from wtforms.fields import StringField, BooleanField
from flask import current_app
from flask_security import hash_password
from flask_security.forms import LoginForm, Required, PasswordField
from flask_security.utils import find_user
import ldap3
from ldap3.core.exceptions import LDAPBindError, LDAPSocketOpenError


class ExtendedLoginForm(LoginForm):
    email = StringField('Benutzername oder E-Mail', [Required()])
    password = PasswordField('Passwort', [Required()])
    remember = BooleanField('Login merken?')

    def validate(self):
        # search for user in the current database
        user = find_user(self.email.data)
        if user is not None:
            # if a user is found we check if it is associated with LDAP or with the local database
            if user.has_role('local'):
                # try authorizing locally using Flask security user datastore
                authorized = super(ExtendedLoginForm, self).validate()

                if authorized:
                    current_app.logger.info(f"User with credentials '{self.email.data}' authorized through local database")
            else:
                # run LDAP authorization
                # if the authorization succeeds we also get the new_user_data dict which contains information about
                # the user's permissions etc.
                authorized, new_user_data = validate_ldap(user.username, self.password.data)

                if authorized:
                    current_app.logger.info(f"User with credentials '{self.email.data}' authorized through LDAP")
                    # update permissions and password/email to stay up to date for login with no network connection
                    user.email = new_user_data['email']
                    user.password = new_user_data['password']
                    for role in new_user_data['roles']:
                        user_datastore.add_role_to_user(user, role)
                    user_datastore.commit()
                    self.user = user
                else:
                    self.password.errors = ['Invalid password']
        else:
            # this means there is no user with that email in the database
            # we assume that the username was entered instead of an email and use that for authentication with LDAP
            username = self.email.data
            # try LDAP authorization and create a new user if it succeeds
            authorized, new_user_data = validate_ldap(username, self.password.data)

            if authorized:
                # if there was no user in the database before we create a new user
                self.user = user_datastore.create_user(username=new_user_data['username'], email=new_user_data['email'],
                                           password=new_user_data['password'], roles=new_user_data['roles'])
                user_datastore.commit()
                current_app.logger.info(f"New admin user '{new_user_data['username']} <{new_user_data['email']}>' created after"
                            " successful LDAP authorization")

        # if any of the authorization methods is successful we authorize the user
        return authorized

def validate_ldap(username, password):
    """Validate the user and password through an LDAP server.

    If the connection completes successfully the given user and password is authorized.
    Then the permissions and additional information of the user are obtained through an LDAP search.
    The data is stored in a dict which will be used later to create/update the entry for the user in the local
    database.

    Parameters
    ----------
    username :  username for the LDAP server
    password :  password for the LDAP server

    Returns
    -------
        bool : result of the authorization process (True = success, False = failure)
        dict : dictionary with information about an authorized user (contains username, email, hashed password,
                roles)
    """

    try:
        con = ldap3.Connection(ldap_server, user=f"uid={username},ou=Users,dc=imaginaerraum,dc=de",
                               password=password, auto_bind=True)
    except ldap3.core.exceptions.LDAPBindError:
        # server reachable but user unauthorized -> fail
        return False, None
    except LDAPSocketOpenError:
        # server not reachable -> fail (but will try authorization from local database later)
        return False, None
    except Exception as e:
        # for other Exceptions we just fail
        return False, None

    # get user data and permissions from LDAP server
    new_user_data = {}
    new_user_data['username'] = username
    new_user_data['password'] = hash_password(password)
    new_user_data['roles'] = []
    lock_permission = con.search('ou=Users,dc=imaginaerraum,dc=de',
                                 f'(&(uid={username})(memberof=cn=Keyholders,ou=Groups,dc=imaginaerraum,dc=de))',
                                 attributes=ldap3.ALL_ATTRIBUTES)
    authorized = True
    if lock_permission:
        new_user_data['email'] = con.entries[0].mail.value
    else:
        authorized = False
    token_granting_permission = con.search('ou=Users,dc=imaginaerraum,dc=de',
                                           f'(&(uid={username})(memberof=cn=Vorstand,ou=Groups,dc=imaginaerraum,dc=de))')
    if token_granting_permission:
        new_user_data['roles'].append('admin')

    return authorized, new_user_data