From c4d8c861713743f9bab0e95325c2af515a9182e5 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 19:45:59 +0200
Subject: [PATCH 01/16] TaskWarrior: Reorder methods

---
 tasklib/backends.py | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index a4d074e..ad5bd6b 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -144,6 +144,17 @@ class TaskWarrior(object):
         if self.version < VERSION_2_4_2:
             self.execute_command(['next'], allow_failure=False)
 
+    def merge_with(self, path, push=False):
+        path = path.rstrip('/') + '/'
+        self.execute_command(['merge', path], config_override={
+            'merge.autopush': 'yes' if push else 'no',
+        })
+
+    def undo(self):
+        self.execute_command(['undo'])
+
+    # Backend interface implementation
+
     def filter_tasks(self, filter_obj):
         self.enforce_recurrence()
         args = ['export', '--'] + filter_obj.get_filter_params()
@@ -190,11 +201,3 @@ class TaskWarrior(object):
         # altering the data before saving
         task.refresh(after_save=True)
 
-    def merge_with(self, path, push=False):
-        path = path.rstrip('/') + '/'
-        self.execute_command(['merge', path], config_override={
-            'merge.autopush': 'yes' if push else 'no',
-        })
-
-    def undo(self):
-        self.execute_command(['undo'])
-- 
2.39.5


From 7b0f22cf6cf519ece57e5282412669f460859293 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 19:51:11 +0200
Subject: [PATCH 02/16] Task: Move TW-specific deletion logic into TW backend

---
 tasklib/backends.py | 3 +++
 tasklib/task.py     | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index ad5bd6b..6bf11bb 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -201,3 +201,6 @@ class TaskWarrior(object):
         # altering the data before saving
         task.refresh(after_save=True)
 
+    def delete_task(self, task):
+        self.execute_command([task['uuid'], 'delete'])
+
diff --git a/tasklib/task.py b/tasklib/task.py
index 7c6dff8..61f944a 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -586,7 +586,7 @@ class Task(TaskResource):
         if self.deleted:
             raise Task.DeletedTask("Task was already deleted")
 
-        self.warrior.execute_command([self['uuid'], 'delete'])
+        self.backend.delete_task(self)
 
         # Refresh the status again, so that we have updated info stored
         self.refresh(only_fields=['status', 'start', 'end'])
-- 
2.39.5


From dcbdcdd11c981b4600ea4a5522230d0456e45d21 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 19:58:18 +0200
Subject: [PATCH 03/16] Task: Move TW-specific start/stop logic into TW backend

---
 tasklib/backends.py | 5 +++++
 tasklib/task.py     | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 6bf11bb..12a9234 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -204,3 +204,8 @@ class TaskWarrior(object):
     def delete_task(self, task):
         self.execute_command([task['uuid'], 'delete'])
 
+    def start_task(self, task):
+        self.execute_command([task['uuid'], 'start'])
+
+    def stop_task(self, task):
+        self.execute_command([task['uuid'], 'stop'])
diff --git a/tasklib/task.py b/tasklib/task.py
index 61f944a..b7bba4b 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -605,7 +605,7 @@ class Task(TaskResource):
         elif self.active:
             raise Task.ActiveTask("Task is already active")
 
-        self.warrior.execute_command([self['uuid'], 'start'])
+        self.backend.start_task(self)
 
         # Refresh the status again, so that we have updated info stored
         self.refresh(only_fields=['status', 'start'])
@@ -620,7 +620,7 @@ class Task(TaskResource):
         if not self.active:
             raise Task.InactiveTask("Cannot stop an inactive task")
 
-        self.warrior.execute_command([self['uuid'], 'stop'])
+        self.backend.stop_task(self)
 
         # Refresh the status again, so that we have updated info stored
         self.refresh(only_fields=['status', 'start'])
-- 
2.39.5


From 5c5b35a097608b63c3d54acf2f07d5cb00e85796 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 20:00:00 +0200
Subject: [PATCH 04/16] backends: Add complete_task to the backend interface

Marking task as 'done' needs to be implemented as a separate
backend operation too.
---
 tasklib/backends.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 12a9234..c99d63f 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -38,6 +38,10 @@ class Backend(object):
     def stop_task(self, task):
         pass
 
