Add widget support to SourceColumn

Allow passing a widget class to SourceColumn. This makes
using lambdas to render model column unnecesary and are
mostly removed too.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/documents/models/document_models.py

@@ -7,12 +7,15 @@ from django.apps import apps
 from django.conf import settings
 from django.core.files import File
 from django.db import models
+from django.template import Context, Template
 from django.urls import reverse
 from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.timezone import now
 from django.utils.translation import ugettext
 from django.utils.translation import ugettext_lazy as _
 
+from mayan.apps.acls.models import AccessControlList
+
 from ..events import (
     event_document_create, event_document_properties_edit,
     event_document_type_change,
@@ -21,6 +24,7 @@ from ..managers import (
     DocumentManager, DuplicatedDocumentManager, FavoriteDocumentManager,
     PassthroughManager, RecentDocumentManager, TrashCanManager
 )
+from ..permissions import permission_document_view
 from ..settings import setting_language
 from ..signals import post_document_type_change
 
@@ -77,7 +81,6 @@ class Document(models.Model):
             'Whether or not this document is in the trash.'
         ), editable=False, verbose_name=_('In trash?')
     )
-    # TODO: set editable to False
     deleted_date_time = models.DateTimeField(
         blank=True, editable=True, help_text=_(
             'The server date and time when the document was moved to the '
@@ -139,6 +142,24 @@ class Document(models.Model):
         if latest_version:
             return latest_version.get_api_image_url(*args, **kwargs)
 
+    def get_duplicates(self):
+        try:
+            return DuplicatedDocument.objects.get(document=self).documents.all()
+        except DuplicatedDocument.DoesNotExist:
+            return Document.objects.none()
+
+    def get_page_count(self):
+        return self.pages.count()
+    get_page_count.short_description = _('Pages')
+
+    def get_rendered_deleted_date_time(self):
+        return Template('{{ instance.deleted_date_time }}').render(
+            context=Context({'instance': self})
+        )
+    get_rendered_deleted_date_time.short_description = _(
+        'Date and time trashed'
+    )
+
     def invalidate_cache(self):
         for document_version in self.versions.all():
             document_version.invalidate_cache()
@@ -285,6 +306,20 @@ class DuplicatedDocument(models.Model):
         return force_text(self.document)
 
 
+class DuplicatedDocumentProxy(Document):
+    class Meta:
+        proxy = True
+        verbose_name = _('Duplicated document')
+        verbose_name_plural = _('Duplicated documents')
+
+    def get_duplicate_count(self, user):
+        queryset = AccessControlList.objects.filter_by_access(
+            permission=permission_document_view, user=user,
+            queryset=self.get_duplicates()
+        )
+        return queryset.count()
+
+
 @python_2_unicode_compatible
 class FavoriteDocument(models.Model):
     """