#!/usr/bin/python2.4
#
# Copyright 2007 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

'''A library that provides a python interface to the Twitter API'''

__author__ = 'dewitt@google.com'
__version__ = '0.7-devel'


import base64
import calendar
import httplib
import os
import rfc822
import sys
import tempfile
import textwrap
import time
import urllib
import urllib2
import urlparse
import gzip
import StringIO

# Choose simplejson or json library by their availability
try:
    import simplejson as json
except ImportError:
    import json

try:
  from hashlib import md5
except ImportError:
  from md5 import md5


CHARACTER_LIMIT = 140

# A singleton representing a lazily instantiated FileCache.
DEFAULT_CACHE = object()


class TwitterError(Exception):
  '''Base class for Twitter errors'''
  
  @property
  def message(self):
    '''Returns the first argument used to construct this error.'''
    return self.args[0]


class Status(object):
  '''A class representing the Status structure used by the twitter API.

  The Status structure exposes the following properties:

      - status.created_at
      - status.created_at_in_seconds # read only
      - status.favorited
      - status.in_reply_to_screen_name
      - status.in_reply_to_user_id
      - status.in_reply_to_status_id
      - status.truncated
      - status.source
      - status.id
      - status.text
      - status.location
      - status.relative_created_at # read only
      - status.user
  '''
  def __init__(self,
               created_at=None,
               favorited=None,
               id=None,
               text=None,
               location=None,
               user=None,
               in_reply_to_screen_name=None,
               in_reply_to_user_id=None,
               in_reply_to_status_id=None,
               truncated=None,
               source=None,
               now=None):
    '''An object to hold a Twitter status message.

    This class is normally instantiated by the twitter.Api class and
    returned in a sequence.

    Note: Dates are posted in the form "Sat Jan 27 04:17:38 +0000 2007"

    @param created_at: The time this status message was posted
    @param favorited: Whether this is a favorite of the authenticated user
    @param id: The unique id of this status message
    @param text: The text of this status message
    @param location: the geolocation string associated with this message
    @param relative_created_at:
        A human readable string representing the posting time
    @param user:
        A twitter.User instance representing the person posting the message
    @param now:
        The current time, if the client choses to set it.  Defaults to the
        wall clock time.
    '''
    self.created_at = created_at
    self.favorited = favorited
    self.id = id
    self.text = text
    self.location = location
    self.user = user
    self.now = now
    self.in_reply_to_screen_name = in_reply_to_screen_name
    self.in_reply_to_user_id = in_reply_to_user_id
    self.in_reply_to_status_id = in_reply_to_status_id
    self.truncated = truncated
    self.source = source

  def GetCreatedAt(self):
    '''Get the time this status message was posted.

    @returns: The time this status message was posted
    '''
    return self._created_at

  def SetCreatedAt(self, created_at):
    '''Set the time this status message was posted.

    @param created_at: The time this status message was created
    '''
    self._created_at = created_at

  created_at = property(GetCreatedAt, SetCreatedAt,
                        doc='The time this status message was posted.')

  def GetCreatedAtInSeconds(self):
    '''Get the time this status message was posted, in seconds since the epoch.

    @returns: The time this status message was posted, in seconds since the epoch.
    '''
    return calendar.timegm(rfc822.parsedate(self.created_at))

  created_at_in_seconds = property(GetCreatedAtInSeconds,
                                   doc="The time this status message was "
                                       "posted, in seconds since the epoch")

  def GetFavorited(self):
    '''Get the favorited setting of this status message.

    @returns: True if this status message is favorited; False otherwise
    '''
    return self._favorited

  def SetFavorited(self, favorited):
    '''Set the favorited state of this status message.

    @param favorited: boolean True/False favorited state of this status message
    '''
    self._favorited = favorited

  favorited = property(GetFavorited, SetFavorited,
                       doc='The favorited state of this status message.')

  def GetId(self):
    '''Get the unique id of this status message.

    @returns: The unique id of this status message
    '''
    return self._id

  def SetId(self, id):
    '''Set the unique id of this status message.

    @param id: The unique id of this status message
    '''
    self._id = id

  id = property(GetId, SetId,
                doc='The unique id of this status message.')

  def GetInReplyToScreenName(self):
    return self._in_reply_to_screen_name

  def SetInReplyToScreenName(self, in_reply_to_screen_name):
    self._in_reply_to_screen_name = in_reply_to_screen_name

  in_reply_to_screen_name = property(GetInReplyToScreenName, SetInReplyToScreenName,
                doc='')

  def GetInReplyToUserId(self):
    return self._in_reply_to_user_id

  def SetInReplyToUserId(self, in_reply_to_user_id):
    self._in_reply_to_user_id = in_reply_to_user_id

  in_reply_to_user_id = property(GetInReplyToUserId, SetInReplyToUserId,
                doc='')

  def GetInReplyToStatusId(self):
    return self._in_reply_to_status_id

  def SetInReplyToStatusId(self, in_reply_to_status_id):
    self._in_reply_to_status_id = in_reply_to_status_id

  in_reply_to_status_id = property(GetInReplyToStatusId, SetInReplyToStatusId,
                doc='')

  def GetTruncated(self):
    return self._truncated

  def SetTruncated(self, truncated):
    self._truncated = truncated

  truncated = property(GetTruncated, SetTruncated,
                doc='')

  def GetSource(self):
    return self._source

  def SetSource(self, source):
    self._source = source

  source = property(GetSource, SetSource,
                doc='')

  def GetText(self):
    '''Get the text of this status message.

    @returns: The text of this status message.
    '''
    return self._text

  def SetText(self, text):
    '''Set the text of this status message.

    @param text: The text of this status message
    '''
    self._text = text

  text = property(GetText, SetText,
                  doc='The text of this status message')

  def GetLocation(self):
    '''Get the geolocation associated with this status message

    @returns: The geolocation string of this status message.
    '''
    return self._location

  def SetLocation(self, location):
    '''Set the geolocation associated with this status message

    @param location: The geolocation string of this status message
    '''
    self._location = location

  location = property(GetLocation, SetLocation,
                      doc='The geolocation string of this status message')

  def GetRelativeCreatedAt(self):
    '''Get a human redable string representing the posting time

    @returns: A human readable string representing the posting time
    '''
    fudge = 1.25
    delta  = long(self.now) - long(self.created_at_in_seconds)

    if delta < (1 * fudge):
      return 'about a second ago'
    elif delta < (60 * (1/fudge)):
      return 'about %d seconds ago' % (delta)
    elif delta < (60 * fudge):
      return 'about a minute ago'
    elif delta < (60 * 60 * (1/fudge)):
      return 'about %d minutes ago' % (delta / 60)
    elif delta < (60 * 60 * fudge) or delta / (60 * 60) == 1:
      return 'about an hour ago'
    elif delta < (60 * 60 * 24 * (1/fudge)):
      return 'about %d hours ago' % (delta / (60 * 60))
    elif delta < (60 * 60 * 24 * fudge) or delta / (60 * 60 * 24) == 1:
      return 'about a day ago'
    else:
      return 'about %d days ago' % (delta / (60 * 60 * 24))

  relative_created_at = property(GetRelativeCreatedAt,
                                 doc='Get a human readable string representing'
                                     'the posting time')

  def GetUser(self):
    '''Get a twitter.User reprenting the entity posting this status message.

    @returns: A twitter.User reprenting the entity posting this status message
    '''
    return self._user

  def SetUser(self, user):
    '''Set a twitter.User reprenting the entity posting this status message.

    @param user: A twitter.User reprenting the entity posting this status message
    '''
    self._user = user

  user = property(GetUser, SetUser,
                  doc='A twitter.User reprenting the entity posting this '
                      'status message')

  def GetNow(self):
    '''Get the wallclock time for this status message.

    Used to calculate relative_created_at.  Defaults to the time
    the object was instantiated.

    @returns: Whatever the status instance believes the current time to be,
        in seconds since the epoch.
    '''
    if self._now is None:
      self._now = time.time()
    return self._now

  def SetNow(self, now):
    '''Set the wallclock time for this status message.

    Used to calculate relative_created_at.  Defaults to the time
    the object was instantiated.

