"""Folder management use cases."""
from typing import List, Optional
from sqlalchemy.orm import Session
from app.models import Folder


class FolderService:
    """Manages folder operations."""
    
    def __init__(self, db: Session):
        self.db = db
    
    def create_folder(
        self,
        name: str,
        org_id: str,
        parent_id: Optional[str] = None
    ) -> dict:
        """Create a new folder."""
        folder = Folder(
            name=name,
            org_id=org_id,
            parent_id=parent_id
        )
        self.db.add(folder)
        self.db.commit()
        self.db.refresh(folder)
        
        return {
            "id": folder.id,
            "name": folder.name,
            "parent_id": folder.parent_id,
            "created_at": folder.created_at
        }
    
    def list_folders(
        self,
        org_id: str,
        parent_id: Optional[str] = None
    ) -> List[dict]:
        """List folders for organization."""
        query = self.db.query(Folder).filter(Folder.org_id == org_id)
        
        if parent_id:
            query = query.filter(Folder.parent_id == parent_id)
        else:
            query = query.filter(Folder.parent_id == None)
        
        folders = query.order_by(Folder.created_at.desc()).all()
        
        return [
            {
                "id": f.id,
                "name": f.name,
                "parent_id": f.parent_id,
                "created_at": f.created_at
            }
            for f in folders
        ]
    
    def delete_folder(self, folder_id: str, org_id: str) -> None:
        """Delete a folder (must be empty)."""
        folder = self.db.query(Folder).filter(
            Folder.id == folder_id,
            Folder.org_id == org_id
        ).first()
        
        if not folder:
            raise ValueError("Folder not found")
        
        # Check if folder has documents
        if folder.documents:
            raise ValueError("Folder must be empty before deletion (contains documents)")
        
        # Check if folder has subfolders
        subfolders = self.db.query(Folder).filter(Folder.parent_id == folder_id).count()
        if subfolders > 0:
            raise ValueError("Folder must be empty before deletion (contains subfolders)")
        
        self.db.delete(folder)
        self.db.commit()