Codebase list sugar-imageviewer-activity / lintian-fixes/main collabwrapper.py
lintian-fixes/main

Tree @lintian-fixes/main (Download .tar.gz)

collabwrapper.py @lintian-fixes/mainraw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
# Copyright (C) 2015 Walter Bender
# Copyright (C) 2015 Sam Parkinson
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this library; if not, write to the Free Software
# Foundation, 51 Franklin Street, Suite 500 Boston, MA 02110-1335 USA

'''
The wrapper module provides an abstraction over the Sugar
collaboration system.

Using CollabWrapper
-------------------
1. Add `get_data` and `set_data` methods to the activity class::

    def get_data(self):
        # return plain python objects - things that can be encoded
        # using the json module
        return dict(
            text=self._entry.get_text()
        )

    def set_data(self, data):
        # data will be the same object returned by get_data
        self._entry.set_text(data.get('text'))

2. Make a CollabWrapper instance::

    def __init__(self, handle):
        sugar3.activity.activity.Activity.__init__(self, handle)
        self._collab = CollabWrapper(self)
        self._collab.connect('message', self.__message_cb)

        # setup your activity here

        self._collab.setup()

3. Post any changes of shared state to the CollabWrapper.  The changes
   will be sent to other buddies if any are connected, for example::

    def __entry_changed_cb(self, *args):
        self._collab.post(dict(
            action='entry_changed',
            new_text=self._entry.get_text()
        ))

4. Handle incoming messages, for example::

    def __message_cb(self, collab, buddy, msg):
        action = msg.get('action')
        if action == 'entry_changed':
            self._entry.set_text(msg.get('new_text'))

'''

import os
import json
import socket
from gettext import gettext as _

import gi
gi.require_version('TelepathyGLib', '0.12')
from gi.repository import GObject
from gi.repository import Gio
from gi.repository import GLib
from gi.repository import TelepathyGLib
import dbus
from dbus import PROPERTIES_IFACE

CHANNEL_INTERFACE = TelepathyGLib.IFACE_CHANNEL
CHANNEL_INTERFACE_GROUP = TelepathyGLib.IFACE_CHANNEL_INTERFACE_GROUP
CHANNEL_TYPE_TEXT = TelepathyGLib.IFACE_CHANNEL_TYPE_TEXT
CHANNEL_TYPE_FILE_TRANSFER = TelepathyGLib.IFACE_CHANNEL_TYPE_FILE_TRANSFER
CONN_INTERFACE_ALIASING = TelepathyGLib.IFACE_CONNECTION_INTERFACE_ALIASING
CONN_INTERFACE = TelepathyGLib.IFACE_CONNECTION
CHANNEL = TelepathyGLib.IFACE_CHANNEL
CLIENT = TelepathyGLib.IFACE_CLIENT
CHANNEL_GROUP_FLAG_CHANNEL_SPECIFIC_HANDLES = \
    TelepathyGLib.ChannelGroupFlags.CHANNEL_SPECIFIC_HANDLES
CONNECTION_HANDLE_TYPE_CONTACT = TelepathyGLib.HandleType.CONTACT
CHANNEL_TEXT_MESSAGE_TYPE_NORMAL = TelepathyGLib.ChannelTextMessageType.NORMAL
SOCKET_ADDRESS_TYPE_UNIX = TelepathyGLib.SocketAddressType.UNIX
SOCKET_ACCESS_CONTROL_LOCALHOST = TelepathyGLib.SocketAccessControl.LOCALHOST

from sugar3.presence import presenceservice
from sugar3.activity.activity import SCOPE_PRIVATE
from sugar3.graphics.alert import NotifyAlert

import logging
_logger = logging.getLogger('CollabWrapper')

ACTION_INIT_REQUEST = '!!ACTION_INIT_REQUEST'
ACTION_INIT_RESPONSE = '!!ACTION_INIT_RESPONSE'
ACTIVITY_FT_MIME = 'x-sugar/from-activity'


class CollabWrapper(GObject.GObject):
    '''
    The wrapper provides a high level abstraction over the
    collaboration system.  The wrapper deals with setting up the
    channels, encoding and decoding messages, initialization and
    alerting the caller to the status.

    An activity instance is initially private, but may be shared.  Once
    shared, an instance will remain shared for as long as the activity
    runs.  On stop, the journal will preserve the instance as shared,
    and on resume the instance will be shared again.

