"""Unit tests for SystemHealthCheck."""
from __future__ import annotations

from pathlib import Path
from unittest.mock import AsyncMock, MagicMock

import pytest

from ha_diag.checks.system_health import SystemHealthCheck, _extract_component_statuses
from ha_diag.config import Settings
from ha_diag.models import HAEventType, Severity
from ha_diag.storage import Storage


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _make_settings(**overrides) -> Settings:
    defaults: dict = {
        "ha_url": "http://test.local:8123",
        "ha_token": "test",
        "node_name": "test-node",
        "location_tag": "test-loc",
        "alert_cooldown_hours": 0.0,
        "check_interval": 60,
        "check_interval_unavailable": 3600,
    }
    defaults.update(overrides)
    return Settings(**defaults)


def _make_client(health=None, error=None):
    client = MagicMock()
    if error:
        client.get_system_health = AsyncMock(side_effect=error)
    else:
        client.get_system_health = AsyncMock(return_value=health or {})
    return client


def _ok_response(*components: str) -> dict:
    return {c: {"type": "result", "data": {"ok": True}} for c in components}


def _error_response(*components: str) -> dict:
    return {c: {"type": "error", "error": f"{c} failed"} for c in components}


# ---------------------------------------------------------------------------
# _extract_component_statuses unit tests
# ---------------------------------------------------------------------------


def test_extract_typed_result_format():
    data = {"recorder": {"type": "result", "data": {"backlog": 0}}}
    result = _extract_component_statuses(data)
    assert result["recorder"]["status"] == "ok"
    assert result["recorder"]["details"] == {"backlog": 0}


def test_extract_typed_error_format():
    data = {"cloud": {"type": "error", "error": "Connection refused"}}
    result = _extract_component_statuses(data)
    assert result["cloud"]["status"] == "error"
    assert "Connection refused" in result["cloud"]["details"]["error"]


def test_extract_legacy_error_field():
    data = {"cloud": {"error": "Timeout"}}
    result = _extract_component_statuses(data)
    assert result["cloud"]["status"] == "error"


def test_extract_nested_checks_format():
    data = {
        "info": {"version": "2024.12.0"},
        "checks": {
            "homeassistant": {"type": "result", "data": {}},
            "recorder": {"type": "error", "error": "DB locked"},
        },
    }
    result = _extract_component_statuses(data)
    assert "homeassistant" not in result or result.get("homeassistant", {}).get("status") == "ok"
    assert result["recorder"]["status"] == "error"
    assert "info" not in result


def test_extract_plain_dict_treated_as_ok():
    data = {"homeassistant": {"version": "2024.12.0", "docker": True}}
    result = _extract_component_statuses(data)
    assert result["homeassistant"]["status"] == "ok"


def test_extract_non_dict_value_skipped():
    data = {"scalar_component": "just-a-string"}
    result = _extract_component_statuses(data)
    assert "scalar_component" not in result


# ---------------------------------------------------------------------------
# SystemHealthCheck run() tests
# ---------------------------------------------------------------------------


@pytest.mark.asyncio
async def test_first_run_no_snapshot_no_event_for_ok(storage: Storage):
    """All components ok on first run — record snapshots, emit nothing."""
    check = SystemHealthCheck(_make_client(_ok_response("homeassistant", "recorder")),
                              storage, _make_settings())
    results = await check.run()
    assert results == []
    snap = await storage.get_system_health_snapshot("homeassistant")
    assert snap is not None
    assert snap["last_status"] == "ok"


@pytest.mark.asyncio
async def test_first_run_error_component_emits_event(storage: Storage):
    """Component in error on first run (no prior snapshot) → ha_system_health_degraded."""
    check = SystemHealthCheck(_make_client(_error_response("cloud")), storage, _make_settings())
    results = await check.run()
    assert len(results) == 1
    r = results[0]
    assert r.event_type == HAEventType.ha_system_health_degraded
    assert r.payload["component"] == "cloud"
    assert r.payload["previous_status"] == "unknown"
    assert r.payload["current_status"] == "error"
    assert r.severity == Severity.warning


@pytest.mark.asyncio
async def test_ok_to_error_transition_emits_event(storage: Storage):
    """Component transitions ok → error → event fired."""
    client_ok = _make_client(_ok_response("cloud"))
    client_err = _make_client(_error_response("cloud"))
    settings = _make_settings()

    await SystemHealthCheck(client_ok, storage, settings).run()
    results = await SystemHealthCheck(client_err, storage, settings).run()

    assert len(results) == 1
    assert results[0].payload["previous_status"] == "ok"
    assert results[0].payload["current_status"] == "error"


@pytest.mark.asyncio
async def test_sustained_error_no_duplicate_event(storage: Storage):
    """Component stays in error across multiple runs — only first run emits."""
    client_ok = _make_client(_ok_response("cloud"))
    client_err = _make_client(_error_response("cloud"))
    settings = _make_settings()

    await SystemHealthCheck(client_ok, storage, settings).run()
    results1 = await SystemHealthCheck(client_err, storage, settings).run()
    results2 = await SystemHealthCheck(client_err, storage, settings).run()
    results3 = await SystemHealthCheck(client_err, storage, settings).run()

    assert len(results1) == 1  # transition fires
    assert results2 == []
    assert results3 == []


@pytest.mark.asyncio
async def test_recovery_clears_alert_and_next_degradation_re_fires(storage: Storage):
    """error → ok → error: second degradation fires a new event."""
    settings = _make_settings()

    # First degradation
    await SystemHealthCheck(_make_client(_ok_response("cloud")), storage, settings).run()
    r1 = await SystemHealthCheck(_make_client(_error_response("cloud")), storage, settings).run()
    assert len(r1) == 1

    # Recovery
    r2 = await SystemHealthCheck(_make_client(_ok_response("cloud")), storage, settings).run()
    assert r2 == []

    # Second degradation
    r3 = await SystemHealthCheck(_make_client(_error_response("cloud")), storage, settings).run()
    assert len(r3) == 1
    assert r3[0].payload["previous_status"] == "ok"


@pytest.mark.asyncio
async def test_multiple_degraded_components_multiple_events(storage: Storage):
    health = {**_error_response("cloud", "recorder"), **_ok_response("homeassistant")}
    check = SystemHealthCheck(_make_client(health), storage, _make_settings())
    results = await check.run()
    components = {r.payload["component"] for r in results}
    assert components == {"cloud", "recorder"}
    assert all(r.event_type == HAEventType.ha_system_health_degraded for r in results)


@pytest.mark.asyncio
async def test_api_error_returns_empty(storage: Storage):
    """If /api/system_health is unreachable, return no results (not an error event)."""
    check = SystemHealthCheck(
        _make_client(error=Exception("timeout")), storage, _make_settings()
    )
    results = await check.run()
    assert results == []


@pytest.mark.asyncio
async def test_payload_contains_details(storage: Storage):
    health = {"recorder": {"type": "error", "error": "DB write lag 5000ms"}}
    check = SystemHealthCheck(_make_client(health), storage, _make_settings())
    results = await check.run()
    assert len(results) == 1
    assert "DB write lag" in results[0].payload["details"]["error"]


@pytest.mark.asyncio
async def test_snapshot_updated_after_recovery(storage: Storage):
    """After a recovery cycle, snapshot shows last_status='ok'."""
    settings = _make_settings()
    await SystemHealthCheck(_make_client(_error_response("cloud")), storage, settings).run()
    await SystemHealthCheck(_make_client(_ok_response("cloud")), storage, settings).run()
    snap = await storage.get_system_health_snapshot("cloud")
    assert snap["last_status"] == "ok"