"""
Utilities for writing command line tools.

$Id$

Copyright (C) 2010  Internet Systems Consortium ("ISC")

Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
"""

import cmd, glob, os.path

try:
  import readline
  have_readline = True
except ImportError:
  have_readline = False

class Cmd(cmd.Cmd):
  """
  Customized subclass of Python cmd module.
  """

  emptyline_repeats_last_command = False

  EOF_exits_command_loop = True

  identchars = cmd.IDENTCHARS + "/-."

  histfile = None

  def __init__(self, argv = None):
    cmd.Cmd.__init__(self)
    if argv:
      self.onecmd(" ".join(argv))
    else:      
      self.cmdloop_with_history()

  def do_EOF(self, arg):
    if self.EOF_exits_command_loop and self.prompt:
      print
    return self.EOF_exits_command_loop

  def do_exit(self, arg):
    return True

  do_quit = do_exit

  def emptyline(self):
    if self.emptyline_repeats_last_command:
      cmd.Cmd.emptyline(self)

  def filename_complete(self, text, line, begidx, endidx):
    result = glob.glob(text + "*")
    if len(result) == 1:
      path = result.pop()
      if os.path.isdir(path) or (os.path.islink(path) and os.path.isdir(os.path.join(path, "."))):
        result.append(path + os.path.sep)
      else:
        result.append(path + " ")
    return result

  def completenames(self, *args):
    result = set(cmd.Cmd.completenames(self, *args))
    if len(result) == 1:
      result.add(result.pop() + " ")
    return list(result)

  if have_readline:

    def cmdloop_with_history(self):
      old_completer_delims = readline.get_completer_delims()
      if self.histfile is not None:
        try:
          readline.read_history_file(self.histfile)
        except IOError:
          pass
      try:
        readline.set_completer_delims("".join(set(old_completer_delims) - set(self.identchars)))
        self.cmdloop()
      finally:
        if self.histfile is not None and readline.get_current_history_length():
          readline.write_history_file(self.histfile)
        readline.set_completer_delims(old_completer_delims)

  else:

    cmdloop_with_history = cmd.Cmd.cmdloop



def yes_or_no(prompt, default = None, require_full_word = False):
  """
  Ask a yes-or-no question.
  """
  prompt = prompt.rstrip() + _yes_or_no_prompts[default]
  while True:
    answer = raw_input(prompt).strip().lower()
    if not answer and default is not None:
      return default
    if answer == "yes" or (not require_full_word and answer.startswith("y")):
      return True
    if answer == "no"  or (not require_full_word and answer.startswith("n")):
      return False
    print 'Please answer "yes" or "no"'

_yes_or_no_prompts = {
  True  : ' ("yes" or "no" ["yes"]) ',
  False : ' ("yes" or "no" ["no"]) ',
  None  : ' ("yes" or "no") ' }