Add support for adding a category to a message

mail-filter.py

@@ -54,13 +54,15 @@ def log(msg, level=logging.INFO):
 class O365MailFilter(object):
     _scopes = [
         'basic',
-        'https://graph.microsoft.com/Mail.ReadWrite'
+        'https://graph.microsoft.com/Mail.ReadWrite',
+        'https://graph.microsoft.com/MailboxSettings.Read'
     ]
 
     def __init__(self, config):
         self._config = config
         self._is_canceled = False
         self._folders = {}
+        self._categories = {}
         self._filtered_cache = {
             'last_reset': None,
             'ids': set()
@@ -114,6 +116,13 @@ class O365MailFilter(object):
                 self._load_folders(mailbox, folder.get_folders(),
                                    current_folder_path)
 
+    def _load_categories(self):
+        """ cache Outlook categories for this account """
+        oc = self._account.outlook_categories()
+        categories = oc.get_categories()
+        for category in categories:
+            self._categories[category.name] = category
+
     def _clear_cache(self):
         """ clear the filtered message cache """
         log('Clearing filtered message cache...', logging.DEBUG)
@@ -135,6 +144,7 @@ class O365MailFilter(object):
         inbox = mailbox.inbox_folder()
 
         self._load_folders(mailbox)
+        self._load_categories()
         self._load_filters()
 
         # set limit to max allowed by O365, which is 999 messages