CGI Session management

#!/usr/bin/python
#
# File Name= "cgi_session.py"
# place file at: /usr/lib/python3.5/cgi_session.py
# import as : from cgi_session import CGISession
#   session=CGISession()
#
# -*- coding: utf-8 -*-

import stat
import sys
import tempfile
import hashlib
import os
import time
import random
import errno
import ast
import pprint
import fcntl


class CGISession:

    __sessionfile = ''
    __newid = ''
    __date = ''
    __tmp = ''

    __pid = ''
    __time = ''
    __rand = ''

    __pp = pprint.PrettyPrinter()
    __fs = ''

    def __init__(
        self,
        id=None,
        directory=None,
        hash='md5',
        ):

        if directory is None:
            self.__directory = tempfile.gettempdir()
        else:
            if not os.path.exists(directory):
                try:
                    os.makedirs(directory)
                except error:
                    if error.errno != errno.EEXIST:
                        raise
            self.__directory = directory

        if hash not in ['md5', 'sha256', 'sha512']:
            self.__hash = 'md5'
        else:
            self.__hash = hash

        if id is None:
            self.__id = self.__genSessionID()
            self.__fs = open(os.path.join(self.__directory,
                             'pycgiession_{0}'.format(self.__id)), 'w')
            fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
            self.__fs.write('{}')
            self.__fs.close()
            self.__sessionfile = os.path.join(self.__directory,
                    'pycgiession_{0}'.format(self.__id))
            os.chmod(self.__sessionfile,stat.S_IRWXU and stat.S_IROTH)
        else:
            try:
                open(os.path.join(self.__directory,
                     'pycgiession_{0}'.format(os.path.basename(id))),
                     'r').close()
                self.__id = os.path.basename(id)
                self.__sessionfile = os.path.join(self.__directory,
                        'pycgiession_{0}'.format(self.__id))
                os.chmod(self.__sessionfile,stat.S_IRWXU and stat.S_IROTH)
            except error:
                if error.errno == errno.ENOENT:
                    self.__id = self.__genSessionID()
                    self.__fs = open(os.path.join(self.__directory,
                            'pycgiession_{0}'.format(self.__id)), 'w')
                    fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
                    self.__fs.write('{}')
                    self.__fs.close()
                    self.__sessionfile = os.path.join(self.__directory,
                            'pycgiession_{0}'.format(self.__id))
                    os.chmod(self.__sessionfile,stat.S_IRWXU and stat.S_IROTH)
                else:
                    raise

    def __genSessionID(self):

        self.__pid = str(os.getpid())
        self.__time = ''.join(map(str, time.gmtime()[0:]))
        self.__rand = str(random.random())

        if self.__hash == 'sha256':
            sha256 = hashlib.sha256()
            sha256.update(self.__pid)
            sha256.update(self.__time)
            sha256.update(self.__rand)
            self.__newid = sha256.hexdigest()
        elif self.__hash == 'sha512':

            sha512 = hashlib.sha512()
            sha512.update(self.__pid)
            sha512.update(self.__time)
            sha512.update(self.__rand)
            self.__newid = sha512.hexdigest()
        else:

            md5 = hashlib.md5()
            md5.update(self.__pid.encode('utf-8'))
            md5.update(self.__time.encode('utf-8'))
            md5.update(self.__rand.encode('utf-8'))
            self.__newid = md5.hexdigest()

        return self.__newid

    def getID(self):
        return self.__id

    def setParam(self, key, value):

        self.__fs = open(self.__sessionfile, 'r')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = self.__fs.readlines()
        self.__fs.close()

        self.__fs = open(self.__sessionfile, 'w')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = ast.literal_eval(self.__date[0])
        self.__date[key] = value

        self.__fs.write(self.__pp.pformat(self.__date))
        self.__fs.close()

    def getParam(self, key):

        self.__fs = open(self.__sessionfile, 'r')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = self.__fs.readline()
        self.__fs.close()
        self.__date = ast.literal_eval(self.__date)
        try:
            self.__date = self.__date[key]
            return self.__date
        except KeyError:
            return None

    def getAll(self):

        self.__fs = open(self.__sessionfile, 'r')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = self.__fs.readlines()
        self.__fs.close()
        self.__date = ast.literal_eval(self.__date[0])
        return self.__date

    def delParam(self, key):

        self.__fs = open(self.__sessionfile, 'r')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = self.__fs.readlines()
        self.__fs.close()

        self.__fs = open(self.__sessionfile, 'w')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__date = ast.literal_eval(self.__date[0])

        try:
            del self.__date[key]
        except KeyError:
            pass

        self.__fs.write(self.__pp.pformat(self.__date))
        self.__fs.close()

    def clear(self):

        self.__fs = open(self.__sessionfile, 'w')
        fcntl.flock(self.__fs.fileno(), fcntl.LOCK_EX)
        self.__fs.write('{}')
        self.__fs.close()

    def delete(self):

        os.remove(self.__sessionfile)
###################################################################
#
#EXAMPLES BELOW:
#
>>> from CGISession import CGISession
>>> session = CGISession()
>>>
>>> session.getID()
'7e487c3c300126fddbecb37b041d66e3'
>>>
>>> session.setParam('name','A')
>>> session.setParam('friends',['C','D','E'])
>>>
>>> session.getParam('name')
'A'
>>> session.getParam('friends')
['C', 'D', 'E']
>>>
>>> session.delParam('name')
>>> session.delParam('friends')
>>>
>>> session.getParam('name')
>>> session.delParam('friends')
>>>
>>> session.delete()
>>>