from zope.interface import implementer
from zope import component
from contextlib import contextmanager

from ceo_common.interfaces import IDatabaseService, IConfig
from ceo_common.errors import DatabaseConnectionError, DatabasePermissionError, UserAlreadyExistsError, \
    UserNotFoundError
from ceo_common.logger_factory import logger_factory
from ceod.utils import gen_password
from ceod.db.utils import response_is_empty

from mysql.connector import connect
from mysql.connector.errors import OperationalError, ProgrammingError

logger = logger_factory(__name__)


@implementer(IDatabaseService)
class MySQLService:

    type = 'mysql'

    def __init__(self):
        config = component.getUtility(IConfig)
        self.auth_username = config.get('mysql_username')
        self.auth_password = config.get('mysql_password')
        self.host = config.get('mysql_host')

    @contextmanager
    def mysql_connection(self):
        try:
            with connect(
                    host=self.host,
                    user=self.auth_username,
                    password=self.auth_password,
            ) as con:
                yield con
        # unable to connect
        except OperationalError as e:
            logger.error(e)
            raise DatabaseConnectionError()
        # invalid credentials / user does not exist / invalid permissions for action
        except ProgrammingError as e:
            logger.error(e)
            raise DatabasePermissionError()

    def create_db(self, username: str) -> str:
        password = gen_password()
        search_for_user = f"SELECT user FROM mysql.user WHERE user='{username}'"
        search_for_db = f"SHOW DATABASES LIKE '{username}'"
        # CREATE USER can't be used in a query with multiple statements
        create_local_user_cmd = f"CREATE USER '{username}'@'localhost' IDENTIFIED VIA unix_socket"
        create_user_cmd = f"CREATE USER '{username}'@'%' IDENTIFIED BY %(password)s"
        create_database = f"""
        CREATE DATABASE {username};
        GRANT ALL PRIVILEGES ON {username}.* TO '{username}'@'localhost' IDENTIFIED VIA unix_socket;
        GRANT ALL PRIVILEGES ON {username}.* TO '{username}'@'%';
        """

        with self.mysql_connection() as con, con.cursor() as cursor:
            if not response_is_empty(search_for_user, con):
                raise UserAlreadyExistsError()
            cursor.execute(create_local_user_cmd)
            cursor.execute(create_user_cmd, {'password': password})
            if response_is_empty(search_for_db, con):
                cursor.execute(create_database)
            return password

    def reset_db_passwd(self, username: str) -> str:
        password = gen_password()
        search_for_user = f"SELECT user FROM mysql.user WHERE user='{username}'"
        reset_password = f"""
        ALTER USER '{username}'@'%' IDENTIFIED BY %(password)s;
        """

        with self.mysql_connection() as con, con.cursor() as cursor:
            if response_is_empty(search_for_user, con):
                raise UserNotFoundError(username)
            cursor.execute(reset_password, {'password': password})
            return password

    def delete_db(self, username: str):
        drop_db = f"DROP DATABASE IF EXISTS {username}"
        drop_user = f"""
        DROP USER IF EXISTS '{username}'@'localhost';
        DROP USER IF EXISTS '{username}'@'%';
        """

        with self.mysql_connection() as con, con.cursor() as cursor:
            cursor.execute(drop_db)
            cursor.execute(drop_user)