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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 3ea09b0d7b7e42b4893c15b7274b7de85c7343bf..dc3a346efebccc30be5d82e1840b635d79c0b5b2 100644 (file)
--- a/todo.py
+++ b/todo.py
@@ -21,54 +21,93 @@ def today_date(with_time=False):
 
 class AttributeWithHistory:
 
-    def __init__(self, default_if_empty, history=None, then_date='2000-01-01', set_check=None, alt_get=None):
+    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 {}
-        self.set_check = set_check
-        self.alt_get = alt_get 
 
     def set(self, value):
-        if self.set_check:
-            self.set_check(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):
-        if self.alt_get:
-            ret = self.alt_get('at', queried_date)
-            if ret is not None:
-                return ret
-        if 0 == len(self.history):
+        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(self.history.keys())[0]]
+        ret = self.history[sorted_dates[0]]
         for date_key, item in self.history.items():
-            if date_key > f'{queried_date} 23:59:59':
+            if date_key > end_of_queried_day:
                 break
             ret = item
         return ret
 
     @property
     def now(self):
-        if self.alt_get:
-            ret = self.alt_get('now')
-            if ret is not None:
-                return ret
         keys = sorted(self.history.keys())
-        return self.default if 0 == len(self.history) else self.history[keys[-1]]
+        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):
-        if self.alt_get:
-            ret = self.alt_get('then')
-            if ret is not None:
-                return ret
         return self.at(self.then_date)
 
 
 
-class Task:
+class TaskLike:
+
+    def __init__(self, db, id_, comment):
+        self.db = db
+        self.id_ = id_
+        self.comment = comment
+
+    @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
+
+    @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,
@@ -76,17 +115,17 @@ class Task:
             title_history=None,
             tags_history=None,
             default_effort_history=None,
-            subtask_ids_history=None,
-            comment=''):
-        self.db = db
-        self.id_ = id_
-        self.title = AttributeWithHistory('', title_history, self.db.selected_date)
-        self.tags = AttributeWithHistory(set(), tags_history, self.db.selected_date)
-        self.default_effort = AttributeWithHistory(0.0, default_effort_history, self.db.selected_date, alt_get=self.subtasks_sum_maker())
-        self.subtask_ids = AttributeWithHistory(set(), subtask_ids_history, self.db.selected_date, set_check=self.subtask_loop_checker())
-        self.comment = comment
-
-        self.visible = True
+            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_):
@@ -96,8 +135,10 @@ 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['subtasks_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):
@@ -105,46 +146,39 @@ class Task:
             '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()},
-            'subtasks_history': {k: list(v) for k, v in self.subtask_ids.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 subtasks(self):
-        subtasks = []
-        for id_ in self.subtask_ids.now:
-            subtasks += [self.db.tasks[id_]]
-        return subtasks
+    def forked_task(self):
+        return self.db.tasks[self.forks_id] if self.forks_id else None
 
-    def subtask_loop_checker(self):
-        def f(subtask_ids_now):
-            loop_msg = "can't set subtask, would create loop"
-            for id_ in subtask_ids_now:
-                if id_ == self.id_:
-                    raise PlomException(loop_msg)
-                elif id_ in self.db.tasks.keys():
-                    subtask = self.db.tasks[id_]
-                    f(subtask.subtask_ids.now)
-        return f 
-
-    def subtasks_sum_maker(self):
-        def f(f_name, queried_date=None):
-            subtask_ids_to_check = getattr(self.subtask_ids, f_name)
-            if queried_date:
-                subtasks = [self.db.tasks[id_] for id_ in subtask_ids_to_check(queried_date)]
-            else:
-                subtasks = [self.db.tasks[id_] for id_ in subtask_ids_to_check]
-            if len(self.subtasks) > 0:
-                summe = 0
-                for subtask in self.subtasks:
-                    if queried_date:
-                        to_add = getattr(subtask.default_effort, f_name)
-                        summe += to_add(queried_date)
-                    else:
-                        summe += getattr(subtask.default_effort, f_name)
-                return summe
-            return None
-        return f
+    @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
+
+    @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 dependers(self):
+        return [t for t in self.db.tasks.values() if self in t.deps]
 
     def matches(self, search):
         if search is None:
@@ -152,6 +186,16 @@ class Task:
         else:
             return search in self.title.now or search in self.comment or search in '$'.join(self.tags.now)
 
