text: import re
  import os
  import socket
  import getpass
  from typing import Dict, Any
  from fnmatch import fnmatch
  
  
  class Error(Exception):
      """An error encountered while parsing a OpenSSH configuration file"""
  
  
  SSH_EXPAND_OPTIONS = ["proxycommand", "controlpath"]
  
  
  def match(hostname, patterns):
      for pattern in patterns:
          if pattern.startswith("!"):
              negate = True
              pattern = pattern[1:]
          else:
              negate = False
  
          if fnmatch(hostname, pattern):
              if negate:
                  return False
              return True
  
      return False
  
  
  # not all SSH options support all the available tokens, but whatever...
  def expand_tokens(s, nickname, options):
      if "%%" in s:
          s = s.replace("%%", "%")
      if "$d" in s:
          s = s.replace("%d", os.path.expanduser("~"))
      if "%h" in s:
          s = s.replace("%h", options["hostname"])
      if "%i" in s:
          s = s.replace("%i", str(os.getuid()))
      if "%L" in s:
          s = s.replace("%L", socket.gethostname())
      if "%l" in s:
          s = s.replace("%l", socket.getfqdn())
      if "%n" in s:
          # The original remote hostname, as given on the command line.
          s = s.replace("%n", nickname)
      if "%p" in s:
          s = s.replace("%p", str(options["port"]))
      if "%r" in s:
          s = s.replace("%r", options["user"])
      if "%u" in s:
          s = s.replace("%u", getpass.getuser())
      return s
  
  
  class SSHOptions:
      def __init__(self, patterns, **options):
          self.patterns = patterns.copy()
          self.options = {}
          for key, value in options.items():
              self.options[key] = value
  
      def set_option(self, key, value):
          self.options[key] = value
  
  
  class SSHConfig:
      """Parse a OpenSSH configuration file and lookup SSH options for connecting to a given host."""
  
      def __init__(self):
          self.blocks = []
  
      def load(self, filename: str):
          """Load and parse a OpenSSH configuration file."""
  
          with open(filename) as fd:
              sshopt = None
  
              for line in fd:
                  line = line.strip()
                  if not line or line.startswith("#"):
                      continue
  
                  m = re.search(r"^host +(.*)$", line, re.I)
                  if m:
                      if sshopt is not None:
                          self.blocks.append(sshopt)
                      patterns = [p.strip() for p in m.group(1).split(",")]
                      sshopt = SSHOptions(patterns)
                      continue
  
                  if sshopt is None:
                      raise Error("Error: expected to be in a 'Host' block!")
                  key, value = line.split(" ", 1)
                  key = key.strip().lower()
                  sshopt.set_option(key, value)
  
              if sshopt is not None:
                  self.blocks.append(sshopt)
  
      def lookup(self, nickname: str) -> Dict[str, Any]:
          """Lookup SSH options for connecting to the server `nickname`."""
  
          options = {}
  
          for block in self.blocks:
              if match(nickname, block.patterns):
                  for opt_name, opt_value in block.options.items():
                      if opt_name not in options:
                          options[opt_name] = opt_value
  
          if "hostname" not in options:
              options["hostname"] = nickname
          if "port" not in options:
              options["port"] = 22
          if "user" not in options:
              options["user"] = getpass.getuser()
  
          for opt in SSH_EXPAND_OPTIONS:
              if opt in options:
                  options[opt] = expand_tokens(options[opt], nickname, options)
  
          for key in options:
              # if the value starts with ~ assume it's a path and expand it
              if isinstance(options[key], str) and options[key].startswith("~"):
                  options[key] = os.path.expanduser(options[key])
  
              if key == "port":
                  options[key] = int(options[key])
  
          return options
  