    When the caller shares an activity instance, they are the leader,
    and other buddies may join.  The instance is now a shared activity.

    When the caller joins a shared activity, the leader will call
    `get_data`, and the caller's `set_data` will be called with the
    result.

    The `joined` signal is emitted when the caller joins a shared
    activity.  One or more `buddy_joined` signals will be emitted before
    this signal.  The signal is not emitted to the caller who first
    shared the activity.  There are no arguments.

    The `buddy_joined` signal is emitted when another buddy joins the
    shared activity.  At least one will be emitted before the `joined`
    signal.  The caller will never be mentioned, but is assumed to be
    part of the set.  The signal passes a
    :class:`sugar3.presence.buddy.Buddy` as the only argument.

    The `buddy_left` signal is emitted when another user leaves the
    shared activity.  The signal is not emitted during quit.  The signal
    passes a :class:`sugar3.presence.buddy.Buddy` as the only argument.

    Any buddy may call `post` to send a message to all buddies.  Each
    buddy will receive a `message` signal.

    The `message` signal is emitted when a `post` is received from any
    buddy.  The signal has two arguments.  The first is a
    :class:`sugar3.presence.buddy.Buddy`. The second is the message.

    Any buddy may call `send_file_memory` or `send_file_file` to
    transfer a file to all buddies.  A description is to be given.
    Each buddy will receive an `incoming_file` signal.

    The `incoming_file` signal is emitted when a file transfer is
    received.  The signal has two arguments.  The first is a
    :class:`IncomingFileTransfer`.  The second is the description.
    '''

    message = GObject.Signal('message', arg_types=[object, object])
    joined = GObject.Signal('joined')
    buddy_joined = GObject.Signal('buddy_joined', arg_types=[object])
    buddy_left = GObject.Signal('buddy_left', arg_types=[object])
    incoming_file = GObject.Signal('incoming_file', arg_types=[object, object])

    def __init__(self, activity):
        _logger.debug('__init__')
        GObject.GObject.__init__(self)
        self.activity = activity
        self.shared_activity = activity.shared_activity
        self._leader = False
        self._init_waiting = False
        self._text_channel = None

    def setup(self):
        '''
        Setup must be called so that the activity can join or share
        if appropriate.

        .. note::
            As soon as setup is called, any signal, `get_data` or
            `set_data` call may occur.  This means that the activity
            must have set up enough so these functions can work.  For
            example, call setup at the end of the activity
            `__init__` function.
        '''
        _logger.debug('setup')
        # Some glue to know if we are launching, joining, or resuming
        # a shared activity.
        if self.shared_activity:
            # We're joining the activity.
            self.activity.connect("joined", self.__joined_cb)

            if self.activity.get_shared():
                _logger.debug('calling _joined_cb')
                self.__joined_cb(self)
            else:
                _logger.debug('Joining activity...')
                self._alert(_('Joining activity...'),
                            _('Please wait for the connection...'))
        else:
            self._leader = True
            if not self.activity.metadata or self.activity.metadata.get(
                    'share-scope', SCOPE_PRIVATE) == \
                    SCOPE_PRIVATE:
                # We are creating a new activity instance.
                _logger.debug('Off-line')
            else:
                # We are sharing an old activity instance.
                _logger.debug('On-line')
                self._alert(_('Resuming shared activity...'),
                            _('Please wait for the connection...'))
            self.activity.connect('shared', self.__shared_cb)

    def _alert(self, title, msg=None):
        a = NotifyAlert()
        a.props.title = title
        a.props.msg = msg
        self.activity.add_alert(a)
        a.connect('response', lambda a, r: self.activity.remove_alert(a))
        a.show()

    def __shared_cb(self, sender):
        ''' Callback for when activity is shared. '''
        _logger.debug('__shared_cb')
        # FIXME: may be called twice, but we should only act once
        self.shared_activity = self.activity.shared_activity
        self._setup_text_channel()
        self._listen_for_channels()

    def __joined_cb(self, sender):
        '''Callback for when an activity is joined.'''
        _logger.debug('__joined_cb')
        self.shared_activity = self.activity.shared_activity
        if not self.shared_activity:
            return

        self._setup_text_channel()
        self._listen_for_channels()
        self._init_waiting = True
        self.post({'action': ACTION_INIT_REQUEST})

        for buddy in self.shared_activity.get_joined_buddies():
            self.buddy_joined.emit(buddy)

        self.joined.emit()

    def _setup_text_channel(self):
        ''' Set up a text channel to use for collaboration. '''
        _logger.debug('_setup_text_channel')
        self._text_channel = _TextChannelWrapper(
            self.shared_activity.telepathy_text_chan,
            self.shared_activity.telepathy_conn)

