"""Tests for the Stage B (B1/B2) ``operations.host`` additions:
``host_resources`` and ``vmware_module_health``.

Everything reads through the ``_read_proc`` seam -- monkeypatched per test to
fixture strings, never a real ``/proc``. ``time.sleep`` is also patched to a
no-op so the two-sample CPU read never actually waits ``cpu_sample_ms``.
"""

from __future__ import annotations

from typing import Any

import pytest

import ci_orchestrator.operations.host as host_module
from ci_orchestrator.operations.host import (
    HostResources,
    RunnerStatus,
    VmwareModuleHealth,
    host_resources,
    vmware_module_health,
)

# ── fixture /proc/stat samples ──────────────────────────────────────────────
# Columns: user nice system idle iowait irq softirq steal guest guest_nice.
# Sample 1: idle=8000+0=8000, total=1000+0+1000+8000=10000
# Sample 2: idle=8200+0=8200, total=1100+0+1100+8200=10400
# idle_delta=200, total_delta=400 -> cpu_pct = 100*(1 - 200/400) = 50.0
_STAT_1 = "cpu  1000 0 1000 8000 0 0 0 0 0 0\ncpu0 1000 0 1000 8000 0 0 0 0 0 0\n"
_STAT_2 = "cpu  1100 0 1100 8200 0 0 0 0 0 0\ncpu0 1100 0 1100 8200 0 0 0 0 0 0\n"

_MEMINFO = (
    "MemTotal:       16384000 kB\n"
    "MemFree:         2000000 kB\n"
    "MemAvailable:    4096000 kB\n"
    "Buffers:          100000 kB\n"
)
# total_gb = 16384000/1024**2 = 15.625; used = (16384000-4096000)/1024**2 = 11.71875

_UPTIME = "123456.78 987654.32\n"
_LOADAVG = "0.50 0.75 1.00 3/456 7890\n"


def _fake_reader(calls: dict[str, int]) -> Any:
    def _read(path: str) -> str:
        calls[path] = calls.get(path, 0) + 1
        if path == "/proc/stat":
            return _STAT_1 if calls[path] == 1 else _STAT_2
        if path == "/proc/meminfo":
            return _MEMINFO
        if path == "/proc/uptime":
            return _UPTIME
        if path == "/proc/loadavg":
            return _LOADAVG
        raise AssertionError(f"unexpected proc path: {path}")

    return _read


def _install_fake_proc(monkeypatch: pytest.MonkeyPatch) -> dict[str, int]:
    calls: dict[str, int] = {}
    monkeypatch.setattr(host_module, "_read_proc", _fake_reader(calls))
    monkeypatch.setattr(host_module.time, "sleep", lambda _seconds: None)
    return calls


# ── host_resources: happy path, two-sample CPU math ─────────────────────────


def test_host_resources_two_sample_cpu_math(monkeypatch: pytest.MonkeyPatch) -> None:
    calls = _install_fake_proc(monkeypatch)
    monkeypatch.setattr(host_module.os, "cpu_count", lambda: 8)

    result = host_resources(cpu_sample_ms=150)

    assert result.cpu_pct == pytest.approx(50.0)
    assert result.ncpu == 8
    assert calls["/proc/stat"] == 2  # exactly two samples, per the B1 spec


def test_host_resources_reads_proc_stat_twice_with_a_sleep_between(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    calls = _install_fake_proc(monkeypatch)
    sleeps: list[float] = []
    monkeypatch.setattr(host_module.time, "sleep", lambda seconds: sleeps.append(seconds))

    host_resources(cpu_sample_ms=200)

    assert calls["/proc/stat"] == 2
    assert sleeps == [pytest.approx(0.2)]


def test_host_resources_mem_used_is_total_minus_available(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    _install_fake_proc(monkeypatch)

    result = host_resources()

    assert result.mem_total_gb == pytest.approx(16384000 / 1024**2)
    assert result.mem_used_gb == pytest.approx((16384000 - 4096000) / 1024**2)


def test_host_resources_uptime_and_loadavg(monkeypatch: pytest.MonkeyPatch) -> None:
    _install_fake_proc(monkeypatch)

    result = host_resources()

    assert result.uptime_sec == 123456
    assert result.load1 == pytest.approx(0.50)
    assert result.load5 == pytest.approx(0.75)
    assert result.load15 == pytest.approx(1.00)


