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Add foreign key restraints, expand and fix tests, add deletion and forking.
[misc] / todo.py
diff --git a/todo.py b/todo.py
index a4d7da0e56fce598906e40ad42fd7a247d3934f7..dc3a346efebccc30be5d82e1840b635d79c0b5b2 100644 (file)
--- a/todo.py
+++ b/todo.py
@@ -11,26 +11,121 @@ server_port = 8082
 DATE_FORMAT = '%Y-%m-%d'
 j2env = JinjaEnv(loader=JinjaFSLoader('todo_templates'))
 
-class Task:
 
-    def __init__(self, db, id_, title_history=None, tags_history=None, default_effort_history=None, links_history=None, comment=''):
-        self.id_ = id_
+
+def today_date(with_time=False):
+    length = 19 if with_time else 10
+    return str(datetime.now())[:length]
+
+
+
+class AttributeWithHistory:
+
+    def __init__(self, parent, name, default_if_empty, history=None, then_date='2000-01-01'):
+        self.parent = parent 
+        self.name = name
+        self.default = default_if_empty
+        self.then_date = then_date
+        self.history = history if history else {}
+
+    def set(self, value):
+        keys = sorted(self.history.keys())
+        if len(self.history) == 0 or value != self.history[keys[-1]]:
+            self.history[today_date(with_time=True)] = value
+
+    def at(self, queried_date):
+        end_of_queried_day = f'{queried_date} 23:59:59'
+        sorted_dates = sorted(self.history.keys())
+        if self.parent.forked_task and (0 == len(sorted_dates) or sorted_dates[0] > end_of_queried_day):
+            return getattr(self.parent.forked_task, self.name).at(queried_date)
+        elif 0 == len(sorted_dates):
+            return self.default
+        ret = self.history[sorted_dates[0]]
+        for date_key, item in self.history.items():
+            if date_key > end_of_queried_day:
+                break
+            ret = item
+        return ret
+
+    @property
+    def now(self):
+        keys = sorted(self.history.keys())
+        if 0 == len(self.history):
+            if self.parent.forked_task:
+                return getattr(self.parent.forked_task, self.name).now
+            return self.default
+        return self.history[keys[-1]]
+
+    @property
+    def then(self):
+        return self.at(self.then_date)
+
+
+
+class TaskLike:
+
+    def __init__(self, db, id_, comment):
         self.db = db
-        self.title_history = title_history if title_history else {}
-        self.tags_history = tags_history if tags_history else {}
-        self.default_effort_history = default_effort_history if default_effort_history else {}
-        self.links_history = links_history if links_history else {}
+        self.id_ = id_
         self.comment = comment
-        self.visible = True
 
-    def _set_with_history(self, history, value):
-        keys = sorted(history.keys())
-        if len(history) == 0 or value != history[keys[-1]]:
-            history[str(datetime.now())[:19]] = value
+    @property
+    def visible(self):
+        visible_by_and = 0 == len([tag for tag in self.db.tag_filter_and
+                                   if not tag in self.tags])
+        visible_by_not = 0 == len([tag for tag in self.db.tag_filter_not
+                                   if tag in self.tags])
+        return visible_by_and and visible_by_not
 
-    def _last_of_history(self, history, default):
-        keys = sorted(history.keys())
-        return default if 0 == len(history) else history[keys[-1]]
+    @property
+    def deps_depth(self):
+        if len(self.deps) == 0:
+            return 0
+        return 1 + max([d.deps_depth for d in self.deps])
+
+    @property
+    def deps_chain(self):
+        all_deps = set()
+        def add_deps(node, all_deps):
+            for dep in node.deps:
+                all_deps.add(dep)
+                add_deps(dep, all_deps)
+        add_deps(self, all_deps)
+        chain = list(all_deps)
+        chain.sort(key=lambda t: t.deps_depth)
+        return chain
+
+    def loop_check(self):
+        loop_msg = "can't set dep, would create loop"
+        def f(node, id_):
+            for dep in node.deps:
+                if id_ == dep.id_:
+                    raise PlomException(loop_msg)
+                f(dep, id_)
+        f(self, self.id_)
+
+
+
+
+class Task(TaskLike):
+
+    def __init__(self,
+            db,
+            id_,
+            title_history=None,
+            tags_history=None,
+            default_effort_history=None,
+            dep_ids_history=None,
+            adoptivity_history=None,
+            comment='',
+            forks_id=None):
+        super().__init__(db, id_, comment)
+        self.forks_id = forks_id 
+        self.title = AttributeWithHistory(self, 'title', '', title_history, self.db.selected_date)
+        self.tags = AttributeWithHistory(self, 'tags', set(), tags_history, self.db.selected_date)
+        self.default_effort = AttributeWithHistory(self, 'default_effort', 0.0, default_effort_history, self.db.selected_date)
+        self.dep_ids = AttributeWithHistory(self, 'dep_ids', set(), dep_ids_history, self.db.selected_date)
+        self.fences_adoptions = AttributeWithHistory(self, 'fences_adoptions', False, adoptivity_history, self.db.selected_date)
 
     @classmethod
     def from_dict(cls, db, d, id_):
@@ -40,157 +135,86 @@ class Task:
                d['title_history'],
                {k: set(v) for k, v in d['tags_history'].items()},
                d['default_effort_history'],
-               {k: set(v) for k, v in d['links_history'].items()},
-               d['comment'])
+               {k: set(v) for k, v in d['deps_history'].items()},
+               d['adoptivity_history'],
+               comment=d['comment'],
+               forks_id=d['forks'])
         return t
 
     def to_dict(self):
         return {
-            'title_history': self.title_history,
-            'default_effort_history': self.default_effort_history,
-            'tags_history': {k: list(v) for k,v in self.tags_history.items()},
-            'links_history': {k: list(v) for k,v in self.links_history.items()},
+            'title_history': self.title.history,
+            'default_effort_history': self.default_effort.history,
+            'tags_history': {k: list(v) for k, v in self.tags.history.items()},
+            'deps_history': {k: list(v) for k, v in self.dep_ids.history.items()},
+            'adoptivity_history': self.fences_adoptions.history,
             'comment': self.comment,
+            'forks': self.forks_id,
         }
 
     @property
-    def default_effort(self):
-        return self._last_of_history(self.default_effort_history, 1)
+    def forked_task(self):
+        return self.db.tasks[self.forks_id] if self.forks_id else None
 
-    @default_effort.setter
-    def default_effort(self, default_effort):
-        self._set_with_history(self.default_effort_history, default_effort)
+    @property
+    def deps(self):
+        deps = []
+        for id_ in self.dep_ids.now:
+            if len(id_) == 0:
+                continue
+            elif id_ not in self.db.tasks.keys():
+                raise PlomException(f'dep referenced on Task {self.id_} not found: {id_}')
+            deps += [self.db.tasks[id_]]
+        return deps
 
-    def default_effort_at(self, queried_date):
-        ret = self.default_effort_history[sorted(self.default_effort_history.keys())[0]]
-        for date_key, default_effort in self.default_effort_history.items():
-            if date_key > f'{queried_date} 23:59:59':
-                break
-            ret = default_effort
-        return ret
+    @property
+    def deps_weight(self):
+        def count_weight(task):
+            sub_count = 1
+            for dep in task.deps:
+                sub_count += count_weight(dep)
+            return sub_count
+        return count_weight(self) 
 
-    @property
-    # def current_default_effort(self):
-    #     return self.default_effort_at(self.db.selected_date)
+    @property
+    def dependers(self):
+        return [t for t in self.db.tasks.values() if self in t.deps]
 
     def matches(self, search):
         if search is None:
             return False
         else:
-            return search in self.title or search in self.comment or search in '$'.join(self.tags) or search in self.title
+            return search in self.title.now or search in self.comment or search in '$'.join(self.tags.now)
 
     @property
-    def title(self):
-        return self._last_of_history(self.title_history, '')
-
-    @title.setter
-    def title(self, title):
-        self._set_with_history(self.title_history, title)
-
-    def title_at(self, queried_date):
-        ret = self.title_history[sorted(self.title_history.keys())[0]]
-        for date_key, title in self.title_history.items():
-            if date_key > f'{queried_date} 23:59:59':
-                break
-            ret = title
-        return ret
-
-    @property
-    def current_title(self):
-        return self.title_at(self.db.selected_date)
-
-    @property
-    def tags(self):
-        return self._last_of_history(self.tags_history, set())
-
-    @tags.setter
-    def tags(self, tags):
-        self._set_with_history(self.tags_history, set(tags))
-
-    @property
-    def links(self):
-        return self._last_of_history(self.links_history, set())
-
-    @links.setter
-    def links(self, links):
-        self._set_with_history(self.links_history, set(links))
+    def latest_effort_date(self):
+        todos = [t for t in self.db.todos.values() if t.task.id_ == self.id_]
+        todos.sort(key=lambda t: t.latest_date)
+        if len(todos) > 0:
+            return todos[-1].latest_date 
+        else:
+            return '' 
 
-    # @property
-    # def id_(self):
-    #     for k, v in self.db.tasks.items():
-    #         if v == self:
-    #             return k
 
 
 class Day:
 
-    # def __init__(self, db, todos=None, comment='', date=None):
     def __init__(self, db, date, comment=''):
         self.date = date 
         self.db = db
         self.comment = comment
-        self.archived = True
-        self.todos = {} # legacy
         self.linked_todos_as_list = []
-        # if todos:
-        #     for id_, todo_dict in todos.items():
-        #         self.add_todo(id_, todo_dict)
 
     @classmethod
     def from_dict(cls, db, d, date=None):
-        # todos = {}
         comment = d['comment'] if 'comment' in d.keys() else ''
         day = cls(db, date, comment)
-        # if 'todos' in d.keys():
-        #     for uuid, todo_dict in d['todos'].items():
-        #         day.add_todo(uuid, todo_dict)
-        # if 'linked_todos' in d.keys():
-        for id_ in d['linked_todos']:
-            # if id_ in day.linked_todos.keys():
-            #     continue
-            # if id_ is None:
-            #     continue
-            # linked_todo = db.todos[id_]
-            # linked_todo._day = day 
-            # day.linked_todos_as_list += [linked_todo]
-            day.linked_todos_as_list += [db.todos[id_]]
         return day
 
     def to_dict(self):
-        d = {'comment': self.comment, 'linked_todos': []}
-        for todo_id in self.linked_todos.keys():
-            d['linked_todos'] += [todo_id]
-        # for task_uuid, todo in self.todos.items():
-        # for id_, todo in self.todos.items():
-        # #     d['todos'][task_uuid] = todo.to_dict()
-        #     new_type_todo_id = f'{self.date}_{task_uuid}'
-        #     if not new_type_todo_id in d['linked_todos']:
-        #         # d['linked_todos'] += [todo.id_] 
-        #         d['linked_todos'] += [new_type_todo_id] 
+        d = {'comment': self.comment}
         return d
 
