task: Add LazyUUIDTaskSet wrapper

[etc/taskwarrior.git] / tasklib / task.py

diff --git a/tasklib/task.py b/tasklib/task.py
index f74e0d25510028853f52c4511b09d37956f32371..6ebee4cc6b7442ceb2b62a3126324fbcc91e30fb 100644 (file)
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -1,103 +1,624 @@
+from __future__ import print_function
+import copy
+import importlib

 import json
 import json

+import logging

 import os
 import os

-import subprocess
-import tempfile
-import uuid
+import six
+import sys

 
 

+from .serializing import SerializingObject

 
 

+DATE_FORMAT = '%Y%m%dT%H%M%SZ'
+REPR_OUTPUT_SIZE = 10

 PENDING = 'pending'
 PENDING = 'pending'

+COMPLETED = 'completed'

 
 

+logger = logging.getLogger(__name__)

 
 

-class TaskWarriorException(Exception):
-    pass

 
 

+class ReadOnlyDictView(object):
+    """
+    Provides simplified read-only view upon dict object.
+    """

 
 

-class Task(object):
+    def __init__(self, viewed_dict):
+        self.viewed_dict = viewed_dict

 
 

-    def __init__(self, warrior, data={}):
-        self.warrior = warrior
-        self._data = data
+    def __getitem__(self, key):
+        return copy.deepcopy(self.viewed_dict.__getitem__(key))
+
+    def __contains__(self, k):
+        return self.viewed_dict.__contains__(k)
+
+    def __iter__(self):
+        for value in self.viewed_dict:
+            yield copy.deepcopy(value)
+
+    def __len__(self):
+        return len(self.viewed_dict)
+
+    def __unicode__(self):
+        return six.u('ReadOnlyDictView: {0}'.format(repr(self.viewed_dict)))
+
+    __repr__ = __unicode__
+
+    def get(self, key, default=None):
+        return copy.deepcopy(self.viewed_dict.get(key, default))
+
+    def items(self):
+        return [copy.deepcopy(v) for v in self.viewed_dict.items()]
+
+    def values(self):
+        return [copy.deepcopy(v) for v in self.viewed_dict.values()]
+
+
+class TaskResource(SerializingObject):
+    read_only_fields = []
+
+    def _load_data(self, data):
+        self._data = dict((key, self._deserialize(key, value))
+                          for key, value in data.items())
+        # We need to use a copy for original data, so that changes
+        # are not propagated.
+        self._original_data = copy.deepcopy(self._data)
+
+    def _update_data(self, data, update_original=False, remove_missing=False):
+        """
+        Low level update of the internal _data dict. Data which are coming as
+        updates should already be serialized. If update_original is True, the
+        original_data dict is updated as well.
+        """
+        self._data.update(dict((key, self._deserialize(key, value))
+                               for key, value in data.items()))
+
+        # In certain situations, we want to treat missing keys as removals
+        if remove_missing:
+            for key in set(self._data.keys()) - set(data.keys()):
+                self._data[key] = None
+
+        if update_original:
+            self._original_data = copy.deepcopy(self._data)

 
     def __getitem__(self, key):
 
     def __getitem__(self, key):

+        # This is a workaround to make TaskResource non-iterable
+        # over simple index-based iteration
+        try:
+            int(key)
+            raise StopIteration
+        except ValueError:
+            pass
+
+        if key not in self._data:
+            self._data[key] = self._deserialize(key, None)
+

         return self._data.get(key)
 
         return self._data.get(key)
 

