from Tkinter import Entry
from string import split

class CommandEntry(Entry):
  def __init__(self, parent, commands):
    Entry.__init__(self, parent)
    self.commands = commands

    # command shortcuts
    for command in commands.keys():
      func = commands[command]
      while 1:
        command = command[:-1]
        if not command:
          break
        try:
          if commands[command]:
            commands[command] = None
          else:
            break
        except KeyError:
          commands[command] = func

    self.bind("<KeyPress-Return>", self.enter)

  def enter(self, event):
    words = split(self.get())
    if words:
      command, words = words[0], words[1:]
      self.delete(0, 'end')
      func = None
      try:
        func = self.commands[command]
        if func:
          func(words)
        else:
          self.error("<ambiguous command %s>" % command)
      except KeyError:
        self.error("<unknown command %s>" % command)    

  def clear(self):
    self.delete(0, "end")

  def set(self, message):
    self.clear()
    self.insert(0, message)

  def error(self, error):
    self.set(error)
    self.bind("<KeyPress>", self.clear_error)

  def clear_error(self, event):
    self.clear()
    self.unbind("<KeyPress>")