-    # def add_todo(self, task_id, dict_source=None):
-    #     new_type_todo_id = f'{self.date}_{task_id}'
-    #     task = self.db.tasks[task_id]
-    #     if new_type_todo_id in self.db.todos.keys():
-    #         todo = self.db.todos[new_type_todo_id]
-    #     # elif task_id in self.db.keys():
-    #     #     todo = self.db.todos[task_id]
-    #     else:
-    #         # todo = Todo.from_dict(self.db, dict_source, id_=new_type_todo_id) if dict_source else Todo(db=self.db, day=self)
-    #         todo = Todo.from_dict(self.db, dict_source)
-    #     # todo._id = new_type_todo_id
-    #     todo._task = self.db.tasks[task_id] 
-    #     todo._id = new_type_todo_id
-    #     todo._day = self 
-    #     # self.todos[task_id] = todo 
-    #     self.linked_todos_as_list += [todo]
-    #     self.db.todos[new_type_todo_id] = todo
-    #     # self.db.todos[todo.task_id] = [todo]
-    #     # self.db.todos_as_list += [todo]
-    #     # self.db.all_todos[todo.task_id] = todo
-    #     return todo 
-
     @property
     def linked_todos(self):
         linked_todos = {}
@@ -204,7 +228,7 @@ class Day:
                      if self.date in todo.efforts.keys()]:
             day_effort = todo.efforts[self.date]
             if todo.done:
-                s += day_effort if day_effort else todo.task.default_effort_at(self.date)
+                s += day_effort if day_effort else todo.task.default_effort.at(self.date)
             elif include_undone:
                 s += day_effort if day_effort else 0 
         return s
@@ -213,98 +237,171 @@ class Day:
     def todos_sum(self):
         return self._todos_sum()
 
-    # @property
-    # def todos_sum2(self):
-    #     return self._todos_sum(True)
+    def sorted_todos(self, done, is_tree_shaped, sort_order, legal_keys):
+        todos = [t for t in self.linked_todos_as_list if t.visible and t.done == done]
+        reverse = False
+        sort_column = sort_order[:]
+        if sort_order and '-' == sort_order[0]:
+            reverse = True
+            sort_column = sort_order[1:]
+        if sort_column in legal_keys:
+            todos.sort(key=lambda t: getattr(t, sort_column))
+        if reverse:
+            todos.reverse()
+        if is_tree_shaped:
+            def walk_tree(todo, sorted_todos):
+                todo.deps = [t for t in sorted_todos if t in todo.deps]
+                for dep in [t for t in sorted_todos if t in todo.deps]:
+                    walk_tree(dep, sorted_todos)
+            if done:
+                trunk = [t for t in todos if len([td for td in t.dependers if td.done]) == 0]
+            else:
+                trunk = [t for t in todos if len(t.dependers) == 0]
+            for node in trunk:
+                walk_tree(node, todos)
+            todos = trunk 
+        return todos
 
-    # @property
-    # def date(self):
-    #     if self._date:
-    #         return self._date
-    #     else:
-    #         for k, v in self.db.days.items():
-    #             # print("DEBUG date", k, v)
-    #             if v == self:
-    #                 return k
-    #     print("DEBUG FAIL", self.test_date, self)
+    @property
+    def visible_in_export(self):
+        return len(self.comment) + len([t for t in self.linked_todos_as_list if t.visible]) > 0
 
 
-class Todo:
 
-    # def __init__(self, db, id_, task, done=False, day_effort=None, comment='', day_tags=None, importance=1.0, efforts=None):
-    def __init__(self, db, id_, task, done=False, comment='', day_tags=None, importance=1.0, efforts=None, children=None):
-        self.id_ = id_
-        self.db = db 
+class Todo(TaskLike):
+
+    def __init__(self,
+                 db,
+                 id_,
+                 task,
+                 done=False,
+                 comment='',
+                 day_tags=None,
+                 importance=1.0,
+                 efforts=None,
+                 dep_ids=None):
+        super().__init__(db, id_, comment)
         self.task = task 
-        self.done = done
-        # self.day_effort = day_effort
+        self._done = done
+        for k in efforts.keys():
+            try:
+                datetime.strptime(k, DATE_FORMAT)
+            except ValueError:
+                raise PlomException(f'Todo creation: bad date string: {k}')
         self.efforts = efforts if efforts else {}
-        self.comment = comment
         self.day_tags = day_tags if day_tags else set()
         self.importance = importance
-        self.children = children if children else [] 
-        self.parent = None 
+        self.dep_ids = dep_ids if dep_ids else set() 
+        self.already_listed = False
+        self.been_observed = False 
 
     @classmethod
     def from_dict(cls, db, d, id_):
-        # todo = cls(db, None, None, d['done'], d['day_effort'], d['comment'], set(d['day_tags']), d['importance'])
-        # todo._task = db.tasks[d['task']] if 'task' in d.keys() else None
-        # todo._efforts = d['efforts'] if 'efforts' in d.keys() else None
-        # todo = cls(db, id_, db.tasks[d['task']], d['done'], d['day_effort'], d['comment'], set(d['day_tags']), d['importance'], d['efforts'])
-        todo = cls(db, id_, db.tasks[d['task']], d['done'], d['comment'], set(d['day_tags']), d['importance'], d['efforts'])
-        if 'children' in d:
-            todo.children = d['children']
+        todo = cls(
+                db,
+                id_,
+                db.tasks[d['task']],
+                d['done'],
+                d['comment'],
+                set(d['day_tags']),
+                d['importance'],
+                d['efforts'],
+                set(d['deps']))
         return todo
 
-    # @classmethod
-    # def OLD_from_dict(cls, day, d):
-    #     todo = cls(day, d['done'], d['day_effort'], d['comment'], set(d['day_tags']), d['importance'])
-    #     if 'efforts' in d.keys():
-    #         todo._efforts = d['efforts']
-    #     return todo
-
     def to_dict(self):
-        # return {'task': self.task.id_, 'done': self.done, 'day_effort': self.day_effort, 'comment': self.comment, 'day_tags': list(self.day_tags), 'importance': self.importance, 'efforts': self.efforts}
-        return {'task': self.task.id_, 'done': self.done, 'comment': self.comment, 'day_tags': list(self.day_tags), 'importance': self.importance, 'efforts': self.efforts, 'children': self.children}
+        return {
+                'task': self.task.id_,
+                'done': self.done,
+                'comment': self.comment,
+                'day_tags': list(self.day_tags),
+                'importance': self.importance,
+                'efforts': self.efforts,
+                'deps': list(self.dep_ids)}
+
+    @property
+    def title(self):
+        return self.task.title.at(self.db.selected_date)
+
+    @property
+    def dated_title(self):
+        return f'{self.earliest_date}:{self.title}'
+
+    @property
+    def deps(self):
+        return [self.db.todos[id_] for id_ in self.dep_ids]
+
+    @deps.setter
+    def deps(self, deps):
+        self.dep_ids = {dep.id_ for dep in deps}
 
     @property
     def default_effort(self):
-        return self.task.default_effort_at(self.sorted_effort_dates[0])
-
-    # @property
-    # def effort(self):
-    #     if self.day_effort:
-    #         return self.day_effort
-    #     else:
-    #         return self.day_effort if self.day_effort else self.default_effort
-
-    # @property
-    # def task(self):
-    #     if self._task:
-    #         return self._task
-    #     # else:
-    #     #     for k, v in self.day.todos.items():
-    #     #         if v == self:
-    #     #             return self.db.tasks[k]
+        return self.task.default_effort.at(self.earliest_date)
 
-    def is_effort_removable(self, date):
-        if not date in self.efforts.keys():
-            return False
-        # if len(self.efforts) == 1:
-        #     return False
-        if self.efforts[date]:
-            return False
-        if self.done and date == self.sorted_effort_dates[-1]:
-            return False
+    @property
+    def done(self):
+        return self.deps_done and self._done
+
+    @done.setter
+    def done(self, doneness):
+        self._done = doneness
+
+    @property
+    def deps_done(self):
+        if len(self.deps) > 0:
+            for dep in self.deps:
+                if not dep.done:
+                    return False
         return True
 
     @property
-    def total_effort(self):
+    def dep_efforts(self):
+        dep_efforts = 0
+        if self.deps:
+            for dep in self.deps: 
+                dep_efforts += dep.all_days_effort
+                dep_efforts += dep.dep_efforts
+        return dep_efforts
+
+    def depender_path(self, dep):
+        if self.dependers:
+            return f'Y{depender.depender_path()}:{self.title}Y'
+        else:
+            return f'X{self.title}X'
+
+    @property
+    def depender_paths(self):
+        paths = []
+        for depender in self.dependers:
+            if len(depender.depender_paths) == 0:
+                 paths += [[depender]]
+            else:
+                for path in depender.depender_paths:
+                    paths += [path + [depender]] 
+        return paths
+
+    @property
+    def shortened_depender_paths(self):
+        new_paths = []
+        for path in self.depender_paths:
+            new_path = []
+            for i, step in enumerate(path):
+                next_step = None if len(path) <= i+1 else path[i+1]
+                for distinct_path in new_paths:
+                    if len(distinct_path) >= i+2 and distinct_path[i+1] == next_step:
+                        step = None
+                new_path += [step]
+            new_paths += [new_path]
+        return new_paths
+
+    @property
+    def all_days_effort(self):
         total = 0
         for effort in self.efforts.values():
             total += effort if effort else 0
         if self.done:
-            total = max(total, self.task.default_effort_at(self.sorted_effort_dates[-1]))
+            total = max(total, self.task.default_effort.at(self.latest_date))
         return total
 
     def matches(self, search):
@@ -313,37 +410,34 @@ class Todo:
         else:
             return search in self.comment or search in '$'.join(self.tags) or search in self.title
 
-    @property
-    def title(self):
-        return self.task.title_at(self.sorted_effort_dates[0])
-
-    @property
-    def path(self):
-        path = ''
-        if self.parent:
-            path = f'{self.parent.path}{self.parent.title}:'
-        return path
+    def is_effort_removable(self, date):
+        if not date in self.efforts.keys():
+            return False
+        if self.efforts[date]:
+            return False
+        if self.done and date == self.latest_date:
+            return False
+        return True
 