    @param now: The wallclock time for this instance.
    '''
    self._now = now

  now = property(GetNow, SetNow,
                 doc='The wallclock time for this status instance.')


  def __ne__(self, other):
    return not self.__eq__(other)

  def __eq__(self, other):
    try:
      return other and \
             self.created_at == other.created_at and \
             self.id == other.id and \
             self.text == other.text and \
             self.location == other.location and \
             self.user == other.user and \
             self.in_reply_to_screen_name == other.in_reply_to_screen_name and \
             self.in_reply_to_user_id == other.in_reply_to_user_id and \
             self.in_reply_to_status_id == other.in_reply_to_status_id and \
             self.truncated == other.truncated and \
             self.favorited == other.favorited and \
             self.source == other.source
    except AttributeError:
      return False

  def __str__(self):
    '''A string representation of this twitter.Status instance.

    The return value is the same as the JSON string representation.

    @returns: A string representation of this twitter.Status instance.
    '''
    return self.AsJsonString()

  def AsJsonString(self):
    '''A JSON string representation of this twitter.Status instance.

    @returns: A JSON string representation of this twitter.Status instance
   '''
    return json.dumps(self.AsDict(), sort_keys=True)

  def AsDict(self):
    '''A dict representation of this twitter.Status instance.

    The return value uses the same key names as the JSON representation.

    @return: A dict representing this twitter.Status instance
    '''
    data = {}
    if self.created_at:
      data['created_at'] = self.created_at
    if self.favorited:
      data['favorited'] = self.favorited
    if self.id:
      data['id'] = self.id
    if self.text:
      data['text'] = self.text
    if self.location:
      data['location'] = self.location  
    if self.user:
      data['user'] = self.user.AsDict()
    if self.in_reply_to_screen_name:
      data['in_reply_to_screen_name'] = self.in_reply_to_screen_name
    if self.in_reply_to_user_id:
      data['in_reply_to_user_id'] = self.in_reply_to_user_id
    if self.in_reply_to_status_id:
      data['in_reply_to_status_id'] = self.in_reply_to_status_id
    if self.truncated is not None:
      data['truncated'] = self.truncated
    if self.favorited is not None:
      data['favorited'] = self.favorited
    if self.source:
      data['source'] = self.source
    return data

  @staticmethod
  def NewFromJsonDict(data):
    '''Create a new instance based on a JSON dict.

    @param data: A JSON dict, as converted from the JSON in the twitter API
    @returns: A twitter.Status instance
    '''
    if 'user' in data:
      user = User.NewFromJsonDict(data['user'])
    else:
      user = None
    return Status(created_at=data.get('created_at', None),
                  favorited=data.get('favorited', None),
                  id=data.get('id', None),
                  text=data.get('text', None),
                  location=data.get('location', None),
                  in_reply_to_screen_name=data.get('in_reply_to_screen_name', None),
                  in_reply_to_user_id=data.get('in_reply_to_user_id', None),
                  in_reply_to_status_id=data.get('in_reply_to_status_id', None),
                  truncated=data.get('truncated', None),
                  source=data.get('source', None),
                  user=user)


class User(object):
  '''A class representing the User structure used by the twitter API.

  The User structure exposes the following properties:

    - user.id
    - user.name
    - user.screen_name
    - user.location
    - user.description
    - user.profile_image_url
    - user.profile_background_tile
    - user.profile_background_image_url
    - user.profile_sidebar_fill_color
    - user.profile_background_color
    - user.profile_link_color
    - user.profile_text_color
    - user.protected
    - user.utc_offset
    - user.time_zone
    - user.url
    - user.status
    - user.statuses_count
    - user.followers_count
    - user.friends_count
    - user.favourites_count
  '''
  def __init__(self,
               id=None,
               name=None,
               screen_name=None,
               location=None,
               description=None,
               profile_image_url=None,
               profile_background_tile=None,
               profile_background_image_url=None,
               profile_sidebar_fill_color=None,
               profile_background_color=None,
               profile_link_color=None,
               profile_text_color=None,
               protected=None,
               utc_offset=None,
               time_zone=None,
               followers_count=None,
               friends_count=None,
               statuses_count=None,
               favourites_count=None,
               url=None,
               status=None):
    self.id = id
    self.name = name
    self.screen_name = screen_name
    self.location = location
    self.description = description
    self.profile_image_url = profile_image_url
    self.profile_background_tile = profile_background_tile
    self.profile_background_image_url = profile_background_image_url
    self.profile_sidebar_fill_color = profile_sidebar_fill_color
    self.profile_background_color = profile_background_color
    self.profile_link_color = profile_link_color
    self.profile_text_color = profile_text_color
    self.protected = protected
    self.utc_offset = utc_offset
    self.time_zone = time_zone
    self.followers_count = followers_count
    self.friends_count = friends_count
    self.statuses_count = statuses_count
    self.favourites_count = favourites_count
    self.url = url
    self.status = status


  def GetId(self):
    '''Get the unique id of this user.

    @returns: The unique id of this user
    '''
    return self._id

  def SetId(self, id):
    '''Set the unique id of this user.

    @param: id: The unique id of this user.
    '''
    self._id = id

  id = property(GetId, SetId,
                doc='The unique id of this user.')

  def GetName(self):
    '''Get the real name of this user.

    @returns: The real name of this user
    '''
    return self._name

  def SetName(self, name):
    '''Set the real name of this user.

    @param name: The real name of this user
    '''
    self._name = name

  name = property(GetName, SetName,
                  doc='The real name of this user.')

  def GetScreenName(self):
    '''Get the short username of this user.

    @returns: The short username of this user
    '''
    return self._screen_name

  def SetScreenName(self, screen_name):
    '''Set the short username of this user.

    @param screen_name: the short username of this user
    '''
    self._screen_name = screen_name

  screen_name = property(GetScreenName, SetScreenName,
                         doc='The short username of this user.')

  def GetLocation(self):
    '''Get the geographic location of this user.

    @returns: The geographic location of this user
    '''
    return self._location

  def SetLocation(self, location):
    '''Set the geographic location of this user.

    @param location: The geographic location of this user
    '''
    self._location = location

  location = property(GetLocation, SetLocation,
                      doc='The geographic location of this user.')

  def GetDescription(self):
    '''Get the short text description of this user.

    @returns: The short text description of this user
    '''
    return self._description

  def SetDescription(self, description):
    '''Set the short text description of this user.

    @param description: The short text description of this user
    '''
    self._description = description

  description = property(GetDescription, SetDescription,
                         doc='The short text description of this user.')

  def GetUrl(self):
    '''Get the homepage url of this user.

    @returns: The homepage url of this user
    '''
    return self._url

  def SetUrl(self, url):
    '''Set the homepage url of this user.

    @param url: The homepage url of this user
    '''
    self._url = url

  url = property(GetUrl, SetUrl,
                 doc='The homepage url of this user.')

  def GetProfileImageUrl(self):
    '''Get the url of the thumbnail of this user.

    @returns: The url of the thumbnail of this user
    '''
    return self._profile_image_url

  def SetProfileImageUrl(self, profile_image_url):
    '''Set the url of the thumbnail of this user.

    @param profile_image_url: The url of the thumbnail of this user
    '''
    self._profile_image_url = profile_image_url

  profile_image_url= property(GetProfileImageUrl, SetProfileImageUrl,
                              doc='The url of the thumbnail of this user.')

  def GetProfileBackgroundTile(self):
    '''Boolean for whether to tile the profile background image.

    @returns: True if the background is to be tiled, False if not, None if unset.
    '''
    return self._profile_background_tile

  def SetProfileBackgroundTile(self, profile_background_tile):
    '''Set the boolean flag for whether to tile the profile background image.

