# Copyright (C) 2020 by Thomas Lindner <tom@dl6tom.de>
# Copyright (C) 2020 by Cathy Hu <cathy.hu@fau.de>
# Copyright (C) 2020 by Christian Hagenest <c.hagenest@pm.me>
#
# SPDX-License-Identifier: 0BSD

""" REST API endpoints for hood admins. """

from fastapi import APIRouter, Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from kibicara import email
from kibicara.model import Admin, AdminHoodRelation
from logging import getLogger
from nacl.encoding import URLSafeBase64Encoder
from nacl.exceptions import CryptoError
from nacl.secret import SecretBox
from nacl.utils import random
from passlib.hash import argon2
from ormantic.exceptions import NoMatch
from pickle import dumps, loads
from pydantic import BaseModel
from smtplib import SMTPException
from sqlite3 import IntegrityError


logger = getLogger(__name__)


class BodyAdmin(BaseModel):
    email: str
    password: str


class BodyAccessToken(BaseModel):
    access_token: str
    token_type: str = 'bearer'


oauth2_scheme = OAuth2PasswordBearer(tokenUrl='/api/admin/login')
secret_box = SecretBox(random(SecretBox.KEY_SIZE))


def to_token(**kwargs):
    return secret_box.encrypt(dumps(kwargs), encoder=URLSafeBase64Encoder).decode(
        'ascii'
    )


def from_token(token):
    return loads(
        secret_box.decrypt(token.encode('ascii'), encoder=URLSafeBase64Encoder)
    )


async def get_auth(email, password):
    try:
        admin = await Admin.objects.get(email=email)
        if argon2.verify(password, admin.passhash):
            return admin
        raise ValueError
    except NoMatch:
        raise ValueError


async def get_admin(access_token=Depends(oauth2_scheme)):
    try:
        admin = await get_auth(**from_token(access_token))
    except (CryptoError, ValueError):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail='Invalid authentication credentials',
            headers={'WWW-Authenticate': 'Bearer'},
        )
    return admin


router = APIRouter()


@router.post(
    '/register/',
    status_code=status.HTTP_202_ACCEPTED,
    response_model=BaseModel,
    operation_id='register',
)
async def admin_register(values: BodyAdmin):
    """ Sends an email with a confirmation link.

    - **email**: E-Mail Address of new hood admin
    - **password**: Password of new hood admin
    """
    if len(values.password) < 8:
        logger.debug('Password is too short')
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST, detail='Password is too short'
        )
    register_token = to_token(**values.__dict__)
    logger.debug(f'register_token={register_token}')
    # TODO implement check to see if email already is in database
    try:
        email.send_email(
            to=values.email,
            subject='Confirm Account',
            # XXX create real confirm link
            body=register_token,
        )
    except (ConnectionRefusedError, SMTPException):
        logger.exception('Email sending failed')
        raise HTTPException(status_code=status.HTTP_502_BAD_GATEWAY)
    return {}


@router.post(
    '/confirm/{register_token}', response_model=BodyAccessToken, operation_id='confirm',
)
async def admin_confirm(register_token: str):
    """ Registration confirmation and account creation.

    - **register_token**: Registration token received in email from /register
    """
    try:
        values = from_token(register_token)
        passhash = argon2.hash(values['password'])
        await Admin.objects.create(email=values['email'], passhash=passhash)
        return BodyAccessToken(access_token=register_token)
    except IntegrityError:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT)


@router.post(
    '/login/', response_model=BodyAccessToken, operation_id='login',
)
async def admin_login(form_data: OAuth2PasswordRequestForm = Depends()):
    """ Get an access token.

    - **username**: Email of a registered hood admin
    - **password**: Password of a registered hood admin
    """
    try:
        await get_auth(form_data.username, form_data.password)
    except ValueError:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail='Incorrect email or password',
        )
    token = to_token(email=form_data.username, password=form_data.password)
    return BodyAccessToken(access_token=token)


@router.get(
    '/hoods/',
    # TODO response_model,
    operation_id='get_hoods',
)
async def admin_hood_read_all(admin=Depends(get_admin)):
    """ Get a list of all hoods of a given admin. """
    return (
        await AdminHoodRelation.objects.select_related('hood').filter(admin=admin).all()
    )