     @property
     def tags(self):
-        return self.day_tags | self.task.tags
-
-    # def internals_empty(self):
-    #     return len(self.comment) == 0 and len(self.day_tags) == 0
-
-    # def ensure_day_efforts_table(self):
-    #     # We don't do this yet at __init__ because self.day.date is unknown, since Todo may be imported with Day, and during the import process the Day is not yet keyed in TodoDB.days.
-    #     if not hasattr(self, '_efforts'):
-    #         self._efforts = {} # {self.day.date: self.day_effort}
-
-    # def set_day_effort(self, date, effort):
-    #     self.ensure_day_efforts_table()
-    #     self._efforts[date] = self.day_effort
+        return self.day_tags | self.task.tags.now
 
     @property
     def day_effort(self):
         return self.efforts[self.db.selected_date]
 
+    @property
+    def effort_at_selected_date(self):
+        if self.db.selected_date in self.efforts.keys() and self.day_effort is not None:
+            return self.day_effort 
+        else:
+            return self.task.default_effort.then
+
+    @property
+    def day(self):
+        return self.db.days[self.earliest_date]
+
     @property
     def sorted_effort_dates(self):
         dates = list(self.efforts.keys())
@@ -351,100 +445,118 @@ class Todo:
         return dates
 
     @property
-    def day(self):
-        if len(self.efforts) == 0:
-            return None
-        todo_start_date = self.sorted_effort_dates[0]
-        return self.db.days[todo_start_date]
-
-    # @property
-    # def efforts(self):
-    #     self.ensure_day_efforts_table()
-    #     return self._efforts
-
-    # @property
-    # def id_(self):
-    #     if self._id:
-    #         return self._id
-    #     for k, v in self.db.todos.items():
-    #         if v == self:
-    #             return k
-    #     # return f'{self.day.date}_{self.task.id_}'
+    def earliest_date(self):
+        return self.sorted_effort_dates[0]
+
+    @property
+    def latest_date(self):
+        return self.sorted_effort_dates[-1]
+
+    @property
+    def has_dependers(self):
+        return len(self.dependers) > 0
+
+    @property
+    def dependers(self):
+        return [t for t in self.db.todos.values() if self.id_ in t.dep_ids]
+
+    @property
+    def has_deps(self):
+        return len(self.deps) > 0
+
+    @property
+    def sort_done(self):
+        return self.day_effort if self.day_effort else 0 
+
+    @property
+    def family_effort(self):
+        return self.effort_at_selected_date + self.dep_efforts
+
+    def closest_adoptable(self, task_id):
+        print("DEBUG closest_adoptable", self.id_)
+        ranked_adoptables = {self.id_: 0} 
+        def collect_downwards(node, ranked_adoptables, n_steps):
+            print("debug called collect_downwards", node.title, n_steps)
+            if not node.id_ in ranked_adoptables.keys():
+                ranked_adoptables[node.id_] = n_steps
+            for dep in node.deps:
+                collect_downwards(dep, ranked_adoptables, n_steps+1)
+        def collect_upwards(node, adoptables, n_steps):
+            print("debug called collect_upwards", node.title, n_steps)
+            collect_downwards(node, ranked_adoptables, n_steps+1)
+            if not node.task.fences_adoptions.now:
+                print("debug not blocking", node.dependers)
+                for depender in node.dependers:
+                    collect_upwards(depender, ranked_adoptables, n_steps+1)
+                if len(node.dependers) == 0:
+                    print("debug NO DEPENDERS, calling day")
+                    for t in self.db.days[self.latest_date].linked_todos_as_list:
+                        print("debug linked_todos_as_list:", t.title, t.id_)
+                        collect_downwards(t, ranked_adoptables, n_steps)
+            else:
+                print("debug BLOCKING")
+        collect_upwards(self, ranked_adoptables, 0)
+        # for depender in self.dependers:
+        #     collect_upwards(depender, ranked_adoptables, 0)
+        del ranked_adoptables[self.id_]
+        for id_, distance in sorted(ranked_adoptables.items(), key=lambda i:i[1], reverse=True):
+            if self.db.todos[id_].task.id_ == task_id:
+                return self.db.todos[id_]
+        return None
+
+
+    def observe(self):
+        self.been_observed = True
+        return '' 
+
 
 
 class TodoDB(PlomDB):
 
-    def __init__(self, prefix, selected_date=None, t_filter_and = None, t_filter_not = None, hide_unchosen=False, hide_done=False):
-        self.prefix = prefix
-        self.selected_date = selected_date if selected_date else str(datetime.now())[:10]
-        self.t_filter_and = t_filter_and if t_filter_and else []
-        self.t_filter_not = t_filter_not if t_filter_not else []
-        self.hide_unchosen = hide_unchosen
-        self.hide_done = hide_done
+    def __init__(self,
+            selected_date=None,
+            tag_filter_and = None,
+            tag_filter_not = None):
+        self.selected_date = selected_date if selected_date else today_date()
+        self.tag_filter_and = tag_filter_and if tag_filter_and else []
+        self.tag_filter_not = tag_filter_not if tag_filter_not else []
+
         self.days = {}
         self.tasks = {}
         self.t_tags = set()
         self.todos = {}
         super().__init__(db_path)
 
+    # savefile I/O
+
     def read_db_file(self, f):
         d = json.load(f)
+
         for id_, t_dict in d['tasks'].items():
             t = self.add_task(id_=id_, dict_source=t_dict)
-            for tag in t.tags:
+            for tag in t.tags.now:
                 self.t_tags.add(tag)
-        # if 'todos' in d.keys():
+        # for task in self.tasks.values():
+        #     for dep in task.deps:
+        #         dep.dependers += [task]
+
         for id_, todo_dict in d['todos'].items():
-            # todo = Todo.from_dict(self, todo_dict, id_)
-            # todo._id = id_ 
-            # self.todos[id_] = todo
-            todo = self.add_todo(todo_dict, id_) # Todo.from_dict(self, todo_dict, id_)
-            self.todos[id_] = todo 
+            todo = self.add_todo(todo_dict, id_)
             for tag in todo.day_tags:
                 self.t_tags.add(tag)
+        # for todo in self.todos.values():
+        #     for dep in todo.deps:
+        #         dep.dependers += [todo]
+
         for date, day_dict in d['days'].items():
             self.add_day(dict_source=day_dict, date=date)
         for todo in self.todos.values():
-            for child_id in todo.children:
-                self.todos[child_id].parent = todo
-            # if len(todo.efforts) == 0:
-            #     print("DEBUG", todo.id_, todo.task.title, todo.efforts)
             for date in todo.efforts.keys():
                 if not date in self.days.keys():
                     self.add_day(date)
-                if not todo in self.days[date].linked_todos_as_list:
-                    self.days[date].linked_todos_as_list += [todo]
-                    # print("DEBUG", todo.title, date)
-                # if type(todo.efforts[date]) == str:
-                #     todo.efforts[date] = float(todo.efforts[date])
-                #     print("DEBUG", todo.title, date, todo.efforts[date])
-        # for todo in self.todos.values():
-        # for day in self.days.values():
-        #     for todo in day.todos.values():
-        #         for tag in todo.day_tags:
-        #             self.t_tags.add(tag)
-        # delete = None
-        # for todo in self.todos.values():
-        #     if len(todo.efforts) == 0:
-        #         print("DEBUG", todo.task.title)
-        #         delete = todo.id_ 
-        # self.delete_todo(delete)
-        self.set_visibilities()
+                self.days[date].linked_todos_as_list += [todo]
 
-    def set_visibilities(self):
-        for uuid, t in self.tasks.items():
-            t.visible = len([tag for tag in self.t_filter_and if not tag in t.tags]) == 0\
-                    and len([tag for tag in self.t_filter_not if tag in t.tags]) == 0\
-                    and ((not self.hide_unchosen) or uuid in self.selected_day.todos.keys())
-        # for day in self.days.values():
-        #     for todo in day.todos.values():
-        #         todo.visible = len([tag for tag in self.t_filter_and if not tag in todo.day_tags | todo.task.tags ]) == 0\
-        #             and len([tag for tag in self.t_filter_not if tag in todo.day_tags | todo.task.tags ]) == 0\
-        #             and ((not self.hide_done) or (not todo.done))
-        for todo in self.todos.values():
-            todo.visible = len([tag for tag in self.t_filter_and if not tag in todo.day_tags | todo.task.tags ]) == 0\
-                and len([tag for tag in self.t_filter_not if tag in todo.day_tags | todo.task.tags ]) == 0\
-                and ((not self.hide_done) or (not todo.done))
+        # self.set_visibilities()
 
     def to_dict(self):
         d = {'tasks': {}, 'days': {}, 'todos': {}}
@@ -452,26 +564,10 @@ class TodoDB(PlomDB):
              d['tasks'][uuid] = t.to_dict()
         for date, day in self.days.items():
             d['days'][date] = day.to_dict()
-            for todo in day.todos.values():
-                d['todos'][todo.id_] = todo.to_dict()
         for id_, todo in self.todos.items():
             d['todos'][id_] = todo.to_dict()
         return d
 
-    # @property
-    # def all_todos(self):
-    #     todos = {}
-    #     for todo in self.todos_as_list:
-    #         todos[todo.id_] = todo
-    #     return todos 
-
-    @property
-    def selected_day(self):
-        if not self.selected_date in self.days.keys():
-            self.days[self.selected_date] = self.add_day(date=self.selected_date)
-            # print("DEBUG selected_day", self.days[self.selected_date].date)
-        return self.days[self.selected_date]
-
     def write(self):
         dates_to_purge = []
         for date, day in self.days.items():
@@ -481,193 +577,127 @@ class TodoDB(PlomDB):
             del self.days[date]
         self.write_text_to_db(json.dumps(self.to_dict()))
 
-    def add_task(self, id_=None, dict_source=None, return_id=False):
+    # properties 
+
+    @property
+    def selected_day(self):
+        if not self.selected_date in self.days.keys():
+            self.days[self.selected_date] = self.add_day(date=self.selected_date)
+        return self.days[self.selected_date]
+
+    # table manipulations 
+
+    def add_day(self, date, dict_source=None):
+        day = Day.from_dict(self, dict_source, date) if dict_source else Day(self, date)
+        self.days[date] = day 
+        return day
+
+    def add_task(self, id_=None, dict_source=None):
         id_ = id_ if id_ else str(uuid4())
         t = Task.from_dict(self, dict_source, id_) if dict_source else Task(self, id_)
         self.tasks[id_] = t
-        if return_id:
-            return id_, t
-        else:
-            return t
+        return t
 
