from typing import Generic, TypeVar, Type, Optional, Any
from collections.abc import AsyncGenerator
import dataclasses
import json

from aiosqlite import Connection

from ..types import Message, Context
from .base import Injector, InjectorWithCleanup

__all__ = [
    "Database",
    "Data",
]


class DatabaseInjector(InjectorWithCleanup[Connection]):
    async def inject(self, message: Message, context: Context) -> Connection:
        return await context.database()

    async def cleanup(self, conn: Connection):
        await conn.close()


Database = DatabaseInjector()

DataType = TypeVar("DataType")


class DataStore(Generic[DataType]):
    def __init__(self, datatype: Type[DataType], connection: Connection):
        if not dataclasses.is_dataclass(datatype):
            raise ValueError
        self.datatype = datatype
        self.connection = connection
        self.table_name = "".join(
            ("_" + c.lower()) if "A" <= c <= "Z" else c for c in datatype.__name__ if c.isalnum()
        ).strip("_")

    async def _setup(self):
        await self.connection.execute(
            f'CREATE TABLE IF NOT EXISTS {self.table_name} ( \
                key TEXT NOT NULL PRIMARY KEY, \
                body TEXT DEFAULT "" \
            )'
        )
        await self.connection.commit()

    async def load(self, key: str) -> Optional[DataType]:
        async with self.connection.execute(
            f"SELECT body FROM {self.table_name} WHERE key = ?", (key,)
        ) as cursor:
            found = await cursor.fetchone()
        if found is None:
            return found
        return self.datatype(**json.loads(found[0]))

    async def load_or(self, key: str, **kw) -> DataType:
        result = await self.load(key)
        if result is not None:
            return result
        result = self.datatype(**kw)
        await self.save(key, result)
        return result

    async def all(self) -> AsyncGenerator[tuple[str, DataType], None]:
        async with self.connection.execute(f"SELECT key, body FROM {self.table_name}") as cursor:
            async for (key, body) in cursor:
                yield (key, self.datatype(**json.loads(body)))

    async def save(self, key: str, obj: DataType):
        blob = json.dumps(dataclasses.asdict(obj))
        await self.connection.execute(
            f"INSERT INTO {self.table_name} VALUES (:key, :body) \
                ON CONFLICT(key) DO UPDATE SET body=:body",
            {"key": key, "body": blob},
        )
        await self.connection.commit()


class DataFor(Injector[Optional[DataType]]):
    def __init__(self, datatype: Type[DataType], key: Injector[str], kwargs: dict[str, Any]):
        self.datatype = datatype
        self.key = key
        self.kwargs = kwargs

    async def inject(self, message: Message, context: Context) -> DataStore[DataType]:
        key = await self.key.inject(message, context)
        async with context.database() as db:
            store = DataStore(self.datatype, db)
            return await store.load_or(key, **self.kwargs)


class Data(InjectorWithCleanup[DataStore[DataType]]):
    def __init__(self, datatype: Type[DataType]):
        self.datatype = datatype
        self.For = lambda key, **kw: DataFor(datatype, key, kw)

    @staticmethod
    async def initialize(datatype: Type[DataType], connection: Connection):
        store = DataStore(datatype, connection)
        await store._setup()

    async def inject(self, message: Message, context: Context) -> DataStore[DataType]:
        store = DataStore(self.datatype, await context.database())
        return store

    async def cleanup(self, store: DataStore[DataType]):
        await store.connection.close()