-    def __setitem__(self, key, val):
-        self._data[key] = val
+    def __setitem__(self, key, value):
+        if key in self.read_only_fields:
+            raise RuntimeError('Field \'%s\' is read-only' % key)
+
+        # Normalize the user input before saving it
+        value = self._normalize(key, value)
+        self._data[key] = value
+
+    def __str__(self):
+        s = six.text_type(self.__unicode__())
+        if not six.PY3:
+            s = s.encode('utf-8')
+        return s
+
+    def __repr__(self):
+        return str(self)
+
+    def export_data(self):
+        """
+        Exports current data contained in the Task as JSON
+        """
+
+        # We need to remove spaces for TW-1504, use custom separators
+        data_tuples = ((key, self._serialize(key, value))
+                       for key, value in six.iteritems(self._data))
+
+        # Empty string denotes empty serialized value, we do not want
+        # to pass that to TaskWarrior.
+        data_tuples = filter(lambda t: t[1] is not '', data_tuples)
+        data = dict(data_tuples)
+        return json.dumps(data, separators=(',', ':'))
+
+    @property
+    def _modified_fields(self):
+        writable_fields = set(self._data.keys()) - set(self.read_only_fields)
+        for key in writable_fields:
+            new_value = self._data.get(key)
+            old_value = self._original_data.get(key)
+
+            # Make sure not to mark data removal as modified field if the
+            # field originally had some empty value
+            if key in self._data and not new_value and not old_value:
+                continue
+
+            if new_value != old_value:
+                yield key
+
+    @property
+    def modified(self):
+        return bool(list(self._modified_fields))
+
+
+class TaskAnnotation(TaskResource):
+    read_only_fields = ['entry', 'description']
+
+    def __init__(self, task, data=None):
+        self.task = task
+        self._load_data(data or dict())
+        super(TaskAnnotation, self).__init__(task.backend)
+
+    def remove(self):
+        self.task.remove_annotation(self)

 
     def __unicode__(self):
 
     def __unicode__(self):

-        return self._data.get('description')
+        return self['description']
+
+    def __eq__(self, other):
+        # consider 2 annotations equal if they belong to the same task, and
+        # their data dics are the same
+        return self.task == other.task and self._data == other._data
+
+    __repr__ = __unicode__
+
+
+class LazyUUIDTask(object):
+    """
+    A lazy wrapper around Task object, referenced by UUID.
+
+    - Supports comparison with LazyUUIDTask or Task objects (equality by UUIDs)
+    - If any attribute other than 'uuid' requested, a lookup in the
+      backend will be performed and this object will be replaced by a proper
+      Task object.
+    """
+
+    def __init__(self, tw, uuid):
+        self._tw = tw
+        self._uuid = uuid
+
+    def __getitem__(self, key):
+        # LazyUUIDTask does not provide anything else other than 'uuid'
+        if key is 'uuid':
+            return self._uuid
+        else:
+            self.replace()
+            return self[key]
+
+    def __getattr__(self, name):
+        # Getattr is called only if the attribute could not be found using
+        # normal means
+        self.replace()
+        return self.name
+
+    def __eq__(self, other):
+        if other['uuid']:
+            # For saved Tasks, just define equality by equality of uuids
+            return self['uuid'] == other['uuid']
+
+    def __hash__(self):
+        return self['uuid'].__hash__()
+
+    def replace(self):
+        """
+        Performs conversion to the regular Task object, referenced by the
+        stored UUID.
+        """
+
+        replacement = self._tw.tasks.get(uuid=self._uuid)
+        self.__class__ = replacement.__class__
+        self.__dict__ = replacement.__dict__
+
+
+class LazyUUIDTaskSet(object):
+    """
+    A lazy wrapper around TaskQuerySet object, for tasks referenced by UUID.
+
+    - Supports 'in' operator with LazyUUIDTask or Task objects
+    - If iteration over the objects in the LazyUUIDTaskSet is requested, the
+      LazyUUIDTaskSet will be converted to QuerySet and evaluated
+    """
+
+    def __init__(self, tw, uuids):
+        self._tw = tw
+        self._uuids = set(uuids)
+
+    def __getattr__(self, name):
+        # Getattr is called only if the attribute could not be found using
+        # normal means
+        self.replace()
+        return self.name
+
+    def __eq__(self, other):
+        return set(t['uuid'] for t in other) == self._uuids
+
+    def __contains__(self, task):
+        return task['uuid'] in self._uuids
+
+    def __len__(self):
+        return len(self._uuids)
+
+    def __iter__(self):
+        self.replace()
+        for task in self:
+            yield task
+
+    def replace(self):
+        """
+        Performs conversion to the regular TaskQuerySet object, referenced by
+        the stored UUIDs.
+        """
+
+        replacement = self._tw.tasks.filter(' '.join(self._uuids))
+        self.__class__ = replacement.__class__
+        self.__dict__ = replacement.__dict__
+
+
+class Task(TaskResource):
+    read_only_fields = ['id', 'entry', 'urgency', 'uuid', 'modified']
+
+    class DoesNotExist(Exception):
+        pass
+
+    class CompletedTask(Exception):
+        """
+        Raised when the operation cannot be performed on the completed task.
+        """
+        pass
+
+    class DeletedTask(Exception):
+        """
+        Raised when the operation cannot be performed on the deleted task.
+        """
+        pass
+
+    class ActiveTask(Exception):
+        """
+        Raised when the operation cannot be performed on the active task.
+        """
+        pass
+
+    class InactiveTask(Exception):
+        """
+        Raised when the operation cannot be performed on an inactive task.
+        """
+        pass
+
+    class NotSaved(Exception):
+        """
+        Raised when the operation cannot be performed on the task, because
+        it has not been saved to TaskWarrior yet.
+        """
+        pass
+
+    @classmethod
+    def from_input(cls, input_file=sys.stdin, modify=None, backend=None):
+        """
+        Creates a Task object, directly from the stdin, by reading one line.
+        If modify=True, two lines are used, first line interpreted as the
+        original state of the Task object, and second line as its new,
+        modified value. This is consistent with the TaskWarrior's hook
+        system.

