from typing import List, Optional
from pydantic import BaseModel
from datetime import datetime

class FoodItem(BaseModel):
    id: int
    name: str
    description: Optional[str] = None
    price: float
    category: str
    available: bool = True
    created_at: datetime
    updated_at: Optional[datetime] = None

def validate_food_item(food_item: FoodItem) -> dict:
    errors = {}
    if not food_item.name.strip():
        errors["name"] = "Name is required"
    if food_item.price <= 0:
        errors["price"] = "Price must be greater than zero"
    if not food_item.category.strip():
        errors["category"] = "Category is required"
    return errors

def get_available_food_items(food_items: List[FoodItem]) -> List[FoodItem]:
    return [item for item in food_items if item.available]

def filter_food_items_by_category(food_items: List[FoodItem], category: str) -> List[FoodItem]:
    return [item for item in food_items if item.category.lower() == category.lower()]

def sort_food_items_by_price(food_items: List[FoodItem], ascending: bool = True) -> List[FoodItem]:
    return sorted(food_items, key=lambda x: x.price, reverse=not ascending)

def get_food_menu(food_items: List[FoodItem]) -> dict:
    menu = {}
    for item in food_items:
        category = item.category
        if category not in menu:
            menu[category] = []
        menu[category].append({
            "id": item.id,
            "name": item.name,
            "description": item.description,
            "price": item.price,
            "available": item.available
        })
    return menu