from __future__ import annotations

import pandas as pd
import pytest

from cosma_log_analyzer.models import Anomaly
from cosma_log_analyzer.rules import (
    BatteryLowRule,
    ImuOutliersRule,
    UsblDistanceSpikeRule,
    UsblSnrLowRule,
    WatchdogImuRule,
    all_rules,
)


def _imu_df(n: int = 600, dt: float = 0.02) -> pd.DataFrame:
    ts = [i * dt for i in range(n)]
    return pd.DataFrame(
        {
            "ts": ts,
            "ax": [0.0] * n,
            "ay": [0.0] * n,
            "az": [9.81] * n,
            "gx": [0.0] * n,
            "gy": [0.0] * n,
            "gz": [0.0] * n,
        }
    )


def test_imu_outliers_fires_on_single_spike() -> None:
    df = _imu_df()
    df.loc[300, ["ax", "ay", "az"]] = [30.0, 30.0, 30.0]
    anomalies = ImuOutliersRule(subject="AUV206").detect(df)
    assert any(a.rule == "imu_outliers" for a in anomalies)
    a = anomalies[0]
    assert isinstance(a, Anomaly)
    assert a.subject == "AUV206"
    assert a.severity == "warn"


def test_imu_outliers_empty_df() -> None:
    assert ImuOutliersRule().detect(pd.DataFrame()) == []


def test_imu_outliers_no_spike_no_anomaly() -> None:
    df = _imu_df()
    assert ImuOutliersRule().detect(df) == []


def test_watchdog_imu_fires_on_gap() -> None:
    df = pd.DataFrame({"ts": [0.0, 0.5, 1.0, 5.0, 5.5]})
    anomalies = WatchdogImuRule(max_gap_s=2.0).detect(df)
    assert len(anomalies) == 1
    assert anomalies[0].context["gap_s"] == pytest.approx(4.0)
    assert anomalies[0].severity == "critical"


def test_watchdog_imu_no_gap() -> None:
    df = pd.DataFrame({"ts": [i * 0.02 for i in range(100)]})
    assert WatchdogImuRule(max_gap_s=2.0).detect(df) == []


def test_watchdog_imu_short_df() -> None:
    assert WatchdogImuRule().detect(pd.DataFrame()) == []
    assert WatchdogImuRule().detect(pd.DataFrame({"ts": [0.0]})) == []


def test_usbl_snr_low_needs_three_consec() -> None:
    df = pd.DataFrame(
        {
            "ts": [0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0],
            "distance_m": [100.0] * 7,
            "snr_db": [10.0, 2.0, 2.0, 2.0, 10.0, 2.0, 10.0],
        }
    )
    anomalies = UsblSnrLowRule(min_snr_db=5.0, consec=3).detect(df)
    assert len(anomalies) == 1
    assert anomalies[0].value == pytest.approx(2.0)


def test_usbl_snr_low_no_run_long_enough() -> None:
    df = pd.DataFrame(
        {
            "ts": [0.0, 0.5, 1.0, 1.5, 2.0],
            "distance_m": [100.0] * 5,
            "snr_db": [2.0, 10.0, 2.0, 10.0, 2.0],
        }
    )
    assert UsblSnrLowRule(min_snr_db=5.0, consec=3).detect(df) == []


def test_usbl_snr_low_empty() -> None:
    assert UsblSnrLowRule().detect(pd.DataFrame()) == []


def test_usbl_distance_spike_fires() -> None:
    df = pd.DataFrame(
        {
            "ts": [0.0, 0.5, 1.0, 1.5],
            "distance_m": [100.0, 100.5, 250.0, 250.5],
            "snr_db": [12.0] * 4,
        }
    )
    anomalies = UsblDistanceSpikeRule(spike_m=50.0, max_dt_s=1.0).detect(df)
    assert len(anomalies) == 1
    assert anomalies[0].value == pytest.approx(149.5)


def test_usbl_distance_spike_ignores_slow_drift() -> None:
    df = pd.DataFrame(
        {
            "ts": [0.0, 2.0, 4.0],  # dt > max_dt_s
            "distance_m": [100.0, 250.0, 400.0],
            "snr_db": [12.0] * 3,
        }
    )
    assert UsblDistanceSpikeRule(spike_m=50.0, max_dt_s=1.0).detect(df) == []


def test_usbl_distance_spike_empty() -> None:
    assert UsblDistanceSpikeRule().detect(pd.DataFrame()) == []


def test_battery_low_fires_on_sustained_drop() -> None:
    ts = [float(i) for i in range(20)]
    voltage = [15.0] * 5 + [13.0] * 10 + [15.0] * 5
    df = pd.DataFrame({"ts": ts, "voltage_v": voltage})
    anomalies = BatteryLowRule(min_voltage_v=13.5, min_duration_s=5.0).detect(df)
    assert len(anomalies) == 1
    assert anomalies[0].severity == "critical"
    assert anomalies[0].value == pytest.approx(13.0)


def test_battery_low_ignores_short_dips() -> None:
    ts = [float(i) for i in range(10)]
    voltage = [15.0, 15.0, 13.0, 13.0, 15.0, 15.0, 13.0, 13.0, 15.0, 15.0]
    df = pd.DataFrame({"ts": ts, "voltage_v": voltage})
    assert BatteryLowRule(min_voltage_v=13.5, min_duration_s=5.0).detect(df) == []


def test_battery_low_empty() -> None:
    assert BatteryLowRule().detect(pd.DataFrame()) == []


def test_battery_low_always_above() -> None:
    df = pd.DataFrame({"ts": [0.0, 1.0, 2.0], "voltage_v": [16.0, 15.5, 15.0]})
    assert BatteryLowRule(min_voltage_v=13.5).detect(df) == []


def test_all_rules_returns_five() -> None:
    rules = all_rules()
    assert len(rules) == 5
    assert {r.name for r in rules} == {
        "imu_outliers",
        "watchdog_imu",
        "usbl_snr_low",
        "usbl_distance_spike",
        "battery_low",
    }


def test_rule_bind_sets_subject() -> None:
    r = BatteryLowRule()
    r.bind("AUV206")
    assert r.subject == "AUV206"


def test_anomaly_severity_validation() -> None:
    with pytest.raises(ValueError):
        Anomaly(
            rule="x", severity="bogus", timestamp=0.0, subject="s", topic="t"
        )


def test_anomaly_json_and_subject() -> None:
    a = Anomaly(
        rule="battery_low",
        severity="critical",
        timestamp=123.0,
        subject="AUV206",
        topic="/mavros/battery",
        value=12.5,
        context={"k": 1},
    )
    assert a.nats_subject() == "cosma.auv.AUV206.anomaly.battery_low"
    assert "battery_low" in a.to_json()