import contextlib

import pymysql
from pymysql.constants import CLIENT

from constants import CONNECTION_TIMEOUT, DEFAULT_SCHEMA


class Database:

    __connection: pymysql.Connection = None
    __host: str = None
    __user: str = None
    __password: str = None
    __database: str = None

    def __init__(self,  host: str, user: str, password: str) -> None:
        self.__host = host
        self.__user = user
        self.__password = password
        self.__database = DEFAULT_SCHEMA

    def connect(self):
        connection = pymysql.connect(host=self.__host, user=self.__user, passwd=self.__password,
                                     database=self.__database, connect_timeout=CONNECTION_TIMEOUT,
                                     client_flag=CLIENT.MULTI_STATEMENTS)
        self.__connection = connection

    @contextlib.contextmanager
    def query(self, query: str):
        if self.__connection is None:
            raise Exception('データベースに接続されていません')

        with self.__connection.cursor() as cursor:
            cursor.execute(query)
            yield cursor

    def close(self):
        self.__connection.close()
        self.__connection = None