-    def add_todo(self, todo_dict=None, id_=None, task=None, efforts=None):
+    def fork_task(self, id_):
+        origin = self.tasks[id_]
+        now = today_date(with_time=True)
+        fork_id = str(uuid4())
+        fork = Task(self, fork_id, {}, {}, {}, {}, origin.comment, id_)
+        self.tasks[fork_id] = fork
+        return fork
+
+    def update_task(self, id_, title, default_effort, tags, fences_adoptions, comment, dep_ids, depender_ids):
+        task = self.tasks[id_] if id_ in self.tasks.keys() else self.add_task(id_)
+        task.title.set(title)
+        task.default_effort.set(default_effort)
+        task.tags.set(tags)
+        task.fences_adoptions.set(fences_adoptions)
+        task.comment = comment 
+        task.dep_ids.set(dep_ids)
+        for depender in task.dependers:
+            if not depender.id_ in depender_ids:
+                depender_dep_ids = depender.dep_ids.now
+                depender_dep_ids.remove(task.id_)
+                depender.dep_ids.set(depender_dep_ids)
+        for depender_id in depender_ids:
+            depender = self.tasks[depender_id]
+            depender_dep_ids = depender.dep_ids.now
+            depender_dep_ids.add(task.id_)
+            depender.dep_ids.set(depender_dep_ids)
+        task.loop_check()
+        return task
+
+    def add_todo(self, todo_dict=None, id_=None, task=None, efforts=None, parenthood='', force_new=False, creator=None):
+        make_children = parenthood != 'childless'
+        adopt_if_possible = parenthood == 'adoption'
         id_ = id_ if id_ else str(uuid4())
         if todo_dict:
             todo = Todo.from_dict(self, todo_dict, id_)
+            self.todos[id_] = todo
         elif task and efforts:
             todo = Todo(self, id_, task, efforts=efforts)
-            children = []
-            for child_id in task.links:
-                child_task = self.tasks[child_id]
-                children += [self.add_todo(task=child_task, efforts=efforts)]
-            todo.children = [child.id_ for child in children]
-        self.todos[id_] = todo 
+            print("DEBUG calling add_todo for", task.title.now, id_) 
+            print("debug creator:", creator) 
+            self.todos[id_] = todo
+            if creator:
+                creator.deps += [todo]
+            # deps = []
+            if make_children and todo.latest_date in self.days.keys():
+                for dep_task in task.deps:
+                    # if Todo expects dependencies, adopt any compatibles found in DB.selected_date
+                    # before creating new depended Todos
+                    dep_todo = None
+                    # if not force_new:
+                    if adopt_if_possible:
+                        print("debug trying adoption for", dep_task.title.now)
+                        # adoptable_todos = [t for t in self.days[todo.latest_date].linked_todos_as_list
+                        #                    if t.task.id_ == dep_task.id_]
+                        # if len(adoptable_todos) > 0:
+                        #     dep_todo = adoptable_todos[0]
+                        dep_todo = todo.closest_adoptable(dep_task.id_)
+                        print("debug GOT ADOPTION", dep_todo)
+                    if not dep_todo:
+                        # dep_todo = self.add_todo(task=dep_task, efforts=efforts, force_new)
+                        print("debug no adoption for", dep_task.title.now, id_)
+                        dep_todo = self.add_todo(task=dep_task, efforts=efforts, parenthood=parenthood, creator=todo)
+                    todo.deps += [dep_todo]
+                    # deps += [dep_todo]
+            # todo.deps = deps 
+        for date in todo.efforts.keys():
+            if date in self.days.keys():  # possibly not all Days have been initialized yet
+                self.days[date].linked_todos_as_list += [todo] 
         return todo
 
-    def add_day(self, date, dict_source=None):
-        day = Day.from_dict(self, dict_source, date) if dict_source else Day(self, date)
-        self.days[date] = day 
-        return day
-
-    # def show_day(self, task_sort=None):
-    #     task_sort = task_sort if task_sort else 'title' 
-    #     current_date = datetime.strptime(self.selected_date, DATE_FORMAT)
-    #     prev_date = current_date - timedelta(days=1)
-    #     prev_date_str = prev_date.strftime(DATE_FORMAT)
-    #     next_date = current_date + timedelta(days=1)
-    #     next_date_str = next_date.strftime(DATE_FORMAT)
-    #     task_rows = []
-    #     for uuid, task in self.tasks.items():
-    #         if not task.visible:
-    #             continue
-    #         todo = None
-    #         if uuid in self.selected_day.todos.keys():
-    #             todo = self.selected_day.todos[uuid]
-    #             if not todo.visible:
-    #                 continue
-    #         task_rows += [{'uuid': uuid, 'task': task, 'todo': todo}] 
-    #     if task_sort == 'title':
-    #         task_rows.sort(key=lambda r: r['task'].title)
-    #     elif task_sort == 'default_effort':
-    #         task_rows.sort(key=lambda r: r['task'].default_effort, reverse=True)
-    #     elif task_sort == 'done':
-    #         task_rows.sort(key=lambda r: 0 if not r['todo'] else r['todo'].day_effort if r['todo'].day_effort else r['task'].default_effort if r['todo'].done else 0, reverse=True)
-    #     elif task_sort == 'importance':
-    #         task_rows.sort(key=lambda r: 0.0 if not r['todo'] else r['todo'].importance, reverse=True)
-    #     elif task_sort == 'chosen':
-    #         task_rows.sort(key=lambda r: False if not r['todo'] else True, reverse=True)
-    #     elif task_sort == 'comment':
-    #         task_rows.sort(key=lambda r: '' if not r['todo'] else r['todo'].comment, reverse=True)
-    #     done_tasks = []
-    #     for uuid, task in self.tasks.items():
-    #         if uuid in self.selected_day.todos.keys():
-    #             todo = self.selected_day.todos[uuid]
-    #             if todo.done:
-    #                 done_tasks += [todo]
-    #     done_tasks.sort(key=lambda t: t.effort, reverse=True)
-    #     return j2env.get_template('day.html').render(db=self, action=self.prefix+'/day', prev_date=prev_date_str, next_date=next_date_str, task_rows=task_rows, sort=task_sort, done_tasks=done_tasks)
-
-    def neighbor_dates(self):
-        current_date = datetime.strptime(self.selected_date, DATE_FORMAT)
-        prev_date = current_date - timedelta(days=1)
-        prev_date_str = prev_date.strftime(DATE_FORMAT)
-        next_date = current_date + timedelta(days=1)
-        next_date_str = next_date.strftime(DATE_FORMAT)
-        return prev_date_str, next_date_str
-
-    def show_do_day(self, sort_order=None):
-        prev_date_str, next_date_str = self.neighbor_dates()
-        todos = [t for t in self.selected_day.linked_todos_as_list if t.visible]
-        if sort_order == 'title':
-            todos.sort(key=lambda t: t.task.title)
-        elif sort_order == 'done':
-            todos.sort(key=lambda t: t.day_effort if t.day_effort else t.default_effort if t.done else 0, reverse=True)
-        elif sort_order == 'default_effort':
-            todos.sort(key=lambda t: t.default_effort, reverse=True)
-        elif sort_order == 'importance':
-            todos.sort(key=lambda t: t.importance, reverse=True)
-        return j2env.get_template('do_day.html').render(
-                day=self.selected_day,
-                tags=self.t_tags,
-                filter_and=self.t_filter_and,
-                filter_not=self.t_filter_not,
-                prev_date=prev_date_str,
-                next_date=next_date_str,
-                todos=todos,
-                sort=sort_order,
-                hide_done=self.hide_done)
-
-    def show_calendar(self, start_date_str, end_date_str):
-        self.t_filter_and = ['calendar']
-        self.t_filter_not = ['deleted']
-        self.set_visibilities()
-        days_to_show = {}
-        todays_date_str = str(datetime.now())[:10]
-        todays_date_obj = datetime.strptime(todays_date_str, DATE_FORMAT) 
-        yesterdays_date_obj = todays_date_obj - timedelta(1)
-        yesterdays_date_str = yesterdays_date_obj.strftime(DATE_FORMAT) 
-        start_date_obj = datetime.strptime(sorted(self.days.keys())[0], DATE_FORMAT)
-        if start_date_str and len(start_date_str) > 0:
-            if start_date_str in {'today', 'yesterday'}:
-                start_date_obj = todays_date_obj if start_date_str == 'today' else yesterdays_date_obj
-            else:
-                start_date_obj = datetime.strptime(start_date_str, DATE_FORMAT)
-        end_date_obj = datetime.strptime(sorted(self.days.keys())[-1], DATE_FORMAT)
-        if end_date_str and len(end_date_str) > 0:
-            if end_date_str in {'today', 'yesterday'}:
-                end_date_obj = todays_date_obj if end_date_str == 'today' else yesterdays_date_obj
-            else:
-                end_date_obj = datetime.strptime(end_date_str, DATE_FORMAT)
-        for n in range(int((end_date_obj - start_date_obj).days) + 1):
-            current_date_obj = start_date_obj + timedelta(n)
-            current_date_str = current_date_obj.strftime(DATE_FORMAT)
-            if current_date_str not in self.days.keys():
-                days_to_show[current_date_str] = self.add_day(current_date_str)
-            else:
-                days_to_show[current_date_str] = self.days[current_date_str]
-            days_to_show[current_date_str].weekday = datetime.strptime(current_date_str, DATE_FORMAT).strftime('%A')[:2]
-        return j2env.get_template('calendar.html').render(db=self, days=days_to_show, action=self.prefix+'/calendar', start_date=start_date_str, end_date=end_date_str)
-
-    def show_todo(self, id_, return_to):
-        todo = self.todos[id_]
-        # if selected_date not in self.days.keys():
-        #     self.days[selected_date] = self.add_day(test_date=f'3:{selected_date}') 
-        #     # print("DEBUG show_todo", self.days[selected_date].date)
-        # if task_uuid in self.days[selected_date].todos:
-        #     todo = self.days[selected_date].todos[task_uuid]
-        # else:
-        #     todo = self.days[selected_date].add_todo(task_uuid)
-        linked_todos = [self.todos[c] for c in todo.children]
-        filtered_todos = [] #[t for t in self.todos.values() if t.visible and t != self and (t not in linked_todos) and (len(search) == 0 or t.matches(search))] 
-        return j2env.get_template('todo.html').render(
-                db=self,
-                todo=todo,
-                filtered_todos=filtered_todos,
-                linked_todos=linked_todos,
-                return_to=return_to)
-
-    # def update_todo_mini(self, task_uuid, date, day_effort, done, importance):
-    #     if date not in self.days.keys():
-    #         self.days[date] = self.add_day(test_date=f'Y:{date}') 
-    #         # print("DEBUG update_todo_min", self.days[date].date)
-    #     if task_uuid in self.days[date].todos.keys():
-    #         todo = self.days[date].todos[task_uuid]
-    #     else:
-    #         todo = self.days[date].add_todo(task_uuid)
-    #     todo.day_effort = day_effort
-    #     todo.done = done
-    #     todo.importance = importance
-    #     return todo
-
-    def collect_tags(self, tags_joined, tags_checked):
-        tags = set()
-        for tag in [tag.strip() for tag in tags_joined.split(';') if tag.strip() != '']:
-            tags.add(tag)
-        for tag in tags_checked:
-            tags.add(tag)
-        return tags
-
-    def update_todo_for_day(self, id_, date, effort, done, comment, importance):
+    def _update_todo_shared(self, id_, done, comment, importance):
         todo = self.todos[id_]
         todo.done = done
-        todo.efforts[date] = effort 
         todo.comment = comment 
         todo.importance = importance 
+        return todo
 
