"""Celery Beat periodic tasks."""
from __future__ import annotations

import json
import logging
from datetime import datetime, timedelta

from celery import shared_task

logger = logging.getLogger(__name__)


@shared_task(name="app.tasks.beat_tasks.apply_worker_concurrency", queue="step_processing")
def apply_worker_concurrency() -> None:
    """Read worker_configs from DB and broadcast pool_grow to workers.

    Runs every 5 minutes via Celery Beat. Signals all workers to adjust their
    pool size to match the max_concurrency setting for each enabled queue.
    """
    try:
        from sqlalchemy import create_engine, select
        from sqlalchemy.orm import Session
        from app.config import settings as app_settings
        from app.models.worker_config import WorkerConfig
        from app.tasks.celery_app import celery_app

        sync_url = app_settings.database_url.replace("+asyncpg", "")
        eng = create_engine(sync_url)
        try:
            with Session(eng) as session:
                configs = session.execute(
                    select(WorkerConfig).where(WorkerConfig.enabled == True)  # noqa: E712
                ).scalars().all()
                for cfg in configs:
                    try:
                        celery_app.control.broadcast(
                            "pool_grow",
                            arguments={"n": cfg.max_concurrency},
                            destination=None,  # all workers
                            reply=False,
                        )
                        logger.info(
                            "[WORKER_SCALE] Signalled pool_grow n=%d for queue %s",
                            cfg.max_concurrency, cfg.queue_name,
                        )
                    except Exception as exc:
                        logger.warning(
                            "[WORKER_SCALE] pool_grow failed for %s: %s",
                            cfg.queue_name, exc,
                        )
        finally:
            eng.dispose()
    except Exception as exc:
        logger.error("apply_worker_concurrency failed: %s", exc)


@shared_task(name="app.tasks.beat_tasks.broadcast_queue_status", queue="step_processing")
def broadcast_queue_status() -> None:
    """Broadcast current queue depths to all WebSocket clients every 10s.

    Publishes to the Redis '__broadcast__' channel which the WebSocket
    subscriber in the FastAPI process forwards to all connected clients.
    """
    try:
        import redis as sync_redis
        from app.config import settings

        r = sync_redis.from_url(settings.redis_url, decode_responses=True)
        depths = {
            "step_processing": r.llen("step_processing"),
            "thumbnail_rendering": r.llen("thumbnail_rendering"),
        }
        event = {"type": "queue_update", "depths": depths}
        r.publish("__broadcast__", json.dumps(event))
        r.close()
        logger.debug("Broadcast queue_update: %s", depths)
    except Exception as exc:
        logger.warning("broadcast_queue_status failed: %s", exc)


@shared_task(name="app.tasks.beat_tasks.recover_stuck_cad_files", queue="step_processing")
def recover_stuck_cad_files() -> None:
    """Reset CAD files stuck in 'processing' for more than 10 minutes to 'failed'.

    This recovers from worker crashes (container restarts, OOM kills) that leave
    the processing_status committed as 'processing' with no task running to complete it.
    Runs every 5 minutes via Celery Beat.
    """
    try:
        from sqlalchemy import create_engine, update, and_
        from sqlalchemy.orm import Session
        from app.config import settings
        from app.models.cad_file import CadFile, ProcessingStatus

        cutoff = datetime.utcnow() - timedelta(minutes=10)
        sync_url = settings.database_url.replace("+asyncpg", "")
        engine = create_engine(sync_url)
        with Session(engine) as session:
            result = session.execute(
                update(CadFile)
                .where(
                    and_(
                        CadFile.processing_status == ProcessingStatus.processing,
                        CadFile.updated_at < cutoff,
                    )
                )
                .values(
                    processing_status=ProcessingStatus.failed,
                    error_message="Processing timed out — worker may have crashed. Use 'Regenerate Thumbnail' to retry.",
                )
                .returning(CadFile.id, CadFile.original_name)
            )
            rows = result.fetchall()
            session.commit()
        engine.dispose()

        if rows:
            names = [r[1] for r in rows]
            logger.warning(
                "recover_stuck_cad_files: reset %d stuck file(s) to failed: %s",
                len(rows), names,
            )
        else:
            logger.debug("recover_stuck_cad_files: no stuck files found")
    except Exception as exc:
        logger.error("recover_stuck_cad_files failed: %s", exc)


@shared_task(name="app.tasks.beat_tasks.recover_stalled_renders", queue="step_processing")
def recover_stalled_renders() -> None:
    """Detect order_lines stuck in render_status='processing' for longer than
    RENDER_STALL_TIMEOUT_MINUTES (default 30) and mark them as failed.

