from common import BaseLinkedModel
from recipes import Recipe
from meals import Meal, find_meal_by_id, mark_purchased
from ingredients import Ingredient, insert_ingredient
from persons import Person
from products import Product

from typing import AsyncIterator, List, ClassVar, Optional

from datetime import datetime

class ShoppingListItem(BaseLinkedModel):
    KEYS: ClassVar[List[str]] = ['id', 'ingredient_id', 'list_id', 'person_id', 'meal_id', 'recipe_id', 'created_date']
    id: int = -1
    list_id: Optional[int] = None
    
    person_id: int = -1
    
    ingredient_id: Optional[int] = None

    recipe_id: Optional[int] = None

    meal_id: Optional[int] = None

    created_date: datetime = datetime.now().astimezone()


from enum import Enum

class StoreEnum(str, Enum):
    woolworths = 'woolworths'
    coles = 'coles'
    home = ''

class ShoppingList(BaseLinkedModel):
    KEYS: ClassVar[List[str]] = ['id', 'created_date', 'store_name']
    id: int = -1
    created_date: datetime = datetime.now().astimezone()
    store_name: StoreEnum = ''
    purchased_by_id: int = -1
    purchased_by: Optional[Person] = None
    items: List[ShoppingListItem] = []

async def create(conn):
    await conn.execute('''
        CREATE TABLE IF NOT EXISTS ShoppingList (
            id INTEGER PRIMARY KEY,
            created_date DATETIME NOT NULL,
            store_name TEXT NOT NULL,
            purchased_by_id INTEGER,
            FOREIGN KEY(purchased_by_id) REFERENCES Person(id)
        );''')
                       
    await conn.execute('''
        CREATE TABLE IF NOT EXISTS ShoppingListItem (
            id INTEGER PRIMARY KEY,
            ingredient_id INTEGER,
            list_id INTEGER,
            person_id INTEGER,
            meal_id INTEGER,
            recipe_id INTEGER,
            created_date DATETIME NOT NULL,
            FOREIGN KEY(ingredient_id) REFERENCES Ingredient(id),
            FOREIGN KEY(list_id) REFERENCES ShoppingList(id),
            FOREIGN KEY(person_id) REFERENCES Person(id),
            FOREIGN KEY(meal_id) REFERENCES Meal(id),
            FOREIGN KEY(recipe_id) REFERENCES Recipe(id)
        );''')

def validate_request(request: ShoppingListItem) -> None:
    if request.person_id < 0:
        raise ValueError('Requests must have a person')
    
    # A request must have either an ingredient or a meal, but not both
    if not request.ingredient_id and not request.meal_id:
        raise ValueError('Request must have either an ingredient or a meal')

async def purchase(conn, shopping_list: ShoppingList) -> None:
    if shopping_list.purchased_by_id is None or shopping_list.purchased_by_id < 0:
        raise ValueError('Shopping list must have a person id')
    
    if shopping_list.items is None or len(shopping_list.items) == 0:
        raise ValueError('Shopping list must have items')
    
    shopping_list.created_date = datetime.now().astimezone()

    async with conn.execute('''
        INSERT INTO ShoppingList (created_date, store_name, purchased_by_id)
        VALUES (?, ?, ?)
    ''', (shopping_list.created_date.isoformat(), shopping_list.store_name, shopping_list.purchased_by_id)) as cursor:
        shopping_list.id = cursor.lastrowid

    for item in shopping_list.items:
        item.list_id = shopping_list.id
        validate_request(item)

        if item.ingredient_id is None or item.ingredient_id < 0:
            raise ValueError('Ingredient request must have a valid ingredient id')

        isMeal = item.meal_id is not None and item.meal_id >= 0
        isPersonRequest = (not isMeal) and item.person_id is not None and item.person_id >= 0

        if not isMeal and not isPersonRequest:
            raise ValueError('Ingredient request must have either a meal or a person id')
        
        if isPersonRequest:
            # Update existing request from its null id, or throw
            async with conn.execute('''
                    UPDATE ShoppingListItem
                    SET list_id = ?
                    WHERE ingredient_id = ? 
                        AND list_id IS NULL 
                        AND person_id = ?
                        AND meal_id IS NULL 
                        AND recipe_id IS NULL
            ''', (shopping_list.id, item.ingredient_id, item.person_id)) as cursor:
                if cursor.rowcount == 0:
                    raise ValueError('Ingredient request must have a valid person id and ingredient id')
                
        elif isMeal:
            # Insert new request for meal
            if item.meal_id is None or item.meal_id < 0:
                raise ValueError('Meal request must have a valid meal id')
            
            async with conn.execute('''
                INSERT INTO ShoppingListItem (ingredient_id, list_id, person_id, meal_id, recipe_id, created_date)
                VALUES (?, ?, ?, ?, ?, ?)
            ''', (item.ingredient_id, shopping_list.id, item.person_id, item.meal_id, item.recipe_id, item.created_date.isoformat())) as cursor:
                item.id = cursor.lastrowid
            
