"""Pure-function tests for host_agent metric expansion."""
from datetime import datetime, timezone

from plugins.host_agent.routes import _expand_sample_to_metrics


NOW = datetime(2026, 4, 14, 12, 0, 0, tzinfo=timezone.utc)


def _sample() -> dict:
    return {
        "ts": NOW.isoformat(),
        "cpu_pct": 12.5,
        "mem": {
            "total_bytes": 16_000_000_000,
            "used_bytes":       8_000_000_000,
            "available_bytes":  8_000_000_000,
            "swap_used_bytes": 0,
        },
        "load": {"1m": 0.1, "5m": 0.2, "15m": 0.3},
        "uptime_secs": 1234,
        "storage": [
            {"mount": "/",         "total_bytes": 1000, "used_bytes": 400},
            {"mount": "/mnt/data", "total_bytes": 2000, "used_bytes": 1800},
        ],
    }


def _by_metric(rows, name):
    return [r for r in rows if r.metric_name == name]


def test_expand_emits_cpu_mem_load_uptime():
    rows = _expand_sample_to_metrics(_sample(), "testhost", NOW)
    names = {r.metric_name for r in rows}
    assert "cpu_pct" in names
    assert "mem_used_pct" in names
    assert "mem_available_bytes" in names
    assert "swap_used_bytes" in names
    assert "load_1m" in names and "load_5m" in names and "load_15m" in names
    assert "uptime_secs" in names


def test_expand_source_module_and_recorded_at():
    rows = _expand_sample_to_metrics(_sample(), "testhost", NOW)
    assert rows, "expected non-empty rows"
    for r in rows:
        assert r.source_module == "host_agent"
        assert r.recorded_at == NOW


def test_expand_cpu_value_and_resource():
    cpu = _by_metric(_expand_sample_to_metrics(_sample(), "testhost", NOW), "cpu_pct")
    assert len(cpu) == 1
    assert cpu[0].value == 12.5
    assert cpu[0].resource_name == "testhost"


def test_expand_mem_used_pct_math():
    # used = total - available = 50%
    used = _by_metric(_expand_sample_to_metrics(_sample(), "testhost", NOW), "mem_used_pct")
    assert len(used) == 1
    assert abs(used[0].value - 50.0) < 0.01


def test_expand_per_mount_disk_metrics():
    rows = _expand_sample_to_metrics(_sample(), "testhost", NOW)
    per_mount = _by_metric(rows, "disk_used_pct")
    assert {r.resource_name for r in per_mount} == {"testhost:/", "testhost:/mnt/data"}
    # Values: / is 40%, /mnt/data is 90%
    by_res = {r.resource_name: r.value for r in per_mount}
    assert abs(by_res["testhost:/"] - 40.0) < 0.01
    assert abs(by_res["testhost:/mnt/data"] - 90.0) < 0.01


def test_expand_disk_worst_is_max():
    worst = _by_metric(_expand_sample_to_metrics(_sample(), "testhost", NOW), "disk_used_pct_worst")
    assert len(worst) == 1
    assert worst[0].resource_name == "testhost"
    assert abs(worst[0].value - 90.0) < 0.01


def test_expand_skips_missing_cpu_and_load():
    sample = {"mem": {"total_bytes": 100, "available_bytes": 50}}
    rows = _expand_sample_to_metrics(sample, "h", NOW)
    names = {r.metric_name for r in rows}
    assert "cpu_pct" not in names
    assert "load_1m" not in names
    assert "uptime_secs" not in names
    assert "mem_used_pct" in names


def test_expand_empty_storage_emits_no_disk_worst():
    sample = {"cpu_pct": 1.0, "storage": []}
    rows = _expand_sample_to_metrics(sample, "h", NOW)
    names = {r.metric_name for r in rows}
    assert "disk_used_pct_worst" not in names
    assert "cpu_pct" in names