from unittest.mock import AsyncMock, MagicMock, call

import pytest

import ingestor.metrics as metrics
from ingestor.managers.server_reader import ServerReader

SERVER_CONFIG = {
    'name': 'kepserver',
    'server_id': 1,  # the slot may carry it as int; the pool keys by str
    'url': 'opc.tcp://kepserver:49320',
    'server_uri': 'urn:sientia:opc-ingestor',
    'use_security': True,
    'subscription_period_ms': 15000.0,
}


def make_reader():
    pool = MagicMock(get=AsyncMock(), evict=AsyncMock())
    reader = ServerReader(
        name='kepserver',
        server_config=SERVER_CONFIG,
        pool=pool,
        sink=AsyncMock(),
        logger=MagicMock(),
        notification_handler=MagicMock(),
        metrics_controller=AsyncMock(),
        metadata={},
    )
    reader.engine = MagicMock(
        subscriptions={},
        pod_id='pod',
        create_subscription=AsyncMock(),
        subscribe=AsyncMock(),
        unsubscribe=AsyncMock(),
        check_cycles=AsyncMock(),
        check_opc_listenning=AsyncMock(return_value=False),
        emit_metric=AsyncMock(),
    )
    return reader, pool


def test_server_cfg_keeps_only_connection_fields():
    reader, _ = make_reader()

    assert reader.server_id == '1'
    assert reader.server_cfg == {
        'url': 'opc.tcp://kepserver:49320',
        'server_uri': 'urn:sientia:opc-ingestor',
        'use_security': True,
        'subscription_period_ms': 15000.0,
    }


@pytest.mark.asyncio
async def test_connect_opens_pooled_connection():
    reader, pool = make_reader()

    await reader.connect()

    # use_security=True: the pool fetches the certificate from MinIO (CertProvider)
    pool.get.assert_awaited_once_with('1', reader.server_cfg)


@pytest.mark.asyncio
async def test_connect_propagates_failure():
    reader, pool = make_reader()
    pool.get.side_effect = ConnectionError('unreachable')

    with pytest.raises(ConnectionError):
        await reader.connect()


@pytest.mark.asyncio
async def test_subscription_calls_delegate_to_engine_per_slot():
    reader, _ = make_reader()
    nodes = {'ns=2;i=2': {'frequency': '1000', 'names': [{'collection': 'raw_a', 'tag_name': 'a'}]}}

    await reader.create_subscription('1')
    await reader.subscribe('1', nodes, 10)
    await reader.unsubscribe('1')

    reader.engine.create_subscription.assert_awaited_once_with('1', reader.server_cfg, '1')
    reader.engine.subscribe.assert_awaited_once_with('1', nodes, 10)
    reader.engine.unsubscribe.assert_awaited_once_with('1')


@pytest.mark.asyncio
async def test_supervision_delegates_to_engine():
    reader, _ = make_reader()
    reader.engine.check_opc_listenning.return_value = True

    await reader.check_cycles()
    lost = await reader.check_opc_listenning()

    reader.engine.check_cycles.assert_awaited_once()
    reader.engine.check_opc_listenning.assert_awaited_once_with('1')
    assert lost is True


def test_subscriptions_are_the_engine_ones():
    reader, _ = make_reader()
    reader.engine.subscriptions['1'] = MagicMock()

    assert reader.subscriptions is reader.engine.subscriptions


@pytest.mark.asyncio
async def test_shutdown_unsubscribes_all_slots_evicts_and_zeroes_metrics():
    reader, pool = make_reader()
    reader.engine.subscriptions.update({'1': MagicMock(), '2': MagicMock()})

    await reader.shutdown()

    reader.engine.unsubscribe.assert_has_awaits([call('1'), call('2')])
    # Dropping the pooled connection makes the next initialization reconnect.
    pool.evict.assert_awaited_once_with('1')
    reader.engine.emit_metric.assert_any_await(
        metric_object=metrics.OPC_CONNECTION_STATUS,
        method='set',
        value=0,
        tags={'pod_id': 'pod', 'server_name': '1', 'server_url': 'opc.tcp://kepserver:49320'},
    )
    reader.engine.emit_metric.assert_any_await(
        metric_object=metrics.OPC_TAGS_SUBSCRIBED,
        method='set',
        value=0,
        tags={'pod_id': 'pod', 'server_name': '1'},
    )


@pytest.mark.asyncio
async def test_shutdown_without_evict_keeps_the_shared_connection():
    """Slot moved to another pod: drop the subscriptions, keep the pooled
    connection for NATS writes/gRPC (review #7)."""
    reader, pool = make_reader()
    reader.engine.subscriptions.update({'1': MagicMock()})

    await reader.shutdown(evict=False)

    reader.engine.unsubscribe.assert_awaited_once_with('1')
    pool.evict.assert_not_awaited()
    for c in reader.engine.emit_metric.await_args_list:
        assert c.kwargs['metric_object'] is not metrics.OPC_CONNECTION_STATUS