    meal_ids = list({ item.meal_id for item in shopping_list.items if item.meal_id is not None and item.meal_id >= 0 })
    await update_purchased_meals(conn, meal_ids)

async def update_purchased_meals(conn, meal_ids: List[int]) -> None:
    if not meal_ids:
        return

    purchased_ingredient_ids = {item.ingredient_id async for item in get_purchased_ingredients(conn, meal_ids)}
    for meal_id in meal_ids:
        meal = await find_meal_by_id(conn, meal_id)
        ingredients = {ingredient.id for recipe in meal.recipes for ingredient in recipe.recipe.ingredients} | \
                      {ingredient.id for ingredient in meal.extra_ingredients}

        remaining_ingredients = ingredients - purchased_ingredient_ids
        if not remaining_ingredients:
            await mark_purchased(conn, meal)
            await remove_request(conn, None, meal=meal)

async def is_requested(conn, meal: Meal) -> bool:
    if meal.id < 0:
        return False

    async with conn.execute('''
        SELECT COUNT(*) FROM ShoppingListItem
        WHERE meal_id = ? AND list_id IS NULL
    ''', (meal.id,)) as cursor:
        row = await cursor.fetchone()
        return row[0] > 0

async def request(conn, person: Person, ingredient: Optional[Ingredient] = None, meal: Optional[Meal] = None) -> ShoppingListItem:
    if ingredient is not None and meal is not None:
        raise ValueError('Cannot request both an ingredient and a meal')

    if ingredient is None and meal is None:
        raise ValueError('Must specify either an ingredient or a meal to request')

    if meal is not None and meal.id < 0:
        raise ValueError('Meal must have a valid id')

    if ingredient is not None and ingredient.id < 0:
        await insert_ingredient(conn, ingredient)

    ingredient_id = ingredient.id if ingredient else None
    meal_id = meal.id if meal else None
    
    item = ShoppingListItem(
        ingredient_id=ingredient_id, 
        person_id=person.id, 
        meal_id=meal_id
    )

    validate_request(item)

    if meal is not None and await is_requested(conn, meal):
        raise ValueError('Meal is already requested')

    async with conn.execute('''
        INSERT INTO ShoppingListItem (ingredient_id, person_id, meal_id, created_date)
        VALUES (?, ?, ?, ?)
    ''', (item.ingredient_id, item.person_id, item.meal_id, item.created_date.isoformat())) as cursor:
        item.id = cursor.lastrowid

    return item

async def remove_request(conn, person: Person = None, meal: Optional[Meal] = None, ingredient: Optional[Ingredient] = None) -> bool:
    if meal is not None:
        async with conn.execute('''
            DELETE FROM ShoppingListItem
            WHERE list_id IS NULL AND meal_id = ?
        ''', (meal.id,)) as cursor:
            return cursor.rowcount > 0

    elif ingredient is not None:
        async with conn.execute('''
            DELETE FROM ShoppingListItem
            WHERE list_id IS NULL AND ingredient_id = ? AND person_id = ?
        ''', (ingredient.id, person.id)) as cursor:
            return cursor.rowcount > 0

    raise ValueError('Must specify either a meal or an ingredient to remove')

async def find_items_by_list_id(conn, list_id: Optional[int]) -> AsyncIterator[ShoppingListItem]:
    request_keys = [f'shoppinglistitem.{key}' for key in ShoppingListItem.KEYS]

    select = f'''
        SELECT {','.join(request_keys)}
        FROM ShoppingListItem
    '''
    
    where, params = ' WHERE list_id IS NULL', ()
    if list_id is not None:
        where, params = ' WHERE list_id = ?', (list_id,)
    
    cursor = await conn.execute(select + where, params)
    
    async for row in cursor:
        request_keys = {k:v for k,v in zip(ShoppingListItem.KEYS, row)}
        request = ShoppingListItem(**request_keys)
        yield request

async def load_shopping_list(conn, id: int) -> ShoppingList:
    shopping_list = None
    async with conn.execute(f'''
        SELECT {','.join(ShoppingList.KEYS)} FROM ShoppingList
        WHERE id = ?
        LIMIT 1
    ''', (id,)) as cursor:
        async for row in cursor:
            shopping_list = ShoppingList(**{k:v for k,v in zip(ShoppingList.KEYS, row)})
            break

    if shopping_list:
        async for item in find_items_by_list_id(conn, shopping_list.id):
            shopping_list.items.append(item)

    return shopping_list

async def get_purchased_ingredients(conn, meal_ids: List[int]) -> AsyncIterator[ShoppingListItem]:
    if not meal_ids:
        return
    
    async with conn.execute(f'''
        SELECT {','.join(ShoppingListItem.KEYS)}
        FROM ShoppingListItem
        WHERE meal_id IN ({','.join(['?'] * len(meal_ids))}) AND list_id IS NOT NULL
    ''', meal_ids) as cursor:
        async for row in cursor:
            yield ShoppingListItem(**{k:v for k,v in zip(ShoppingListItem.KEYS, row)})