+    @abc.abstractmethod
+    def complete_task(self, task):
+        pass
+
     @abc.abstractmethod
     def sync(self):
         """Syncs the backend database with the taskd server"""
-- 
2.39.5


From 15c5d693afb61c72f6a6984c25dacb8610b2d9a8 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 20:06:03 +0200
Subject: [PATCH 05/16] Task: Move TW-specific completion logic into TW backend

---
 tasklib/backends.py | 8 ++++++++
 tasklib/task.py     | 6 +-----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index c99d63f..e7b9a74 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -213,3 +213,11 @@ class TaskWarrior(object):
 
     def stop_task(self, task):
         self.execute_command([task['uuid'], 'stop'])
+
+    def complete_task(self, task):
+        # Older versions of TW do not stop active task at completion
+        if self.version < VERSION_2_4_0 and task.active:
+            task.stop()
+
+        self.execute_command([task['uuid'], 'done'])
+
diff --git a/tasklib/task.py b/tasklib/task.py
index b7bba4b..3f53511 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -637,11 +637,7 @@ class Task(TaskResource):
         elif self.deleted:
             raise Task.DeletedTask("Deleted task cannot be completed")
 
-        # Older versions of TW do not stop active task at completion
-        if self.warrior.version < VERSION_2_4_0 and self.active:
-            self.stop()
-
-        self.warrior.execute_command([self['uuid'], 'done'])
+        self.backend.complete_task(self)
 
         # Refresh the status again, so that we have updated info stored
         self.refresh(only_fields=['status', 'start', 'end'])
-- 
2.39.5


From 4a289416db9f24d81cacd14da40f5db196454e79 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 20:39:42 +0200
Subject: [PATCH 06/16] backends: Add refresh_task to the Backend interface

---
 tasklib/backends.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index e7b9a74..bf4cd67 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -42,6 +42,14 @@ class Backend(object):
     def complete_task(self, task):
         pass
 
+    @abc.abstractmethod
+    def refresh_task(self, task):
+        """
+        Refreshes the given task. Returns new data dict with serialized
+        attributes.
+        """
+        pass
+
     @abc.abstractmethod
     def sync(self):
         """Syncs the backend database with the taskd server"""
-- 
2.39.5


From 398bbf824e6143cf760002af3065897011e469f0 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 20:44:01 +0200
Subject: [PATCH 07/16] Task: Move TW-specific refresh behaviour to TW backend

---
 tasklib/backends.py | 42 +++++++++++++++++++++++++++++++++++++++++-
 tasklib/task.py     | 37 +------------------------------------
 2 files changed, 42 insertions(+), 37 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index bf4cd67..92102cb 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -1,4 +1,5 @@
 import abc
+import json
 import os
 import re
 import subprocess
@@ -43,7 +44,7 @@ class Backend(object):
         pass
 
     @abc.abstractmethod
-    def refresh_task(self, task):
+    def refresh_task(self, task, after_save=False):
         """
         Refreshes the given task. Returns new data dict with serialized
         attributes.
@@ -229,3 +230,42 @@ class TaskWarrior(object):
 
         self.execute_command([task['uuid'], 'done'])
 
+    def refresh_task(self, task, after_save=False):
+        # We need to use ID as backup for uuid here for the refreshes
+        # of newly saved tasks. Any other place in the code is fine
+        # with using UUID only.
+        args = [task['uuid'] or task['id'], 'export']
+        output = self.execute_command(args)
+
+        def valid(output):
+            return len(output) == 1 and output[0].startswith('{')
+
+        # For older TW versions attempt to uniquely locate the task
+        # using the data we have if it has been just saved.
+        # This can happen when adding a completed task on older TW versions.
+        if (not valid(output) and self.version < VERSION_2_4_5
+                and after_save):
+
+            # Make a copy, removing ID and UUID. It's most likely invalid
+            # (ID 0) if it failed to match a unique task.
+            data = copy.deepcopy(task._data)
+            data.pop('id', None)
+            data.pop('uuid', None)
+
+            taskfilter = TaskFilter(self)
+            for key, value in data.items():
+                taskfilter.add_filter_param(key, value)
+
+            output = self.execute_command(['export', '--'] +
+                taskfilter.get_filter_params())
+
+        # If more than 1 task has been matched still, raise an exception
+        if not valid(output):
+            raise TaskWarriorException(
+                "Unique identifiers {0} with description: {1} matches "
+                "multiple tasks: {2}".format(
+                task['uuid'] or task['id'], task['description'], output)
+            )
+
+        return json.loads(output[0])
+
diff --git a/tasklib/task.py b/tasklib/task.py
index 3f53511..5a86529 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -708,43 +708,8 @@ class Task(TaskResource):
         if not self.saved:
             raise Task.NotSaved("Task needs to be saved to be refreshed")
 
