from datetime import datetime
from enum import Enum
from typing import Any, AsyncIterator, ClassVar, List, Optional

from pydantic import Field

from common import BaseLinkedModel
from ingredients import Ingredient, insert_ingredient
from meals import Meal, find_meal_by_id, mark_purchased
from persons import Person


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 = Field(default_factory=lambda: datetime.now().astimezone())


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 = Field(default_factory=lambda: datetime.now().astimezone())
    store_name: StoreEnum = StoreEnum.home
    purchased_by_id: int = -1
    purchased_by: Optional[Person] = None
    items: List[ShoppingListItem] = Field(default_factory=list)


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)
        );"""
    )
    # Useful indexes for queries
    await conn.execute("CREATE INDEX IF NOT EXISTS idx_shopping_item_list_id ON ShoppingListItem(list_id);")
    await conn.execute("CREATE INDEX IF NOT EXISTS idx_shopping_item_meal_id ON ShoppingListItem(meal_id);")
    await conn.execute("CREATE INDEX IF NOT EXISTS idx_shopping_item_person_null_list ON ShoppingListItem(person_id, ingredient_id) WHERE list_id IS NULL;")


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)
        if not meal:
            continue
        ingredients = {
            ingredient.id
            for mr in meal.recipes
            for ingredient in (mr.recipe.ingredients if mr.recipe else [])
        } | {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, person=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: Optional[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 if person else -1),
        ) 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_cols = [f"shoppinglistitem.{key}" for key in ShoppingListItem.KEYS]

    select = f"""
        SELECT {','.join(request_cols)}
        FROM ShoppingListItem
    """

    where: str
    params: tuple[Any, ...]
    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_map = {k: v for k, v in zip(ShoppingListItem.KEYS, row)}
        request = ShoppingListItem(**request_map)
        yield request


async def load_shopping_list(conn, id: int) -> Optional[ShoppingList]:
    shopping_list: Optional[ShoppingList] = 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)})