    @param profile_background_tile: Boolean flag for whether to tile or not.
    '''
    self._profile_background_tile = profile_background_tile

  profile_background_tile = property(GetProfileBackgroundTile, SetProfileBackgroundTile,
                                     doc='Boolean for whether to tile the background image.')

  def GetProfileBackgroundImageUrl(self):
    return self._profile_background_image_url

  def SetProfileBackgroundImageUrl(self, profile_background_image_url):
    self._profile_background_image_url = profile_background_image_url

  profile_background_image_url = property(GetProfileBackgroundImageUrl, SetProfileBackgroundImageUrl,
                                          doc='The url of the profile background of this user.')

  def GetProfileSidebarFillColor(self):
    return self._profile_sidebar_fill_color

  def SetProfileSidebarFillColor(self, profile_sidebar_fill_color):
    self._profile_sidebar_fill_color = profile_sidebar_fill_color

  profile_sidebar_fill_color = property(GetProfileSidebarFillColor, SetProfileSidebarFillColor)

  def GetProfileBackgroundColor(self):
    return self._profile_background_color

  def SetProfileBackgroundColor(self, profile_background_color):
    self._profile_background_color = profile_background_color

  profile_background_color = property(GetProfileBackgroundColor, SetProfileBackgroundColor)

  def GetProfileLinkColor(self):
    return self._profile_link_color

  def SetProfileLinkColor(self, profile_link_color):
    self._profile_link_color = profile_link_color

  profile_link_color = property(GetProfileLinkColor, SetProfileLinkColor)

  def GetProfileTextColor(self):
    return self._profile_text_color

  def SetProfileTextColor(self, profile_text_color):
    self._profile_text_color = profile_text_color

  profile_text_color = property(GetProfileTextColor, SetProfileTextColor)

  def GetProtected(self):
    return self._protected

  def SetProtected(self, protected):
    self._protected = protected

  protected = property(GetProtected, SetProtected)

  def GetUtcOffset(self):
    return self._utc_offset

  def SetUtcOffset(self, utc_offset):
    self._utc_offset = utc_offset

  utc_offset = property(GetUtcOffset, SetUtcOffset)

  def GetTimeZone(self):
    '''Returns the current time zone string for the user.

    @returns: The descriptive time zone string for the user.
    '''
    return self._time_zone

  def SetTimeZone(self, time_zone):
    '''Sets the user's time zone string.

    @param time_zone: The descriptive time zone to assign for the user.
    '''
    self._time_zone = time_zone

  time_zone = property(GetTimeZone, SetTimeZone)

  def GetStatus(self):
    '''Get the latest twitter.Status of this user.

    @returns: The latest twitter.Status of this user
    '''
    return self._status

  def SetStatus(self, status):
    '''Set the latest twitter.Status of this user.

    @param status: The latest twitter.Status of this user
    '''
    self._status = status

  status = property(GetStatus, SetStatus,
                  doc='The latest twitter.Status of this user.')

  def GetFriendsCount(self):
    '''Get the friend count for this user.
    
    @returns: The number of users this user has befriended.
    '''
    return self._friends_count

  def SetFriendsCount(self, count):
    '''Set the friend count for this user.

    @param count: The number of users this user has befriended.
    '''
    self._friends_count = count

  friends_count = property(GetFriendsCount, SetFriendsCount,
                  doc='The number of friends for this user.')

  def GetFollowersCount(self):
    '''Get the follower count for this user.
    
    @returns: The number of users following this user.
    '''
    return self._followers_count

  def SetFollowersCount(self, count):
    '''Set the follower count for this user.

    @param count: The number of users following this user.
    '''
    self._followers_count = count

  followers_count = property(GetFollowersCount, SetFollowersCount,
                  doc='The number of users following this user.')

  def GetStatusesCount(self):
    '''Get the number of status updates for this user.
    
    @returns: The number of status updates for this user.
    '''
    return self._statuses_count

  def SetStatusesCount(self, count):
    '''Set the status update count for this user.

    @param count: The number of updates for this user.
    '''
    self._statuses_count = count

  statuses_count = property(GetStatusesCount, SetStatusesCount,
                  doc='The number of updates for this user.')

  def GetFavouritesCount(self):
    '''Get the number of favourites for this user.
    
    @returns: The number of favourites for this user.
    '''
    return self._favourites_count

  def SetFavouritesCount(self, count):
    '''Set the favourite count for this user.

    @param count: The number of favourites for this user.
    '''
    self._favourites_count = count

  favourites_count = property(GetFavouritesCount, SetFavouritesCount,
                  doc='The number of favourites for this user.')

  def __ne__(self, other):
    return not self.__eq__(other)

  def __eq__(self, other):
    try:
      return other and \
             self.id == other.id and \
             self.name == other.name and \
             self.screen_name == other.screen_name and \
             self.location == other.location and \
             self.description == other.description and \
             self.profile_image_url == other.profile_image_url and \
             self.profile_background_tile == other.profile_background_tile and \
             self.profile_background_image_url == other.profile_background_image_url and \
             self.profile_sidebar_fill_color == other.profile_sidebar_fill_color and \
             self.profile_background_color == other.profile_background_color and \
             self.profile_link_color == other.profile_link_color and \
             self.profile_text_color == other.profile_text_color and \
             self.protected == other.protected and \
             self.utc_offset == other.utc_offset and \
             self.time_zone == other.time_zone and \
             self.url == other.url and \
             self.statuses_count == other.statuses_count and \
             self.followers_count == other.followers_count and \
             self.favourites_count == other.favourites_count and \
             self.friends_count == other.friends_count and \
             self.status == other.status
    except AttributeError:
      return False

  def __str__(self):
    '''A string representation of this twitter.User instance.

    The return value is the same as the JSON string representation.

    @returns: A string representation of this twitter.User instance.
    '''
    return self.AsJsonString()

  def AsJsonString(self):
    '''A JSON string representation of this twitter.User instance.

    @returns: A JSON string representation of this twitter.User instance
   '''
    return json.dumps(self.AsDict(), sort_keys=True)

  def AsDict(self):
    '''A dict representation of this twitter.User instance.

    The return value uses the same key names as the JSON representation.

    @return: A dict representing this twitter.User instance
    '''
    data = {}
    if self.id:
      data['id'] = self.id
    if self.name:
      data['name'] = self.name
    if self.screen_name:
      data['screen_name'] = self.screen_name
    if self.location:
      data['location'] = self.location
    if self.description:
      data['description'] = self.description
    if self.profile_image_url:
      data['profile_image_url'] = self.profile_image_url
    if self.profile_background_tile is not None:
      data['profile_background_tile'] = self.profile_background_tile
    if self.profile_background_image_url:
      data['profile_sidebar_fill_color'] = self.profile_background_image_url
    if self.profile_background_color:
      data['profile_background_color'] = self.profile_background_color
    if self.profile_link_color:
      data['profile_link_color'] = self.profile_link_color
    if self.profile_text_color:
      data['profile_text_color'] = self.profile_text_color
    if self.protected is not None:
      data['protected'] = self.protected
    if self.utc_offset:
      data['utc_offset'] = self.utc_offset
    if self.time_zone:
      data['time_zone'] = self.time_zone
    if self.url:
      data['url'] = self.url
    if self.status:
      data['status'] = self.status.AsDict()
    if self.friends_count:
      data['friends_count'] = self.friends_count
    if self.followers_count:
      data['followers_count'] = self.followers_count
    if self.statuses_count:
      data['statuses_count'] = self.statuses_count
    if self.favourites_count:
      data['favourites_count'] = self.favourites_count
    return data

  @staticmethod
  def NewFromJsonDict(data):
    '''Create a new instance based on a JSON dict.

    @param data: A JSON dict, as converted from the JSON in the twitter API
    @returns: A twitter.User instance
    '''
    if 'status' in data:
      status = Status.NewFromJsonDict(data['status'])
    else:
      status = None
    return User(id=data.get('id', None),
                name=data.get('name', None),
                screen_name=data.get('screen_name', None),
                location=data.get('location', None),
                description=data.get('description', None),
                statuses_count=data.get('statuses_count', None),
                followers_count=data.get('followers_count', None),
                favourites_count=data.get('favourites_count', None),
                friends_count=data.get('friends_count', None),
                profile_image_url=data.get('profile_image_url', None),
                profile_background_tile = data.get('profile_background_tile', None),
                profile_background_image_url = data.get('profile_background_image_url', None),
                profile_sidebar_fill_color = data.get('profile_sidebar_fill_color', None),
                profile_background_color = data.get('profile_background_color', None),
                profile_link_color = data.get('profile_link_color', None),
                profile_text_color = data.get('profile_text_color', None),
                protected = data.get('protected', None),
                utc_offset = data.get('utc_offset', None),
                time_zone = data.get('time_zone', None),
                url=data.get('url', None),
                status=status)

class DirectMessage(object):
  '''A class representing the DirectMessage structure used by the twitter API.

  The DirectMessage structure exposes the following properties:

    - direct_message.id
    - direct_message.created_at
    - direct_message.created_at_in_seconds # read only
    - direct_message.sender_id
    - direct_message.sender_screen_name
    - direct_message.recipient_id
    - direct_message.recipient_screen_name
    - direct_message.text
  '''

  def __init__(self,
               id=None,
               created_at=None,
               sender_id=None,
               sender_screen_name=None,
               recipient_id=None,
               recipient_screen_name=None,
               text=None):
    '''An object to hold a Twitter direct message.