-        # We need to use ID as backup for uuid here for the refreshes
-        # of newly saved tasks. Any other place in the code is fine
-        # with using UUID only.
-        args = [self['uuid'] or self['id'], 'export']
-        output = self.warrior.execute_command(args)
-
-        def valid(output):
-            return len(output) == 1 and output[0].startswith('{')
-
-        # For older TW versions attempt to uniquely locate the task
-        # using the data we have if it has been just saved.
-        # This can happen when adding a completed task on older TW versions.
-        if (not valid(output) and self.warrior.version < VERSION_2_4_5
-                and after_save):
-
-            # Make a copy, removing ID and UUID. It's most likely invalid
-            # (ID 0) if it failed to match a unique task.
-            data = copy.deepcopy(self._data)
-            data.pop('id', None)
-            data.pop('uuid', None)
-
-            taskfilter = TaskFilter(self.warrior)
-            for key, value in data.items():
-                taskfilter.add_filter_param(key, value)
-
-            output = self.warrior.execute_command(['export', '--'] +
-                taskfilter.get_filter_params())
-
-        # If more than 1 task has been matched still, raise an exception
-        if not valid(output):
-            raise TaskWarriorException(
-                "Unique identifiers {0} with description: {1} matches "
-                "multiple tasks: {2}".format(
-                self['uuid'] or self['id'], self['description'], output)
-            )
+        new_data = self.backend.refresh_task(self, after_save=after_save)
 
-        new_data = json.loads(output[0])
         if only_fields:
             to_update = dict(
                 [(k, new_data.get(k)) for k in only_fields])
-- 
2.39.5


From e52d223ba61ad4b121e91223ce33e860735ed6db Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 21:47:06 +0200
Subject: [PATCH 08/16] backends: Make filter classes backend-specific

---
 tasklib/backends.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 92102cb..6aadf7a 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -4,6 +4,7 @@ import os
 import re
 import subprocess
 
+from tasklib.task import TaskFilter
 
 VERSION_2_1_0 = six.u('2.1.0')
 VERSION_2_2_0 = six.u('2.2.0')
@@ -18,6 +19,8 @@ VERSION_2_4_5 = six.u('2.4.5')
 
 class Backend(object):
 
+    filter_class = TaskFilter
+
     @abc.abstractmethod
     def filter_tasks(self, filter_obj):
         """Returns a list of Task objects matching the given filter"""
@@ -252,7 +255,7 @@ class TaskWarrior(object):
             data.pop('id', None)
             data.pop('uuid', None)
 
-            taskfilter = TaskFilter(self)
+            taskfilter = self.filter_class(self)
             for key, value in data.items():
                 taskfilter.add_filter_param(key, value)
 
-- 
2.39.5


From 71d228aa43ba3912ad252a9724b14fcb5a6cd12d Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 21:47:26 +0200
Subject: [PATCH 09/16] TaskWarrior: Implement sync method

---
 tasklib/backends.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 6aadf7a..80928f1 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -272,3 +272,5 @@ class TaskWarrior(object):
 
         return json.loads(output[0])
 
+    def sync(self):
+        self.execute_command(['sync'])
-- 
2.39.5


From 0aa410df86d4a16b4117858a96147e896c2a7d35 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 21:57:06 +0200
Subject: [PATCH 10/16] backends: Add method for annotations to the backend
 interface

---
 tasklib/backends.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 80928f1..a1d858f 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -54,6 +54,14 @@ class Backend(object):
         """
         pass
 
+    @abc.abstractmethod
+    def annotate_task(self, task, annotation):
+        pass
+
+    @abc.abstractmethod
+    def denotate_task(self, task, annotation):
+        pass
+
     @abc.abstractmethod
     def sync(self):
         """Syncs the backend database with the taskd server"""
-- 
2.39.5