        # Tell the text channel what callback to use for incoming
        # text messages.
        self._text_channel.set_received_callback(self.__received_cb)

        # Tell the text channel what callbacks to use when buddies
        # come and go.
        self.shared_activity.connect('buddy-joined', self.__buddy_joined_cb)
        self.shared_activity.connect('buddy-left', self.__buddy_left_cb)

    def _listen_for_channels(self):
        _logger.debug('_listen_for_channels')
        conn = self.shared_activity.telepathy_conn
        conn.connect_to_signal('NewChannels', self.__new_channels_cb)

    def __new_channels_cb(self, channels):
        _logger.debug('__new_channels_cb')
        conn = self.shared_activity.telepathy_conn
        for path, props in channels:
            if props[CHANNEL + '.Requested']:
                continue  # This channel was requested by me

            channel_type = props[CHANNEL + '.ChannelType']
            if channel_type == CHANNEL_TYPE_FILE_TRANSFER:
                self._handle_ft_channel(conn, path, props)

    def _handle_ft_channel(self, conn, path, props):
        _logger.debug('_handle_ft_channel')
        ft = IncomingFileTransfer(conn, path, props)
        if ft.description == ACTION_INIT_RESPONSE:
            ft.connect('ready', self.__ready_cb)
            ft.accept_to_memory()
        else:
            desc = json.loads(ft.description)
            self.incoming_file.emit(ft, desc)

    def __ready_cb(self, ft, stream):
        _logger.debug('__ready_cb')
        if self._init_waiting:
            stream.close(None)
            # FIXME:  The data prop seems to just be the raw pointer
            gbytes = stream.steal_as_bytes()
            data = gbytes.get_data()
            _logger.debug('Got init data from buddy: %r', data)
            data = json.loads(data)
            self.activity.set_data(data)
            self._init_waiting = False

    def __received_cb(self, buddy, msg):
        '''Process a message when it is received.'''
        _logger.debug('__received_cb')
        action = msg.get('action')
        if action == ACTION_INIT_REQUEST:
            if self._leader:
                data = self.activity.get_data()
                if data is not None:
                    data = json.dumps(data)
                    OutgoingBlobTransfer(
                        buddy,
                        self.shared_activity.telepathy_conn,
                        data,
                        self.get_client_name(),
                        ACTION_INIT_RESPONSE,
                        ACTIVITY_FT_MIME)
            return

        if buddy:
            nick = buddy.props.nick
        else:
            nick = '???'
        _logger.debug('Received message from %s: %r', nick, msg)
        self.message.emit(buddy, msg)

    def send_file_memory(self, buddy, data, description):
        '''
        Send a one to one file transfer from memory to a buddy.  The
        buddy will get the file transfer and description through the
        `incoming_transfer` signal.

        Args:
            buddy (sugar3.presence.buddy.Buddy), buddy to send to.
            data (str), the data to send.
            description (object), a json encodable description for the
                transfer.  This will be given to the
                `incoming_transfer` signal at the buddy.
        '''
        OutgoingBlobTransfer(
            buddy,
            self.shared_activity.telepathy_conn,
            data,
            self.get_client_name(),
            json.dumps(description),
            ACTIVITY_FT_MIME)

    def send_file_file(self, buddy, path, description):
        '''
        Send a one to one file transfer from a filesystem path to a
        given buddy.  The buddy will get the file transfer and
        description through the `incoming_transfer` signal.

        Args:
            buddy (sugar3.presence.buddy.Buddy), buddy to send to.
            path (str), path of the file containing the data to send.
            description (object), a json encodable description for the
                transfer.  This will be given to the
                `incoming_transfer` signal at the buddy.
        '''
        OutgoingFileTransfer(
            buddy,
            self.shared_activity.telepathy_conn,
            path,
            self.get_client_name(),
            json.dumps(description),
            ACTIVITY_FT_MIME)

    def post(self, msg):
        '''
        Send a message to all buddies.  If the activity is not shared,
        no message is sent.