    This class is normally instantiated by the twitter.Api class and
    returned in a sequence.

    Note: Dates are posted in the form "Sat Jan 27 04:17:38 +0000 2007"

    @param id: The unique id of this direct message
    @param created_at: The time this direct message was posted
    @param sender_id: The id of the twitter user that sent this message
    @param sender_screen_name: The name of the twitter user that sent this message
    @param recipient_id: The id of the twitter that received this message
    @param recipient_screen_name: The name of the twitter that received this message
    @param text: The text of this direct message
    '''
    self.id = id
    self.created_at = created_at
    self.sender_id = sender_id
    self.sender_screen_name = sender_screen_name
    self.recipient_id = recipient_id
    self.recipient_screen_name = recipient_screen_name
    self.text = text

  def GetId(self):
    '''Get the unique id of this direct message.

    @returns: The unique id of this direct message
    '''
    return self._id

  def SetId(self, id):
    '''Set the unique id of this direct message.

    @param id: The unique id of this direct message
    '''
    self._id = id

  id = property(GetId, SetId,
                doc='The unique id of this direct message.')

  def GetCreatedAt(self):
    '''Get the time this direct message was posted.

    @returns: The time this direct message was posted
    '''
    return self._created_at

  def SetCreatedAt(self, created_at):
    '''Set the time this direct message was posted.

    @param created_at: The time this direct message was created
    '''
    self._created_at = created_at

  created_at = property(GetCreatedAt, SetCreatedAt,
                        doc='The time this direct message was posted.')

  def GetCreatedAtInSeconds(self):
    '''Get the time this direct message was posted, in seconds since the epoch.

    @returns: The time this direct message was posted, in seconds since the epoch.
    '''
    return calendar.timegm(rfc822.parsedate(self.created_at))

  created_at_in_seconds = property(GetCreatedAtInSeconds,
                                   doc="The time this direct message was "
                                       "posted, in seconds since the epoch")

  def GetSenderId(self):
    '''Get the unique sender id of this direct message.

    @returns: The unique sender id of this direct message
    '''
    return self._sender_id

  def SetSenderId(self, sender_id):
    '''Set the unique sender id of this direct message.

    @param sender_id: The unique sender id of this direct message
    '''
    self._sender_id = sender_id

  sender_id = property(GetSenderId, SetSenderId,
                doc='The unique sender id of this direct message.')

  def GetSenderScreenName(self):
    '''Get the unique sender screen name of this direct message.

    @returns: The unique sender screen name of this direct message
    '''
    return self._sender_screen_name

  def SetSenderScreenName(self, sender_screen_name):
    '''Set the unique sender screen name of this direct message.

    @param sender_screen_name: The unique sender screen name of this direct
        message
    '''
    self._sender_screen_name = sender_screen_name

  sender_screen_name = property(GetSenderScreenName, SetSenderScreenName,
                doc='The unique sender screen name of this direct message.')

  def GetRecipientId(self):
    '''Get the unique recipient id of this direct message.

    @returns: The unique recipient id of this direct message
    '''
    return self._recipient_id

  def SetRecipientId(self, recipient_id):
    '''Set the unique recipient id of this direct message.

    @param recipient id: The unique recipient id of this direct message
    '''
    self._recipient_id = recipient_id

  recipient_id = property(GetRecipientId, SetRecipientId,
                doc='The unique recipient id of this direct message.')

  def GetRecipientScreenName(self):
    '''Get the unique recipient screen name of this direct message.

    @returns: The unique recipient screen name of this direct message
    '''
    return self._recipient_screen_name

  def SetRecipientScreenName(self, recipient_screen_name):
    '''Set the unique recipient screen name of this direct message.

    @param recipient_screen_name: The unique recipient screen name of this direct message
    '''
    self._recipient_screen_name = recipient_screen_name

  recipient_screen_name = property(GetRecipientScreenName, SetRecipientScreenName,
                doc='The unique recipient screen name of this direct message.')

  def GetText(self):
    '''Get the text of this direct message.

    @returns: The text of this direct message.
    '''
    return self._text

  def SetText(self, text):
    '''Set the text of this direct message.

    @param text: The text of this direct message
    '''
    self._text = text

  text = property(GetText, SetText,
                  doc='The text of this direct message')

  def __ne__(self, other):
    return not self.__eq__(other)

  def __eq__(self, other):
    try:
      return other and \
          self.id == other.id and \
          self.created_at == other.created_at and \
          self.sender_id == other.sender_id and \
          self.sender_screen_name == other.sender_screen_name and \
          self.recipient_id == other.recipient_id and \
          self.recipient_screen_name == other.recipient_screen_name and \
          self.text == other.text
    except AttributeError:
      return False

  def __str__(self):
    '''A string representation of this twitter.DirectMessage instance.

    The return value is the same as the JSON string representation.

    @returns: A string representation of this twitter.DirectMessage instance.
    '''
    return self.AsJsonString()

  def AsJsonString(self):
    '''A JSON string representation of this twitter.DirectMessage instance.

    @returns: A JSON string representation of this twitter.DirectMessage instance
   '''
    return json.dumps(self.AsDict(), sort_keys=True)

  def AsDict(self):
    '''A dict representation of this twitter.DirectMessage instance.

    The return value uses the same key names as the JSON representation.

    @returns: A dict representing this twitter.DirectMessage instance
    '''
    data = {}
    if self.id:
      data['id'] = self.id
    if self.created_at:
      data['created_at'] = self.created_at
    if self.sender_id:
      data['sender_id'] = self.sender_id
    if self.sender_screen_name:
      data['sender_screen_name'] = self.sender_screen_name
    if self.recipient_id:
      data['recipient_id'] = self.recipient_id
    if self.recipient_screen_name:
      data['recipient_screen_name'] = self.recipient_screen_name
    if self.text:
      data['text'] = self.text
    return data

  @staticmethod
  def NewFromJsonDict(data):
    '''Create a new instance based on a JSON dict.

    @param data: A JSON dict, as converted from the JSON in the twitter API
    @returns: A twitter.DirectMessage instance
    '''
    return DirectMessage(created_at=data.get('created_at', None),
                         recipient_id=data.get('recipient_id', None),
                         sender_id=data.get('sender_id', None),
                         text=data.get('text', None),
                         sender_screen_name=data.get('sender_screen_name', None),
                         id=data.get('id', None),
                         recipient_screen_name=data.get('recipient_screen_name', None))

class Api(object):
  '''A python interface into the Twitter API

  By default, the Api caches results for 1 minute.

  Example usage:

      - To create an instance of the twitter.Api class, with no authentication:

          >>> import twitter
          >>> api = twitter.Api()

      - To fetch the most recently posted public twitter status messages:

          >>> statuses = api.GetPublicTimeline()
          >>> print [s.user.name for s in statuses]
          [u'DeWitt', u'Kesuke Miyagi', u'ev', u'Buzz Andersen', u'Biz Stone'] #...

      - To fetch a single user's public status messages, where "user" is either
        a Twitter "short name" or their user id.

          >>> statuses = api.GetUserTimeline(user)
          >>> print [s.text for s in statuses]

      - To use authentication, instantiate the twitter.Api class with a
        username and password:

          >>> api = twitter.Api(username='twitter user', password='twitter pass')

      - To fetch your friends (after being authenticated):

          >>> users = api.GetFriends()
          >>> print [u.name for u in users]

      - To post a twitter status message (after being authenticated):

          >>> status = api.PostUpdate('I love python-twitter!')
          >>> print status.text
          I love python-twitter!

      - There are many other methods, including:

          >>> api.PostUpdates(status)
          >>> api.PostDirectMessage(user, text)
          >>> api.GetUser(user)
          >>> api.GetReplies()
          >>> api.GetUserTimeline(user)
          >>> api.GetStatus(id)
          >>> api.DestroyStatus(id)
          >>> api.GetFriendsTimeline(user)
          >>> api.GetFriends(user)
          >>> api.GetFollowers()
          >>> api.GetFeatured()
          >>> api.GetDirectMessages()
          >>> api.PostDirectMessage(user, text)
          >>> api.DestroyDirectMessage(id)
          >>> api.DestroyFriendship(user)
          >>> api.CreateFriendship(user)
          >>> api.GetUserByEmail(email)
          >>> api.VerifyCredentials()
  '''

  DEFAULT_CACHE_TIMEOUT = 60 # cache for 1 minute

  _API_REALM = 'Twitter API'

  def __init__(self,
               username=None,
               password=None,
               input_encoding=None,
               request_headers=None,
               cache=DEFAULT_CACHE,
               shortner=None,
               base_url=None,
               use_gzip_compression=False):
    '''Instantiate a new twitter.Api object.