From 1a429b9309cf543e937c9b8b061d0f99d1acffbe Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 22:16:48 +0200
Subject: [PATCH 11/16] backends: Move TW-specific annotation logic to TW
 backend

---
 tasklib/backends.py | 8 ++++++++
 tasklib/task.py     | 7 +++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index a1d858f..f0c73ef 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -241,6 +241,14 @@ class TaskWarrior(object):
 
         self.execute_command([task['uuid'], 'done'])
 
+    def annotate_task(self, task, annotation):
+        args = [task['uuid'], 'annotate', annotation]
+        self.execute_command(args)
+
+    def denotate_task(self, task, annotation):
+        args = [task['uuid'], 'denotate', annotation]
+        self.execute_command(args)
+
     def refresh_task(self, task, after_save=False):
         # We need to use ID as backup for uuid here for the refreshes
         # of newly saved tasks. Any other place in the code is fine
diff --git a/tasklib/task.py b/tasklib/task.py
index 5a86529..9ae63d4 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -653,8 +653,7 @@ class Task(TaskResource):
         if not self.saved:
             raise Task.NotSaved("Task needs to be saved to add annotation")
 
-        args = [self['uuid'], 'annotate', annotation]
-        self.warrior.execute_command(args)
+        self.backend.annotate_task(self, annotation)
         self.refresh(only_fields=['annotations'])
 
     def remove_annotation(self, annotation):
@@ -663,8 +662,8 @@ class Task(TaskResource):
 
         if isinstance(annotation, TaskAnnotation):
             annotation = annotation['description']
-        args = [self['uuid'], 'denotate', annotation]
-        self.warrior.execute_command(args)
+
+        self.backend.denotate_task(self, annotation)
         self.refresh(only_fields=['annotations'])
 
     def _get_modified_fields_as_args(self):
-- 
2.39.5


From fda5cf272018a0596c3ea97c9d4658cf0b5fa048 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:22:38 +0200
Subject: [PATCH 12/16] Task: Conversion of modified fields to TW Cli args is
 TW-specific, move to backend

---
 tasklib/backends.py | 39 ++++++++++++++++++++++++++++++++++++++-
 tasklib/task.py     | 36 ------------------------------------
 2 files changed, 38 insertions(+), 37 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index f0c73ef..38b88b1 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -121,6 +121,43 @@ class TaskWarrior(object):
         stdout, stderr = [x.decode('utf-8') for x in p.communicate()]
         return stdout.strip('\n')
 
+    def _get_modified_task_fields_as_args(self, task):
+        args = []
+
+        def add_field(field):
+            # Add the output of format_field method to args list (defaults to
+            # field:value)
+            serialized_value = task._serialize(field, task._data[field])
+
+            # Empty values should not be enclosed in quotation marks, see
+            # TW-1510
+            if serialized_value is '':
+                escaped_serialized_value = ''
+            else:
+                escaped_serialized_value = six.u("'{0}'").format(serialized_value)
+
+            format_default = lambda: six.u("{0}:{1}").format(field,
+                                                      escaped_serialized_value)
+
+            format_func = getattr(task, 'format_{0}'.format(field),
+                                  format_default)
+
+            args.append(format_func())
+
+        # If we're modifying saved task, simply pass on all modified fields
+        if task.saved:
+            for field in task._modified_fields:
+                add_field(field)
+        # For new tasks, pass all fields that make sense
+        else:
+            for field in task._data.keys():
+                if field in task.read_only_fields:
+                    continue
+                add_field(field)
+
+        return args
+
+
     def get_config(self):
         raw_output = self.execute_command(
                 ['show'],
@@ -198,7 +235,7 @@ class TaskWarrior(object):
         """Save a task into TaskWarrior database using add/modify call"""
 
         args = [task['uuid'], 'modify'] if task.saved else ['add']
-        args.extend(task._get_modified_fields_as_args())
+        args.extend(self._get_modified_task_fields_as_args(task))
         output = self.execute_command(args)
 