# ── host_resources: degrade to zeros on OSError, never raise ────────────────


def test_host_resources_degrades_to_zeros_on_oserror(monkeypatch: pytest.MonkeyPatch) -> None:
    def _boom(_path: str) -> str:
        raise OSError("no /proc on this platform")

    monkeypatch.setattr(host_module, "_read_proc", _boom)
    monkeypatch.setattr(host_module.os, "cpu_count", lambda: 4)

    result = host_resources()

    assert result == HostResources(
        cpu_pct=0.0,
        ncpu=4,
        mem_total_gb=0.0,
        mem_used_gb=0.0,
        uptime_sec=0,
        load1=0.0,
        load5=0.0,
        load15=0.0,
    )


def test_host_resources_degrades_to_zeros_when_second_stat_sample_fails(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    """The first ``/proc/stat`` read can succeed and the second still fail."""
    calls = {"n": 0}

    def _flaky(path: str) -> str:
        if path != "/proc/stat":
            raise AssertionError("should not reach meminfo after stat blows up")
        calls["n"] += 1
        if calls["n"] == 1:
            return _STAT_1
        raise OSError("gone")

    monkeypatch.setattr(host_module, "_read_proc", _flaky)
    monkeypatch.setattr(host_module.time, "sleep", lambda _s: None)

    result = host_resources()

    assert result.cpu_pct == 0.0
    assert result.uptime_sec == 0


# ── vmware_module_health: /proc/modules parsing ─────────────────────────────


def _fake_runner_status(statuses: list[RunnerStatus]) -> Any:
    def _query(_names: list[str]) -> list[RunnerStatus]:
        return statuses

    return _query


def test_vmware_module_health_both_modules_loaded(monkeypatch: pytest.MonkeyPatch) -> None:
    modules_text = "vmmon 57344 1 - Live 0x0000000000000000\nvmnet 69632 3 - Live 0x0000000000000000\n"
    monkeypatch.setattr(host_module, "_read_proc", lambda _path: modules_text)
    monkeypatch.setattr(
        host_module,
        "runner_status",
        _fake_runner_status([RunnerStatus(name="vmware-host.service", active=True, sub_state="running")]),
    )

    result = vmware_module_health()

    assert result == VmwareModuleHealth(
        vmmon_loaded=True,
        vmnet_loaded=True,
        host_service_active=True,
        host_service_sub_state="running",
    )


def test_vmware_module_health_modules_absent(monkeypatch: pytest.MonkeyPatch) -> None:
    modules_text = "usbcore 300000 4 - Live 0x0000000000000000\n"
    monkeypatch.setattr(host_module, "_read_proc", lambda _path: modules_text)
    monkeypatch.setattr(
        host_module,
        "runner_status",
        _fake_runner_status([RunnerStatus(name="vmware-host.service", active=False, sub_state="dead")]),
    )

    result = vmware_module_health()

    assert result.vmmon_loaded is False
    assert result.vmnet_loaded is False
    assert result.host_service_active is False
    assert result.host_service_sub_state == "dead"


def test_vmware_module_health_degrades_on_proc_modules_oserror(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    def _boom(_path: str) -> str:
        raise OSError("no /proc/modules")

    monkeypatch.setattr(host_module, "_read_proc", _boom)
    monkeypatch.setattr(
        host_module,
        "runner_status",
        _fake_runner_status([RunnerStatus(name="vmware-host.service", active=True, sub_state="running")]),
    )

    result = vmware_module_health()

    assert result.vmmon_loaded is False
    assert result.vmnet_loaded is False
    # A /proc/modules failure must not also blank the (independent) service query.
    assert result.host_service_active is True


def test_vmware_module_health_degrades_when_runner_status_raises(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    monkeypatch.setattr(host_module, "_read_proc", lambda _path: "vmmon 1 1 - Live 0x0\n")

    def _boom(_names: list[str]) -> list[RunnerStatus]:
        raise RuntimeError("systemctl vanished")

    monkeypatch.setattr(host_module, "runner_status", _boom)

    result = vmware_module_health()

    assert result.vmmon_loaded is True
    assert result.host_service_active is False
    assert result.host_service_sub_state == "unknown"