    @param username: The username of the twitter account.  [optional]
    @param password: The password for the twitter account. [optional]
    @param input_encoding: The encoding used to encode input strings.
        [optional]
    @param request_header: A dictionary of additional HTTP request headers.
        [optional]
    @param cache: The cache instance to use. Defaults to DEFAULT_CACHE.
        Use None to disable caching. [optional]
    @param shortner: The shortner instance to use.  Defaults to None.
        See shorten_url.py for an example shortner. [optional]
    @param base_url: The base URL to use to contact the Twitter API.
        Defaults to https://twitter.com. [optional]
    @param use_gzip_compression: Set to True to tell enable gzip compression
        for any call made to Twitter.  Defaults to False. [optional]
    '''
    self.SetCache(cache)
    self._urllib = urllib2
    self._cache_timeout = Api.DEFAULT_CACHE_TIMEOUT
    self._InitializeRequestHeaders(request_headers)
    self._InitializeUserAgent()
    self._InitializeDefaultParameters()
    self._input_encoding = input_encoding
    self._use_gzip = use_gzip_compression
    self.SetCredentials(username, password)
    if base_url is None:
      self.base_url = 'https://twitter.com'
    else:
      self.base_url = base_url

  def GetPublicTimeline(self,
                        since_id=None):
    '''Fetch the sequnce of public twitter.Status message for all users.

    @param since_id: Returns only public statuses with an ID greater than
        (that is, more recent than) the specified ID. [optional]

    @returns: An sequence of twitter.Status instances, one for each message
    '''
    parameters = {}

    if since_id:
      parameters['since_id'] = since_id

    url  = '%s/statuses/public_timeline.json' % self.base_url
    json = self._FetchUrl(url,  parameters=parameters)
    data = json.loads(json)

    self._CheckForTwitterError(data)

    return [Status.NewFromJsonDict(x) for x in data]

  def FilterPublicTimeline(self,
                           term,
                           since_id=None):
    '''Filter the public twitter timeline by a given search term on
    the local machine.

    @param term: term to search by.
    @param since_id: Returns only public statuses with an ID greater than
        (that is, more recent than) the specified ID. [optional]

    @returns: A sequence of twitter.Status instances, one for each message
      containing the term
    '''
    statuses = self.GetPublicTimeline(since_id)
    results  = []

    for s in statuses:
      if s.text.lower().find(term.lower()) != -1:
        results.append(s)

    return results

  def GetSearch(self,
                term,
                geocode=None,
                since_id=None,
                per_page=15,
                page=1,
                lang="en",
                show_user="true",
                query_users=False):
    '''Return twitter search results for a given term.

    @param term: term to search by.
    @param since_id: Returns only public statuses with an ID greater than
        (that is, more recent than) the specified ID. [optional]
    @param geocode: geolocation information in the form (latitude, longitude,
        radius) [optional]
    @param per_page: number of results to return.  Default is 15 [optional]
    @param page: which page of search results to return
    @param lang: language for results.  Default is English [optional]
    @param show_user: prefixes screen name in status
    @param query_users: If set to False, then all users only have screen_name
        and profile_image_url available.
        If set to True, all information of users are available,
        but it uses lots of request quota, one per status.
    @returns: A sequence of twitter.Status instances, one for each message
        containing the term
    '''
    # Build request parameters
    parameters = {}

    if since_id:
      parameters['since_id'] = since_id

    if not term:
      return []

    parameters['q'] = urllib.quote_plus(term)
    parameters['show_user'] = show_user
    parameters['lang'] = lang
    parameters['rpp'] = per_page
    parameters['page'] = page

    if geocode is not None:
      parameters['geocode'] = ','.join(map(str, geocode))

    # Make and send requests
    url  = 'http://search.twitter.com/search.json'
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)

    self._CheckForTwitterError(data)

    results = []

    for x in data['results']:
      temp = Status.NewFromJsonDict(x)

      if query_users:
        # Build user object with new request
        temp.user = self.GetUser(urllib.quote(x['from_user']))
      else:
        temp.user = User(screen_name=x['from_user'], profile_image_url=x['profile_image_url'])

      results.append(temp)

    # Return built list of statuses
    return results # [Status.NewFromJsonDict(x) for x in data['results']]

  def GetFriendsTimeline(self,
                         user=None,
                         count=None,
                         since=None,
                         since_id=None):
    '''Fetch the sequence of twitter.Status messages for a user's friends

    The twitter.Api instance must be authenticated if the user is private.

    @param user: Specifies the ID or screen name of the user for whom to return
        the friends_timeline.  If unspecified, the username and password
        must be set in the twitter.Api instance.  [Optional]
    @param count: Specifies the number of statuses to retrieve. May not be
        greater than 200. [Optional]
    @param since: Narrows the returned results to just those statuses created
        after the specified HTTP-formatted date. [Optional]
    @param since_id: Returns only public statuses with an ID greater than (that
        is, more recent than) the specified ID. [Optional]

    @returns: A sequence of twitter.Status instances, one for each message
    '''
    if not user and not self._username:
      raise TwitterError("User must be specified if API is not authenticated.")
    if user:
      url = '%s/statuses/friends_timeline/%s.json' % (self.base_url, user)
    else:
      url = '%s/statuses/friends_timeline.json' % self.base_url
    parameters = {}
    if count is not None:
      try:
        if int(count) > 200:
          raise TwitterError("'count' may not be greater than 200")
      except ValueError:
        raise TwitterError("'count' must be an integer")
      parameters['count'] = count
    if since:
      parameters['since'] = since
    if since_id:
      parameters['since_id'] = since_id
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [Status.NewFromJsonDict(x) for x in data]

  def GetUserTimeline(self,
                      id=None,
                      user_id=None,
                      screen_name=None,
                      since_id=None,
                      max_id=None,
                      count=None,
                      page=None):
    '''Fetch the sequence of public Status messages for a single user.

    The twitter.Api instance must be authenticated if the user is private.

    @param id: Specifies the ID or screen name of the user for whom to return
        the user_timeline. [optional]
    @param user_id: Specfies the ID of the user for whom to return the
        user_timeline. Helpful for disambiguating when a valid user ID
        is also a valid screen name. [optional]
    @param screen_name: Specfies the screen name of the user for whom to return
        the user_timeline. Helpful for disambiguating when a valid screen
        name is also a user ID. [optional]
    @param since_id: Returns only public statuses with an ID greater than (that
        is, more recent than) the specified ID. [optional]
    @param max_id: Returns only statuses with an ID less than (that is, older
        than) or equal to the specified ID. [optional]
    @param count: Specifies the number of statuses to retrieve. May not be
        greater than 200.  [optional]
    @param page: Specifies the page of results to retrieve. Note: there are
         pagination limits. [optional]

    @returns: A sequence of Status instances, one for each message up to count
    '''
    parameters = {}

    if id:
      url = '%s/statuses/user_timeline/%s.json' % (self.base_url, id)
    elif user_id:
      url = '%s/statuses/user_timeline.json?user_id=%d' % (self.base_url, user_id)
    elif screen_name:
      url = ('%s/statuses/user_timeline.json?screen_name=%s' % (self.base_url,
             screen_name))
    elif not self._username:
      raise TwitterError("User must be specified if API is not authenticated.")
    else:
      url = '%s/statuses/user_timeline.json' % self.base_url

    if since_id:
      try:
        parameters['since_id'] = long(since_id)
      except:
        raise TwitterError("since_id must be an integer")

    if max_id:
      try:
        parameters['max_id'] = long(max_id)
      except:
        raise TwitterError("max_id must be an integer")

    if count:
      try:
        parameters['count'] = int(count)
      except:
        raise TwitterError("count must be an integer")

    if page:
      try:
        parameters['page'] = int(page)
      except:
        raise TwitterError("page must be an integer")

    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [Status.NewFromJsonDict(x) for x in data]

  def GetStatus(self, id):
    '''Returns a single status message.

    The twitter.Api instance must be authenticated if the status message is private.

    @param id: The numerical ID of the status you're trying to retrieve.

    @returns: A twitter.Status instance representing that status message
    '''
    try:
      if id:
        long(id)
    except:
      raise TwitterError("id must be an long integer")
    url = '%s/statuses/show/%s.json' % (self.base_url, id)
    json = self._FetchUrl(url)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return Status.NewFromJsonDict(data)

  def DestroyStatus(self, id):
    '''Destroys the status specified by the required ID parameter.