         # Parse out the new ID, if the task is being added for the first time
diff --git a/tasklib/task.py b/tasklib/task.py
index 9ae63d4..081646d 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -666,42 +666,6 @@ class Task(TaskResource):
         self.backend.denotate_task(self, annotation)
         self.refresh(only_fields=['annotations'])
 
-    def _get_modified_fields_as_args(self):
-        args = []
-
-        def add_field(field):
-            # Add the output of format_field method to args list (defaults to
-            # field:value)
-            serialized_value = self._serialize(field, self._data[field])
-
-            # Empty values should not be enclosed in quotation marks, see
-            # TW-1510
-            if serialized_value is '':
-                escaped_serialized_value = ''
-            else:
-                escaped_serialized_value = six.u("'{0}'").format(serialized_value)
-
-            format_default = lambda: six.u("{0}:{1}").format(field,
-                                                      escaped_serialized_value)
-
-            format_func = getattr(self, 'format_{0}'.format(field),
-                                  format_default)
-
-            args.append(format_func())
-
-        # If we're modifying saved task, simply pass on all modified fields
-        if self.saved:
-            for field in self._modified_fields:
-                add_field(field)
-        # For new tasks, pass all fields that make sense
-        else:
-            for field in self._data.keys():
-                if field in self.read_only_fields:
-                    continue
-                add_field(field)
-
-        return args
-
     def refresh(self, only_fields=None, after_save=False):
         # Raise error when trying to refresh a task that has not been saved
         if not self.saved:
-- 
2.39.5


From 6ca4e493312239436a5d8339741f22f1cd535883 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:28:02 +0200
Subject: [PATCH 13/16] Task: Move formatters to TaskWarrior backend

---
 tasklib/backends.py | 33 +++++++++++++++++++++++++++++++--
 tasklib/task.py     | 27 ---------------------------
 2 files changed, 31 insertions(+), 29 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 38b88b1..02d412c 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -139,10 +139,10 @@ class TaskWarrior(object):
             format_default = lambda: six.u("{0}:{1}").format(field,
                                                       escaped_serialized_value)
 
-            format_func = getattr(task, 'format_{0}'.format(field),
+            format_func = getattr(self, 'format_{0}'.format(field),
                                   format_default)
 
-            args.append(format_func())
+            args.append(format_func(task))
 
         # If we're modifying saved task, simply pass on all modified fields
         if task.saved:
@@ -157,6 +157,35 @@ class TaskWarrior(object):
 
         return args
 
+    def format_depends(self, task):
+        # We need to generate added and removed dependencies list,
+        # since Taskwarrior does not accept redefining dependencies.
+
+        # This cannot be part of serialize_depends, since we need
+        # to keep a list of all depedencies in the _data dictionary,
+        # not just currently added/removed ones
+
+        old_dependencies = task._original_data.get('depends', set())
+
+        added = self['depends'] - old_dependencies
+        removed = old_dependencies - self['depends']
+
+        # Removed dependencies need to be prefixed with '-'
+        return 'depends:' + ','.join(
+                [t['uuid'] for t in added] +
+                ['-' + t['uuid'] for t in removed]
+            )
+
+    def format_description(self, task):
+        # Task version older than 2.4.0 ignores first word of the
+        # task description if description: prefix is used
+        if self.version < VERSION_2_4_0:
+            return task._data['description']
+        else:
+            return six.u("description:'{0}'").format(task._data['description'] or '')
+
+
+    # Public interface
 
     def get_config(self):
         raw_output = self.execute_command(
diff --git a/tasklib/task.py b/tasklib/task.py
index 081646d..211573d 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -549,33 +549,6 @@ class Task(TaskResource):
 
         return super(Task, self).serialize_depends(cur_dependencies)
 
-    def format_depends(self):
-        # We need to generate added and removed dependencies list,
-        # since Taskwarrior does not accept redefining dependencies.
-
-        # This cannot be part of serialize_depends, since we need
-        # to keep a list of all depedencies in the _data dictionary,
-        # not just currently added/removed ones
-
-        old_dependencies = self._original_data.get('depends', set())
-
-        added = self['depends'] - old_dependencies
-        removed = old_dependencies - self['depends']
-
-        # Removed dependencies need to be prefixed with '-'
-        return 'depends:' + ','.join(
-                [t['uuid'] for t in added] +
-                ['-' + t['uuid'] for t in removed]
-            )
-
-    def format_description(self):
-        # Task version older than 2.4.0 ignores first word of the
-        # task description if description: prefix is used
-        if self.warrior.version < VERSION_2_4_0:
-            return self._data['description']
-        else:
-            return six.u("description:'{0}'").format(self._data['description'] or '')
-
     def delete(self):
         if not self.saved:
             raise Task.NotSaved("Task needs to be saved before it can be deleted")
-- 
2.39.5