 
 

-    def regenerate_uuid(self):
-        self['uuid'] = str(uuid.uuid4())
+        Object created by this method should not be saved, deleted
+        or refreshed, as t could create a infinite loop. For this
+        reason, TaskWarrior instance is set to None.
+
+        Input_file argument can be used to specify the input file,
+        but defaults to sys.stdin.
+        """
+
+        # Detect the hook type if not given directly
+        name = os.path.basename(sys.argv[0])
+        modify = name.startswith('on-modify') if modify is None else modify
+
+        # Create the TaskWarrior instance if none passed
+        if backend is None:
+            backends = importlib.import_module('tasklib.backends')
+            hook_parent_dir = os.path.dirname(os.path.dirname(sys.argv[0]))
+            backend = backends.TaskWarrior(data_location=hook_parent_dir)
+
+        # TaskWarrior instance is set to None
+        task = cls(backend)
+
+        # Load the data from the input
+        task._load_data(json.loads(input_file.readline().strip()))
+
+        # If this is a on-modify event, we are provided with additional
+        # line of input, which provides updated data
+        if modify:
+            task._update_data(json.loads(input_file.readline().strip()),
+                              remove_missing=True)
+
+        return task
+
+    def __init__(self, backend, **kwargs):
+        super(Task, self).__init__(backend)
+
+        # Check that user is not able to set read-only value in __init__
+        for key in kwargs.keys():
+            if key in self.read_only_fields:
+                raise RuntimeError('Field \'%s\' is read-only' % key)
+
+        # We serialize the data in kwargs so that users of the library
+        # do not have to pass different data formats via __setitem__ and
+        # __init__ methods, that would be confusing
+
+        # Rather unfortunate syntax due to python2.6 comaptiblity
+        self._data = dict((key, self._normalize(key, value))
+                          for (key, value) in six.iteritems(kwargs))
+        self._original_data = copy.deepcopy(self._data)
+
+        # Provide read only access to the original data
+        self.original = ReadOnlyDictView(self._original_data)
+
+    def __unicode__(self):
+        return self['description']
+
+    def __eq__(self, other):
+        if self['uuid'] and other['uuid']:
+            # For saved Tasks, just define equality by equality of uuids
+            return self['uuid'] == other['uuid']
+        else:
+            # If the tasks are not saved, compare the actual instances
+            return id(self) == id(other)
+
+    def __hash__(self):
+        if self['uuid']:
+            # For saved Tasks, just define equality by equality of uuids
+            return self['uuid'].__hash__()
+        else:
+            # If the tasks are not saved, return hash of instance id
+            return id(self).__hash__()
+
+    @property
+    def completed(self):
+        return self['status'] == six.text_type('completed')
+
+    @property
+    def deleted(self):
+        return self['status'] == six.text_type('deleted')
+
+    @property
+    def waiting(self):
+        return self['status'] == six.text_type('waiting')
+
+    @property
+    def pending(self):
+        return self['status'] == six.text_type('pending')
+
+    @property
+    def active(self):
+        return self['start'] is not None
+
+    @property
+    def saved(self):
+        return self['uuid'] is not None or self['id'] is not None
+
+    def serialize_depends(self, cur_dependencies):
+        # Check that all the tasks are saved
+        for task in (cur_dependencies or set()):
+            if not task.saved:
+                raise Task.NotSaved('Task \'%s\' needs to be saved before '
+                                    'it can be set as dependency.' % task)
+
+        return super(Task, self).serialize_depends(cur_dependencies)

 
     def delete(self):
 
     def delete(self):