-    def update_todo(self, id_, efforts, done, comment, day_tags_joined, day_tags_checked, importance):
-        if len(efforts) == 0:
+    def update_todo_for_day(self, id_, date, effort, done, comment, importance):
+        todo = self._update_todo_shared(id_, done, comment, importance)
+        todo.efforts[date] = effort 
+
+    def update_todo(self, id_, efforts, done, comment, tags, importance, deps, depender_ids):
+        todo = self._update_todo_shared(id_, done, comment, importance)
+        if len(efforts) == 0 and not todo.deps:
             raise PlomException('todo must have at least one effort!')
-        todo = self.todos[id_]
-        todo.done = done
         todo.efforts = efforts 
-        for date in todo.efforts:
+        for date in todo.efforts.keys():
             if not date in self.days.keys():
                 self.add_day(date=date) 
             if not self in self.days[date].linked_todos_as_list:
                 self.days[date].linked_todos_as_list += [todo]
-        todo.comment = comment 
-        todo.day_tags = self.collect_tags(day_tags_joined, day_tags_checked) 
-        todo.importance = importance 
+        todo.day_tags = tags
+        todo.deps = deps 
+        for depender_id in depender_ids:
+            depender = self.todos[depender_id]
+            depender.dep_ids.add(todo.id_)
+        for depender in todo.dependers:
+            if not depender.id_ in depender_ids:
+                depender.dep_ids.remove(todo.id_)
+        todo.loop_check()
 
     def delete_todo(self, id_):
         todo = self.todos[id_]
@@ -676,101 +706,313 @@ class TodoDB(PlomDB):
             dates_to_delete += [date]
         for date in dates_to_delete:
             self.delete_effort(todo, date, force=True)
+        for depender in todo.dependers:
+            depender.dep_ids.remove(todo.id_)
         del self.todos[id_]
 
+    def delete_task(self, id_):
+        del self.tasks[id_]
+
     def delete_effort(self, todo, date, force=False):
         if (not force) and len(todo.efforts) == 1:
             raise PlomException('todo must retain at least one effort!')
         self.days[date].linked_todos_as_list.remove(todo)
         del todo.efforts[date]
 
+    # views
+
+    def get_message(self, message):
+        return j2env.get_template('message.html').render(message=message)
+
+    def get_calendar_export(self, start_date_str, end_date_str):
+        days_to_show = self.init_calendar_items(start_date_str, end_date_str)
+        return j2env.get_template('calendar_export.html').render(days=days_to_show)
+
+    def get_calendar(self, start_date_str, end_date_str):
+        days_to_show = self.init_calendar_items(start_date_str, end_date_str)
+        return j2env.get_template('calendar.html').render(
+                selected_date=self.selected_date,
+                days=days_to_show,
+                start_date=start_date_str,
+                end_date=end_date_str)
+
+    def get_day_todos(self, undone_sort_order=None, done_sort_order=None, is_tree_shaped=False, todo_parenthood=None):
+        legal_undone_sort_keys = {'title', 'sort_done', 'default_effort', 'importance'} 
+        legal_done_sort_keys = {'title', 'effort_at_selected_date', 'family_effort'} 
+
+        current_date = datetime.strptime(self.selected_date, DATE_FORMAT)
+        prev_date = current_date - timedelta(days=1)
+        prev_date_str = prev_date.strftime(DATE_FORMAT)
+        next_date = current_date + timedelta(days=1)
+        next_date_str = next_date.strftime(DATE_FORMAT)
+
+        adoptable_past_todos = []
+        for todo in [t for t in self.todos.values()
+                     if t.visible
+                     and (not t.done)
+                     and t.earliest_date < self.selected_date]:
+             adoptable_past_todos += [todo] 
+        undone_todos = self.selected_day.sorted_todos(False, is_tree_shaped, undone_sort_order,
+                                                      legal_undone_sort_keys)
+        done_todos = self.selected_day.sorted_todos(True, is_tree_shaped, done_sort_order,
+                                                    legal_done_sort_keys)
+
+        return j2env.get_template('day_todos.html').render(
+                day=self.selected_day,
+                tags=self.t_tags,
+                filter_and=self.tag_filter_and,
+                filter_not=self.tag_filter_not,
+                prev_date=prev_date_str,
+                adoptable_past_todos=adoptable_past_todos,
+                next_date=next_date_str,
+                all_tasks=[t for t in self.tasks.values()],
+                undone_todos=undone_todos,
+                done_todos=done_todos,
+                is_tree_shaped=is_tree_shaped,
+                undone_sort=undone_sort_order,
+                done_sort=done_sort_order,
+                parenthood=todo_parenthood)
+
+    def get_todo(self, id_, parenthood):
+        todo = self.todos[id_]
+        filtered_tasks = [t for t in self.tasks.values()
+                          if t != todo.task] 
+        filtered_todos = [t for t in self.todos.values()
+                          if t != todo
+                          and t not in todo.deps]
+
+        legal_dates = list(todo.efforts.keys())
+        date_filtered_todos = [] 
+        for date in legal_dates:
+            for filtered_todo in filtered_todos:
+                if filtered_todo in date_filtered_todos:
+                    continue
+                if date in filtered_todo.efforts.keys():
+                    date_filtered_todos += [filtered_todo]
+
+        dep_slots = []
+        for dep in todo.task.deps:
+            dep_slots += [{'task': dep,
+                               'todos': [t for t in todo.deps if t.task == dep]}]
+
+        suggested_todos = {}
+        for dep in todo.task.deps:
+            suggested_todos[dep.id_] = [t for t in date_filtered_todos if t.task.id_ == dep.id_]
+        additional_deps = [t for t in todo.deps if not t.task in todo.task.deps]
+
+        return j2env.get_template('todo.html').render(
+                tags=self.t_tags,
+                todo=todo,
+                filtered_todos=date_filtered_todos,
+                filtered_tasks=filtered_tasks,
+                dep_slots=dep_slots,
+                suggested_todos=suggested_todos,
+                additional_deps=additional_deps,
+                parentood=parenthood, 
+                dep_todos=todo.deps)
+
+    def get_task(self, id_):
+        if id_:
+            if not id_ in self.tasks.keys():
+                raise PlomException('no Task for ID')
+            task = self.tasks[id_]
+        else:
+            task = self.add_task()
+        if not id_:
+            task.default_effort.set(1.0)
+        filtered_tasks = [t for t in self.tasks.values()
+                          if t != task
+                          and (t not in task.deps)]
 
-    # def update_todo(self, task_uuid, date, day_effort, done, comment, day_tags_joined, day_tags_checked, importance):
-    #     day_effort = float(day_effort) if len(day_effort) > 0 else None
-    #     importance = float(importance)
-    #     todo = self.update_todo_mini(task_uuid, date, day_effort, done, importance)
-    #     todo.comment = comment
-    #     todo.day_tags = self.collect_tags(day_tags_joined, day_tags_checked) 
-
-    # def link_day_with_todo(self, date, todo_id):
-    #     print("DEBUG link", date, todo_id)
-    #     todo_creation_date, task_uuid = todo_id.split('_')
-    #     todo = self.days[todo_creation_date].todos[task_uuid]
-    #     if date in todo.efforts.keys():
-    #         raise PlomException('todo already linked to respective day')
-    #     todo.set_day_effort(date, None)
-    #     if date not in self.days.keys():
-    #         print("DEBUG link_day_with_todo", date)
-    #         self.days[date] = self.add_day(test_date=f'Z:{date}') 
-    #     self.days[date].linked_todos_as_list += [todo]
-    #     print("DEBUG", date, self.days[date].linked_todos)
-
-    def show_task(self, id_, return_to='', search=''):
-        task = self.tasks[id_] if id_ else self.add_task()
-        selected = task.id_ in self.selected_day.todos.keys()
-        linked_tasks = [self.tasks[l] for l in task.links]
-        filtered_tasks = [t for t in self.tasks.values() if t.visible and t != self and (t not in linked_tasks) and (len(search) == 0 or t.matches(search))] 
         return j2env.get_template('task.html').render(
-                db=self,
-                search=search,
+                selected_date=self.selected_date,
                 tags=self.t_tags, 
-                filter_and=self.t_filter_and,
-                filter_not=self.t_filter_not,
                 filtered_tasks=filtered_tasks,
-                linked_tasks=linked_tasks,
-                task=task,
-                return_to=return_to)
+                task=task)
+
+    def get_tasks(self, search, sort_order=None):
+        filtered_tasks = [] 
+        for task in [t for t in self.tasks.values() if (not search) or t.matches(search)]:
+            filtered_tasks += [task]
+        reverse = False
+        sort_column = sort_order 
+        if sort_order and '-' == sort_order[0]:
+            reverse = True
+            sort_column = sort_order[1:]
+        if sort_column == 'title':
+            filtered_tasks.sort(key=lambda t: t.title.now)
+        elif sort_column == 'default_effort':
+            filtered_tasks.sort(key=lambda t: t.default_effort.now)
+        elif sort_column == 'weight':
+            filtered_tasks.sort(key=lambda t: t.deps_weight)
+        elif sort_column == 'latest_effort_date':
+            filtered_tasks.sort(key=lambda t: t.latest_effort_date)
+        if reverse:
+            filtered_tasks.reverse()
+        return j2env.get_template('tasks.html').render(
+                sort=sort_order,
+                tasks=filtered_tasks,
+                tags=self.t_tags,
+                filter_and=self.tag_filter_and,
+                filter_not=self.tag_filter_not,
+                search=search)
 
-    def update_task(self, id_, title, default_effort, tags_joined, tags_checked, links, comment):
-        task = self.tasks[id_] if id_ in self.tasks.keys() else self.add_task(id_)
-        task.title = title
-        task.default_effort = float(default_effort) if len(default_effort) > 0 else None
-        task.tags = self.collect_tags(tags_joined, tags_checked) 
-        task.links = links
-        task.comment = comment 
+    # posts
 
