import gc
import ssl

from celery import Celery
from celery.signals import task_postrun

from app.core.config import settings

_use_ssl = settings.ENVIRONMENT != "local"
_scheme = "rediss" if _use_ssl else "redis"
_redis_url = f"{_scheme}://{settings.REDIS_HOST}:{settings.REDIS_PORT}/0"
_ssl_opts = {"ssl_cert_reqs": ssl.CERT_NONE} if _use_ssl else None

celery_app = Celery(
    "fansifter_clipper_tasks",
    broker=_redis_url,
    backend=_redis_url,
)

celery_app.conf.update(
    broker_use_ssl=_ssl_opts,
    redis_backend_use_ssl=_ssl_opts,
    task_serializer="json",
    accept_content=["json"],
    result_serializer="json",
    timezone="UTC",
    enable_utc=True,
    task_track_started=True,
    result_expires=3600,

    # Timeouts — video processing can take 20-30 min for a full clip run
    task_time_limit=2700,       # 45 min hard kill (SIGKILL)
    task_soft_time_limit=2400,  # 40 min soft kill (raises SoftTimeLimitExceeded)

    # Memory management
    # Restart the worker process after each task so OpenCV / MediaPipe / NumPy
    # buffers are freed at the OS level.  The startup cost (~1-2s to reload
    # MediaPipe models) is acceptable for tasks that run for minutes.
    worker_max_tasks_per_child=1,
    # Hard memory ceiling: kill & replace the worker if RSS exceeds 6 GB.
    # Frame-by-frame processing of a 4K source can peak at 3-4 GB; this
    # leaves headroom while preventing runaway OOM situations.
    worker_max_memory_per_child=6_291_456,  # 6 GB in KB

    # Never pre-fetch more than one task — keeps a second heavy job from
    # piling up in the same worker while the first is still running.
    worker_prefetch_multiplier=1,

    # Reliability — only acknowledge after the task finishes so a crashed
    # worker doesn't silently drop a clip generation job.
    task_acks_late=True,
    task_reject_on_worker_lost=True,
)


@task_postrun.connect
def task_postrun_handler(sender=None, **kwargs):
    """Explicit GC pass after each task, before worker_max_tasks_per_child recycles the process."""
    gc.collect()


# Import tasks to register them with Celery
# This must be done after celery_app is created
from app.tasks import social_analysis, video_processing  # noqa: E402, F401