    Tries to revoke the Celery task if a celery_task_id is stored in render_job_doc.
    Emits a single batch system alert to admins via CHANNEL_ALERT.
    Runs every 5 minutes via Celery Beat.
    """
    RENDER_STALL_TIMEOUT_MINUTES = 30
    try:
        from sqlalchemy import create_engine, select
        from sqlalchemy.orm import Session
        from app.config import settings
        from app.domains.orders.models import OrderLine
        from app.domains.notifications.service import emit_notification_sync, CHANNEL_ALERT
        from app.tasks.celery_app import celery_app

        cutoff = datetime.utcnow() - timedelta(minutes=RENDER_STALL_TIMEOUT_MINUTES)
        sync_url = settings.database_url.replace("+asyncpg", "")
        engine = create_engine(sync_url)

        stalled_ids: list[str] = []

        with Session(engine) as session:
            rows = session.execute(
                select(OrderLine).where(
                    OrderLine.render_status == "processing",
                    OrderLine.render_started_at < cutoff,
                )
            ).scalars().all()

            for line in rows:
                elapsed_minutes = int(
                    (datetime.utcnow() - line.render_started_at).total_seconds() / 60
                )
                # Try to revoke the Celery task if we have its ID
                job_doc = line.render_job_doc or {}
                celery_task_id = job_doc.get("celery_task_id")
                if celery_task_id:
                    try:
                        celery_app.control.revoke(celery_task_id, terminate=True)
                        logger.info(
                            "[WORKER_RECOVERY] Revoked Celery task %s for order_line %s",
                            celery_task_id, line.id,
                        )
                    except Exception as revoke_exc:
                        logger.warning(
                            "[WORKER_RECOVERY] Could not revoke task %s: %s",
                            celery_task_id, revoke_exc,
                        )

                # Update render_job_doc with failure info
                updated_doc = dict(job_doc)
                updated_doc["state"] = "failed"
                updated_doc["error"] = (
                    f"Stalled render terminated by health recovery after {RENDER_STALL_TIMEOUT_MINUTES}min"
                )

                line.render_status = "failed"
                line.render_job_doc = updated_doc

                stalled_ids.append(str(line.id))
                logger.warning(
                    "[WORKER_RECOVERY] Stalled render for order_line %s terminated after %dmin",
                    line.id, elapsed_minutes,
                )

            if stalled_ids:
                session.commit()

        engine.dispose()

        if stalled_ids:
            emit_notification_sync(
                action="worker.recovery",
                entity_type="system",
                details={
                    "message": (
                        f"Worker recovery: {len(stalled_ids)} stalled render(s) terminated "
                        f"after {RENDER_STALL_TIMEOUT_MINUTES}min timeout"
                    ),
                    "stalled_order_line_ids": stalled_ids,
                    "count": len(stalled_ids),
                },
                channel=CHANNEL_ALERT,
            )
            logger.warning(
                "recover_stalled_renders: terminated %d stalled render(s): %s",
                len(stalled_ids), stalled_ids,
            )
        else:
            logger.debug("recover_stalled_renders: no stalled renders found")
    except Exception as exc:
        logger.error("recover_stalled_renders failed: %s", exc)


@shared_task(name="app.tasks.beat_tasks.batch_render_notifications", queue="step_processing")
def batch_render_notifications() -> None:
    """Check for orders where all lines are terminal but no batch notification emitted yet.

    This acts as a safety net for batch notifications that may have been missed
    if the order completion hook failed or was skipped. Runs every 60 seconds.
    """
    try:
        from sqlalchemy import create_engine, select
        from sqlalchemy.orm import Session
        from app.config import settings
        from app.domains.orders.models import Order, OrderStatus
        from app.domains.notifications.models import AuditLog
        from app.domains.notifications.service import (
            emit_batch_render_notification_sync,
            CHANNEL_NOTIFICATION,
        )

        sync_url = settings.database_url.replace("+asyncpg", "")
        engine = create_engine(sync_url)

        with Session(engine) as session:
            # Find all completed orders
            completed_order_ids: list[str] = [
                str(oid) for oid in session.execute(
                    select(Order.id).where(Order.status == OrderStatus.completed)
                ).scalars().all()
            ]

            if not completed_order_ids:
                engine.dispose()
                logger.debug("batch_render_notifications: no completed orders found")
                return

            # Find which of those already have a batch notification
            notified_ids_raw = session.execute(
                select(AuditLog.entity_id).where(
                    AuditLog.entity_type == "order",
                    AuditLog.action == "order.completed",
                    AuditLog.channel == CHANNEL_NOTIFICATION,
                    AuditLog.entity_id.in_(completed_order_ids),
                )
            ).scalars().all()
            notified_ids = set(notified_ids_raw)

        engine.dispose()

        orders_needing_notification = [
            oid for oid in completed_order_ids if oid not in notified_ids
        ]

        if not orders_needing_notification:
            logger.debug("batch_render_notifications: no orders need batch notification")
            return

        logger.info(
            "batch_render_notifications: emitting batch notifications for %d order(s)",
            len(orders_needing_notification),
        )
        for order_id in orders_needing_notification:
            try:
                emit_batch_render_notification_sync(str(order_id))
            except Exception as exc:
                logger.error(
                    "batch_render_notifications: failed for order %s: %s", order_id, exc
                )

    except Exception as exc:
        logger.error("batch_render_notifications failed: %s", exc)