-    def show_tasks(self, expand_uuid):
-        expanded_tasks = {}
-        if expand_uuid:
-            for uuid in self.tasks[expand_uuid].links:
-                expanded_tasks[uuid] = self.tasks[uuid]
-        return j2env.get_template('tasks.html').render(db=self, action=self.prefix+'/tasks', expand_uuid=expand_uuid, expanded_tasks=expanded_tasks)
-
-    def show_new_day(self, search, hide_chosen_tasks, sort_order=None):
-        prev_date_str, next_date_str = self.neighbor_dates()
-        chosen_todos = self.selected_day.linked_todos_as_list
-        relevant_todos = []
-        for todo in self.todos.values():
-            if todo.done or (not todo.visible) or (not todo.matches(search)) or todo in self.selected_day.linked_todos_as_list: # or todo.day.date == self.selected_day.date:  # TODO or todo is linked by day  
+    def post_todo(self, id_, postvars, todo_parenthood):
+        if postvars.has('delete') and (not id_ in self.todos.keys()):
+            raise PlomException('can only do this on Todo that already exists')
+        old_todo = self.todos[id_] if id_ in self.todos.keys() else None
+        latest_date = self.selected_date 
+        efforts = {}
+        for i, date in enumerate(postvars.get_all('effort_date', [])):
+            if '' == date:
                 continue
-            relevant_todos += [todo] 
-        tasks = []
-        chosen_tasks = [todo.task for todo in self.selected_day.linked_todos_as_list]
-        for uuid, task in self.tasks.items():
-            if (not task.visible) or (not task.matches(search)) or (hide_chosen_tasks and task in chosen_tasks):
+            latest_date = date
+            efforts[date] = postvars.get_at_index('effort', i, float_if_possible=True)
+        if postvars.has('delete'): 
+            raise PlomException('can only do this on Task that already exists')
+            has_day_effort = len([e for e in efforts.values() if e is not None]) > 0
+            if postvars.has('done')\
+                    or postvars.get('comment')\
+                    or postvars.get_all('tag', [])\
+                    or has_day_effort:
+                raise PlomException('will not remove todo of preserve-worthy values')
+            self.delete_todo(id_) 
+            return False
+        elif postvars.has('update'):
+            if postvars.has('delete_effort'):
+                for date in postvars.get_all('delete_effort'):
+                    self.delete_effort(old_todo, date)
+                    del efforts[date]
+            deps = [self.todos[adopt_id] for adopt_id in postvars.get_all('adopt_dep', [])
+                    if adopt_id in self.todos.keys()] 
+            birth_dep_ids = postvars.get_all('birth_dep', [])
+            for bad_id in [bad_id for bad_id in birth_dep_ids if not bad_id in self.tasks.keys()]:
+                raise PlomException('submitted illegal dep ID')
+            tasks_to_birth = [self.tasks[dep_id] for dep_id in birth_dep_ids]
+            for task in tasks_to_birth:
+                deps += [self.add_todo(task=task,
+                                       efforts={latest_date: None},
+                                       parenthood=todo_parenthood)]
+            depender_ids = postvars.get_all('depender', [])
+            self.update_todo(id_=id_,
+                             efforts=efforts,
+                             done=postvars.has('done'),
+                             comment=postvars.get('comment', ''),
+                             tags=postvars.get_all('tag', []),
+                             importance=postvars.get('importance', float_if_possible=True),
+                             deps=deps,
+                             depender_ids=depender_ids)
+        return True 
+
+    def post_task(self, id_, postvars):
+           if (postvars.has('delete') or postvars.has('fork')) and (not id_ in self.tasks.keys()):
+               raise PlomException('can only do this on Task that already exists')
+           if postvars.has('delete'):
+               if [t for t in self.todos.values() if id_ == t.task.id_]:
+                   raise PlomException('will not remove Task describing existing Todos')
+               if postvars.get('title', '')\
+                       or postvars.get_all('tag', [])\
+                       or postvars.get_all('dep', [])\
+                       or postvars.get('comment', ''):
+                   raise PlomException('will not remove Task of preserve-worthy values')
+               self.delete_task(id_)
+               return None 
+           elif postvars.has('update'):
+               dep_ids = postvars.get_all('dep', [])
+               for bad_id in [bad_id for bad_id in dep_ids if not bad_id in self.tasks.keys()]:
+                   raise PlomException('submitted illegal dep ID')
+               depender_ids = postvars.get_all('depender', [])
+               for bad_id in [bad_id_ for bad_id in depender_ids if not bad_id in self.tasks.keys()]:
+                   raise PlomException('submitted illegal dep ID')
+               task = self.update_task(
+                       id_=id_,
+                       title=postvars.get('title', ''),
+                       default_effort=postvars.get('default_effort', float_if_possible=True), 
+                       tags=postvars.get_all('tag', []),
+                       comment=postvars.get('comment', ''),
+                       fences_adoptions=postvars.get('fences_adoptions', False),
+                       dep_ids=dep_ids,
+                       depender_ids=depender_ids)
+               if postvars.has('add_as_todo'):
+                   self.add_todo(task=task, efforts={postvars.get('new_todo_date'): None})
+           elif postvars.has('fork'):
+               t = self.fork_task(id_)
+               return t.id_
+           return id_
+
+    def post_day_todos(self, postvars, todo_parenthood):
+        if not postvars.has('update'):
+            return
+        self.selected_date = postvars.get('date') 
+        self.selected_day.comment = postvars.get('day_comment', '') 
+        task_id = postvars.get('choose_task', None)
+        if task_id:
+            if task_id not in self.tasks.keys():
+                raise PlomException('illegal task ID entered')
+            self.add_todo(task=self.tasks[task_id], efforts={self.selected_date: None},
+                          parenthood=todo_parenthood)
+        for todo_id in postvars.get_all('choose_todo', []):
+            self.todos[todo_id].efforts[self.selected_date] = None
+        for i, todo_id in enumerate(postvars.get_all('todo_id', [])):
+            old_todo = self.todos[todo_id]
+            done = todo_id in postvars.get_all('done', [])
+            day_effort_input = postvars.get_at_index('effort', i, '') 
+            day_effort = float(day_effort_input) if len(day_effort_input) > 0 else None
+            comment = postvars.get_at_index('effort_comment', i, '') 
+            if (day_effort is not None) and (not done) and day_effort < 0 and 0 == len(comment):
+                if len(old_todo.efforts) > 1:
+                    self.delete_effort(old_todo, self.selected_date) 
+                else:
+                    self.delete_todo(todo_id)
                 continue
-            tasks += [task]
-        if sort_order == 'title':
-            chosen_todos.sort(key=lambda t: t.title)
-            relevant_todos.sort(key=lambda t: t.title)
-            tasks.sort(key=lambda t: t.title)
-        elif sort_order == 'effort':
-            chosen_todos.sort(key=lambda t: t.day_effort if t.day_effort else t.default_effort if t.done else 0, reverse=True)
-            relevant_todos.sort(key=lambda t: t.total_effort, reverse=True)
-            tasks.sort(key=lambda t: t.default_effort, reverse=True)
-        return j2env.get_template('new_day.html').render(
-                sort=sort_order,
-                tags=self.t_tags,
-                chosen_todos=chosen_todos,
-                filter_and=self.t_filter_and,
-                filter_not=self.t_filter_not,
-                day=self.selected_day,
-                prev_date=prev_date_str,
-                next_date=next_date_str,
-                tasks=tasks,
-                hide_chosen_tasks=hide_chosen_tasks,
-                relevant_todos=relevant_todos,
-                search=search)
+            importance = float(postvars.get_at_index('importance', i))
+            if old_todo\
+                    and old_todo.done == done\
+                    and old_todo.day_effort == day_effort\
+                    and comment == old_todo.comment\
+                    and old_todo.importance == importance:
+                continue
+            self.update_todo_for_day(
+                    todo_id,
+                    self.selected_date,
+                    day_effort,
+                    done,
+                    comment,
+                    importance)
+
+    # helpers
+
+    def init_calendar_items(self, start_date_str, end_date_str):
+        self.tag_filter_and = ['calendar']
+        self.tag_filter_not = ['deleted']
+
+        todays_date_obj = datetime.strptime(today_date(), DATE_FORMAT) 
+        yesterdays_date_obj = todays_date_obj - timedelta(1)
+        def get_day_limit_obj(index, day_limit_string):
+            date_obj = datetime.strptime(sorted(self.days.keys())[index], DATE_FORMAT)
+            if day_limit_string and len(day_limit_string) > 0:
+                if day_limit_string in {'today', 'yesterday'}:
+                    date_obj = todays_date_obj if day_limit_string == 'today' else yesterdays_date_obj
+                else:
+                    date_obj = datetime.strptime(day_limit_string, DATE_FORMAT)
+            return date_obj
+        start_date_obj = get_day_limit_obj(0, start_date_str)
+        end_date_obj = get_day_limit_obj(-1, end_date_str)
+
+        days_to_show = {}
+        for n in range(int((end_date_obj - start_date_obj).days) + 1):
+            date_obj = start_date_obj + timedelta(n)
+            date_str = date_obj.strftime(DATE_FORMAT)
+            if date_str not in self.days.keys():
+                days_to_show[date_str] = self.add_day(date_str)
+            else:
+                days_to_show[date_str] = self.days[date_str]
+            days_to_show[date_str].month_title = date_obj.strftime('%B') if date_obj.day == 1 else None 
+            days_to_show[date_str].weekday = datetime.strptime(date_str, DATE_FORMAT).strftime('%A')[:2]
+        return days_to_show
+
 
 
 class ParamsParser:
@@ -779,45 +1021,77 @@ class ParamsParser:
         self.params = parse_qs(parsed_url_query)
         self.cookie_db = cookie_db
 
-    def get(self, key, default=None):
-        boolean = bool == type(default) 
+    def get(self, key, default=None, as_bool=False):
         param = self.params.get(key, [default])[0]
-        if boolean:
-            param = param != '0' 
+        if as_bool:
+            if param == '0':
+                param = False
+            elif param is not None:
+                param = True
         return param 
 
