import json
from unittest.mock import AsyncMock, MagicMock, patch

import pytest

from ingestor.adapters.nats_consumer import NatsWriteConsumer


def make_consumer(**kwargs):
    return NatsWriteConsumer(
        nats_url='nats://localhost:4222',
        write_engine=AsyncMock(),
        logger=MagicMock(),
        **kwargs,
    )


@pytest.mark.asyncio
async def test_handle_valid_json_dispatches_to_write_engine():
    consumer = make_consumer()
    payload = {'server_id': 'srv1', 'addr': 'ns=2;i=5', 'value': 1.0, 'data_type': 'float'}
    msg = MagicMock(data=json.dumps(payload).encode())

    await consumer._handle(msg)

    consumer.write_engine.write.assert_awaited_once_with(payload)


@pytest.mark.asyncio
async def test_handle_invalid_json_drops_message_and_logs_error():
    consumer = make_consumer()
    msg = MagicMock(data=b'not-json')

    await consumer._handle(msg)

    consumer.write_engine.write.assert_not_awaited()
    consumer.logger.error.assert_called_once()


@pytest.mark.asyncio
async def test_start_subscribes_with_subject_and_queue():
    consumer = make_consumer(subject='opc.write', queue='gateway-writers')
    mock_nc = AsyncMock()
    mock_nc.subscribe = AsyncMock()

    with patch('ingestor.adapters.nats_consumer.nats') as mock_nats:
        mock_nats.connect = AsyncMock(return_value=mock_nc)
        await consumer.start()

    mock_nats.connect.assert_awaited_once_with(servers='nats://localhost:4222')
    mock_nc.subscribe.assert_awaited_once_with(
        'opc.write', queue='gateway-writers', cb=consumer._handle
    )


@pytest.mark.asyncio
async def test_stop_before_start_does_not_raise():
    consumer = make_consumer()

    await consumer.stop()  # no raise


@pytest.mark.asyncio
async def test_stop_after_start_drains_and_unsubscribes():
    consumer = make_consumer()
    mock_nc = AsyncMock()
    mock_sub = AsyncMock()
    mock_nc.subscribe = AsyncMock(return_value=mock_sub)

    with patch('ingestor.adapters.nats_consumer.nats') as mock_nats:
        mock_nats.connect = AsyncMock(return_value=mock_nc)
        await consumer.start()
        await consumer.stop()

    mock_sub.unsubscribe.assert_awaited_once()
    mock_nc.drain.assert_awaited_once()