import datetime
import json
from datetime import timedelta

import requests
from authlib.oauth2.rfc6749 import OAuth2Token
from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.utils import timezone
from django.utils.timezone import now

from konova.models import UuidModel
from konova.sub_settings.sso_settings import OAUTH_CLIENT_ID, OAUTH_CLIENT_SECRET, SSO_SERVER_BASE
from konova.utils.generators import generate_token


class APIUserToken(models.Model):
    token = models.CharField(
        primary_key=True,
        max_length=1000,
        default=generate_token,
    )
    valid_until = models.DateField(
        blank=True,
        null=True,
        help_text="Token is only valid until this date. Forever if null/blank.",
    )
    is_active = models.BooleanField(
        default=False,
        help_text="Must be activated by an admin"
    )

    def __str__(self):
        return self.token

    @staticmethod
    def get_user_from_token(token: str):
        """ Getter for the related user object

        Args:
            token (str): The used token

        Returns:
            user (User): Otherwise None
        """
        _today = timezone.now().date()
        try:
            token_obj = APIUserToken.objects.get(
                token=token,
            )
            if not token_obj.is_active:
                raise PermissionError("Token unverified")
            if token_obj.valid_until is not None and token_obj.valid_until < _today:
                raise PermissionError("Token validity expired")
        except ObjectDoesNotExist:
            raise PermissionError("Token unknown")
        return token_obj.user


class OAuthToken(UuidModel):
    access_token = models.CharField(
        max_length=255,
        blank=False,
        null=False,
        db_comment="OAuth access token"
    )
    refresh_token = models.CharField(
        max_length=255,
        blank=False,
        null=False,
        db_comment="OAuth refresh token"
    )
    expires_on = models.DateTimeField(
        db_comment="When the token will be expired"
    )

    ASSUMED_LATENCY = 1000  # assumed latency between creation and receiving of an access token

    def __str__(self):
        return str(self.access_token)

    @staticmethod
    def create_from_oauth2_token(oauth2_token: OAuth2Token):
        """
        Creates an OAuthToken based on retrieved access token data (OAuth2.0 specification)

        Args:
            oauth2_token (str): OAuth2.0 response data

        Returns:

        """
        oauth_token = OAuthToken()

        oauth_token.access_token = oauth2_token.get("access_token")
        oauth_token.refresh_token = oauth2_token.get("refresh_token")
        oauth_token.expires_on = datetime.datetime.fromtimestamp(oauth2_token.get("expires_at"))

        assert (oauth_token.access_token is not None and
                oauth_token.refresh_token is not None and
                oauth_token.expires_on is not None)

        return oauth_token

    def refresh(self):
        url = f"{SSO_SERVER_BASE}o/token/"
        params = {
            "grant_type": "refresh_token",
            "refresh_token": self.refresh_token,
            "client_id": OAUTH_CLIENT_ID,
            "client_secret": OAUTH_CLIENT_SECRET
        }
        response = requests.post(
            url,
            params
        )
        _now = now()
        is_response_invalid = response.status_code != 200
        if is_response_invalid:
            raise RuntimeError(f"Refreshing token not possible: {response.status_code}")

        response_content = response.content.decode("utf-8")
        response_content = json.loads(response_content)

        access_token = response_content.get("access_token")
        refresh_token = response_content.get("refresh_token")
        expires_in = response_content.get("expires")

        self.access_token = access_token
        self.refresh_token = refresh_token
        self.expires_in = expires_in
        self.save()

        return self

    def update_and_get_user(self):
        from user.models import User
        url = f"{SSO_SERVER_BASE}users/oauth/data/"

        access_token = self.access_token
        response = requests.get(
            url,
            headers={
                "Authorization": f"Bearer {access_token}",
            }
        )

        is_response_code_invalid = response.status_code != 200
        if is_response_code_invalid:
            raise RuntimeError(f"OAuth user data fetching unsuccessful: {response.status_code}")

        response_content = response.content.decode("utf-8")
        response_content = json.loads(response_content)
        user = User.oauth_update_user(response_content)

        return user

    def revoke(self) -> int:
        """ Revokes the OAuth2 token of the user

        (/o/revoke_token/ indeed removes the corresponding access token on provider side and invalidates the
        submitted refresh token in one step)

        Returns:
            revocation_status_code (int): HTTP status code for revocation of refresh_token
        """
        revoke_url = f"{SSO_SERVER_BASE}o/revoke_token/"
        token = self.refresh_token
        revocation_status_code = requests.post(
                revoke_url,
                data={
                    'token': token,
                    'token_type_hint': "refresh_token",
                },
                auth=(OAUTH_CLIENT_ID, OAUTH_CLIENT_SECRET),
            ).status_code

        return revocation_status_code