, headers=headers)

    assert response.status_code == 200
    assert response.headers["content-type"].startswith("text/event-stream")


def test_json_only_accept_is_rejected_with_documented_code(
    monkeypatch: pytest.MonkeyPatch
) -> None:
    with app_with_query(monkeypatch, StubQuery()) as client:
        response = client.get(EVENTS_PATH, headers={"Accept": "application/json"})

    assert response.status_code == 406
    assert response.json()["error"]["code"] == "SSE_NOT_ACCEPTABLE"
    assert response.json()["error"]["retryable"] is False
    assert response.json()["error"]["field_errors"] == []


def test_visibility_is_checked_before_accept(
    monkeypatch: pytest.MonkeyPatch
) -> None:
    """不可见运行的非法 Accept 也必须得到 `RUN_NOT_FOUND`，不泄露存在性差异。"""
    cases = [{"Accept": "application/json"}, {}]
    for headers in cases:
        with app_with_query(monkeypatch, MissingQuery()) as client:
            response = client.get(EVENTS_PATH, headers=headers)

        assert response.status_code == 404
        assert response.json()["error"]["code"] == "RUN_NOT_FOUND"


def test_unacceptable_accept_does_not_start_a_stream(
    monkeypatch: pytest.MonkeyPatch
) -> None:
    """拒绝必须发生在响应头发送前：文档 §6.4 要求此时返回统一 JSON 错误。"""
    with app_with_query(monkeypatch, StubQuery()) as client:
        response = client.get(EVENTS_PATH, headers={"Accept": "application/json"})

    assert response.headers["content-type"].startswith("application/json")