"""
interface/consumer/run_consumer.py
────────────────────────────────────
Standalone async consumer — Entry Point 2 (Google Colab / local).

This script:
    1. Wires all dependencies (same repos, broker, processor, model as the API).
    2. Connects to RabbitMQ.
    3. Runs ProcessAndPredictUseCase for every message consumed.

Usage:
    python -m src.interface.consumer.run_consumer

Colab usage:
    !python -m src.interface.consumer.run_consumer

The consumer runs indefinitely until interrupted (Ctrl+C or Colab cell stop).
"""
from __future__ import annotations

import asyncio
import signal
import sys
from typing import Any

from src.application.use_cases.process_and_predict import ProcessAndPredictUseCase
from src.infrastructure.database.connection import create_all_tables, dispose_engine, get_session_factory
from src.infrastructure.database.repositories.ppg_repository import SQLAlchemyPPGRepository
from src.infrastructure.database.repositories.prediction_repository import SQLAlchemyPredictionRepository
from src.infrastructure.messaging.rabbitmq_broker import RabbitMQBroker
from src.infrastructure.model.gan_vgtlnet_service import GANVGTLNetService
from src.infrastructure.model.mock_model_service import MockModelService
from src.infrastructure.processing.scipy_signal_processor import ScipySignalProcessor
from src.shared.config import get_settings
from src.shared.constants import PPG_QUEUE_NAME
from src.shared.logger import get_logger

logger = get_logger(__name__)


async def run() -> None:
    """
    Bootstrap and run the message queue consumer.

    Dependency wiring mirrors the API's dependencies.py — the use case is
    identical, only the bootstrapping mechanism differs.
    """
    settings = get_settings()

    logger.info("=" * 60)
    logger.info("BP Monitoring Pipeline — Consumer starting up")
    logger.info("Database : %s", settings.database_url.split("@")[-1])
    logger.info("Broker   : %s", settings.rabbitmq_url.split("@")[-1])
    logger.info("Mock Model: %s", settings.use_mock_model)
    logger.info("=" * 60)

    # ── Create DB tables (dev/SQLite) ─────────────────────────────────────────
    if settings.debug or "sqlite" in settings.database_url:
        await create_all_tables()

    # ── Wire dependencies ─────────────────────────────────────────────────────
    broker = RabbitMQBroker(url=settings.rabbitmq_url)
    signal_processor = ScipySignalProcessor()
    model_service = MockModelService() if settings.use_mock_model else GANVGTLNetService()

    # Load model
    logger.info("Loading model (%s)…", model_service.model_version)
    await model_service.load_model()
    logger.info("Model ready.")

    # Connect broker
    await broker.connect()
    logger.info("Connected to RabbitMQ.")

    # ── Message handler ───────────────────────────────────────────────────────
    session_factory = get_session_factory()

    async def handle_message(payload: dict[str, Any]) -> None:
        """
        Invoked for each message dequeued from PPG_QUEUE_NAME.

        Creates a new DB session per message (request-scoped isolation).
        """
        signal_id = payload.get("id", "<unknown>")
        logger.info("Received message for signal_id=%s", signal_id)

        async with session_factory() as session:
            ppg_repo = SQLAlchemyPPGRepository(session)
            prediction_repo = SQLAlchemyPredictionRepository(session)

            use_case = ProcessAndPredictUseCase(
                ppg_repo=ppg_repo,
                prediction_repo=prediction_repo,
                signal_processor=signal_processor,
                model_service=model_service,
            )

            try:
                prediction = await use_case.execute(payload)
                await session.commit()
                logger.info(
                    "Prediction stored: id=%s SBP=%.1f DBP=%.1f",
                    prediction.id,
                    prediction.predicted_sbp,
                    prediction.predicted_dbp,
                )
            except Exception as exc:
                await session.rollback()
                logger.error(
                    "Failed to process signal_id=%s: %s", signal_id, exc, exc_info=True
                )
                raise  # re-raise so the broker nacks the message

    # ── Start consuming ───────────────────────────────────────────────────────
    logger.info("Listening on queue '%s'… (Ctrl+C to stop)", PPG_QUEUE_NAME)
    try:
        await broker.consume(queue_name=PPG_QUEUE_NAME, handler=handle_message)
    finally:
        await broker.disconnect()
        await dispose_engine()
        logger.info("Consumer shut down cleanly.")


def main() -> None:
    """CLI entry point."""
    loop = asyncio.get_event_loop()

    # Handle Ctrl+C gracefully
    def _handle_sigint(*_: Any) -> None:
        logger.info("Interrupt received — shutting down consumer…")
        for task in asyncio.all_tasks(loop):
            task.cancel()

    signal.signal(signal.SIGINT, _handle_sigint)

    try:
        loop.run_until_complete(run())
    except asyncio.CancelledError:
        pass
    finally:
        loop.close()


if __name__ == "__main__":
    main()