From 5ba0e1105517f8b0e22b0bcf5c79f40a0fb644d9 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:38:22 +0200
Subject: [PATCH 14/16] filters: Move TaskFilter into separate module

---
 tasklib/filters.py | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 tasklib/task.py    | 49 ---------------------------------------------
 2 files changed, 50 insertions(+), 49 deletions(-)
 create mode 100644 tasklib/filters.py

diff --git a/tasklib/filters.py b/tasklib/filters.py
new file mode 100644
index 0000000..1899d1d
--- /dev/null
+++ b/tasklib/filters.py
@@ -0,0 +1,50 @@
+from tasklib.serializing import SerializingObject
+
+
+class TaskFilter(SerializingObject):
+    """
+    A set of parameters to filter the task list with.
+    """
+
+    def __init__(self, warrior, filter_params=None):
+        self.filter_params = filter_params or []
+        super(TaskFilter, self).__init__(warrior)
+
+    def add_filter(self, filter_str):
+        self.filter_params.append(filter_str)
+
+    def add_filter_param(self, key, value):
+        key = key.replace('__', '.')
+
+        # Replace the value with empty string, since that is the
+        # convention in TW for empty values
+        attribute_key = key.split('.')[0]
+
+        # Since this is user input, we need to normalize before we serialize
+        value = self._normalize(attribute_key, value)
+        value = self._serialize(attribute_key, value)
+
+        # If we are filtering by uuid:, do not use uuid keyword
+        # due to TW-1452 bug
+        if key == 'uuid':
+            self.filter_params.insert(0, value)
+        else:
+            # Surround value with aphostrophes unless it's a empty string
+            value = "'%s'" % value if value else ''
+
+            # We enforce equality match by using 'is' (or 'none') modifier
+            # Without using this syntax, filter fails due to TW-1479
+            # which is, however, fixed in 2.4.5
+            if self.warrior.version < VERSION_2_4_5:
+                modifier = '.is' if value else '.none'
+                key = key + modifier if '.' not in key else key
+
+            self.filter_params.append(six.u("{0}:{1}").format(key, value))
+
+    def get_filter_params(self):
+        return [f for f in self.filter_params if f]
+
+    def clone(self):
+        c = self.__class__(self.warrior)
+        c.filter_params = list(self.filter_params)
+        return c
diff --git a/tasklib/task.py b/tasklib/task.py
index 211573d..614fd56 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -653,55 +653,6 @@ class Task(TaskResource):
         else:
             self._load_data(new_data)
 
-class TaskFilter(SerializingObject):
-    """
-    A set of parameters to filter the task list with.
-    """
-
-    def __init__(self, warrior, filter_params=None):
-        self.filter_params = filter_params or []
-        super(TaskFilter, self).__init__(warrior)
-
-    def add_filter(self, filter_str):
-        self.filter_params.append(filter_str)
-
-    def add_filter_param(self, key, value):
-        key = key.replace('__', '.')
-
-        # Replace the value with empty string, since that is the
-        # convention in TW for empty values
-        attribute_key = key.split('.')[0]
-
-        # Since this is user input, we need to normalize before we serialize
-        value = self._normalize(attribute_key, value)
-        value = self._serialize(attribute_key, value)
-
-        # If we are filtering by uuid:, do not use uuid keyword
-        # due to TW-1452 bug
-        if key == 'uuid':
-            self.filter_params.insert(0, value)
-        else:
-            # Surround value with aphostrophes unless it's a empty string
-            value = "'%s'" % value if value else ''
-
-            # We enforce equality match by using 'is' (or 'none') modifier
-            # Without using this syntax, filter fails due to TW-1479
-            # which is, however, fixed in 2.4.5
-            if self.warrior.version < VERSION_2_4_5:
-                modifier = '.is' if value else '.none'
-                key = key + modifier if '.' not in key else key
-
-            self.filter_params.append(six.u("{0}:{1}").format(key, value))
-
-    def get_filter_params(self):
-        return [f for f in self.filter_params if f]
-
-    def clone(self):
-        c = self.__class__(self.warrior)
-        c.filter_params = list(self.filter_params)
-        return c
-
-
 class TaskQuerySet(object):
     """
     Represents a lazy lookup for a task objects.
-- 
2.39.5


