from datetime import datetime
from unittest.mock import AsyncMock, MagicMock

import pytest
from asyncua import ua

import ingestor.metrics as metrics
from ingestor.engines.active_read import ActiveReadEngine


def make_engine():
    eng = ActiveReadEngine(
        pool=AsyncMock(),
        sink=AsyncMock(),
        logger=MagicMock(),
        notification_handler=MagicMock(),
        metrics_controller=AsyncMock(),
    )
    eng.emit_metric = AsyncMock()
    return eng


def make_dv(value=42.0, status='Good', source_ts=None, server_ts=None):
    source_ts = source_ts or datetime(2026, 7, 13, 12, 0, 0)
    server_ts = server_ts or source_ts
    return ua.DataValue(
        ua.Variant(value),
        StatusCode_=ua.StatusCode(getattr(ua.StatusCodes, status)),
        SourceTimestamp=source_ts,
        ServerTimestamp=server_ts,
    )


def make_client(dv=None):
    node = MagicMock()
    node.read_data_value = AsyncMock(return_value=dv or make_dv())
    client = MagicMock()
    client.get_node = MagicMock(return_value=node)
    return client, node


NAMES = [{'tag_name': 'a', 'model_id': 'm1', 'collection': 'coll'}]


@pytest.mark.asyncio
async def test_read_now_persists_and_returns_fields_when_names_given():
    eng = make_engine()
    client, node = make_client()
    eng.pool.get.return_value = client

    result = await eng.read_now('srv1', 'ns=2;i=5', names=NAMES)

    client.get_node.assert_called_once_with('ns=2;i=5')
    node.read_data_value.assert_awaited_once()
    eng.sink.publish_reading.assert_awaited_once()
    _, kwargs = eng.sink.publish_reading.call_args
    assert kwargs['tag'] == 'ns=2;i=5'
    assert kwargs['value'] == 42.0
    assert kwargs['names'] == NAMES
    assert result['value'] == 42.0
    assert result['opc_status_code'] == 'Good'
    assert result['persisted'] is True
    assert result['source_timestamp'].startswith('2026-07-13 12:00:00')
    assert result['server_timestamp'].startswith('2026-07-13 12:00:00')
    eng.emit_metric.assert_any_await(
        metric_object=metrics.OPC_ACTIVE_READ_TOTAL,
        tags={'pod_id': eng.pod_id, 'server_name': 'srv1', 'result': 'success'},
    )
    latency_call = next(
        c
        for c in eng.emit_metric.await_args_list
        if c.kwargs['metric_object'] is metrics.OPC_ACTIVE_READ_LATENCY
    )
    assert latency_call.kwargs['method'] == 'observe'
    assert latency_call.kwargs['value'] >= 0
    lag_call = next(
        c for c in eng.emit_metric.await_args_list if c.kwargs['metric_object'] is metrics.OPC_READ_LAG
    )
    assert lag_call.kwargs['method'] == 'set'


@pytest.mark.asyncio
async def test_read_now_without_names_does_not_persist():
    eng = make_engine()
    client, _ = make_client()
    eng.pool.get.return_value = client

    result = await eng.read_now('srv1', 'ns=2;i=5')

    eng.sink.publish_reading.assert_not_awaited()
    assert result['persisted'] is False


@pytest.mark.asyncio
async def test_read_now_error_emits_metric_and_reraises():
    eng = make_engine()
    node = MagicMock()
    node.read_data_value = AsyncMock(side_effect=RuntimeError('boom'))
    client = MagicMock()
    client.get_node = MagicMock(return_value=node)
    eng.pool.get.return_value = client

    with pytest.raises(RuntimeError, match='boom'):
        await eng.read_now('srv1', 'ns=2;i=5')

    eng.emit_metric.assert_any_await(
        metric_object=metrics.OPC_ACTIVE_READ_TOTAL,
        tags={'pod_id': eng.pod_id, 'server_name': 'srv1', 'result': 'error'},
    )
    eng.sink.publish_reading.assert_not_awaited()


def make_slot(cycle_multiple=None, enabled=True):
    active_read = {'enabled': enabled}
    if cycle_multiple is not None:
        active_read['cycle_multiple'] = cycle_multiple
    return {
        'srv_name': {
            'server_id': 'srv1',
            'url': 'opc.tcp://x',
            'tags': {
                'ns=2;i=5': {'frequency': 1000, 'names': NAMES, 'active_read': active_read},
            },
        }
    }


@pytest.mark.asyncio
async def test_scheduled_tick_respects_cycle_multiple():
    eng = make_engine()
    eng.read_now = AsyncMock()
    slot = make_slot(cycle_multiple=3)

    await eng.scheduled_tick(slot)
    await eng.scheduled_tick(slot)
    eng.read_now.assert_not_awaited()
    await eng.scheduled_tick(slot)
    eng.read_now.assert_awaited_once_with(
        'srv1', 'ns=2;i=5', names=NAMES, server_cfg={'server_id': 'srv1', 'url': 'opc.tcp://x'}
    )


@pytest.mark.asyncio
async def test_scheduled_tick_skips_disabled_tags():
    eng = make_engine()
    eng.read_now = AsyncMock()
    slot = make_slot(enabled=False)

    await eng.scheduled_tick(slot)

    eng.read_now.assert_not_awaited()


@pytest.mark.asyncio
async def test_scheduled_tick_continues_past_tag_error():
    eng = make_engine()
    bad_slot = make_slot(cycle_multiple=1)
    good_names = [{'tag_name': 'b', 'model_id': 'm2', 'collection': 'coll'}]
    bad_slot['srv_name']['tags']['ns=2;i=6'] = {
        'frequency': 1000,
        'names': good_names,
        'active_read': {'enabled': True, 'cycle_multiple': 1},
    }

    calls = []

    async def fake_read_now(server_id, addr, names=None, server_cfg=None):
        calls.append(addr)
        if addr == 'ns=2;i=5':
            raise RuntimeError('boom')

    eng.read_now = AsyncMock(side_effect=fake_read_now)

    await eng.scheduled_tick(bad_slot)

    assert set(calls) == {'ns=2;i=5', 'ns=2;i=6'}
    eng.logger.error.assert_called_once()