import os
import time
import logging

class RollingLogger(object):
    def __init__(self):
        self.NUMBER_OF_LOGS = 10
        self.initialize_logger_settings()

    def initialize_logger_settings(self):
        """Set logger configuration settings"""

        self.initialize_log_directory()
        logging.basicConfig(filename= self.path + self.filename,
                            filemode='w',
                            level=logging.INFO,
                            format='%(asctime)s.%(msecs)03d,%(message)s',
                            datefmt='%d-%b-%y,%H:%M:%S')
        logging.info('Successfully loaded logger configuration settings')

    def initialize_log_directory(self):
        """Create directory and log file"""

        self.path = 'logs/'

        if not os.path.exists(self.path):
            os.makedirs(self.path)
            self.filename = 'log0000.log'
        else:
            self.filename = self.get_next_log_file_name()

    def get_next_log_file_name(self):
        """Scans log directory for latest log file and returns a new filename"""

        def extract_digits(filename):
            s = ''
            for char in filename:
                if char.isdigit():
                    s += char
            return int(s)

        l = [extract_digits(filename) for filename in os.listdir(self.path)]
        # Directory is empty
        if not l:
            return 'log0000.log'
        # Directory has files so find latest
        else:
            latest_file_number = max(l)
            return 'log' + '{0:04d}'.format(latest_file_number + 1) + '.log'

logger = RollingLogger()