        Args:
            msg (object): json encodable object to send,
                eg. :class:`dict` or :class:`str`.
        '''
        if self._text_channel is not None:
            self._text_channel.post(msg)

    def __buddy_joined_cb(self, sender, buddy):
        '''A buddy joined.'''
        self.buddy_joined.emit(buddy)

    def __buddy_left_cb(self, sender, buddy):
        '''A buddy left.'''
        self.buddy_left.emit(buddy)

    def get_client_name(self):
        '''
        Get the name of the activity's telepathy client.

        Returns: str, telepathy client name
        '''
        return CLIENT + '.' + self.activity.get_bundle_id()

    @GObject.property
    def leader(self):
        '''
        Boolean of if this client is the leader in this activity.  The
        way the leader is decided may change, however there should only
        ever be one leader for an activity.
        '''
        return self._leader


FT_STATE_NONE = 0
FT_STATE_PENDING = 1
FT_STATE_ACCEPTED = 2
FT_STATE_OPEN = 3
FT_STATE_COMPLETED = 4
FT_STATE_CANCELLED = 5

FT_REASON_NONE = 0
FT_REASON_REQUESTED = 1
FT_REASON_LOCAL_STOPPED = 2
FT_REASON_REMOTE_STOPPED = 3
FT_REASON_LOCAL_ERROR = 4
FT_REASON_LOCAL_ERROR = 5
FT_REASON_REMOTE_ERROR = 6


class _BaseFileTransfer(GObject.GObject):
    '''
    The base file transfer should not be used directly.  It is used as a
    base class for the incoming and outgoing file transfers.

    Props:
        filename (str), metadata provided by the buddy
        file_size (str), size of the file being sent/received, in bytes
        description (str), metadata provided by the buddy
        mime_type (str), metadata provided by the buddy
        buddy (:class:`sugar3.presence.buddy.Buddy`), other party
            in the transfer
        reason_last_change (FT_REASON_*), reason for the last state change

    GObject Props:
        state (FT_STATE_*), current state of the transfer
        transferred_bytes (int), number of bytes transferred so far
    '''

    def __init__(self):
        GObject.GObject.__init__(self)
        self._state = FT_STATE_NONE
        self._transferred_bytes = 0

        self.channel = None
        self.buddy = None
        self.filename = None
        self.file_size = None
        self.description = None
        self.mime_type = None
        self.reason_last_change = FT_REASON_NONE

    def set_channel(self, channel):
        '''
        Setup the file transfer to use a given telepathy channel.  This
        should only be used by direct subclasses of the base file transfer.
        '''
        self.channel = channel
        self.channel[CHANNEL_TYPE_FILE_TRANSFER].connect_to_signal(
            'FileTransferStateChanged', self.__state_changed_cb)
        self.channel[CHANNEL_TYPE_FILE_TRANSFER].connect_to_signal(
            'TransferredBytesChanged', self.__transferred_bytes_changed_cb)
        self.channel[CHANNEL_TYPE_FILE_TRANSFER].connect_to_signal(
            'InitialOffsetDefined', self.__initial_offset_defined_cb)

        channel_properties = self.channel[PROPERTIES_IFACE]

        props = channel_properties.GetAll(CHANNEL_TYPE_FILE_TRANSFER)
        self._state = props['State']
        self.filename = props['Filename']
        self.file_size = props['Size']
        self.description = props['Description']
        self.mime_type = props['ContentType']

    def __transferred_bytes_changed_cb(self, transferred_bytes):
        _logger.debug('__transferred_bytes_changed_cb %r', transferred_bytes)
        self.props.transferred_bytes = transferred_bytes

    def _set_transferred_bytes(self, transferred_bytes):
        self._transferred_bytes = transferred_bytes

    def _get_transferred_bytes(self):
        return self._transferred_bytes

    transferred_bytes = GObject.property(type=int,
                                         default=0,
                                         getter=_get_transferred_bytes,
                                         setter=_set_transferred_bytes)

    def __initial_offset_defined_cb(self, offset):
        _logger.debug('__initial_offset_defined_cb %r', offset)
        self.initial_offset = offset

    def __state_changed_cb(self, state, reason):
        _logger.debug('__state_changed_cb %r %r', state, reason)
        self.reason_last_change = reason
        self.props.state = state

    def _set_state(self, state):
        self._state = state

    def _get_state(self):
        return self._state

    state = GObject.property(type=int, getter=_get_state, setter=_set_state)

    def cancel(self):
        '''
        Request that telepathy close the file transfer channel

        Spec:  http://telepathy.freedesktop.org/spec/Channel.html#Method:Close
        '''
        self.channel[CHANNEL].Close()


class IncomingFileTransfer(_BaseFileTransfer):
    '''
    An incoming file transfer from another buddy.  You need to first accept
    the transfer (either to memory or to a file).  Then you need to listen
    to the state and wait until the transfer is completed.  Then you can
    read the file that it was saved to, or access the
    :class:`Gio.MemoryOutputStream` from the `output` property.

