Make GmailFolder sync GMail labels

When synclabels config flag is set to "yes" for the GMail repo,
offlineimap fetches the message labels along with the messages, and
embeds them into the body under the header X-Keywords (or whatever
'labelsheader' was set to), as a comma separated list.

It also adds an extra pass to savemessageto, that performs label
synchronization on existing messages from GMail to local, the same way
it is done with flags.

We also introduce GmailMaildir repository that adds functionality to
change message labels.  It keeps track of messages modification time,
so one can quickly detect when the labels may have changed.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

offlineimap/repository/Gmail.py

@@ -36,6 +36,13 @@ class GmailRepository(IMAPRepository):
                                 'ssl', 'yes')
         IMAPRepository.__init__(self, reposname, account)
 
+        if self.account.getconfboolean('synclabels', 0) and \
+              self.account.getconf('status_backend', 'plain') != 'sqlite':
+            raise OfflineImapError("The Gmail repository needs the sqlite backend to sync labels.\n"
+                                   "To enable it add 'status_backend = sqlite' in the account section",
+                                   OfflineImapError.ERROR.REPO)
+
+
     def gethost(self):
         """Return the server name to connect to.
 
@@ -71,4 +78,3 @@ class GmailRepository(IMAPRepository):
     def getspamfolder(self):
         #: Gmail also deletes messages upon EXPUNGE in the Spam folder
         return  self.getconf('spamfolder','[Gmail]/Spam')
-

offlineimap/repository/GmailMaildir.py

@@ -0,0 +1,37 @@
+# Maildir repository support
+# Copyright (C) 2002 John Goerzen
+# <jgoerzen@complete.org>
+#
+#    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 2 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 program; if not, write to the Free Software
+#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+
+from offlineimap.repository.Maildir import MaildirRepository
+from offlineimap.folder.GmailMaildir import GmailMaildirFolder
+from offlineimap.error import OfflineImapError
+
+class GmailMaildirRepository(MaildirRepository):
+    def __init__(self, reposname, account):
+        """Initialize a MaildirRepository object.  Takes a path name
+        to the directory holding all the Maildir directories."""
+        super(GmailMaildirRepository, self).__init__(reposname, account)
+        if self.account.getconfboolean('synclabels', 0) and \
+              self.account.getconf('status_backend', 'plain') != 'sqlite':
+            raise OfflineImapError("The GmailMaildir repository needs the sqlite backend to sync labels.\n"
+                                   "To enable it add 'status_backend = sqlite' in the account section",
+                                   OfflineImapError.ERROR.REPO)
+
+
+
+    def getfoldertype(self):
+        return GmailMaildirFolder

offlineimap/repository/Maildir.py

@@ -177,10 +177,9 @@ class MaildirRepository(BaseRepository):
                 self.debug("  This is maildir folder '%s'." % foldername)
                 if self.getconfboolean('restoreatime', False):
                     self._append_folder_atimes(foldername)
-                retval.append(folder.Maildir.MaildirFolder(self.root,
-                                                           foldername,
-                                                           self.getsep(),
-                                                           self))
+                fd = self.getfoldertype()(self.root, foldername,
+                                          self.getsep(), self)
+                retval.append(fd)
 
             if self.getsep() == '/' and dirname != '':
                 # Recursively check sub-directories for folders too.
@@ -194,6 +193,9 @@ class MaildirRepository(BaseRepository):
             self.folders = self._getfolders_scandir(self.root)
         return self.folders
 
+    def getfoldertype(self):
+        return folder.Maildir.MaildirFolder
+
     def forgetfolders(self):
         """Forgets the cached list of folders, if any.  Useful to run
         after a sync run."""

offlineimap/repository/__init__.py

@@ -23,6 +23,7 @@ except ImportError: #python2
 from offlineimap.repository.IMAP import IMAPRepository, MappedIMAPRepository
 from offlineimap.repository.Gmail import GmailRepository
 from offlineimap.repository.Maildir import MaildirRepository
+from offlineimap.repository.GmailMaildir import GmailMaildirRepository
 from offlineimap.repository.LocalStatus import LocalStatusRepository
 from offlineimap.error import OfflineImapError
 
@@ -46,7 +47,8 @@ class Repository(object):
         elif reqtype == 'local':
             name = account.getconf('localrepository')
             typemap = {'IMAP': MappedIMAPRepository,
-                       'Maildir': MaildirRepository}
+                       'Maildir': MaildirRepository,
+                       'GmailMaildir': GmailMaildirRepository}
 
         elif reqtype == 'status':
             # create and return a LocalStatusRepository
@@ -84,4 +86,3 @@ class Repository(object):
         :param regtype: 'remote', 'local', or 'status'
         """
         pass
-