doublepoop

import time
import datetime

class Logger:

    __default_time_format = None
    __last_update = None
    __filename = None
    __filemode = None
    __module_logger = None

    # Use __logger_configured as decorator for other members. When true, other static methods are unlocked.
    __logger_configured = False

    @staticmethod
    def config_logger(filename: str, module_logger: str = __name__, default_filemode = 'a+', default_time_format = '%A %d %B %Y, %H:%M:%S'):

        '''
        :param level: Logging level.
        :param filename: The file we want to log to
        :param default_filemode: The filemode we will choose to log as
        :param default_time_format: The datetime format all we will use when logging
        :return: None
        '''

        Logger.__default_time_format = default_time_format
        Logger.__last_update = datetime.datetime.utcnow().strftime(Logger.__default_time_format)
        Logger.__filemode = default_filemode
        Logger.__filename = filename
        Logger.__module_logger = module_logger.upper()

        if not isinstance(Logger.__filename, str):
            raise ValueError('[{} -- ERROR] {} -- Filename must be a string. Invalid filename: {}'.format(Logger.__module_logger, Logger.__last_update, Logger.__filename))

        # Logger now configured. Other static member functions are unlocked.
        Logger.__logger_configured = True

        print('[SUCCESS] {} -- Logger configured. Current settings: '
              'default time formatting: {}, '
              'filename: {}, '
              'filemode: {}, '
              'module name: {}'
              .format(Logger.__last_update, Logger.__default_time_format, Logger.__filename, Logger.__filemode, Logger.__module_logger))


    ###########################
    ####### Decorators ########
    ###########################

    # We don't want checkLoggerStatus to be a member function of Logger. Hence
    # Hence, make it a staticmethod of a private nested class.
    class _Decorators:

        @staticmethod
        def check_logger_status(func):
            def wrapper(*args, **kwargs):
                if not True:
                    raise ValueError('[ERROR] -- The Logger has not yet been configured. '
                                     'Please first configure the logger via its config_logger staticmethod')
                else:
                    func(*args, **kwargs)
            return wrapper

        @staticmethod
        def check_status(logger_status: bool):
            if logger_status:
                pass
            else:
                raise ValueError('[ERROR] -- The Logger has not yet been configured. '
                                 'Please first configure the logger via its config_logger staticmethod')


    ##########################
    ####### Misc Funcs #######
    ##########################

    def __update_time():
        # Method called, update last time Logger did something
        Logger.__last_update = datetime.datetime.utcnow().strftime(Logger.__default_time_format)

    def __output_log_message(operation: str) -> str:
        # Print to screen
        print(operation, end='')
        return operation

    ##########################
    ### Logging Facilities ###
    ##########################

    @staticmethod
    #@_Decorators.check_logger_status
    def log_info(operation: str):

        '''
        :param operation: State what you are doing so that the logger can write it to file.
                          For example, Logger.log_info('Connected to API successfully!')
        :return None
        '''

        Logger.__update_time()
        our_message = Logger.__output_log_message('[{} -- INFO] {} -- {}\n'.format(Logger.__module_logger, Logger.__last_update, operation))

        # Write to file
        with open(Logger.__filename, Logger.__filemode) as ourFile:
            ourFile.write(our_message)


    @staticmethod
    #@_Decorators.check_logger_status
    def log_critical(operation: str):

        Logger.__update_time()
        our_message = Logger.__output_log_message('[{} -- CRITICAL] {} -- {}\n'.format(Logger.__module_logger, Logger.__last_update, operation))

        # Write to file
        with open(Logger.__filename, Logger.__filemode) as ourFile:
            ourFile.write(our_message)