-    def get_cookied(self, key, default=None):
-        param = self.get(key, default)
-        if param == '-':
-            param = None
-            if key in self.cookie_db.keys():
-                del self.cookie_db[key]
-        if param is None and key in self.cookie_db.keys():
-            param = self.cookie_db[key]
-        if param is not None:
-            self.cookie_db[key] = param
-        return param
-
-    def get_cookied_chain(self, key, default=None):
-        # default = default if default else ['-']
-        params = self.params.get(key, default)
-        if params == ['-']:
+    def cookie_key_from_params_key(self, prefix, key):
+        return f'{prefix}:{key}' if prefix else key
+
+    def _get_cookied(self, cookie_key, params):
+        if params in [['-'], '-']:
             params = None 
-            if key in self.cookie_db.keys():
-                del self.cookie_db[key]
-        if params is None and key in self.cookie_db.keys():
-            params = self.cookie_db[key]
+            if cookie_key in self.cookie_db.keys():
+                del self.cookie_db[cookie_key]
+        if params is None and cookie_key in self.cookie_db.keys():
+            params = self.cookie_db[cookie_key]
         if params is not None:
-            self.cookie_db[key] = params
+            self.cookie_db[cookie_key] = params
         return params
 
+    def get_cookied(self, key, default=None, prefix=None, as_bool=False):
+        cookie_key = self.cookie_key_from_params_key(prefix, key) 
+        param = self.get(key, default, as_bool)
+        return self._get_cookied(cookie_key, param)
+
+    def get_cookied_chain(self, key, default=None, prefix=None):
+        cookie_key = self.cookie_key_from_params_key(prefix, key) 
+        params = self.params.get(key, default)
+        return self._get_cookied(cookie_key, params)
+
+
+
+class PostvarsParser:
+
+    def __init__(self, postvars):
+        self.postvars = postvars
+
+    def has(self, key):
+        return key in self.postvars.keys()
+
+    def get(self, key, on_empty=None, float_if_possible=False):
+        return self.get_at_index(key, 0, on_empty, float_if_possible)
+
+    def get_at_index(self, key, i, on_empty=None, float_if_possible=False):
+        if self.has(key) and len(self.postvars[key][i]) > 0:
+            val = self.postvars[key][i] 
+        else:
+            val = on_empty 
+        if float_if_possible and val is not None:
+            return float(val)
+        else:
+            return val 
+
+    def get_all(self, key, on_empty=None):
+        if self.has(key) and len(self.postvars[key]) > 0:
+            return [v for v in self.postvars[key] if len(v) > 0]
+        return on_empty
+
+    def set(self, key, value):
+        self.postvars[key] = [value]
+
+
 
 class TodoHandler(PlomHandler):
 
     def config_init(self):
         return {
             'cookie_name': 'todo_cookie',
-            'prefix': '',
             'cookie_path': '/'
         }
 
@@ -825,293 +1099,120 @@ class TodoHandler(PlomHandler):
         default_path = '/todo'
         handler.add_route('GET', default_path, self.show_db)
         handler.add_route('POST', default_path, self.write_db)
-        return 'todo', {'cookie_name': 'todo_cookie', 'prefix': default_path, 'cookie_path': default_path}
+        return 'todo', {'cookie_name': 'todo_cookie', 'cookie_path': default_path}
 
     def do_POST(self):
-        self.try_do(self.config_init)
         self.try_do(self.write_db)
 
     def write_db(self):
         from urllib.parse import urlencode
         config = self.apps['todo'] if hasattr(self, 'apps') else self.config_init()
-        length = int(self.headers['content-length'])
-        postvars = parse_qs(self.rfile.read(length).decode(), keep_blank_values=1)
         parsed_url = urlparse(self.path)
-        site = path_split(urlparse(self.path).path)[1]
-        # site = path_split(parsed_url.path)[1]
-        db = TodoDB(prefix=config['prefix'])
+        site = path_split(parsed_url.path)[1]
+        length = int(self.headers['content-length'])
+        postvars = PostvarsParser(parse_qs(self.rfile.read(length).decode(), keep_blank_values=1))
+
+        db = TodoDB()
         redir_params = []
-        for param_name, filter_db_name in {('t_and', 't_filter_and'), ('t_not', 't_filter_not')}:
+        # if we do encounter a filter post, we repost it (and if empty, the emptying command '-')
+        for param_name, filter_db_name in {('and_tag', 'tag_filter_and'),
+                                           ('not_tag', 'tag_filter_not')}:
             filter_db = getattr(db, filter_db_name)
-            if param_name in postvars.keys():
-                for target in postvars[param_name]:
+            if postvars.has(param_name): 
+                for target in postvars.get_all(param_name, []):
                     if len(target) > 0 and not target in filter_db:
                         filter_db += [target]
                 if len(filter_db) == 0:
                     redir_params += [(param_name, '-')]
             redir_params += [(param_name, f) for f in filter_db]
-
-        def collect_checked(prefix, postvars):
-            tags_checked = []
-            for k in postvars.keys():
-                if k.startswith(prefix):
-                    tags_checked += [k[len(prefix):]]
-            return tags_checked
-        
-        if 'calendar' == site:
-            redir_params += [('start', postvars['start'][0] if len(postvars['start'][0]) > 0 else '-')]
-            redir_params += [('end', postvars['end'][0] if len(postvars['end'][0]) > 0 else '-')]
-
+        if site in {'calendar', 'todo'}:
+            redir_params += [('end', postvars.get('end', '-'))]
+            redir_params += [('start', postvars.get('start', '-'))]
+        if site in {'day_todos', 'todo'}:
+            todo_parenthood = postvars.get('parenthood')
+            redir_params += [('parenthood', todo_parenthood)]
+        if site in {'todo', 'task'}:
+            id_ = postvars.get('id')
+
+        if 'tasks' == site:
+            redir_params += [('search', postvars.get('search', ''))]
         elif 'todo' == site:
-            # task_uuid = postvars['task_uuid'][0]
-            todo_id = postvars['todo_id'][0]
-            # date = postvars['date'][0]
-            old_todo = db.todos[todo_id] 
-            efforts = {}
-            for i, date in enumerate(postvars['effort_date']):
-                if '' == date:
-                    continue
-                efforts[date] = float(postvars['effort'][i]) if len(postvars['effort'][i]) > 0 else None 
-            if 'delete_effort' in postvars.keys():
-                for date in postvars['delete_effort']:
-                    del efforts[date]
-            if 'delete' in postvars.keys():
-                # old_todo = db.days[date].todos[task_uuid]
-                if 'done' in postvars or postvars['comment'][0] != '' or len(collect_checked('day_tag_', postvars)) > 0 or postvars['joined_day_tags'][0] != '' or len(efforts) > 0:
-                    raise PlomException('will not remove todo of preserve-worthy values')
-                db.delete_todo(todo_id) 
-                # db.write()
-                # self.redirect('new_day')
+            if db.post_todo(id_, postvars, todo_parenthood):
+                redir_params += [('id', id_)]
             else:
-                # redir_params += [('task', task_uuid), ('date', date)]
-                redir_params += [('id', todo_id)]
-                # db.update_todo(task_uuid, date, postvars['day_effort'][0], 'done' in postvars.keys(), postvars['comment'][0], postvars['joined_day_tags'][0], collect_checked('day_tag_', postvars), postvars['importance'][0])
-                # efforts = {}
-                # for i, date in enumerate(postvars['effort_date']):
-                #     if '' == date:
-                #         continue
-                #     efforts[date] = postvars['effort'][i] if len(postvars['effort'][i]) > 0 else None 
-                if 'delete_effort' in postvars.keys():
-                    for date in postvars['delete_effort']:
-                        db.delete_effort(old_todo, date)
-                db.update_todo(id_=todo_id,
-                               efforts=efforts,
-                               done='done' in postvars.keys(),
-                               comment=postvars['comment'][0],
-                               day_tags_joined=postvars['joined_day_tags'][0],
-                               day_tags_checked=collect_checked('day_tag_', postvars),
-                               importance=float(postvars['importance'][0]))
-
+                site = 'calendar'
         elif 'task' == site:
-            id_ = postvars['id'][0]
-            redir_params += [('id', id_)]
-            if 'filter' in postvars.keys():
-                redir_params += [('search', postvars['search'][0])]
-            elif 'title' in postvars.keys():
-                links = [] if not 'link_task' in postvars.keys() else postvars['link_task']
-                # db.update_task(id_, postvars['title'][0], postvars['default_effort'][0], postvars['joined_tags'][0], collect_checked('tag_', postvars), collect_checked('link_', postvars), postvars['comment'][0])
-                db.update_task(id_, postvars['title'][0], postvars['default_effort'][0], postvars['joined_tags'][0], collect_checked('tag_', postvars), links, postvars['comment'][0])
-                # if 'as_todo' in postvars.keys() and id_ not in db.selected_day.todos.keys():
-                #     db.update_todo_mini(id_, db.selected_date, None, False, 1.0)
-                # elif 'as_todo' not in postvars.keys() and id_ in db.selected_day.todos.keys():
-                #     todo = db.selected_day.todos[id_]
-                #     if todo.internals_empty() and (not todo.done) and todo.day_effort is None:
-                #         del db.selected_day.todos[id_]
-                #     else:
-                #         raise PlomException('cannot deselect task as todo of preserve-worthy values')
-
-        elif 'new_day' == site:
-            if 'filter' in postvars.keys():
-                redir_params += [('search', postvars['search'][0])]
-                redir_params += [('hide_chosen_tasks', int('hide_chosen_tasks' in postvars.keys()))]
-            else:
-                db.selected_date = postvars['date'][0]
-                todos_to_shrink = []
-                todos_to_delete = []
-                for todo in db.selected_day.linked_todos_as_list:
-                    if todo.visible and not ('chosen_todo' in postvars.keys() and todo.id_ in postvars['chosen_todo']):
-                        if len(todo.comment) > 0 or len(todo.day_tags) > 0 or not todo.is_effort_removable(db.selected_date):
-                            # print("DEBUG", len(todo.comment) > 0, len(todo.day_tags) > 0, todo.is_effort_removable(db.selected_date))
-                            raise PlomException('will not remove effort of preserve-worthy values')
-                        if len(todo.efforts) > 1:
-                            todos_to_shrink += [todo]
-                            # db.delete_effort(todo, db.selected_date)
-                        else:
-                            todos_to_delete += [todo]
-                            # db.delete_todo(todo.id_)
-                for todo in todos_to_shrink:
-                    db.delete_effort(todo, db.selected_date)
-                for todo in todos_to_delete:
-                    db.delete_todo(todo.id_)
-                if 'choose_task' in postvars.keys():
-                    for id_ in postvars['choose_task']:
-                        db.add_todo(task=db.tasks[id_], efforts={db.selected_date: None})
-                if 'choose_todo' in postvars.keys():
-                    for id_ in postvars['choose_todo']:
-                        todo = db.todos[id_]
-                        todo.efforts[db.selected_date] = None
-
-            # if 'choose_task' in postvars.keys():
-            #     for i, uuid in enumerate(postvars['choose_task']):
-            #          if not uuid in db.selected_day.todos.keys():
-            #             # task = db.tasks[uuid]
-            #              db.update_todo_mini(uuid, db.selected_date, None, False, 1.0)
-            # if 'choose_todo' in postvars.keys():
-            #     for i, id_ in enumerate(postvars['choose_todo']):
-            #         if not id_ in [todo.id_ for todo in db.selected_day.linked_todos_as_list]:
-            #             db.link_day_with_todo(db.selected_date, id_)
-
-        elif 'do_day' == site:
-            if 'filter' in postvars.keys():
-                redir_params += [('hide_done', int('hide_done' in postvars.keys()))]
+            ret = db.post_task(id_, postvars)
+            if ret:
+                redir_params += [('id', ret)]
             else:
-                db.selected_date = postvars['date'][0]
-                redir_params += [('date', db.selected_date)]
-                db.selected_day.comment = postvars['day_comment'][0]
-                if 'todo_id' in postvars.keys():
-                    for i, todo_id in enumerate(postvars['todo_id']):
-                        old_todo = None if not todo_id in db.todos.keys() else db.todos[todo_id]
-                        done = ('done' in postvars) and (todo_id in postvars['done'])
-                        day_effort_input = postvars['effort'][i]
-                        day_effort = float(day_effort_input) if len(day_effort_input) > 0 else None
-                        comment = postvars['effort_comment'][i]
-                        importance = float(postvars['importance'][i])
-                        if old_todo and old_todo.done == done and old_todo.day_effort == day_effort and comment == old_todo.comment and old_todo.importance == importance:
-                            continue
-                        db.update_todo_for_day(todo_id, db.selected_date, day_effort, done, comment, importance)
-
-        elif 'day' == site:
-            # always store the two hide params in the URL if possible … TODO: find out if really necessary
-            if 'expect_unchosen_done' in postvars.keys():
-                redir_params += [('hide_unchosen', int('hide_unchosen' in postvars.keys()))] + [('hide_done', int('hide_done' in postvars.keys()))]
-
-            if 'date' in postvars.keys():
-                db.selected_date = postvars['date'][0]
-                if 'day_comment' in postvars.keys():
-                    db.selected_day.comment = postvars['day_comment'][0]
-                redir_params += [('date', db.selected_date)]
-
-                # handle todo list updates via task UUIDs
-                if 't_uuid' in postvars.keys():
-                    for i, uuid in enumerate(postvars['t_uuid']):
-                        task = db.tasks[uuid]
-                        old_todo = None if not uuid in db.selected_day.todos.keys() else db.selected_day.todos[uuid]
-                        selects_as_todo = 'choose' in postvars and uuid in postvars['choose']
-                        too_much_keepworthy_data = ('done' in postvars and uuid in postvars['done']) or postvars['day_effort'][i] != '' or (old_todo and not old_todo.internals_empty())
-                        if old_todo and too_much_keepworthy_data and not selects_as_todo:
-                            raise PlomException('cannot deselect task as todo of preserve-worthy values')
-                        elif old_todo and not selects_as_todo:
-                            del db.selected_day.todos[uuid]
-                        elif too_much_keepworthy_data or selects_as_todo:
-                            done = ('done' in postvars) and (uuid in postvars['done'])
-                            day_effort_input = postvars['day_effort'][i]
-                            day_effort = float(day_effort_input) if len(day_effort_input) > 0 else None
-                            importance = float(postvars['importance'][i])
-                            if old_todo and old_todo.done == done and old_todo.day_effort == day_effort and old_todo.importance == importance:
-                                continue
-                            db.update_todo_mini(uuid, db.selected_date, day_effort, done, importance)
-
-        if 'return_to' in postvars.keys() and len(postvars['return_to'][0]) > 0:
-            homepage = postvars['return_to'][0]
-        else:
-            encoded_params = urlencode(redir_params)
-            # homepage = f'{parsed_url.path}?{encoded_params}'
-            homepage = f'{site}?{encoded_params}'
+                site = 'calendar'
+        elif 'day_todos' == site:
+            db.post_day_todos(postvars, todo_parenthood)
+            redir_params += [('date', db.selected_date)]
+
+        encoded_params = urlencode(redir_params)
+        homepage = f'{site}?{encoded_params}'
         db.write()
         self.redirect(homepage)
 