-        self.warrior.delete_task(self['uuid'])
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved before it can be deleted")
+
+        # Refresh the status, and raise exception if the task is deleted
+        self.refresh(only_fields=['status'])
+
+        if self.deleted:
+            raise Task.DeletedTask("Task was already deleted")
+
+        self.backend.delete_task(self)
+
+        # Refresh the status again, so that we have updated info stored
+        self.refresh(only_fields=['status', 'start', 'end'])
+
+    def start(self):
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved before it can be started")
+
+        # Refresh, and raise exception if task is already completed/deleted
+        self.refresh(only_fields=['status'])
+
+        if self.completed:
+            raise Task.CompletedTask("Cannot start a completed task")
+        elif self.deleted:
+            raise Task.DeletedTask("Deleted task cannot be started")
+        elif self.active:
+            raise Task.ActiveTask("Task is already active")
+
+        self.backend.start_task(self)
+
+        # Refresh the status again, so that we have updated info stored
+        self.refresh(only_fields=['status', 'start'])
+
+    def stop(self):
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved before it can be stopped")
+
+        # Refresh, and raise exception if task is already completed/deleted
+        self.refresh(only_fields=['status'])
+
+        if not self.active:
+            raise Task.InactiveTask("Cannot stop an inactive task")
+
+        self.backend.stop_task(self)
+
+        # Refresh the status again, so that we have updated info stored
+        self.refresh(only_fields=['status', 'start'])

 
     def done(self):
 
     def done(self):

-        self.warrior.complete_task(self['uuid'])
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved before it can be completed")

 
 

-    def save(self, delete_first=True):
-        if self['uuid'] and delete_first:
-            self.delete()
-        if not self['uuid'] or delete_first:
-            self.regenerate_uuid()
-        self.warrior.import_tasks([self._data])
+        # Refresh, and raise exception if task is already completed/deleted
+        self.refresh(only_fields=['status'])

 
 

-    __repr__ = __unicode__
+        if self.completed:
+            raise Task.CompletedTask("Cannot complete a completed task")
+        elif self.deleted:
+            raise Task.DeletedTask("Deleted task cannot be completed")
+
+        self.backend.complete_task(self)
+
+        # Refresh the status again, so that we have updated info stored
+        self.refresh(only_fields=['status', 'start', 'end'])
+
+    def save(self):
+        if self.saved and not self.modified:
+            return
+
+        # All the actual work is done by the backend
+        self.backend.save_task(self)
+
+    def add_annotation(self, annotation):
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved to add annotation")
+
+        self.backend.annotate_task(self, annotation)
+        self.refresh(only_fields=['annotations'])
+
+    def remove_annotation(self, annotation):
+        if not self.saved:
+            raise Task.NotSaved("Task needs to be saved to remove annotation")
+
+        if isinstance(annotation, TaskAnnotation):
+            annotation = annotation['description']
+
+        self.backend.denotate_task(self, annotation)
+        self.refresh(only_fields=['annotations'])
+
+    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:
+            raise Task.NotSaved("Task needs to be saved to be refreshed")
+
+        new_data = self.backend.refresh_task(self, after_save=after_save)
+
+        if only_fields:
+            to_update = dict(
+                [(k, new_data.get(k)) for k in only_fields])
+            self._update_data(to_update, update_original=True)
+        else:
+            self._load_data(new_data)
+
+
+class TaskQuerySet(object):
+    """
+    Represents a lazy lookup for a task objects.
+    """
+
+    def __init__(self, backend, filter_obj=None):
+        self.backend = backend
+        self._result_cache = None
+        self.filter_obj = filter_obj or self.backend.filter_class(backend)
+
+    def __deepcopy__(self, memo):
+        """
+        Deep copy of a QuerySet doesn't populate the cache
+        """
+        obj = self.__class__(backend=self.backend)
+        for k, v in self.__dict__.items():
+            if k in ('_iter', '_result_cache'):
+                obj.__dict__[k] = None
+            else:
+                obj.__dict__[k] = copy.deepcopy(v, memo)
+        return obj
+
+    def __repr__(self):
+        data = list(self[:REPR_OUTPUT_SIZE + 1])
+        if len(data) > REPR_OUTPUT_SIZE:
+            data[-1] = "...(remaining elements truncated)..."
+        return repr(data)
+
+    def __len__(self):
+        if self._result_cache is None:
+            self._result_cache = list(self)
+        return len(self._result_cache)
+
+    def __iter__(self):
+        if self._result_cache is None:
+            self._result_cache = self._execute()
+        return iter(self._result_cache)
+
+    def __getitem__(self, k):
+        if self._result_cache is None:
+            self._result_cache = list(self)
+        return self._result_cache.__getitem__(k)
+
+    def __bool__(self):
+        if self._result_cache is not None:
+            return bool(self._result_cache)
+        try:
+            next(iter(self))
+        except StopIteration:
+            return False
+        return True
+
+    def __nonzero__(self):
+        return type(self).__bool__(self)
+
+    def _clone(self, klass=None, **kwargs):
+        if klass is None:
+            klass = self.__class__
+        filter_obj = self.filter_obj.clone()
+        c = klass(backend=self.backend, filter_obj=filter_obj)
+        c.__dict__.update(kwargs)
+        return c
+
+    def _execute(self):
+        """
+        Fetch the tasks which match the current filters.
+        """
+        return self.backend.filter_tasks(self.filter_obj)
+
+    def all(self):
+        """
+        Returns a new TaskQuerySet that is a copy of the current one.
+        """
+        return self._clone()
+
+    def pending(self):
+        return self.filter(status=PENDING)
+
+    def completed(self):
+        return self.filter(status=COMPLETED)