    The `output` property is different depending on how the file was accepted.
    If the file was accepted to a file on the file system, it is a string
    representing the path to the file.  If the file was accepted to memory,
    it is a :class:`Gio.MemoryOutputStream`.
    '''

    ready = GObject.Signal('ready', arg_types=[object])

    def __init__(self, connection, object_path, props):
        _BaseFileTransfer.__init__(self)

        channel = {}
        proxy = dbus.Bus().get_object(connection.bus_name, object_path)
        channel[PROPERTIES_IFACE] = dbus.Interface(proxy, PROPERTIES_IFACE)
        channel[CHANNEL] = dbus.Interface(proxy, CHANNEL)
        channel[CHANNEL_TYPE_FILE_TRANSFER] = dbus.Interface(
            proxy, CHANNEL_TYPE_FILE_TRANSFER)
        self.set_channel(channel)

        self.connect('notify::state', self.__notify_state_cb)

        self._destination_path = None
        self._output_stream = None
        self._socket_address = None
        self._socket = None
        self._splicer = None

    def accept_to_file(self, destination_path):
        '''
        Accept the file transfer and write it to a new file.  The file must
        already exist.

        Args:
            destination_path (str): the path where a new file will be
                created and saved to
        '''
        if os.path.exists(destination_path):
            raise ValueError('Destination path already exists: %r' %
                             destination_path)

        self._destination_path = destination_path
        self._accept()

    def accept_to_memory(self):
        '''
        Accept the file transfer.  Once the state is FT_STATE_OPEN, a
        :class:`Gio.MemoryOutputStream` accessible via the output prop.
        '''
        self._destination_path = None
        self._accept()

    def _accept(self):
        channel_ft = self.channel[CHANNEL_TYPE_FILE_TRANSFER]
        self._socket_address = channel_ft.AcceptFile(
            SOCKET_ADDRESS_TYPE_UNIX,
            SOCKET_ACCESS_CONTROL_LOCALHOST,
            '',
            0,
            byte_arrays=True)

    def __notify_state_cb(self, file_transfer, pspec):
        _logger.debug('__notify_state_cb %r', self.props.state)
        if self.props.state == FT_STATE_OPEN:
            # Need to hold a reference to the socket so that python doesn't
            # close the fd when it goes out of scope
            self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
            self._socket.connect(self._socket_address)
            input_stream = Gio.UnixInputStream.new(self._socket.fileno(), True)

            if self._destination_path is not None:
                destination_file = Gio.File.new_for_path(
                    self._destination_path)
                if self.initial_offset == 0:
                    self._output_stream = destination_file.create(
                        Gio.FileCreateFlags.PRIVATE, None)
                else:
                    self._output_stream = destination_file.append_to()
            else:
                if hasattr(Gio.MemoryOutputStream, 'new_resizable'):
                    self._output_stream = \
                        Gio.MemoryOutputStream.new_resizable()
                else:
                    self._output_stream = Gio.MemoryOutputStream()

            self._output_stream.splice_async(
                input_stream,
                Gio.OutputStreamSpliceFlags.CLOSE_SOURCE |
                Gio.OutputStreamSpliceFlags.CLOSE_TARGET,
                GLib.PRIORITY_LOW, None, self.__splice_done_cb, None)

    def __splice_done_cb(self, output_stream, res, user):
        _logger.debug('__splice_done_cb')
        self.ready.emit(self._destination_path or self._output_stream)

    @GObject.Property
    def output(self):
        return self._destination_path or self._output_stream


class _BaseOutgoingTransfer(_BaseFileTransfer):
    '''
    This class provides the base of an outgoing file transfer.

    You can override the `_get_input_stream` method to return any type of
    Gio input stream.  This will then be used to provide the file if
    requested by the application.  You also need to call `_create_channel`
    with the length of the file in bytes during your `__init__`.