+    @property
+    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 '' 
+
+
 
 class Day:
 
@@ -159,22 +203,16 @@ class Day:
         self.date = date 
         self.db = db
         self.comment = comment
-        self.archived = True
         self.linked_todos_as_list = []
-        self.todos = {}
 
     @classmethod
     def from_dict(cls, db, d, date=None):
         comment = d['comment'] if 'comment' in d.keys() else ''
         day = cls(db, date, comment)
-        for id_ in d['linked_todos']:
-            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]
+        d = {'comment': self.comment}
         return d
 
     @property
@@ -199,8 +237,38 @@ class Day:
     def todos_sum(self):
         return self._todos_sum()
 
+    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 visible_in_export(self):
+        return len(self.comment) + len([t for t in self.linked_todos_as_list if t.visible]) > 0
+
+
 
-class Todo:
+class Todo(TaskLike):
 
     def __init__(self,
                  db,
@@ -211,18 +279,21 @@ class Todo:
                  day_tags=None,
                  importance=1.0,
                  efforts=None,
-                 child_ids=None):
-        self.id_ = id_
-        self.db = db 
+                 dep_ids=None):
+        super().__init__(db, id_, comment)
         self.task = task 
         self._done = done
-        self._efforts = efforts if efforts else {}
-        self.comment = comment
+        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.day_tags = day_tags if day_tags else set()
         self.importance = importance
-        self.child_ids = child_ids if child_ids else [] 
-
-        self.parents = [] 
+        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_):
@@ -235,7 +306,7 @@ class Todo:
                 set(d['day_tags']),
                 d['importance'],
                 d['efforts'],
-                d['children'])
+                set(d['deps']))
         return todo
 
     def to_dict(self):
@@ -246,23 +317,23 @@ class Todo:
                 'day_tags': list(self.day_tags),
                 'importance': self.importance,
                 'efforts': self.efforts,
-                'children': self.child_ids}
+                'deps': list(self.dep_ids)}
 
     @property
-    def parent(self):
-        return self.parents[0] if len(self.parents) > 0 else None 
+    def title(self):
+        return self.task.title.at(self.db.selected_date)
 
     @property
-    def title(self):
-        return self.task.title.at(self.earliest_date)
+    def dated_title(self):
+        return f'{self.earliest_date}:{self.title}'
 
     @property
-    def children(self):
-        return [self.db.todos[id_] for id_ in self.child_ids]
+    def deps(self):
+        return [self.db.todos[id_] for id_ in self.dep_ids]
 
-    @children.setter
-    def children(self, children):
-        self.child_ids = [child.id_ for child in children]
+    @deps.setter
+    def deps(self, deps):
+        self.dep_ids = {dep.id_ for dep in deps}
 
     @property
     def default_effort(self):
@@ -270,45 +341,59 @@ class Todo:
 
     @property
     def done(self):
-        if len(self.children) > 0:
-            for child in self.children:
-                if not child.done:
-                    return False
-            return True
-        else:
-            return self._done
+        return self.deps_done and self._done
 
     @done.setter
     def done(self, doneness):
         self._done = doneness
 
     @property
-    def efforts(self):
-        if self.children:
-            efforts = {} 
-            for date in self._efforts.keys():
-                efforts[date] = None
-            for child in self.children:
-                to_add = None 
-                for date, effort in child.efforts.items():
-                    if not date in efforts.keys():
-                        efforts[date] = None 
-                    if effort is not None:
-                        to_add = effort
-                    elif child.done:
-                        to_add = child.task.default_effort.at(date)
-                if to_add is not None:
-                    if efforts[date] is not None:
-                        efforts[date] += to_add
-                    else:
-                        efforts[date] = to_add
-            return efforts
+    def deps_done(self):
+        if len(self.deps) > 0:
+            for dep in self.deps:
+                if not dep.done:
+                    return False
+        return True
+
+    @property
+    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 self._efforts
+            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
 