 
 

+    def filter(self, *args, **kwargs):
+        """
+        Returns a new TaskQuerySet with the given filters added.
+        """
+        clone = self._clone()
+        for f in args:
+            clone.filter_obj.add_filter(f)
+        for key, value in kwargs.items():
+            clone.filter_obj.add_filter_param(key, value)
+        return clone

 
 

-class TaskWarrior(object):
-
-    def __init__(self, data_location='~/.task', create=True):
-        if not os.path.exists(data_location):
-            os.makedirs(data_location)
-        self.config = {
-            'data.location': os.path.expanduser(data_location),
-        }
-
-    def _generate_command(self, command):
-        args = ['task', 'rc:/']
-        for item in self.config.items():
-            args.append('rc.{0}={1}'.format(*item))
-        args.append(command)
-        return ' '.join(args)
-
-    def _execute(self, command):
-        p = subprocess.Popen(self._generate_command(command), shell=True,
-                             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-        stdout, stderr = p.communicate()
-        if p.returncode:
-            raise TaskWarriorException(stderr.strip())
-        return stdout.strip().split('\n')
-
-    def get_tasks(self, project=None, status=PENDING):
-        command = 'export status:{0}'.format(status)
-        if project is not None:
-            command += ' project:{0}'.format(project)
-        tasks = []
-        for line in self._execute(command):
-            if line:
-                tasks.append(Task(self, json.loads(line.strip(','))))
-        return tasks
-
-    def get_task(self, task_id):
-        command = '{0} export'.format(task_id)
-        return Task(self, json.loads(self._execute(command)[0]))
-
-    def add_task(self, description, project=None):
-        args = ['add', description]
-        if project is not None:
-            args.append('project:{0}'.format(project))
-        self._execute(' '.join(args))
-
-    def delete_task(self, task_id):
-        self._execute('{0} rc.confirmation:no delete'.format(task_id))
-
-    def complete_task(self, task_id):
-        self._execute('{0} done'.format(task_id))
-
-    def import_tasks(self, tasks):
-        fd, path = tempfile.mkstemp()
-        with open(path, 'w') as f:
-            f.write(json.dumps(tasks))
-        self._execute('import {0}'.format(path))
+    def get(self, **kwargs):
+        """
+        Performs the query and returns a single object matching the given
+        keyword arguments.
+        """
+        clone = self.filter(**kwargs)
+        num = len(clone)
+        if num == 1:
+            return clone._result_cache[0]
+        if not num:
+            raise Task.DoesNotExist(
+                'Task matching query does not exist. '
+                'Lookup parameters were {0}'.format(kwargs))
+        raise ValueError(
+            'get() returned more than one Task -- it returned {0}! '
+            'Lookup parameters were {1}'.format(num, kwargs))