"""
Scanner service for initial library scan and one-time bootstrap of the
default source root on first boot.
"""
import os
import logging
from sqlalchemy import select

from app.database import AsyncSessionLocal
from app.models import SourceRoot
from app.tasks.scan import scan_all_source_roots
from app.config import settings

logger = logging.getLogger(__name__)

# The single host → container mount path. The compose file mounts whatever
# the user set as PHOTO_DIRS at this path.
DEFAULT_LIBRARY_PATH = "/photos"
DEFAULT_LIBRARY_NAME = "Library"


async def bootstrap_default_source_root() -> None:
    """If no source roots exist in the DB, create one pointing at the default
    library mount. Lets a fresh install pick up photos with zero
    configuration: the user only needs to set PHOTO_DIRS in .env.
    """
    if not os.path.isdir(DEFAULT_LIBRARY_PATH):
        logger.warning(
            f"Default library path {DEFAULT_LIBRARY_PATH} is not mounted; "
            "set PHOTO_DIRS in .env and recreate the container."
        )
        return

    async with AsyncSessionLocal() as session:
        result = await session.execute(select(SourceRoot))
        if result.scalars().first() is not None:
            return  # Already have at least one source root, leave it alone.

        source_root = SourceRoot(
            name=DEFAULT_LIBRARY_NAME,
            path=DEFAULT_LIBRARY_PATH,
        )
        session.add(source_root)
        await session.commit()
        logger.info(
            f"Bootstrapped default source root: {DEFAULT_LIBRARY_NAME} → "
            f"{DEFAULT_LIBRARY_PATH}"
        )


async def start_initial_scan():
    """Start the initial library scan.

    NOTE: the folder watcher (watch_folders task) is intentionally NOT
    dispatched here. It's an infinite loop celery task and every backend
    restart was queuing a new instance, eventually pinning every worker
    and starving scan_folder dispatches. Re-enabling it needs a Redis
    lock or a dedicated long-running container — until then the user
    triggers scans manually via "Scan all folders".
    """
    try:
        scan_all_source_roots.delay()
        logger.info("Initial scan queued successfully")
    except Exception as e:
        logger.error(f"Failed to start initial scan: {e}")