from __future__ import annotations

from ipaddress import IPv4Address
from typing import Optional

from pydantic import BaseModel

"""
class DNSEntry(BaseModel):

    Represents an entry in the DNS cache.

    :param domain_name: The domain name which a node would like to access.
    :param ip_address: The IP address through which the domain name is reachable.


    domain_name: str
    ip_address: IPv4Address
"""


class DNSRequest(BaseModel):
    """Represents a DNS Request packet of a network frame.

    :param sender_mac_addr: Sender MAC address.
    :param sender_ip: Sender IP address.
    :param target_mac_addr: Target MAC address.
    :param target_ip: Target IP address.
    :param domain_name_request: Domain Name Request for IP address.
    """

    sender_mac_addr: str
    "Sender MAC address."
    sender_ip: IPv4Address
    "Sender IP address."
    target_mac_addr: Optional[str] = None
    "Target MAC address of the DNS Server."
    target_ip: IPv4Address
    "Target IP address of the DNS Server."
    domain_name_request: str
    "Domain Name Request for IP address."


class DNSReply(BaseModel):
    """Represents a DNS Reply packet of a network frame.

    :param sender_mac_addr: Sender MAC address.
    :param sender_ip: Sender IP address.
    :param target_mac_addr: Target MAC address of DNS Client.
    :param target_ip: Target IP address of DNS Client.
    :param domain_name_ip_address: IP Address of the Domain Name requested.
    """

    sender_mac_addr: str
    "Sender MAC address."
    sender_ip: IPv4Address
    "Sender IP address."
    target_mac_addr: Optional[str] = None
    "Target MAC address of the DNS Server."
    target_ip: IPv4Address
    "Target IP address of the DNS Server."
    domain_name_ip_address: IPv4Address
    "IP Address of the Domain Name requested."


class DNSPacket(BaseModel):
    """
    Represents the DNS layer of a network frame.

    :param dns_request: DNS Request packet sent by DNS Client.
    :param dns_reply: DNS Reply packet generated by DNS Server.

    :Example:

    >>> dns_request = DNSPacket(
    ...     dns_request=DNSRequest(sender_mac_addr="aa:bb:cc:dd:ee:ff", sender_ip = IPv4Address("192.168.0.1"),
    ...            target_ip = IPv4Address("192.168.0.2"), domain_name_request="www.google.co.uk"),
    ...     dns_reply=None
    ... )
    >>> dns_response = DNSPacket(
    ...     dns_request=DNSRequest(sender_mac_addr="aa:bb:cc:dd:ee:ff", sender_ip = IPv4Address("192.168.0.1"),
    ...            target_ip = IPv4Address("192.168.0.2"), domain_name_request="www.google.co.uk"),
    ...     dns_reply=DNSReply(sender_mac_addr="gg:hh:ii:jj:kk:ll", sender_ip = IPv4Address("192.168.0.2"),
    ...            target_ip = IPv4Address("192.168.0.1"), domain_name_ip_address=IPv4Address("142.250.179.227"))
    ... )
    """

    dns_request: DNSRequest
    "DNS Request packet sent by DNS Client."
    dns_reply: Optional[DNSReply] = None
    "DNS Reply packet generated by DNS Server."

    def generate_reply(self, domain_ip_address: IPv4Address) -> DNSPacket:
        """Generate a new DNSPacket to be sent as a response with a DNS Reply packet which contains the IP address.

        :param domain_ip_address: The IP address that was being sought after from the original target domain name.
        :return: A new instance of DNSPacket.
        """
        return DNSPacket(
            dns_request=DNSRequest(
                sender_mac_addr=self.dns_request.sender_mac_addr,
                sender_ip=self.dns_request.sender_ip,
                target_mac_addr=self.dns_request.target_mac_addr,
                target_ip=self.dns_request.target_ip,
                domain_name_request=self.dns_request.domain_name_request,
            ),
            dns_reply=DNSReply(
                sender_mac_addr=self.dns_request.target_mac_addr,
                sender_ip=self.dns_request.target_ip,
                target_mac_addr=self.dns_request.sender_mac_addr,
                target_ip=self.dns_request.sender_ip,
                domain_name_ip_address=domain_ip_address,
            ),
        )