import re
import socket
import ssl
import datetime

from typing import Optional

from nntp.tiny.socket   import Connection
from nntp.tiny.host     import Host
from nntp.tiny.response import Response, ResponseCode
from nntp.tiny.remote   import RemoteNewsgroup
from nntp.tiny.message  import MessageRange

class ClientException(Exception):
    pass

class ClientEOFException(ClientException):
    def __str__(self):
        return 'Unexpected client EOF'

class Client(Connection):
    RE_SPLIT = re.compile(r'\s+')

    def _read_response(self):
        line = self.readline()

        if line == '':
            raise ClientEOFException()

        parts = self.RE_SPLIT.split(line.rstrip(), 1)

        if len(parts) == 0:
            return
        elif len(parts) == 1:
            return Response(ResponseCode(int(parts[0])))
        else:
            return Response(ResponseCode(int(parts[0])), parts[1])

    def __init__(self, host: str, port: int, tls: bool=False):
        sock = socket.create_connection((host, port))

        if tls:
            sslctx = ssl.create_default_context()
            sslctx.check_hostname = False
            sslctx.verify_mode    = ssl.CERT_NONE

            if Host.is_hostname(host):
                sock = sslctx.wrap_socket(sock, server_hostname=host)
            else:
                sock = sslctx.wrap_socket(sock)

        self.host = host
        self.port = port

        super().__init__(sock)

        response = self._read_response()

        if response is None:
            raise ClientException('Server not ready')

    def request(self, *args):
        self.print(' '.join(args))

        return self._read_response()

    def each_response_line(self):
        while True:
            line = self.readline()

            if line == '':
                raise ClientEOFException()

            line = line.rstrip()

            if line == '.':
                break

            yield line

    def each_newsgroup_since(self, timestamp: datetime.datetime):
        date = timestamp.strftime('%Y%m%d')
        time = timestamp.strftime('%H%M%S')

        response = self.request('NEWGROUPS', date, time)

        for line in self.each_response_line():
            parts = self.RE_SPLIT.split(line)

            if len(parts) != 4:
                raise ClientException('Unexpected result from NEWGROUPS')
            
            yield RemoteNewsgroup(parts[0],
                                  int(parts[1]),
                                  int(parts[2]),
                                  parts[3] == 'y')