"""telemetry 模块测试

验证：
1. 默认配置（otel_enabled=False）下 setup 是 noop，不初始化任何 provider。
2. enabled=true + endpoint 时 setup 注册真实 TracerProvider；shutdown 复位。
3. instrument_app 在 setup 之前调用也要真的装上中间件（三个服务都是导入期打桩）。
4. traced / set_attributes / record_error 的行为。

不打真实网络：OTLPSpanExporter 创建时不发请求，BatchSpanProcessor 异步批量
上报在没有 span 产生时也不会触发。span 断言用独立的 InMemory provider，不碰
全局 provider——OTel 的全局 provider 只允许设置一次，测试间共享会互相污染。
"""
from __future__ import annotations

import pytest
from fastapi import FastAPI
from opentelemetry import trace
from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import SimpleSpanProcessor
from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
from opentelemetry.trace import StatusCode

from app.shared import telemetry
from app.shared.config import Settings
from app.shared.errors import OrderGuardError
from app.shared.telemetry import is_initialized, setup_telemetry, shutdown_telemetry


@pytest.fixture
def spans(monkeypatch) -> InMemorySpanExporter:
    """把 telemetry 内部取到的 tracer 换成写内存的，用于断言 span

    不用全局 provider：`trace.set_tracer_provider` 只生效一次，一旦别的用例先
    设过，这里再设就被忽略（OTel 只打一条 warning），断言会莫名其妙拿不到 span。
    """
    exporter = InMemorySpanExporter()
    provider = TracerProvider()
    provider.add_span_processor(SimpleSpanProcessor(exporter))
    monkeypatch.setattr(telemetry.trace, "get_tracer", provider.get_tracer)
    return exporter


def test_disabled_is_noop():
    """otel_enabled=False 时 setup/instrument/shutdown 都不初始化 provider"""
    settings = Settings(_env_file=None)  # 默认 otel_enabled=False
    setup_telemetry(settings, service_name="test-disabled")
    assert not is_initialized()


def test_instrument_app_works_before_setup_telemetry(monkeypatch):
    """回归：instrument_app 必须在 setup_telemetry 之前也能真的装上中间件

    三个服务都在模块导入时执行 `app = create_app()`（内部调 instrument_app），
    而 setup_telemetry 要等 lifespan 才跑。曾经这里用 `_provider is None` 做前置
    判断，于是导入期一律 return，FastAPI 从来没被打桩过——一条 server span 都
    没有。这条用例把那个顺序钉住。
    """
    monkeypatch.setattr(
        telemetry, "get_settings", lambda: Settings(_env_file=None, otel_enabled=True)
    )
    assert not is_initialized()  # 尚未 setup，正是导入期的状态

    app = FastAPI()
    try:
        telemetry.instrument_app(app)
        assert app._is_instrumented_by_opentelemetry
    finally:
        FastAPIInstrumentor.uninstrument_app(app)


def test_instrument_app_skipped_when_otel_disabled(monkeypatch):
    """otel 关闭时不装中间件，省掉一层用不上的开销"""
    monkeypatch.setattr(
        telemetry, "get_settings", lambda: Settings(_env_file=None, otel_enabled=False)
    )
    app = FastAPI()
    telemetry.instrument_app(app)
    assert not getattr(app, "_is_instrumented_by_opentelemetry", False)


async def test_traced_records_span_and_reraises(spans):
    """traced 成功时留一个 span；异常时记 ERROR 状态并原样抛出"""

    @telemetry.traced("unit.ok")
    async def ok() -> str:
        return "done"

    @telemetry.traced("unit.boom")
    async def boom() -> None:
        raise OrderGuardError("金额超限")

    assert await ok() == "done"
    with pytest.raises(OrderGuardError):
        await boom()

    finished = {s.name: s for s in spans.get_finished_spans()}
    assert finished["unit.ok"].status.status_code is not StatusCode.ERROR
    failed = finished["unit.boom"]
    assert failed.status.status_code is StatusCode.ERROR
    # AppError 的对外错误码要落在 span 上：排查时按码筛比按异常类名筛更贴近上游
    assert failed.attributes["error.type"] == "OrderGuardError"
    assert failed.attributes["error.code"] == OrderGuardError("x").err_code


async def test_traced_nests_under_caller_span(spans):
    """traced 出来的 span 要挂在调用方的 span 底下，而不是各自成为孤立 trace"""

    @telemetry.traced("unit.child")
    async def child() -> None:
        return None

    tracer = telemetry.trace.get_tracer(__name__)
    with tracer.start_as_current_span("unit.root"):
        await child()

    by_name = {s.name: s for s in spans.get_finished_spans()}
    assert by_name["unit.child"].parent.span_id == by_name["unit.root"].context.span_id
    # 同一条 trace 才能在观测后台里连成一条链路
    assert by_name["unit.child"].context.trace_id == by_name["unit.root"].context.trace_id


def test_set_attributes_skips_none(spans):
    """可选字段为 None 时不落属性，避免一堆 None 噪声"""
    tracer = telemetry.trace.get_tracer(__name__)
    with tracer.start_as_current_span("unit.attrs") as span:
        telemetry.set_attributes(span, {"a": 1, "b": None, "c": "x"})

    attributes = spans.get_finished_spans()[0].attributes
    assert attributes["a"] == 1
    assert attributes["c"] == "x"
    assert "b" not in attributes


def test_enabled_initializes_and_shutdown_releases():
    """enabled=true 时 setup 注册 TracerProvider，shutdown 后 _provider 复位"""
    settings = Settings(
        _env_file=None,
        otel_enabled=True,
        otel_endpoint="http://localhost:4318/v1/traces",
    )
    try:
        setup_telemetry(settings, service_name="test-enabled")
        assert is_initialized()
        provider = trace.get_tracer_provider()
        # 初始化后是真实 SDK provider（class 名是 TracerProvider）；
        # SDK 启动前的占位 provider 不属于这个类型
        assert isinstance(provider, TracerProvider)
    finally:
        shutdown_telemetry()
        # 解除 httpx 全局 monkey-patch，避免污染其它测试
        try:
            HTTPXClientInstrumentor().uninstrument()
        except Exception:
            pass
    assert not is_initialized()