import typing

import pymysql


class Database:
    __instance: 'Database' = None
    __client: pymysql.Connection = None

    def __new__(cls, *args, **kwargs):
        if cls.__instance is None:
            cls.__instance = super().__new__(cls)
        return cls.__instance

    def __init__(self):
        self.__create_con()

    def __create_con(self):
        # TODO Set to environment variables. Use pydantic-settings
        self.__client = pymysql.connect(
            host='127.0.0.1',
            port=3306,
            user='root',
            password='root',
            db='jde',
            charset='utf8'
        )

    def __execute_cmd(self, wrapper, *args, **kwargs):
        with self.__client.cursor() as cursor:
            data = wrapper(cursor, *args, **kwargs)
        self.__client.commit()
        return data

    @classmethod
    def _fetch_all(cls, cursor: pymysql.cursors.Cursor, sql: str, *args) -> list:
        #todo research formatting input values in sql queries. Which type of args?
        cursor.execute(sql, *args)
        return cursor.fetchall()

    @classmethod
    def _fetch_one(cls, cursor: pymysql.cursors.Cursor, sql: str, *args) -> typing.Any:
        #todo research formatting input values in sql queries. Which type of args?
        cursor.execute(sql, *args)
        return cursor.fetchone()

    @classmethod
    def _execute(cls, cursor: pymysql.cursors.Cursor, sql: str, *args) -> None:
        #todo research formatting input values in sql queries. Which type of args?
        cursor.execute(sql, *args)

    def fetch_all(self, sql: str, *args) -> list:
        return self.__execute_cmd(self._fetch_all, sql, *args)

    def fetch_one(self, sql: str, *args) -> typing.Any | None:
        return self.__execute_cmd(self._fetch_one, sql, *args)

    def execute(self, sql: str, *args) -> None:
        return self.__execute_cmd(self._execute, sql, *args)