from django.conf import settings
from ldap3 import Server, Connection, ObjectDef, Writer, SUBTREE
import logging

logger = logging.getLogger(__name__)
server = Server(settings.AUTH_LDAP_SERVER_URI)


def create_user(user, password, firstname, lastname, email):
    logger.debug("In create_user")
    conn = Connection(server, settings.AUTH_LDAP_BIND_DN,
                      settings.AUTH_LDAP_BIND_PASSWORD)
    if not conn.bind():
        logger.error("conn.bind() returned False. Could not connect.")
        raise Exception('Could not connect to LDAP Server')

    obj_new_user = ObjectDef(['inetOrgPerson', 'posixAccount'], conn)
    uidNumber = get_max_uid() + 1
    logger.debug("uidNumber={uidNumber}".format(uidNumber=uidNumber))
    results = True
    while results:
        results = conn.search(
            search_base=settings.LDAP_CUSTOMER_DN,
            search_filter=(
                '(&(objectClass=inetOrgPerson)(objectClass=posixAccount)'
                '(objectClass=top)(uidNumber={uidNumber}))'.format(
                    uidNumber=uidNumber
                )
            ),
            search_scope=SUBTREE,
            attributes=['uidNumber'],
        )
        if results:
            logger.debug("{uid} exists. Trying next.".format(uid=uidNumber))
            uidNumber += 1

    logger.debug("{uid} does not exist. Using it".format(uid=uidNumber))
    set_max_uid(uidNumber)
    w = Writer(conn, obj_new_user)
    dn = 'uid=%s,%s' % (user, settings.LDAP_CUSTOMER_DN)
    w.new(dn)
    w[0].givenName = firstname
    w[0].sn = lastname
    w[0].cn = firstname + " " + lastname
    w[0].mail = email
    w[0].userPassword = password
    w[0].gidNumber = settings.LDAP_IPV6_WORK_USER_GROUP
    w[0].uidNumber = uidNumber
    w[0].homeDirectory = "/home/" + user

    if not w.commit():
        conn.unbind()
        logger.error("w.commit() returned False. Could not write user.")
        raise Exception("Couldn't write user")
    logger.debug("Created user {user} successfully.".format(user=user))
    conn.unbind()
    return True


def set_max_uid(max_uid):
    """
    a utility function to save max_uid value to a file

    :param max_uid: an integer representing the max uid
    :return:
    """
    with open(settings.LDAP_MAX_UID_PATH, 'w+') as handler:
        handler.write(str(max_uid))


def get_max_uid():
    """
    A utility function to read the max uid value that was previously set

    :return: An integer representing the max uid value that was previously set
    """
    try:
        with open(settings.LDAP_MAX_UID_PATH, 'r+') as handler:
            try:
                return_value = int(handler.read())
            except ValueError as ve:
                logger.error(
                    "Error reading int value from {}. {}"
                    "Returning default value {} instead".format(
                        settings.LDAP_MAX_UID_PATH,
                        str(ve),
                        settings.LDAP_DEFAULT_START_UID
                    )
                )
                return_value = settings.LDAP_DEFAULT_START_UID
            return return_value
    except FileNotFoundError as fnfe:
        logger.error("File not found : " + str(fnfe))
        retrun_value = settings.LDAP_DEFAULT_START_UID
        logger.error("So, returning UID={}".format(retrun_value))
        return retrun_value