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−#!/usr/bin/env python
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−#
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−# Copyright 2007 Google Inc.
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−#
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−# Licensed under the Apache License, Version 2.0 (the "License");
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−# you may not use this file except in compliance with the License.
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−# You may obtain a copy of the License at
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−#
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−#     http://www.apache.org/licenses/LICENSE-2.0
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−#
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−# Unless required by applicable law or agreed to in writing, software
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−# distributed under the License is distributed on an "AS IS" BASIS,
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−# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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−# See the License for the specific language governing permissions and
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−# limitations under the License.
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−#
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−
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−"""XMPP webapp handler classes.
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−
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−This module provides handler classes for XMPP bots, including both basic
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−messaging functionality and a command handler for commands such as "/foo bar"
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−"""
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−
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−
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−
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−import logging
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−from google.appengine.api import xmpp
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−from google.appengine.ext import webapp
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−
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−
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−class BaseHandler(webapp.RequestHandler):
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−  """A webapp baseclass for XMPP handlers.
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−
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−  Implements a straightforward message delivery pattern. When a message is
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−  received, message_received is called with a Message object that encapsulates
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−  the relevant details. Users can reply using the standard XMPP API, or the
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−  convenient .reply() method on the Message object.
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−  """
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−
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−  def message_received(self, message):
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−    """Called when a message is sent to the XMPP bot.
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−
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−    Args:
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−      message: Message: The message that was sent by the user.
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−    """
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−    raise NotImplementedError()
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−
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−  def handle_exception(self, exception, debug_mode):
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−    """Called if this handler throws an exception during execution.
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−
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−    Args:
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−      exception: the exception that was thrown
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−      debug_mode: True if the web application is running in debug mode
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−    """
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−    super(BaseHandler, self).handle_exception(exception, debug_mode)
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−    if self.xmpp_message:
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−      self.xmpp_message.reply('Oops. Something went wrong.')
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−
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−  def post(self):
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−    try:
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−      self.xmpp_message = xmpp.Message(self.request.POST)
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−    except xmpp.InvalidMessageError, e:
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−      logging.error("Invalid XMPP request: Missing required field %s", e[0])
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−      return
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−    self.message_received(self.xmpp_message)
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−
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−
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−class CommandHandlerMixin(object):
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−  """A command handler for XMPP bots.
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−
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−  Implements a command handler pattern. XMPP messages are processed by calling
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−  message_received. Message objects handled by this class are annotated with
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−  'command' and 'arg' fields. On receipt of a message starting with a forward
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−  or backward slash, the handler calls a method named after the command - eg,
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−  if the user sends "/foo bar", the handler will call foo_command(message).
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−  If no handler method matches, unhandled_command is called. The default behaviour
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−  of unhandled_command is to send the message "Unknown command" back to
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−  the sender.
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−
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−  If the user sends a message not prefixed with a slash,
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−  text_message(message) is called.
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−  """
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−
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−  def unhandled_command(self, message):
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−    """Called when an unknown command is sent to the XMPP bot.
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−
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−    Args:
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−      message: Message: The message that was sent by the user.
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−    """
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−    message.reply('Unknown command')
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−
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−  def text_message(self, message):
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−    """Called when a message not prefixed by a /command is sent to the XMPP bot.
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−
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−    Args:
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−      message: Message: The message that was sent by the user.
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−    """
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−    pass
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−
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−  def message_received(self, message):
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−    """Called when a message is sent to the XMPP bot.
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−
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−    Args:
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−      message: Message: The message that was sent by the user.
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−    """
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−    if message.command:
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−      handler_name = '%s_command' % (message.command,)
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−      handler = getattr(self, handler_name, None)
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−      if handler:
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−        handler(message)
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−      else:
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−        self.unhandled_command(message)
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−    else:
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−      self.text_message(message)
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−
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−
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−class CommandHandler(CommandHandlerMixin, BaseHandler):
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−  """A webapp implementation of CommandHandlerMixin."""
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−  pass