from functools import wraps
from json import load
from os import environ

from flask import redirect, session, url_for
from ldap3 import (
    ALL_ATTRIBUTES,
    HASHED_SALTED_SHA512,
    MODIFY_REPLACE,
    Connection,
    Server,
)
from ldap3.core.exceptions import LDAPException
from ldap3.utils.hashed import hashed

with open(environ["APP_CONFIG"]) as f:
    APP_CONFIG = load(f)


def login_required(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        if session.get("is_logged_in"):
            if try_auth(
                session["username"],
                session["password"],
            ):
                ldap = connect()

                return func(ldap, **kwargs)
            else:
                return redirect(url_for("login"))
        else:
            return redirect(url_for("login"))

    return wrapper


def admin_required(func):
    @wraps(func)
    @login_required
    def wrapper(*args, **kwargs):
        if session.get("is_logged_in"):
            if try_auth(
                session["username"],
                session["password"],
            ):
                ldap = connect()

                ldap.search(
                    APP_CONFIG["ldap"]["user_base"],
                    APP_CONFIG["template"]["group_admin"].format(session["username"]),
                    attributes=["uid"],
                )

                if len(ldap.entries) == 1:
                    return func(ldap, **kwargs)
                else:
                    return redirect(url_for("selfservice"))
            else:
                return redirect(url_for("login"))
        else:
            return redirect(url_for("login"))

    return wrapper


def try_auth(user, password):
    try:
        connect(
            user=APP_CONFIG["template"]["user_dn"].format(user),
            password=password,
        )
        return True
    except LDAPException:
        return False


def connect(user=None, password=None):
    server = Server(APP_CONFIG["ldap"]["server"])

    if not user and not password:
        user = APP_CONFIG["ldap"]["username"]
        password = APP_CONFIG["ldap"]["password"]

    conn = Connection(
        server,
        user=user,
        password=password,
    )
    conn.bind()

    if conn.result["result"] != 0:
        raise LDAPException(conn.result["description"])

    return conn


def get_user(ldap, username):
    ldap.search(
        APP_CONFIG["ldap"]["user_base"],
        APP_CONFIG["template"]["user_search"].format(username),
        attributes=ALL_ATTRIBUTES,
    )
    if len(ldap.entries) == 1:
        return ldap.entries[0]
    else:
        raise UserNotFoundException(username)


def update_user(ldap, username, settings):
    attrs = {}
    for attr, value in settings.items():
        attrs[attr] = [(MODIFY_REPLACE, value)]

    return ldap.modify(
        APP_CONFIG["template"]["user_dn"].format(username),
        attrs,
    )


def update_user_password(ldap, username, password):
    return update_user(
        ldap,
        username,
        {
            "userPassword": hashed(HASHED_SALTED_SHA512, password),
        },
    )


class UserNotFoundException(Exception):
    pass