from typing import List, Dict, Optional, Union, Any
from datetime import datetime
from sqlalchemy.orm import Session
from sqlalchemy import and_, or_
from models.food import Food
from schemas.food import FoodCreate, FoodUpdate

def get_available_menu_items(db: Session) -> List[Food]:
    """
    Get all currently available food items in the menu.
    
    Args:
        db: Database session
        
    Returns:
        List of available Food objects
    """
    return db.query(Food).filter(Food.is_available == True).all()

def filter_menu_by_category(db: Session, category: str) -> List[Food]:
    """
    Filter menu items by food category.
    
    Args:
        db: Database session
        category: Food category to filter by
        
    Returns:
        List of Food objects in the specified category
    """
    return db.query(Food).filter(
        and_(
            Food.category == category,
            Food.is_available == True
        )
    ).all()

def search_menu_items(
    db: Session, 
    search_term: str,
    category: Optional[str] = None
) -> List[Food]:
    """
    Search menu items by name or description.
    
    Args:
        db: Database session
        search_term: Term to search for
        category: Optional category filter
        
    Returns:
        List of matching Food objects
    """
    query = db.query(Food).filter(
        and_(
            Food.is_available == True,
            or_(
                Food.name.ilike(f"%{search_term}%"),
                Food.description.ilike(f"%{search_term}%")
            )
        )
    )
    
    if category:
        query = query.filter(Food.category == category)
        
    return query.all()

def format_menu_item(food: Food) -> Dict[str, Any]:
    """
    Format a food item for API response.
    
    Args:
        food: Food object to format
        
    Returns:
        Formatted food item dictionary
    """
    return {
        "id": food.id,
        "name": food.name,
        "description": food.description,
        "price": float(food.price),
        "category": food.category,
        "is_vegetarian": food.is_vegetarian,
        "calories": food.calories,
        "image_url": food.image_url
    }

def validate_food_data(food_data: Union[FoodCreate, FoodUpdate]) -> Dict[str, str]:
    """
    Validate food item data before creation/update.
    
    Args:
        food_data: Food data to validate
        
    Returns:
        Dictionary with error message if validation fails, empty dict if successful
    """
    errors = {}
    
    if food_data.price <= 0:
        errors["price"] = "Price must be greater than 0"
        
    if food_data.calories < 0:
        errors["calories"] = "Calories cannot be negative"
        
    if len(food_data.name) < 2:
        errors["name"] = "Name must be at least 2 characters long"
        
    if len(food_data.description) < 10:
        errors["description"] = "Description must be at least 10 characters long"
        
    return errors