"""Unit tests for the self-fd watchdog (no DB, no network).

Exercises the fd accounting, the percentage/warning floor, and that the
recorder degrades to a no-op where fd accounting isn't available. The DB session
and the alert pipeline are faked — we only assert that the right metrics get
handed to record_metric.
"""
import asyncio
import logging

import steward.core.alerts as alerts
import steward.core.self_monitor as sm


# ── fd accounting ────────────────────────────────────────────────────────────

def test_count_open_fds_sane_or_none():
    n = sm.count_open_fds()
    # On the Linux CI image /proc exists; stdin/stdout/stderr are always open.
    assert n is None or n >= 3


def test_fd_soft_limit_positive_or_none():
    soft = sm.fd_soft_limit()
    assert soft is None or soft > 0


# ── fake session / app plumbing ──────────────────────────────────────────────

class _Ctx:
    async def __aenter__(self):
        return self

    async def __aexit__(self, *_):
        return False


class _FakeSession(_Ctx):
    def begin(self):
        return _Ctx()


class _FakeApp:
    def db_sessionmaker(self):
        return _FakeSession()


def _patch_recorder(monkeypatch):
    recorded: list[tuple] = []

    async def fake_record_metric(session, source_module, resource_name, metric_name, value):
        recorded.append((source_module, resource_name, metric_name, value))

    monkeypatch.setattr(alerts, "record_metric", fake_record_metric)
    return recorded


# ── record_self_metrics ──────────────────────────────────────────────────────

def test_records_both_fd_metrics(monkeypatch):
    recorded = _patch_recorder(monkeypatch)
    monkeypatch.setattr(sm, "count_open_fds", lambda: 50)
    monkeypatch.setattr(sm, "fd_soft_limit", lambda: 1000)

    asyncio.run(sm.record_self_metrics(_FakeApp()))

    assert ("steward", "process", "open_fds", 50.0) in recorded
    assert ("steward", "process", "open_fds_pct", 5.0) in recorded


def test_no_pct_metric_when_limit_unknown(monkeypatch):
    recorded = _patch_recorder(monkeypatch)
    monkeypatch.setattr(sm, "count_open_fds", lambda: 50)
    monkeypatch.setattr(sm, "fd_soft_limit", lambda: None)

    asyncio.run(sm.record_self_metrics(_FakeApp()))

    metric_names = [m for (_s, _r, m, _v) in recorded]
    assert "open_fds" in metric_names
    assert "open_fds_pct" not in metric_names   # meaningless without a ceiling


def test_warns_past_floor(monkeypatch, caplog):
    _patch_recorder(monkeypatch)
    monkeypatch.setattr(sm, "count_open_fds", lambda: 900)
    monkeypatch.setattr(sm, "fd_soft_limit", lambda: 1000)   # 90% ≥ FD_WARN_PCT
    monkeypatch.setattr(sm, "_warned", False)

    with caplog.at_level(logging.WARNING, logger=sm.logger.name):
        asyncio.run(sm.record_self_metrics(_FakeApp()))

    assert any("soft limit" in r.message for r in caplog.records)


def test_no_warning_below_floor(monkeypatch, caplog):
    _patch_recorder(monkeypatch)
    monkeypatch.setattr(sm, "count_open_fds", lambda: 100)
    monkeypatch.setattr(sm, "fd_soft_limit", lambda: 1000)   # 10%
    monkeypatch.setattr(sm, "_warned", False)

    with caplog.at_level(logging.WARNING, logger=sm.logger.name):
        asyncio.run(sm.record_self_metrics(_FakeApp()))

    assert not any("soft limit" in r.message for r in caplog.records)


def test_noop_when_fd_count_unavailable(monkeypatch):
    # /proc absent → must return before touching the DB.
    monkeypatch.setattr(sm, "count_open_fds", lambda: None)

    class _Boom:
        def db_sessionmaker(self):
            raise AssertionError("must not open a session when fds are unknown")

    asyncio.run(sm.record_self_metrics(_Boom()))   # no raise