-    @efforts.setter
-    def efforts(self, efforts_dict):
-        self._efforts = efforts_dict
+    @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):
@@ -334,13 +419,6 @@ class Todo:
             return False
         return True
 
-    @property
-    def path(self):
-        path = ''
-        if self.parent:
-            path = f'{self.parent.path}{self.parent.title}:'
-        return path
-
     @property
     def tags(self):
         return self.day_tags | self.task.tags.now
@@ -349,6 +427,13 @@ class Todo:
     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]
@@ -367,22 +452,74 @@ class Todo:
     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
+            tag_filter_and = None,
+            tag_filter_not = None):
         self.selected_date = selected_date if selected_date else today_date()
-        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
+        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 = {}
@@ -394,26 +531,32 @@ class TodoDB(PlomDB):
 
     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.now:
                 self.t_tags.add(tag)
+        # for task in self.tasks.values():
+        #     for dep in task.deps:
+        #         dep.dependers += [task]
+
         for id_, todo_dict in d['todos'].items():
             todo = self.add_todo(todo_dict, id_)
-            self.todos[id_] = todo 
             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 in todo.children:
-                child.parents += [todo]
             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]
-        self.set_visibilities()
+                self.days[date].linked_todos_as_list += [todo]
+
+        self.set_visibilities()
 
     def to_dict(self):
         d = {'tasks': {}, 'days': {}, 'todos': {}}
@@ -421,8 +564,6 @@ 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
@@ -457,25 +598,74 @@ class TodoDB(PlomDB):
         self.tasks[id_] = t
         return t
 
-    def update_task(self, id_, title, default_effort, tags, subtask_ids, comment):
+    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.subtask_ids.set(subtask_ids)
+        task.fences_adoptions.set(fences_adoptions)
         task.comment = comment 
-
-    def add_todo(self, todo_dict=None, id_=None, task=None, efforts=None):
+        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_task in task.subtasks:
-                children += [self.add_todo(task=child_task, efforts=efforts)]
-            todo.child_ids = [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 _update_todo_shared(self, id_, done, comment, importance):
@@ -489,18 +679,25 @@ class TodoDB(PlomDB):
         todo = self._update_todo_shared(id_, done, comment, importance)
         todo.efforts[date] = effort 
 
-    def update_todo(self, id_, efforts, done, comment, tags, importance, children):
+    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.children:
+        if len(efforts) == 0 and not todo.deps:
             raise PlomException('todo must have at least one effort!')
-        todo.children = children
         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.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_]
@@ -509,10 +706,13 @@ class TodoDB(PlomDB):
             dates_to_delete += [date]
         for date in dates_to_delete:
             self.delete_effort(todo, date, force=True)
-        for parent in todo.parents:
-            parent.child_ids.remove(todo.id_)
+        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!')
@@ -521,66 +721,67 @@ class TodoDB(PlomDB):
 