    The twitter.Api instance must be authenticated and thee
    authenticating user must be the author of the specified status.

    @param id: The numerical ID of the status you're trying to destroy.

    @returns: A twitter.Status instance representing the destroyed status message
    '''
    try:
      if id:
        long(id)
    except:
      raise TwitterError("id must be an integer")
    url = '%s/statuses/destroy/%s.json' % (self.base_url, id)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return Status.NewFromJsonDict(data)

  def PostUpdate(self, status, in_reply_to_status_id=None):
    '''Post a twitter status message from the authenticated user.

    The twitter.Api instance must be authenticated.

    @param status: The message text to be posted.  Must be less than or equal
        to 140 characters.
    @param in_reply_to_status_id: The ID of an existing status that the status
        to be posted is in reply to.  This implicitly sets the 
        in_reply_to_user_id attribute of the resulting status to the user ID of
        the message being replied to.  Invalid/missing status IDs will be
        ignored. [Optional]
    @returns: A twitter.Status instance representing the message posted.
    '''
    if not self._username:
      raise TwitterError("The twitter.Api instance must be authenticated.")

    url = '%s/statuses/update.json' % self.base_url

    if len(status) > CHARACTER_LIMIT:
      raise TwitterError("Text must be less than or equal to %d characters. "
                         "Consider using PostUpdates." % CHARACTER_LIMIT)

    data = {'status': status}
    if in_reply_to_status_id:
      data['in_reply_to_status_id'] = in_reply_to_status_id
    json = self._FetchUrl(url, post_data=data)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return Status.NewFromJsonDict(data)

  def PostUpdates(self, status, continuation=None, **kwargs):
    '''Post one or more twitter status messages from the authenticated user.

    Unlike api.PostUpdate, this method will post multiple status updates
    if the message is longer than 140 characters.

    The twitter.Api instance must be authenticated.

    @param status: The message text to be posted.  May be longer than 140 
        characters.
    @param continuation: The character string, if any, to be appended to all
        but the last message.  Note that Twitter strips trailing '...' strings
        from messages.  Consider using the unicode \u2026 character
        (horizontal ellipsis) instead. [Defaults to None]
    @param **kwargs: See api.PostUpdate for a list of accepted parameters.
    @returns: A of list twitter.Status instance representing the messages posted.
    '''
    results = list()
    if continuation is None:
      continuation = ''
    line_length = CHARACTER_LIMIT - len(continuation)
    lines = textwrap.wrap(status, line_length)
    for line in lines[0:-1]:
      results.append(self.PostUpdate(line + continuation, **kwargs))
    results.append(self.PostUpdate(lines[-1], **kwargs))
    return results

  def GetReplies(self, since=None, since_id=None, page=None): 
    '''Get a sequence of status messages representing the 20 most recent
    replies (status updates prefixed with @username) to the authenticating
    user.

    @param page: 
    @param since: Narrows the returned results to just those statuses created
        after the specified HTTP-formatted date. [optional]
    @param since_id: Returns only public statuses with an ID greater than (that
        is, more recent than) the specified ID. [Optional]

    @returns: A sequence of twitter.Status instances, one for each reply to the
        user.
    '''
    url = '%s/statuses/replies.json' % self.base_url
    if not self._username:
      raise TwitterError("The twitter.Api instance must be authenticated.")
    parameters = {}
    if since:
      parameters['since'] = since
    if since_id:
      parameters['since_id'] = since_id
    if page:
      parameters['page'] = page
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [Status.NewFromJsonDict(x) for x in data]

  def GetFriends(self, user=None, page=None):
    '''Fetch the sequence of twitter.User instances, one for each friend.

    The twitter.Api instance must be authenticated.

    @param user: the username or id of the user whose friends you are fetching.
        If not specified, defaults to the authenticated user. [optional]

    @returns: A sequence of twitter.User instances, one for each friend
    '''
    if not user and not self._username:
      raise TwitterError("twitter.Api instance must be authenticated")
    if user:
      url = '%s/statuses/friends/%s.json' % (self.base_url, user)
    else:
      url = '%s/statuses/friends.json' % self.base_url
    parameters = {}
    if page:
      parameters['page'] = page
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [User.NewFromJsonDict(x) for x in data]

  def GetFriendIDs(self, user=None, page=None):
      '''Returns a list of twitter user id's for every person
      the specified user is following.

      @param user: The id or screen_name of the user to retrieve the id list
        for [optional]
      @param page: Specifies the page number of the results beginning at 1.
          A single page contains 5000 ids. This is recommended for users
          with large id lists. If not provided all id's are returned. 
          (Please note that the result set isn't guaranteed to be 5000 
          every time as suspended users will be filtered.) [optional]

      @returns: A list of integers, one for each user id.
      '''
      if not user and not self._username:
          raise TwitterError("twitter.Api instance must be authenticated")
      if user:
          url = '%s/friends/ids/%s.json' % (self.base_url, user)
      else:
          url = '%s/friends/ids.json' % self.base_url
      parameters = {}
      if page:
          parameters['page'] = page
      json = self._FetchUrl(url, parameters=parameters)
      data = json.loads(json)
      self._CheckForTwitterError(data)
      return data

  def GetFollowers(self, page=None):
    '''Fetch the sequence of twitter.User instances, one for each follower

    The twitter.Api instance must be authenticated.

    @returns: A sequence of twitter.User instances, one for each follower
    '''
    if not self._username:
      raise TwitterError("twitter.Api instance must be authenticated")
    url = '%s/statuses/followers.json' % self.base_url
    parameters = {}
    if page:
      parameters['page'] = page
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [User.NewFromJsonDict(x) for x in data]

  def GetFeatured(self):
    '''Fetch the sequence of twitter.User instances featured on twitter.com

    The twitter.Api instance must be authenticated.

    @returns: A sequence of twitter.User instances
    '''
    url = '%s/statuses/featured.json' % self.base_url
    json = self._FetchUrl(url)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [User.NewFromJsonDict(x) for x in data]

  def GetUser(self, user):
    '''Returns a single user.

    The twitter.Api instance must be authenticated.

    @param user: The username or id of the user to retrieve.

    @returns: A twitter.User instance representing that user
    '''
    url = '%s/users/show/%s.json' % (self.base_url, user)
    json = self._FetchUrl(url)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)

  def GetDirectMessages(self, since=None, since_id=None, page=None):
    '''Returns a list of the direct messages sent to the authenticating user.

    The twitter.Api instance must be authenticated.

    @param since: Narrows the returned results to just those statuses created
        after the specified HTTP-formatted date. [optional]
    @param since_id: Returns only public statuses with an ID greater than (that
        is, more recent than) the specified ID. [Optional]

    @returns: A sequence of twitter.DirectMessage instances
    '''
    url = '%s/direct_messages.json' % self.base_url
    if not self._username:
      raise TwitterError("The twitter.Api instance must be authenticated.")
    parameters = {}
    if since:
      parameters['since'] = since
    if since_id:
      parameters['since_id'] = since_id
    if page:
      parameters['page'] = page 
    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return [DirectMessage.NewFromJsonDict(x) for x in data]

  def PostDirectMessage(self, user, text):
    '''Post a twitter direct message from the authenticated user

    The twitter.Api instance must be authenticated.

    @param user: The ID or screen name of the recipient user.
    @param text: The message text to be posted.  Must be less than 140 characters.

    @returns: A twitter.DirectMessage instance representing the message posted
    '''
    if not self._username:
      raise TwitterError("The twitter.Api instance must be authenticated.")
    url = '%s/direct_messages/new.json' % self.base_url
    data = {'text': text, 'user': user}
    json = self._FetchUrl(url, post_data=data)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return DirectMessage.NewFromJsonDict(data)

  def DestroyDirectMessage(self, id):
    '''Destroys the direct message specified in the required ID parameter.

    The twitter.Api instance must be authenticated, and the
    authenticating user must be the recipient of the specified direct
    message.

    @param id: The id of the direct message to be destroyed

    @returns: A twitter.DirectMessage instance representing the message destroyed
    '''
    url = '%s/direct_messages/destroy/%s.json' % (self.base_url, id)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return DirectMessage.NewFromJsonDict(data)

  def CreateFriendship(self, user):
    '''Befriends the user specified in the user parameter as the authenticating user.