     def do_GET(self):
-        self.try_do(self.config_init)
         self.try_do(self.show_db)
 
     def show_db(self):
         config = self.apps['todo'] if hasattr(self, 'apps') else self.config_init()
-        cookie_db = self.get_cookie_db(config['cookie_name'])
         parsed_url = urlparse(self.path)
         site = path_split(parsed_url.path)[1]
-        # params = parse_qs(parsed_url.query)
-        params = ParamsParser(parsed_url.query, cookie_db)
 
-        # def get_param(param_name, boolean=False, chained=False, none_as_empty_string=False):
-        #     if chained:
-        #         param = params.get(param_name, None)
-        #     elif none_as_empty_string:
-        #         param = params.get(param_name, [''])[0]
-        #     else: 
-        #         param = params.get(param_name, [None])[0]
-        #     if (not chained and param == '-') or (chained and param == ['-']):
-        #         param = None
-        #         if param_name in cookie_db.keys():
-        #             del cookie_db[param_name]
-        #     if param is None and param_name in cookie_db.keys():
-        #         param = cookie_db[param_name]
-        #     if param is not None:
-        #         if boolean:
-        #             param = param != '0'
-        #             cookie_db[param_name] = str(int(param))
-        #         else:
-        #             cookie_db[param_name] = param
-        #     elif param is boolean:
-        #         param = False
-        #     return param
-
-        selected_date = t_filter_and = t_filter_not = None
-        hide_unchosen = hide_done = False
-        # return_to = params.get('return_to', [''])[0]
-        return_to = params.get('return_to', '')
-        if site in {'do_day', 'new_day'}:
+        cookie_db = self.get_cookie_db(config['cookie_name'])
+        params = ParamsParser(parsed_url.query, cookie_db)
+        selected_date = tag_filter_and = tag_filter_not = None
+        if site in {'day_todos', 'calendar', 'task'}:
             selected_date = params.get_cookied('date')
-        if site in {'do_day', 'new_day', 'task'}:
-            t_filter_and = params.get_cookied_chain('t_and')
-            # t_filter_not = params.get_cookied_chain('t_not', ['deleted', 'cancelled'])
-            t_filter_not = params.get_cookied_chain('t_not')
-        # if site in {'day','tasks', 'task', 'new_day'}:
-        #     t_filter_and = get_param('t_and', chained=True)
-        #     t_filter_not = get_param('t_not', chained=True)
-        if 'do_day' == site:
-            # hide_unchosen = get_param('hide_unchosen', boolean=True)
-            hide_done = params.get('hide_done', False) 
-        db = TodoDB(config['prefix'], selected_date, t_filter_and, t_filter_not, hide_unchosen, hide_done)
-        if 'do_day' == site:
-            sort_order = params.get_cookied('sort')
-            page = db.show_do_day(sort_order)
-        elif 'new_day' == site:
-            sort_order = params.get_cookied('sort')
-            hide_chosen_tasks = params.get('hide_chosen_tasks', False)
-            search = params.get('search', '')
-            page = db.show_new_day(search, hide_chosen_tasks, sort_order)
+        if site in {'day_todos', 'tasks'}:
+            tag_filter_and = params.get_cookied_chain('and_tag', prefix=site)
+            tag_filter_not = params.get_cookied_chain('not_tag', prefix=site)
+        if site in {'day_todos', 'todo'}:
+            todo_parenthood = params.get_cookied('parenthood', prefix=site)
+        if site in {'calendar', 'calendar_export', ''}:
+            start_date = params.get_cookied('start', prefix=site)
+            end_date = params.get_cookied('end', prefix=site)
+        if site in {'todo', 'task'}:
+            id_ = params.get('id')
+
+        db = TodoDB(selected_date, tag_filter_and, tag_filter_not)
+        if 'reset_cookie' == site:
+            cookie_db = {  # sensible defaults
+                params.cookie_key_from_params_key('day_todos', 'tree'): True,
+                params.cookie_key_from_params_key('todo', 'and_tag'): ['default'],
+                params.cookie_key_from_params_key('todo', 'not_tag'): ['ignore'],
+                params.cookie_key_from_params_key('todo', 'start'): 'yesterday',
+                params.cookie_key_from_params_key('todo', 'end'): 'today'}
+            page = db.get_message('cookie unset!')
+        elif 'day_todos' == site:
+            tree_view = params.get_cookied('tree', prefix=site, as_bool=True)
+            undone_sort_order = params.get_cookied('undone_sort', prefix=site)
+            done_sort_order = params.get_cookied('done_sort', prefix=site)
+            page = db.get_day_todos(undone_sort_order, done_sort_order, tree_view, todo_parenthood)
         elif site == 'todo':
-            todo_id = params.get('id')
-            page = db.show_todo(todo_id, return_to)
-            # todo_id = params.get('id')
-            # if todo_id:
-            #     todo_date, task_uuid = todo_id.split('_') 
-            # else:
-            #     todo_date = params.get('date')
-            #     task_uuid = params.get('task')
-            # page = db.show_todo(task_uuid, todo_date, return_to)
+            page = db.get_todo(id_, parenthood=todo_parenthood)
         elif 'task' == site:
-            id_ = params.get('id')
-            search = params.get('search', '')
-            page = db.show_task(id_, return_to, search)
+            page = db.get_task(id_)
         elif 'tasks' == site:
-            expand_uuid = params.get('expand_uuid')
-            page = db.show_tasks(expand_uuid)
+            sort_order = params.get_cookied('sort', prefix=site)
+            search = params.get('search', '')
+            page = db.get_tasks(search, sort_order)
         elif 'add_task' == site:
-            page = db.show_task(None)
-        elif 'unset_cookie' == site:
-            page = 'no cookie to unset.'
-            if len(cookie_db) > 0:
-                self.unset_cookie(config['cookie_name'], config['cookie_path'])
-                page = 'cookie unset!'
-        else:
-            start_date = params.get_cookied('start')
-            end_date = params.get_cookied('end')
-            page = db.show_calendar(start_date, end_date)
-        if 'unset_cookie' != site:
-            self.set_cookie(config['cookie_name'], config['cookie_path'], cookie_db)
+            page = db.get_task(None)
+        elif 'calendar_export' == site:
+            page = db.get_calendar_export(start_date, end_date)
+        else:  # 'calendar' == site
+            page = db.get_calendar(start_date, end_date)
+
+        self.set_cookie(config['cookie_name'], config['cookie_path'], cookie_db)
         self.send_HTML(page)
 
 
+
 if __name__ == "__main__":
     run_server(server_port, TodoHandler)