     # views
 
-    def show_calendar(self, start_date_str, end_date_str):
-        self.t_filter_and = ['calendar']
-        self.t_filter_not = ['deleted']
-        self.set_visibilities()
-        start_date_obj, end_date_obj = self.get_limit_days_from_date_strings(start_date_str, 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]
+    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 show_do_todos(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
-                 and not t.children]
-        if sort_order == 'title':
-            todos.sort(key=lambda t: t.task.title.then)
-        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_todos.html').render(
+    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.t_filter_and,
-                filter_not=self.t_filter_not,
+                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,
-                todos=todos,
-                sort=sort_order,
-                hide_done=self.hide_done)
-
-    def show_todo(self, id_, return_to, search, start_date, end_date):
+                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_]
-        start_day, end_day = self.get_limit_days_from_date_strings(start_date, end_date)
-        if start_day < datetime.now() - timedelta(days=2):
-            end_day = start_day + timedelta(days=3)
-            end_date = end_day.strftime(DATE_FORMAT)
-        legal_dates = []
-        for n in range(int((end_day - start_day).days) + 1):
-            day = start_day + timedelta(n)
-            legal_dates += [day.strftime(DATE_FORMAT)]
+        filtered_tasks = [t for t in self.tasks.values()
+                          if t != todo.task] 
         filtered_todos = [t for t in self.todos.values()
-                          if t.visible
-                          and t != todo
-                          and (len(search) == 0 or t.matches(search))] 
+                          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:
@@ -588,107 +789,205 @@ class TodoDB(PlomDB):
                     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(
-                filter_and=self.t_filter_and,
-                filter_not=self.t_filter_not,
                 tags=self.t_tags,
                 todo=todo,
                 filtered_todos=date_filtered_todos,
-                child_todos=todo.children,
-                return_to=return_to,
-                start_date=start_date,
-                end_date=end_date)
-
-    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()
+                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.visible
-                          and t != task
-                          and (t not in task.subtasks)
-                          and (len(search) == 0 or t.matches(search))] 
+                          if t != task
+                          and (t not in task.deps)]
+
         return j2env.get_template('task.html').render(
-                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,
-                task=task,
-                return_to=return_to)
-
-    def show_tasks(self, expand_uuid):
-        expanded_tasks = {}
-        if expand_uuid:
-            for uuid in self.tasks[expand_uuid].subtask_ids.now:
-                expanded_tasks[uuid] = self.tasks[uuid]
+                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(
-                db=self,
-                filter_and=self.t_filter_and,
-                filter_not=self.t_filter_not,
-                expand_uuid=expand_uuid,
-                expanded_tasks=expanded_tasks)
-
-    def show_pick_tasks(self, search, hide_chosen_tasks, sort_order=None):
-        prev_date_str, next_date_str = self.neighbor_dates()
+                sort=sort_order,
+                tasks=filtered_tasks,
+                tags=self.t_tags,
+                filter_and=self.tag_filter_and,
+                filter_not=self.tag_filter_not,
+                search=search)
 
-        chosen_todos = self.selected_day.linked_todos_as_list
+    # posts
 
-        relevant_todos = []
-        for todo in self.todos.values():
-            if todo.done\
-                    or (not todo.visible)\
-                    or (not todo.matches(search))\
-                    or todo.earliest_date >= self.selected_date:
+    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.then)
-        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.all_days_effort, reverse=True)
-            tasks.sort(key=lambda t: t.default_effort.then, reverse=True)
-
-        return j2env.get_template('pick_tasks.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 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.now]) == 0\
-                    and len([tag for tag in self.t_filter_not if tag in t.tags.now]) == 0\
-                    and ((not self.hide_unchosen) or uuid in self.selected_day.todos.keys())
-        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.now ]) == 0\
-                and len([tag for tag in self.t_filter_not if tag in todo.day_tags | todo.task.tags.now ]) == 0\
-                and ((not self.hide_done) or (not todo.done))
+    def init_calendar_items(self, start_date_str, end_date_str):
+        self.tag_filter_and = ['calendar']
+        self.tag_filter_not = ['deleted']
 
-    def get_limit_days_from_date_strings(self, start_date_str, end_date_str):
         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):
@@ -701,15 +1000,18 @@ class TodoDB(PlomDB):
             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)
-        return start_date_obj, end_date_obj
 
-    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
+        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
 
 
 
@@ -719,37 +1021,40 @@ 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):
-        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:
 
@@ -759,49 +1064,34 @@ class PostvarsParser:
     def has(self, key):
         return key in self.postvars.keys()
 
-    def get(self, key, on_empty=None):
-        return self.get_at_index(key, 0, on_empty)
+    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):
+    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:
-            return self.postvars[key][i] 
-        return on_empty 
-
-    def get_float_if_possible(self, key):
-        s = self.get(key)
-        if s is not None:
-            return float(s)
+            val = self.postvars[key][i] 
+        else:
+            val = on_empty 
+        if float_if_possible and val is not None:
+            return float(val)
         else:
-            return None
+            return val 
 
     def get_all(self, key, on_empty=None):
         if self.has(key) and len(self.postvars[key]) > 0:
-            return self.postvars[key] 
+            return [v for v in self.postvars[key] if len(v) > 0]
         return on_empty
 