From ff45f9122b3f1a441491d9bcb0d9681039baea38 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:52:49 +0200
Subject: [PATCH 15/16] TaskFilter: Rename TaskFilter to TaskWarriorFilter

---
 tasklib/backends.py | 4 ++--
 tasklib/filters.py  | 2 +-
 tasklib/task.py     | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tasklib/backends.py b/tasklib/backends.py
index 02d412c..51285b5 100644
--- a/tasklib/backends.py
+++ b/tasklib/backends.py
@@ -4,7 +4,7 @@ import os
 import re
 import subprocess
 
-from tasklib.task import TaskFilter
+from tasklib.filters import TaskWarriorFilter
 
 VERSION_2_1_0 = six.u('2.1.0')
 VERSION_2_2_0 = six.u('2.2.0')
@@ -19,7 +19,7 @@ VERSION_2_4_5 = six.u('2.4.5')
 
 class Backend(object):
 
-    filter_class = TaskFilter
+    filter_class = TaskWarriorFilter
 
     @abc.abstractmethod
     def filter_tasks(self, filter_obj):
diff --git a/tasklib/filters.py b/tasklib/filters.py
index 1899d1d..211302f 100644
--- a/tasklib/filters.py
+++ b/tasklib/filters.py
@@ -1,7 +1,7 @@
 from tasklib.serializing import SerializingObject
 
 
-class TaskFilter(SerializingObject):
+class TaskWarriorFilter(SerializingObject):
     """
     A set of parameters to filter the task list with.
     """
diff --git a/tasklib/task.py b/tasklib/task.py
index 614fd56..d39c10c 100644
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -54,7 +54,7 @@ class ReadOnlyDictView(object):
 
 class SerializingObject(object):
     """
-    Common ancestor for TaskResource & TaskFilter, since they both
+    Common ancestor for TaskResource & TaskWarriorFilter, since they both
     need to serialize arguments.
 
     Serializing method should hold the following contract:
@@ -661,7 +661,7 @@ class TaskQuerySet(object):
     def __init__(self, warrior=None, filter_obj=None):
         self.warrior = warrior
         self._result_cache = None
-        self.filter_obj = filter_obj or TaskFilter(warrior)
+        self.filter_obj = filter_obj or TaskWarriorFilter(warrior)
 
     def __deepcopy__(self, memo):
         """
-- 
2.39.5


From f986b814683ddee836b534f344bca017ac697c58 Mon Sep 17 00:00:00 2001
From: Tomas Babej <tomasbabej@gmail.com>
Date: Sat, 8 Aug 2015 23:55:47 +0200
Subject: [PATCH 16/16] filters: Define TaskFilter base class

---
 tasklib/filters.py | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/tasklib/filters.py b/tasklib/filters.py
index 211302f..7b44e98 100644
--- a/tasklib/filters.py
+++ b/tasklib/filters.py
@@ -1,7 +1,35 @@
+import abc
 from tasklib.serializing import SerializingObject
 
 
-class TaskWarriorFilter(SerializingObject):
+class TaskFilter(object):
+    """
+    Abstract base class that defines interface of a TaskFilter.
+    """
+
+    @abc.abstractmethod
+    def add_filter(self, arg):
+        """
+        Processes an non-keyword filter.
+        """
+        pass
+
+    @abc.abstractmethod
+    def add_filter_param(self, key, value):
+        """
+        Processes a keyword filter.
+        """
+        pass
+
+    @abc.abstractmethod
+    def clone(self):
+        """
+        Returns a new deep copy of itself.
+        """
+        pass
+
+
+class TaskWarriorFilter(TaskFilter, SerializingObject):
     """
     A set of parameters to filter the task list with.
     """
-- 
2.39.5