    The twitter.Api instance must be authenticated.

    @param user: The ID or screen name of the user to befriend.
    @returns: A twitter.User instance representing the befriended user.
    '''
    url = '%s/friendships/create/%s.json' % (self.base_url, user)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)

  def DestroyFriendship(self, user):
    '''Discontinues friendship with the user specified in the user parameter.

    The twitter.Api instance must be authenticated.

    @param user: The ID or screen name of the user  with whom to discontinue
        friendship.
    @returns: A twitter.User instance representing the discontinued friend.
    '''
    url = '%s/friendships/destroy/%s.json' % (self.base_url, user)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)

  def CreateFavorite(self, status):
    '''Favorites the status specified in the status parameter as the
    authenticating user.
    Returns the favorite status when successful.

    The twitter.Api instance must be authenticated.

    @param status: The twitter.Status instance to mark as a favorite.
    @returns: A twitter.Status instance representing the newly-marked favorite.
    '''
    url = '%s/favorites/create/%s.json' % (self.base_url, status.id)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return Status.NewFromJsonDict(data)

  def DestroyFavorite(self, status):
    '''Un-favorites the status specified in the ID parameter as the authenticating user.
    Returns the un-favorited status in the requested format when successful.

    The twitter.Api instance must be authenticated.

    @param status: The twitter.Status to unmark as a favorite.
    @returns: A twitter.Status instance representing the newly-unmarked favorite.
    '''
    url = '%s/favorites/destroy/%s.json' % (self.base_url, status.id)
    json = self._FetchUrl(url, post_data={})
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return Status.NewFromJsonDict(data)

  def GetFavorites(self,
                   user=None,
                   page=None):
    '''Return a list of Status objects representing favorited tweets.
    By default, returns the (up to) 20 most recent tweets for the
    authenticated user.
    
    @param user: The username or id of the user whose favorites you are
        fetching. If not specified, defaults to the authenticated user.
        [optional]
    
    @param page: Retrieves the 20 next most recent favorite statuses.
        [optional]
    '''
    parameters = {}

    if page:
      parameters['page'] = page

    if user:
      url = '%s/favorites/%s.json' % (self.base_url, user)
    elif not user and not self._username:
      raise TwitterError("User must be specified if API is not authenticated.")
    else:
      url = '%s/favorites.json' % self.base_url

    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)

    self._CheckForTwitterError(data)

    return [Status.NewFromJsonDict(x) for x in data]

  def GetMentions(self,
                  since_id=None,
                  max_id=None,
                  page=None):
    '''Returns the 20 most recent mentions (status containing @username)
    for the authenticating user.
    
    @param since_id: Returns only public statuses with an ID greater than
        (that is, more recent than) the specified ID. [optional]
    
    @param max_id: Returns only statuses with an ID less than
        (that is, older than) the specified ID.  [optional]
    
    @param page: Retrieves the 20 next most recent replies. [optional]
    
    @returns: A sequence of twitter.Status instances, one for each mention of 
        the user. see:
        http://apiwiki.twitter.com/REST-API-Documentation#statuses/mentions
    '''

    url = '%s/statuses/mentions.json' % self.base_url

    if not self._username:
      raise TwitterError("The twitter.Api instance must be authenticated.")

    parameters = {}

    if since_id:
      parameters['since_id'] = since_id
    if max_id:
      parameters['max_id'] = max_id
    if page:
      parameters['page'] = page

    json = self._FetchUrl(url, parameters=parameters)
    data = json.loads(json)

    self._CheckForTwitterError(data)

    return [Status.NewFromJsonDict(x) for x in data]

  def GetUserByEmail(self, email):
    '''Returns a single user by email address.

    @param email: The email of the user to retrieve.
    @returns: A twitter.User instance representing that user
    '''
    url = '%s/users/show.json?email=%s' % (self.base_url, email)
    json = self._FetchUrl(url)
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)

  def VerifyCredentials(self):
    '''Returns a twitter.User instance if the authenticating user is valid.

    @returns: A twitter.User instance representing that user if the
      credentials are valid, None otherwise.
    '''
    if not self._username:
      raise TwitterError("Api instance must first be given user credentials.")
    url = '%s/account/verify_credentials.json' % self.base_url
    try:
      json = self._FetchUrl(url, no_cache=True)
    except urllib2.HTTPError, http_error:
      if http_error.code == httplib.UNAUTHORIZED:
        return None
      else:
        raise http_error
    data = json.loads(json)
    self._CheckForTwitterError(data)
    return User.NewFromJsonDict(data)

  def SetCredentials(self, username, password):
    '''Set the username and password for this instance

    @param username: The twitter username.
    @param password: The twitter password.
    '''
    self._username = username
    self._password = password

  def ClearCredentials(self):
    '''Clear the username and password for this instance
    '''
    self._username = None
    self._password = None

  def SetCache(self, cache):
    '''Override the default cache.  Set to None to prevent caching.

    @param cache: an instance that supports the same API as the twitter._FileCache
    '''
    if cache == DEFAULT_CACHE:
      self._cache = _FileCache()
    else:
      self._cache = cache

  def SetUrllib(self, urllib):
    '''Override the default urllib implementation.

    @param urllib: an instance that supports the same API as the urllib2 module
    '''
    self._urllib = urllib

  def SetCacheTimeout(self, cache_timeout):
    '''Override the default cache timeout.

    @param cache_timeout: time, in seconds, that responses should be reused.
    '''
    self._cache_timeout = cache_timeout

  def SetUserAgent(self, user_agent):
    '''Override the default user agent

    @param user_agent: a string that should be send to the server as the User-agent
    '''
    self._request_headers['User-Agent'] = user_agent

  def SetXTwitterHeaders(self, client, url, version):
    '''Set the X-Twitter HTTP headers that will be sent to the server.

    @param client: The client name as a string.  Will be sent to the server as
         the 'X-Twitter-Client' header.
    @param url: The URL of the meta.xml as a string.  Will be sent to the server
         as the 'X-Twitter-Client-URL' header.
    @param version: The client version as a string.  Will be sent to the server
         as the 'X-Twitter-Client-Version' header.
    '''
    self._request_headers['X-Twitter-Client'] = client
    self._request_headers['X-Twitter-Client-URL'] = url
    self._request_headers['X-Twitter-Client-Version'] = version

  def SetSource(self, source):
    '''Suggest the "from source" value to be displayed on the Twitter web site.

    The value of the 'source' parameter must be first recognized by
    the Twitter server.  New source values are authorized on a case by
    case basis by the Twitter development team.

    @param source: The source name as a string.  Will be sent to the server as
        the 'source' parameter.
    '''
    self._default_params['source'] = source

  def GetRateLimitStatus(self):
    '''Fetch the rate limit status for the currently authorized user.
    
    @returns: A dictionary containing the time the limit will reset 
        (reset_time), the number of remaining hits allowed before the reset
        (remaining_hits), the number of hits allowed in a 60-minute period 
        (hourly_limit), and the time of the reset in seconds since The Epoch
        (reset_time_in_seconds).
    '''
    url  = '%s/account/rate_limit_status.json' % self.base_url
    json = self._FetchUrl(url, no_cache=True)
    data = json.loads(json)

    self._CheckForTwitterError(data)

    return data

  def MaximumHitFrequency(self):
    '''Determines the minimum number of seconds that a program must wait before
    hitting the server again without exceeding the rate_limit imposed for the
    currently authenticated user.
    
