"""CRUD operations for Docker images."""
from datetime import datetime
from typing import List, Optional

from sqlalchemy import select, delete, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.docker_image import DockerImage


class DockerImageRepository:
    """Repository for Docker image CRUD operations."""

    def __init__(self, session: AsyncSession):
        self.session = session

    async def get(self, image_db_id: int) -> Optional[DockerImage]:
        """Get an image by its database ID."""
        result = await self.session.execute(
            select(DockerImage).where(DockerImage.id == image_db_id)
        )
        return result.scalar_one_or_none()

    async def get_by_image_id(self, host_id: str, image_id: str) -> Optional[DockerImage]:
        """Get an image by host ID and Docker image ID."""
        result = await self.session.execute(
            select(DockerImage).where(
                DockerImage.host_id == host_id,
                DockerImage.image_id == image_id
            ).limit(1)
        )
        return result.scalars().first()

    async def list_by_host(self, host_id: str) -> List[DockerImage]:
        """List all images for a host."""
        result = await self.session.execute(
            select(DockerImage)
            .where(DockerImage.host_id == host_id)
            .order_by(DockerImage.last_update_at.desc())
        )
        return list(result.scalars().all())

    async def count_by_host(self, host_id: str) -> dict:
        """Count images and total size for a host."""
        result = await self.session.execute(
            select(
                func.count(DockerImage.id).label('total'),
                func.coalesce(func.sum(DockerImage.size), 0).label('total_size')
            ).where(DockerImage.host_id == host_id)
        )
        row = result.one()
        return {
            "total": row.total or 0,
            "total_size": row.total_size or 0
        }

    async def upsert(
        self,
        host_id: str,
        image_id: str,
        repo_tags: Optional[List[str]] = None,
        size: Optional[int] = None,
        created: Optional[datetime] = None
    ) -> DockerImage:
        """Create or update an image."""
        existing = await self.get_by_image_id(host_id, image_id)
        
        if existing:
            existing.repo_tags = repo_tags
            existing.size = size
            existing.created = created
            existing.last_update_at = datetime.utcnow()
            return existing
        
        image = DockerImage(
            host_id=host_id,
            image_id=image_id,
            repo_tags=repo_tags,
            size=size,
            created=created
        )
        self.session.add(image)
        return image

    async def delete_by_host(self, host_id: str) -> int:
        """Delete all images for a host."""
        result = await self.session.execute(
            delete(DockerImage).where(DockerImage.host_id == host_id)
        )
        return result.rowcount

    async def delete_stale(self, host_id: str, current_image_ids: List[str]) -> int:
        """Delete images that no longer exist on the host."""
        if not current_image_ids:
            return await self.delete_by_host(host_id)
        
        result = await self.session.execute(
            delete(DockerImage).where(
                DockerImage.host_id == host_id,
                DockerImage.image_id.notin_(current_image_ids)
            )
        )
        return result.rowcount