from typing import List, Dict, Optional
from sqlalchemy.orm import Session
from models.meal import Meal

def get_all_meals(db: Session) -> List[Meal]:
    """
    Get a list of all available meals.

    Args:
        db: Database session

    Returns:
        List of Meal objects
    """
    return db.query(Meal).all()

def filter_meals_by_category(db: Session, category: str) -> List[Meal]:
    """
    Get a list of meals filtered by category.

    Args:
        db: Database session
        category: Category to filter by

    Returns:
        List of Meal objects matching the category
    """
    return db.query(Meal).filter(Meal.category == category).all()

def filter_meals_by_price_range(db: Session, min_price: float, max_price: float) -> List[Meal]:
    """
    Get a list of meals filtered by price range.

    Args:
        db: Database session
        min_price: Minimum price
        max_price: Maximum price

    Returns:
        List of Meal objects within the specified price range
    """
    return db.query(Meal).filter(Meal.price >= min_price, Meal.price <= max_price).all()

def get_meal_by_id(db: Session, meal_id: int) -> Optional[Meal]:
    """
    Get a meal by its ID.

    Args:
        db: Database session
        meal_id: ID of the meal

    Returns:
        Meal object if found, None otherwise
    """
    return db.query(Meal).filter(Meal.id == meal_id).first()

def update_meal_details(db: Session, meal_id: int, meal_data: Dict) -> Optional[Meal]:
    """
    Update details of a meal.

    Args:
        db: Database session
        meal_id: ID of the meal to update
        meal_data: Dictionary containing updated meal data

    Returns:
        Updated Meal object if successful, None otherwise
    """
    meal = get_meal_by_id(db, meal_id)
    if meal:
        for key, value in meal_data.items():
            setattr(meal, key, value)
        db.commit()
        db.refresh(meal)
        return meal
    return None