    @returns: The minimum second interval that a program must use so as to not
        exceed the rate_limit imposed for the user.
    '''
    rate_status = self.GetRateLimitStatus()
    reset_time  = rate_status.get('reset_time', None)
    limit       = rate_status.get('remaining_hits', None)

    if reset_time and limit:
      # put the reset time into a datetime object
      reset = datetime.datetime(*rfc822.parsedate(reset_time)[:7])

      # find the difference in time between now and the reset time + 1 hour
      delta = reset + datetime.timedelta(hours=1) - datetime.datetime.utcnow()

      # determine the minimum number of seconds allowed as a regular interval
      max_frequency = int(delta.seconds / limit)

      # return the number of seconds
      return max_frequency

    return 0

  def _BuildUrl(self, url, path_elements=None, extra_params=None):
    # Break url into consituent parts
    (scheme, netloc, path, params, query, fragment) = urlparse.urlparse(url)

    # Add any additional path elements to the path
    if path_elements:
      # Filter out the path elements that have a value of None
      p = [i for i in path_elements if i]
      if not path.endswith('/'):
        path += '/'
      path += '/'.join(p)

    # Add any additional query parameters to the query string
    if extra_params and len(extra_params) > 0:
      extra_query = self._EncodeParameters(extra_params)
      # Add it to the existing query
      if query:
        query += '&' + extra_query
      else:
        query = extra_query

    # Return the rebuilt URL
    return urlparse.urlunparse((scheme, netloc, path, params, query, fragment))

  def _InitializeRequestHeaders(self, request_headers):
    if request_headers:
      self._request_headers = request_headers
    else:
      self._request_headers = {}

  def _InitializeUserAgent(self):
    user_agent = 'Python-urllib/%s (python-twitter/%s)' % \
                 (self._urllib.__version__, __version__)
    self.SetUserAgent(user_agent)

  def _InitializeDefaultParameters(self):
    self._default_params = {}

  def _AddAuthorizationHeader(self, username, password):
    if username and password:
      basic_auth = base64.encodestring('%s:%s' % (username, password))[:-1]
      self._request_headers['Authorization'] = 'Basic %s' % basic_auth

  def _RemoveAuthorizationHeader(self):
    if self._request_headers and 'Authorization' in self._request_headers:
      del self._request_headers['Authorization']

  def _DecompressGzippedResponse(self, response):
    raw_data = response.read()
    if response.headers.get('content-encoding', None) == 'gzip':
      url_data = gzip.GzipFile(fileobj=StringIO.StringIO(raw_data)).read()
    else:
      url_data = raw_data
    return url_data

  def _GetOpener(self, url, username=None, password=None):
    if username and password:
      self._AddAuthorizationHeader(username, password)
      handler = self._urllib.HTTPBasicAuthHandler()
      (scheme, netloc, path, params, query, fragment) = urlparse.urlparse(url)
      handler.add_password(Api._API_REALM, netloc, username, password)
      opener = self._urllib.build_opener(handler)
    else:
      opener = self._urllib.build_opener()
    opener.addheaders = self._request_headers.items()
    return opener

  def _Encode(self, s):
    if self._input_encoding:
      return unicode(s, self._input_encoding).encode('utf-8')
    else:
      return unicode(s).encode('utf-8')

  def _EncodeParameters(self, parameters):
    '''Return a string in key=value&key=value form

    Values of None are not included in the output string.

    @param parameters: A dict of (key, value) tuples, where value is encoded as
        specified by self._encoding
    @returns: A URL-encoded string in "key=value&key=value" form
    '''
    if parameters is None:
      return None
    else:
      return urllib.urlencode(dict([(k, self._Encode(v)) for k, v in parameters.items() if v is not None]))

  def _EncodePostData(self, post_data):
    '''Return a string in key=value&key=value form

    Values are assumed to be encoded in the format specified by self._encoding,
    and are subsequently URL encoded.

    @param post_data: A dict of (key, value) tuples, where value is encoded as
        specified by self._encoding
    @returns: A URL-encoded string in "key=value&key=value" form
    '''
    if post_data is None:
      return None
    else:
      return urllib.urlencode(dict([(k, self._Encode(v)) for k, v in post_data.items()]))

  def _CheckForTwitterError(self, data):
    """Raises a TwitterError if twitter returns an error message.

    @param data: A python dict created from the Twitter json response
    @raises: TwitterError wrapping the twitter error message if one exists.
    """
    # Twitter errors are relatively unlikely, so it is faster
    # to check first, rather than try and catch the exception
    if 'error' in data:
      raise TwitterError(data['error'])

  def _FetchUrl(self,
                url,
                post_data=None,
                parameters=None,
                no_cache=None,
                use_gzip_compression=None):
    '''Fetch a URL, optionally caching for a specified time.

    @param url: The URL to retrieve
    @param post_data: A dict of (str, unicode) key/value pairs.
        If set, POST will be used.
    @param parameters: A dict whose key/value pairs should encoded and added
        to the query string. [optional]
    @param no_cache: If true, overrides the cache on the current request
    @param use_gzip_compression: If True, tells the server to gzip-compress the
        response. It does not apply to POST requests.
        Defaults to None, which will get the value to use from
        the instance variable self._use_gzip [optional]

    @returns: A string containing the body of the response.
    '''
    # Build the extra parameters dict
    extra_params = {}
    if self._default_params:
      extra_params.update(self._default_params)
    if parameters:
      extra_params.update(parameters)

    # Add key/value parameters to the query string of the url
    url = self._BuildUrl(url, extra_params=extra_params)

    # Get a url opener that can handle basic auth
    opener = self._GetOpener(url, username=self._username, password=self._password)

    if use_gzip_compression is None:
      use_gzip = self._use_gzip
    else:
      use_gzip = use_gzip_compression
      
    # Set up compression
    if use_gzip and not post_data:
      opener.addheaders.append(('Accept-Encoding', 'gzip'))

    encoded_post_data = self._EncodePostData(post_data)

    # Open and return the URL immediately if we're not going to cache
    if encoded_post_data or no_cache or not self._cache or not self._cache_timeout:
      response = opener.open(url, encoded_post_data)
      url_data = self._DecompressGzippedResponse(response)
      opener.close()
    else:
      # Unique keys are a combination of the url and the username
      if self._username:
        key = self._username + ':' + url
      else:
        key = url

      # See if it has been cached before
      last_cached = self._cache.GetCachedTime(key)

      # If the cached version is outdated then fetch another and store it
      if not last_cached or time.time() >= last_cached + self._cache_timeout:
        response = opener.open(url, encoded_post_data)
        url_data = self._DecompressGzippedResponse(response)
        opener.close()
        self._cache.Set(key, url_data)
      else:
        url_data = self._cache.Get(key)

    # Always return the latest version
    return url_data


class _FileCacheError(Exception):
  '''Base exception class for FileCache related errors'''

class _FileCache(object):

  DEPTH = 3

  def __init__(self,root_directory=None):
    self._InitializeRootDirectory(root_directory)

  def Get(self,key):
    path = self._GetPath(key)
    if os.path.exists(path):
      return open(path).read()
    else:
      return None

  def Set(self,key,data):
    path = self._GetPath(key)
    directory = os.path.dirname(path)
    if not os.path.exists(directory):
      os.makedirs(directory)
    if not os.path.isdir(directory):
      raise _FileCacheError('%s exists but is not a directory' % directory)
    temp_fd, temp_path = tempfile.mkstemp()
    temp_fp = os.fdopen(temp_fd, 'w')
    temp_fp.write(data)
    temp_fp.close()
    if not path.startswith(self._root_directory):
      raise _FileCacheError('%s does not appear to live under %s' %
                            (path, self._root_directory))
    if os.path.exists(path):
      os.remove(path)
    os.rename(temp_path, path)

  def Remove(self,key):
    path = self._GetPath(key)
    if not path.startswith(self._root_directory):
      raise _FileCacheError('%s does not appear to live under %s' %
                            (path, self._root_directory ))
    if os.path.exists(path):
      os.remove(path)

  def GetCachedTime(self,key):
    path = self._GetPath(key)
    if os.path.exists(path):
      return os.path.getmtime(path)
    else:
      return None

  def _GetUsername(self):
    '''Attempt to find the username in a cross-platform fashion.'''
    try:
      return os.getenv('USER') or \
             os.getenv('LOGNAME') or \
             os.getenv('USERNAME') or \
             os.getlogin() or \
             'nobody'
    except (IOError, OSError), e:
      return 'nobody'

  def _GetTmpCachePath(self):
    username = self._GetUsername()
    cache_directory = 'python.cache_' + username
    return os.path.join(tempfile.gettempdir(), cache_directory)

  def _InitializeRootDirectory(self, root_directory):
    if not root_directory:
      root_directory = self._GetTmpCachePath()
    root_directory = os.path.abspath(root_directory)
    if not os.path.exists(root_directory):
      os.mkdir(root_directory)
    if not os.path.isdir(root_directory):
      raise _FileCacheError('%s exists but is not a directory' %
                            root_directory)
    self._root_directory = root_directory

  def _GetPath(self,key):
    try:
        hashed_key = md5(key).hexdigest()
    except TypeError:
        hashed_key = md5.new(key).hexdigest()
        
    return os.path.join(self._root_directory,
                        self._GetPrefix(hashed_key),
                        hashed_key)

  def _GetPrefix(self,hashed_key):
    return os.path.sep.join(hashed_key[0:_FileCache.DEPTH])