    Args:
        buddy (sugar3.presence.buddy.Buddy), who to send the transfer to
        conn (telepathy.client.conn.Connection), telepathy connection to
            use to send the transfer.  Eg. `shared_activity.telepathy_conn`
        filename (str), metadata sent to the receiver
        description (str), metadata sent to the receiver
        mime (str), metadata sent to the receiver
    '''

    def __init__(self, buddy, conn, filename, description, mime):
        _BaseFileTransfer.__init__(self)
        self.connect('notify::state', self.__notify_state_cb)

        self._socket_address = None
        self._socket = None
        self._splicer = None
        self._conn = conn
        self._filename = filename
        self._description = description
        self._mime = mime
        self.buddy = buddy

    def _create_channel(self, file_size):
        object_path, properties_ = self._conn.CreateChannel(dbus.Dictionary({
            CHANNEL + '.ChannelType': CHANNEL_TYPE_FILE_TRANSFER,
            CHANNEL + '.TargetHandleType': CONNECTION_HANDLE_TYPE_CONTACT,
            CHANNEL + '.TargetHandle': self.buddy.contact_handle,
            CHANNEL_TYPE_FILE_TRANSFER + '.Filename': self._filename,
            CHANNEL_TYPE_FILE_TRANSFER + '.Description': self._description,
            CHANNEL_TYPE_FILE_TRANSFER + '.Size': file_size,
            CHANNEL_TYPE_FILE_TRANSFER + '.ContentType': self._mime,
            CHANNEL_TYPE_FILE_TRANSFER + '.InitialOffset': 0}, signature='sv'))
        channel = {}
        proxy = dbus.Bus().get_object(self._conn.bus_name, object_path)
        channel[PROPERTIES_IFACE] = dbus.Interface(proxy, PROPERTIES_IFACE)
        channel[CHANNEL] = dbus.Interface(proxy, CHANNEL)
        channel[CHANNEL_TYPE_FILE_TRANSFER] = dbus.Interface(
            proxy, CHANNEL_TYPE_FILE_TRANSFER)
        self.set_channel(channel)

        channel_file_transfer = self.channel[CHANNEL_TYPE_FILE_TRANSFER]
        self._socket_address = channel_file_transfer.ProvideFile(
            SOCKET_ADDRESS_TYPE_UNIX, SOCKET_ACCESS_CONTROL_LOCALHOST, '',
            byte_arrays=True)

    def _get_input_stream(self):
        raise NotImplementedError()

    def __notify_state_cb(self, file_transfer, pspec):
        if self.props.state == FT_STATE_OPEN:
            # Need to hold a reference to the socket so that python doesn't
            # closes the fd when it goes out of scope
            self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
            self._socket.connect(self._socket_address)
            output_stream = Gio.UnixOutputStream.new(
                self._socket.fileno(), True)

            input_stream = self._get_input_stream()
            output_stream.splice_async(
                input_stream,
                Gio.OutputStreamSpliceFlags.CLOSE_SOURCE |
                Gio.OutputStreamSpliceFlags.CLOSE_TARGET,
                GLib.PRIORITY_LOW, None, None, None)


class OutgoingFileTransfer(_BaseOutgoingTransfer):
    '''
    An outgoing file transfer to send from a file (on the computer's file
    system).

    Note that the `path` argument is the path for the file that will be
    sent, whereas the `filename` argument is only for metadata.

    Args:
        path (str), path of the file to send
    '''

    def __init__(self, buddy, conn, path, filename, description, mime):
        _BaseOutgoingTransfer.__init__(
            self, buddy, conn, filename, description, mime)

        self._path = path
        file_size = os.stat(path).st_size
        self._create_channel(file_size)

    def _get_input_stream(self):
        return Gio.File.new_for_path(self._path).read(None)


class OutgoingBlobTransfer(_BaseOutgoingTransfer):
    '''
    An outgoing file transfer to send from a string in memory.