-    def get_defined_tags(self, joined_key, key_prefix):
-        tags = set()
-        tags_checked = []
-        for k in self.postvars.keys():
-            if k.startswith(key_prefix):
-                tags_checked += [k[len(key_prefix):]]
-        tags_joined = self.get(joined_key, '')
-        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 set(self, key, value):
         self.postvars[key] = [value]
 
 
+
 class TodoHandler(PlomHandler):
 
     def config_init(self):
         return {
             'cookie_name': 'todo_cookie',
-            'prefix': '',
             'cookie_path': '/'
         }
 
@@ -809,7 +1099,7 @@ 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.write_db)
@@ -822,10 +1112,11 @@ class TodoHandler(PlomHandler):
         length = int(self.headers['content-length'])
         postvars = PostvarsParser(parse_qs(self.rfile.read(length).decode(), keep_blank_values=1))
 
-        db = TodoDB(prefix=config['prefix'])
+        db = TodoDB()
         redir_params = []
         # if we do encounter a filter post, we repost it (and if empty, the emptying command '-')
-        for param_name, filter_db_name in {('t_and', 't_filter_and'), ('t_not', 't_filter_not')}:
+        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 postvars.has(param_name): 
                 for target in postvars.get_all(param_name, []):
@@ -837,120 +1128,31 @@ class TodoHandler(PlomHandler):
         if site in {'calendar', 'todo'}:
             redir_params += [('end', postvars.get('end', '-'))]
             redir_params += [('start', postvars.get('start', '-'))]
-        if site in {'todo', 'task', 'pick_tasks'}:
-            redir_params += [('search', postvars.get('search', ''))]
-            redir_params += [('search', postvars.get('search', ''))]
-            redir_params += [('search', postvars.get('search', ''))]
-        if postvars.has('filter'): 
-            postvars.set('return_to', '')
-        
-        if 'todo' == site:
-            todo_id = postvars.get('todo_id')
-            redir_params += [('id', todo_id)]
-            old_todo = db.todos[todo_id] if todo_id in db.todos.keys() else None
-            efforts = {}
-            for i, date in enumerate(postvars.get_all('effort_date', [])):
-                if '' == date:
-                    continue
-                try:
-                    datetime.strptime(date, DATE_FORMAT)
-                except ValueError:
-                    raise PlomException(f'bad date string')
-                efforts[date] = None
-                if not (old_todo and old_todo.children):
-                    efforts[date] = postvars.get_at_index('effort', i, None) 
-            if postvars.has('delete'): 
-                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 len(postvars.get_defined_tags('joined_day_tags', 'day_tag_')) > 0\
-                        or has_day_effort:
-                    raise PlomException('will not remove todo of preserve-worthy values')
-                db.delete_todo(todo_id) 
-                if not postvars.get('return_to'):
-                    postvars.set('return_to', 'calendar')
-            elif postvars.has('update'):
-                if postvars.has('delete_effort'):
-                    for date in postvars.get_all('delete_effort'):
-                        db.delete_effort(old_todo, date)
-                        del efforts[date]
-                children = [db.todos[id_] for id_ in postvars.get_all('adopt_child', [])] 
-                db.update_todo(id_=todo_id,
-                               efforts=efforts,
-                               done=postvars.has('done'),
-                               comment=postvars.get('comment', ''),
-                               tags=postvars.get_defined_tags('joined_day_tags', 'day_tag_'),
-                               importance=float(postvars.get('importance')),
-                               children=children)
+        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:
+            if db.post_todo(id_, postvars, todo_parenthood):
+                redir_params += [('id', id_)]
+            else:
+                site = 'calendar'
         elif 'task' == site:
-            task_id = postvars.get('task_id')
-            if postvars.has('update'):
-                db.update_task(
-                        id_=task_id,
-                        title=postvars.get('title', ''),
-                        default_effort=postvars.get_float_if_possible('default_effort'), 
-                        tags=postvars.get_defined_tags('joined_tags', 'tag_'),
-                        subtask_ids=postvars.get_all('subtask', []),
-                        comment=postvars.get('comment', ''))
-            redir_params += [('id', task_id)]
-
-        elif 'pick_tasks' == site:
-            redir_params += [('hide_chosen_tasks', int(postvars.has('hide_chosen_tasks')))]
-            if postvars.has('update'):
-                db.selected_date = postvars.get('date')
-                todos_to_shrink = []
-                todos_to_delete = []
-                for todo in db.selected_day.linked_todos_as_list:
-                    if todo.visible and not todo.id_ in postvars.get_all('chosen_todo', []):
-                        if len(todo.comment) > 0\
-                                or len(todo.day_tags) > 0\
-                                or not 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]
-                        else:
-                            todos_to_delete += [todo]
-                for todo in todos_to_shrink:
-                    db.delete_effort(todo, db.selected_date)
-                for todo in todos_to_delete:
-                    db.delete_todo(todo.id_)
-                for id_ in postvars.get_all('choose_task', []):
-                    db.add_todo(task=db.tasks[id_], efforts={db.selected_date: None})
-                for id_ in postvars.get_all('choose_todo', []):
-                    db.todos[id_].efforts[db.selected_date] = None
-
-        elif 'do_todos' == site:
-            redir_params += [('hide_done', int(postvars.has('hide_done')))]
-            if postvars.has('update'): 
-                db.selected_date = postvars.get('date') 
-                redir_params += [('date', db.selected_date)]
-                db.selected_day.comment = postvars.get('day_comment', '') 
-                for i, todo_id in enumerate(postvars.get_all('todo_id')):
-                    old_todo = None if not todo_id in db.todos.keys() else db.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, '') 
-                    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
-                    db.update_todo_for_day(
-                            todo_id,
-                            db.selected_date,
-                            day_effort,
-                            done,
-                            comment,
-                            importance)
-
-        homepage = postvars.get('return_to')
-        if not homepage:
-            encoded_params = urlencode(redir_params)
-            homepage = f'{site}?{encoded_params}'
+            ret = db.post_task(id_, postvars)
+            if ret:
+                redir_params += [('id', ret)]
+            else:
+                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)
 
