import re
from dataclasses import dataclass
from datetime import datetime
from typing import List, Optional
from enum import StrEnum

line_pattern = re.compile(r"(?P<timestamp>\w{3}\s+\d{1,2}\s\d{2}:\d{2}:\d{2})\s(?P<hostname>\S+)\ssshd\[(?P<pid>\d+)\]:\s(?P<message>.+)")
ipv4_pattern = re.compile(r"(?P<address>(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))")
user_pattern = re.compile(r"([Ii]nvalid user |Failed password for(?: invalid user)? |Too many authentication failures for |Accepted password for |user[= ])(?P<user>\w+)")

@dataclass
class Line:
    timestamp: datetime
    hostname: str
    pid: int
    message: str
    original_line: str

class MessageType(StrEnum):
  SUCCESSFUL_LOGIN = "successful login",
  INVALID_USERNAME = "invalid username",
  INVALID_PASSWORD = "invalid password",
  FAILED_LOGIN = "failed login",
  CLOSED_CONNECTION = "closed connection",
  BREAK_IN_ATTEMPT = "break-in attempt",
  OTHER = "other"

#1.1.1
def parse_line(line: str) -> Line:
  data = line_pattern.match(line)
  if data is None:
    raise Exception(f"invalid data: {data}")

  
  return Line (
      timestamp=datetime.strptime(data.group("timestamp"), "%b %d %H:%M:%S"),
      hostname=data.group("hostname"),
      pid=int(data.group("pid")),
      message=data.group("message"),
      original_line=line
  )
  

#1.1.2
def get_ipv4s_from_log(log: Line) -> List[str]:
  return ipv4_pattern.findall(log.message)

#1.1.3
def get_user_from_log(log: Line) -> Optional[str]:
  user = user_pattern.search(log.message)
  return user.group("user") if user else None

#1.1.4
def get_message_type(message: str) -> MessageType:
  msg = message.lower()
  if ("accepted password for" in msg 
      or "session opened" in msg):
    return MessageType.SUCCESSFUL_LOGIN
  elif "invalid user" in msg:
    return MessageType.INVALID_USERNAME
  elif "failed password for" in msg:
    return MessageType.INVALID_PASSWORD
  elif ("authentication failure" in msg 
      or "did not receive identification string" in msg):
    return MessageType.FAILED_LOGIN
  elif ("connection closed" in msg 
      or "received disconnect" in msg 
      or "session closed" in msg
      or "connection reset by peer" in msg):
    return MessageType.CLOSED_CONNECTION
  elif "break-in attempt" in msg:
    return MessageType.BREAK_IN_ATTEMPT
  else:
    return MessageType.OTHER