    Args:
        blob (str), data to send
    '''

    def __init__(self, buddy, conn, blob, filename, description, mime):
        _BaseOutgoingTransfer.__init__(
            self, buddy, conn, filename, description, mime)

        self._blob = blob
        self._create_channel(len(self._blob))

    def _get_input_stream(self):
        return Gio.MemoryInputStream.new_from_data(self._blob, None)


class _TextChannelWrapper(object):
    '''Wrapper for a telepathy Text Channel'''

    def __init__(self, text_chan, conn):
        '''Connect to the text channel'''
        self._activity_cb = None
        self._activity_close_cb = None
        self._text_chan = text_chan
        self._conn = conn
        self._signal_matches = []
        m = self._text_chan[CHANNEL_INTERFACE].connect_to_signal(
            'Closed', self._closed_cb)
        self._signal_matches.append(m)

    def post(self, msg):
        if msg is not None:
            _logger.debug('post')
            self._send(json.dumps(msg))

    def _send(self, text):
        '''Send text over the Telepathy text channel.'''
        _logger.debug('sending %s' % text)

        if self._text_chan is not None:
            self._text_chan[CHANNEL_TYPE_TEXT].Send(
                CHANNEL_TEXT_MESSAGE_TYPE_NORMAL, text)

    def close(self):
        '''Close the text channel.'''
        _logger.debug('Closing text channel')
        try:
            self._text_chan[CHANNEL_INTERFACE].Close()
        except Exception:
            _logger.debug('Channel disappeared!')
            self._closed_cb()

    def _closed_cb(self):
        '''Clean up text channel.'''
        for match in self._signal_matches:
            match.remove()
        self._signal_matches = []
        self._text_chan = None
        if self._activity_close_cb is not None:
            self._activity_close_cb()

    def set_received_callback(self, callback):
        '''Connect the function callback to the signal.

        callback -- callback function taking buddy and text args
        '''
        if self._text_chan is None:
            return
        self._activity_cb = callback
        m = self._text_chan[CHANNEL_TYPE_TEXT].connect_to_signal(
            'Received', self._received_cb)
        self._signal_matches.append(m)

    def handle_pending_messages(self):
        '''Get pending messages and show them as received.'''
        for identity, timestamp, sender, type_, flags, text in \
            self._text_chan[
                CHANNEL_TYPE_TEXT].ListPendingMessages(False):
            self._received_cb(identity, timestamp, sender, type_, flags, text)

    def _received_cb(self, identity, timestamp, sender, type_, flags, text):
        '''Handle received text from the text channel.

        Converts sender to a Buddy.
        Calls self._activity_cb which is a callback to the activity.
        '''
        _logger.debug('received_cb %r %s' % (type_, text))
        if type_ != 0:
            # Exclude any auxiliary messages
            return

        msg = json.loads(text)

        if self._activity_cb:
            try:
                self._text_chan[CHANNEL_INTERFACE_GROUP]
            except Exception:
                # One to one XMPP chat
                nick = self._conn[
                    CONN_INTERFACE_ALIASING].RequestAliases([sender])[0]
                buddy = {'nick': nick, 'color': '#000000,#808080'}
                _logger.debug('exception: recieved from sender %r buddy %r' %
                              (sender, buddy))
            else:
                # XXX: cache these
                buddy = self._get_buddy(sender)
                _logger.debug('Else: recieved from sender %r buddy %r' %
                              (sender, buddy))

            self._activity_cb(buddy, msg)
            self._text_chan[
                CHANNEL_TYPE_TEXT].AcknowledgePendingMessages([identity])
        else:
            _logger.debug('Throwing received message on the floor'
                          ' since there is no callback connected. See'
                          ' set_received_callback')

    def set_closed_callback(self, callback):
        '''Connect a callback for when the text channel is closed.

        callback -- callback function taking no args

        '''
        _logger.debug('set closed callback')
        self._activity_close_cb = callback

    def _get_buddy(self, cs_handle):
        '''Get a Buddy from a (possibly channel-specific) handle.'''
        # XXX This will be made redundant once Presence Service
        # provides buddy resolution

        # Get the Presence Service
        pservice = presenceservice.get_instance()

        # Get the Telepathy Connection
        tp_name, tp_path = pservice.get_preferred_connection()
        obj = dbus.Bus().get_object(tp_name, tp_path)
        conn = dbus.Interface(obj, CONN_INTERFACE)
        group = self._text_chan[CHANNEL_INTERFACE_GROUP]
        my_csh = group.GetSelfHandle()
        if my_csh == cs_handle:
            handle = conn.GetSelfHandle()
        elif (group.GetGroupFlags() &
              CHANNEL_GROUP_FLAG_CHANNEL_SPECIFIC_HANDLES):
            handle = group.GetHandleOwners([cs_handle])[0]
        else:
            handle = cs_handle

            # XXX: deal with failure to get the handle owner
            assert handle != 0

        return pservice.get_buddy_by_telepathy_handle(
            tp_name, tp_path, handle)