@@ -961,55 +1163,56 @@ class TodoHandler(PlomHandler):
         config = self.apps['todo'] if hasattr(self, 'apps') else self.config_init()
         parsed_url = urlparse(self.path)
         site = path_split(parsed_url.path)[1]
+
         cookie_db = self.get_cookie_db(config['cookie_name'])
         params = ParamsParser(parsed_url.query, cookie_db)
-
-        selected_date = t_filter_and = t_filter_not = None
-        hide_unchosen = hide_done = False
-        return_to = params.get('return_to', '')
-        if site in {'do_todos', 'pick_tasks', 'calendar'}:
+        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_todos', 'pick_tasks', 'task', 'todo'}:
-            t_filter_and = params.get_cookied_chain('t_and')
-            t_filter_not = params.get_cookied_chain('t_not')
-        if 'do_todos' == site:
-            hide_done = params.get('hide_done', False) 
-        db = TodoDB(config['prefix'], selected_date, t_filter_and, t_filter_not, hide_unchosen, hide_done)
+        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')
-        if site in {'todo', 'task', 'pick_tasks'}:
-            search = params.get('search', '')
-        if site in {'do_todos', 'pick_tasks'}:
-            sort_order = params.get_cookied('sort')
-        if site in {'calendar', 'todo'}:
-            start_date = params.get_cookied('start')
-            end_date = params.get_cookied('end')
-        if 'do_todos' == site:
-            page = db.show_do_todos(sort_order)
-        elif 'pick_tasks' == site:
-            hide_chosen_tasks = params.get('hide_chosen_tasks', False)
-            page = db.show_pick_tasks(search, hide_chosen_tasks, sort_order)
+
+        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':
-            page = db.show_todo(id_, return_to, search, start_date, end_date)
+            page = db.get_todo(id_, parenthood=todo_parenthood)
         elif 'task' == site:
-            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:
-            page = db.show_calendar(start_date, end_date)
+            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)
 
-        if 'unset_cookie' != site:
-            self.set_cookie(config['cookie_name'], config['cookie_path'], cookie_db)
+        self.set_cookie(config['cookie_name'], config['cookie_path'], cookie_db)
         self.send_HTML(page)
 
 
+
 if __name__ == "__main__":
     run_server(server_port, TodoHandler)