X-Git-Url: https://git.madduck.net/etc/taskwarrior.git/blobdiff_plain/ff45f9122b3f1a441491d9bcb0d9681039baea38..e9ac4a95bfab8a3e323e15f5f26a6302a87384a3:/tasklib/backends.py

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 51285b5..0d01470 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -5,6 +5,9 @@ import re
 import subprocess
 
 from tasklib.filters import TaskWarriorFilter
+from tasklib.serializing import local_zone
+
+DATE_FORMAT_CALC = '%Y-%m-%dT%H:%M:%S'
 
 VERSION_2_1_0 = six.u('2.1.0')
 VERSION_2_2_0 = six.u('2.2.0')
@@ -19,7 +22,10 @@ VERSION_2_4_5 = six.u('2.4.5')
 
 class Backend(object):
 
-    filter_class = TaskWarriorFilter
+    @abc.abstractproperty
+    def filter_class(self):
+        """Returns the TaskFilter class used by this backend"""
+        pass
 
     @abc.abstractmethod
     def filter_tasks(self, filter_obj):
@@ -67,6 +73,13 @@ class Backend(object):
         """Syncs the backend database with the taskd server"""
         pass
 
+    def convert_datetime_string(self, value):
+        """
+        Converts TW syntax datetime string to a localized datetime
+        object. This method is not mandatory.
+        """
+        raise NotImplemented
+
 
 class TaskWarriorException(Exception):
     pass
@@ -184,6 +197,23 @@ class TaskWarrior(object):
         else:
             return six.u("description:'{0}'").format(task._data['description'] or '')
 
+    def convert_datetime_string(self, value):
+
+        if self.version >= VERSION_2_4_0:
+            # For strings, use 'task calc' to evaluate the string to datetime
+            # available since TW 2.4.0
+            args = value.split()
+            result = self.execute_command(['calc'] + args)
+            naive = datetime.datetime.strptime(result[0], DATE_FORMAT_CALC)
+            localized = local_zone.localize(naive)
+        else:
+            raise ValueError("Provided value could not be converted to "
+                             "datetime, its type is not supported: {}"
+                             .format(type(value)))
+
+    @property
+    def filter_class(self):
+        return TaskWarriorFilter
 
     # Public interface