from rest_framework.authentication import BaseAuthentication
from rest_framework_simplejwt.tokens import AccessToken
from rest_framework_simplejwt.exceptions import InvalidToken, AuthenticationFailed
from .mongo_auth import MongoBackend
from django.utils.translation import gettext_lazy as _

class MongoJWTAuthentication(BaseAuthentication):
    """
    Custom JWT Authentication that retrieves users from MongoDB instead of Django ORM.
    """
    def authenticate(self, request):
        header = self.get_header(request)
        if header is None:
            return None

        raw_token = self.get_raw_token(header)
        if raw_token is None:
            return None

        try:
            validated_token = AccessToken(raw_token)
        except Exception:
            raise InvalidToken(_('Token is invalid or expired'))

        user = self.get_user(validated_token)
        if not user:
            return None # Pass to next authentication class (e.g. standard JWT for SQLite)
            
        return user, validated_token

    def get_header(self, request):
        auth = request.META.get('HTTP_AUTHORIZATION', '').split()
        if not auth or auth[0].lower() != 'bearer':
            return None
        return auth

    def get_raw_token(self, header):
        if len(header) != 2:
            return None
        return header[1]

    def get_user(self, validated_token):
        """
        Attempts to find and return a user using the given validated token.
        """
        try:
            user_id = validated_token['user_id']
        except KeyError:
            raise InvalidToken(_('Token contained no recognizable user identification'))

        backend = MongoBackend()
        user = backend.get_user(user_id)

        if not user:
            return None
            # raise AuthenticationFailed(_('User not found'), code='user_not_found')

        if not user.is_active:
            raise AuthenticationFailed(_('User is inactive'), code='user_inactive')

        return user