From c93240eca745958fa3d98835fa1b60ae8fd13ac0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Laura=20Kl=C3=BCnder?= <laura@codingcatgirl.de>
Date: Thu, 15 Jun 2017 00:07:19 +0200
Subject: [PATCH] implement first filter updates for existing objects

---
 src/c3nav/editor/models.py   |  4 +++
 src/c3nav/editor/wrappers.py | 52 +++++++++++++++++++++++++++++++-----
 2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/src/c3nav/editor/models.py b/src/c3nav/editor/models.py
index fc5c51d7..b5abc968 100644
--- a/src/c3nav/editor/models.py
+++ b/src/c3nav/editor/models.py
@@ -85,6 +85,10 @@ class ChangeSet(models.Model):
             else:
                 self.m2m_remove_existing.setdefault(model, {}).setdefault(change.obj_pk, set()).add(value)
 
+    def get_changed_values(self, model, name):
+        return tuple((pk, values[name])
+                     for pk, values in self.updated_existing.get(model, {}).items() if name in values)
+
     @classmethod
     def qs_base(cls, hide_applied=True):
         qs = cls.objects.prefetch_related('changes').select_related('author')
diff --git a/src/c3nav/editor/wrappers.py b/src/c3nav/editor/wrappers.py
index dfd061a2..8c21b87b 100644
--- a/src/c3nav/editor/wrappers.py
+++ b/src/c3nav/editor/wrappers.py
@@ -256,14 +256,54 @@ class BaseQueryWrapper(BaseWrapper):
     def order_by(self, *args):
         return self._wrap_queryset(self.get_queryset().order_by(*args))
 
-    def _filter_kwarg(self, name, value):
-        if name.endswith('__in'):
-            value = tuple((item._obj if isinstance(item, ModelInstanceWrapper) else item) for item in value)
+    def _filter_values(self, q, field_name, check):
+        other_values = self._changeset.get_changed_values(self._obj.model, field_name)
+        add_pks = []
+        remove_pks = []
+        for pk, new_value in other_values:
+            (add_pks if check(new_value) else remove_pks).append(pk)
+        return (q & ~Q(pk__in=remove_pks)) | Q(pk__in=add_pks)
 
-        if isinstance(value, ModelInstanceWrapper):
-            value = value._obj
+    def _filter_kwarg(self, filter_name, filter_value):
+        print(filter_name, '=', filter_value, sep='')
 
-        return Q(**{name: value})
+        segments = filter_name.split('__')
+        field_name = segments.pop(0)
+        try:
+            class_value = getattr(self._obj.model, field_name)
+        except AttributeError:
+            raise ValueError('%s has no attribute %s' % (self._obj.model, field_name))
+
+        q = Q(**{filter_name: filter_value})
+
+        if isinstance(class_value, ForwardManyToOneDescriptor):
+            if not segments:
+                raise NotImplementedError
+
+            filter_type = segments.pop(0)
+
+            if not segments and filter_type == 'in':
+                filter_name = field_name+'__pk__in'
+                filter_value = tuple(obj.pk for obj in filter_value)
+                filter_type = 'pk'
+                segments = ['in']
+                q = Q(**{filter_name: filter_value})
+
+            if filter_type == 'pk' and segments == ['in']:
+                return self._filter_values(q, field_name, lambda val: val in filter_value)
+
+            if segments:
+                raise NotImplementedError
+
+            if filter_type == 'isnull':
+                return self._filter_values(q, field_name, lambda val: (val is None) is filter_value)
+
+        raise NotImplementedError('cannot filter %s by %s (%s)' % (self._obj.model, filter_name, class_value))
+
+        if isinstance(filter_value, ModelInstanceWrapper):
+            filter_value = filter_value._obj
+
+        return Q(**{filter_name: filter_value})
 
     def _filter_q(self, q):
         result = Q(*((self._filter_q(c) if isinstance(c, Q) else self._filter_kwarg(*c)) for c in q.children))