"""
Middlewares of the require_ipv6 Django app
"""

from django.conf import settings
from django.core.exceptions import MiddlewareNotUsed, SuspiciousOperation
from django.shortcuts import render
from ipware import get_client_ip
import ipaddress
import logging

logger = logging.getLogger(__name__)


class RequireIPv6Middleware:
    """
    A middleware that responds with an error if request is not done via IPv6
    """

    def __init__(self, get_response):
        # Requirement on IPv6 can be disabled by explicitly using a `True` value
        # in setting `REQUIRE_IPV6_DISABLE`
        should_disable = getattr(settings, "REQUIRE_IPV6_DISABLE", False) is True

        if should_disable:
            logger.warning("RequireIPv6 Middleware is disabled per settings.")
            raise MiddlewareNotUsed

        self.get_response = get_response

    def __call__(self, request):
        client_ip_address_as_string = get_client_ip(request)[0]

        try:
            client_ip_address = ipaddress.ip_address(client_ip_address_as_string)
        except ValueError:
            raise SuspiciousOperation(
                "Invalid client IP address: %s" % client_ip_address_as_string
            )

        if not isinstance(client_ip_address, ipaddress.IPv6Address):
            # Client does not use IPv6, render appropriate error page
            return render(request, "require_ipv6/error.html", status=400)

        # Client uses IPv6, continue processing request
        return self.get_response(request)