Add support for new document page structure

Documents now have their own dedicated DocumentPage
submodel. The old DocumentPage is now called DocumentVersionPage.
This allows mappings between document pages and document version
pages, allowing renumbering, appending pages.
DocumentPages have a content_object to map them to any other
object. For now they only map to DocumentVersionPages.
New option added to the version upload form to append the
pages of the new version.
A new view was added to just append new pages with wraps the
new document version upload form and hides the append pages
checkbox set to True.
Add a new action, reset_pages to reset the pages of the
document to those of the latest version.

Missing: appending tests, checks for proper content_object in OCR and
document parsing.

Author: Roberto Rosario <roberto.rosario@mayan-edms.com>
Date:   Thu Oct 11 12:00:25 2019 -0400

mayan/apps/documents/api_views.py

@@ -33,10 +33,14 @@ from .serializers import (
     DocumentTypeSerializer, DocumentVersionSerializer,
     NewDocumentSerializer, NewDocumentVersionSerializer,
     RecentDocumentSerializer, WritableDocumentSerializer,
-    WritableDocumentTypeSerializer, WritableDocumentVersionSerializer
+    WritableDocumentTypeSerializer, WritableDocumentVersionSerializer,
+    DocumentVersionPageSerializer
 )
 from .settings import settings_document_page_image_cache_time
-from .tasks import task_generate_document_page_image
+from .tasks import (
+    task_generate_document_page_image,
+    task_generate_document_version_page_image
+)
 
 logger = logging.getLogger(__name__)
 
@@ -168,13 +172,8 @@ class APIDocumentPageImageView(generics.RetrieveAPIView):
         )
         return document
 
-    def get_document_version(self):
-        return get_object_or_404(
-            self.get_document().versions.all(), pk=self.kwargs['version_pk']
-        )
-
     def get_queryset(self):
-        return self.get_document_version().pages_all.all()
+        return self.get_document().pages_all.all()
 
     def get_serializer(self, *args, **kwargs):
         return None
@@ -221,6 +220,95 @@ class APIDocumentPageImageView(generics.RetrieveAPIView):
             return response
 
 
+class APIDocumentVersionPageImageView(generics.RetrieveAPIView):
+    """
+    get: Returns an image representation of the selected document version page.
+    """
+    lookup_url_kwarg = 'page_pk'
+
+    def get_document(self):
+        if self.request.method == 'GET':
+            permission_required = permission_document_view
+        else:
+            permission_required = permission_document_edit
+
+        document = get_object_or_404(Document.passthrough, pk=self.kwargs['pk'])
+
+        AccessControlList.objects.check_access(
+            obj=document, permissions=(permission_required,),
+            user=self.request.user
+        )
+        return document
+
+    def get_document_version(self):
+        return get_object_or_404(
+            self.get_document().versions.all(), pk=self.kwargs['version_pk']
+        )
+
+    def get_queryset(self):
+        return self.get_document_version().pages.all()
+
+    def get_serializer(self, *args, **kwargs):
+        return None
+
+    def get_serializer_class(self):
+        return None
+
+    @cache_control(private=True)
+    def retrieve(self, request, *args, **kwargs):
+        width = request.GET.get('width')
+        height = request.GET.get('height')
+        zoom = request.GET.get('zoom')
+
+        if zoom:
+            zoom = int(zoom)
+
+        rotation = request.GET.get('rotation')
+
+        if rotation:
+            rotation = int(rotation)
+
+        maximum_layer_order = request.GET.get('maximum_layer_order')
+        if maximum_layer_order:
+            maximum_layer_order = int(maximum_layer_order)
+
+        task = task_generate_document_version_page_image.apply_async(
+            kwargs=dict(
+                document_version_page_id=self.get_object().pk, width=width,
+                height=height, zoom=zoom, rotation=rotation,
+                maximum_layer_order=maximum_layer_order,
+                user_id=request.user.pk
+            )
+        )
+
+        cache_filename = task.get(timeout=DOCUMENT_IMAGE_TASK_TIMEOUT)
+        cache_file = self.get_object().cache_partition.get_file(filename=cache_filename)
+        with cache_file.open() as file_object:
+            response = HttpResponse(file_object.read(), content_type='image')
+            if '_hash' in request.GET:
+                patch_cache_control(
+                    response=response,
+                    max_age=settings_document_page_image_cache_time.value
+                )
+            return response
+
+
+class APIDocumentPageListView(generics.ListAPIView):
+    serializer_class = DocumentPageSerializer
+
+    def get_document(self):
+        document = get_object_or_404(Document, pk=self.kwargs['pk'])
+
+        AccessControlList.objects.check_access(
+            obj=document, permissions=(permission_document_view,),
+            user=self.request.user
+        )
+        return document
+
+    def get_queryset(self):
+        return self.get_document().pages.all()
+
+
 class APIDocumentPageView(generics.RetrieveUpdateAPIView):
     """
     get: Returns the selected document page details.
@@ -230,6 +318,33 @@ class APIDocumentPageView(generics.RetrieveUpdateAPIView):
     lookup_url_kwarg = 'page_pk'
     serializer_class = DocumentPageSerializer
 
+    def get_document(self):
+        if self.request.method == 'GET':
+            permission_required = permission_document_view
+        else:
+            permission_required = permission_document_edit
+
+        document = get_object_or_404(Document, pk=self.kwargs['pk'])
+
+        AccessControlList.objects.check_access(
+            obj=document, permissions=(permission_required,),
+            user=self.request.user
+        )
+        return document
+
+    def get_queryset(self):
+        return self.get_document().pages.all()
+
+
+class APIDocumentVersionPageView(generics.RetrieveUpdateAPIView):
+    """
+    get: Returns the selected document verion page details.
+    patch: Edit the selected document version page.
+    put: Edit the selected document version page.
+    """
+    lookup_url_kwarg = 'page_pk'
+    serializer_class = DocumentVersionPageSerializer
+
     def get_document(self):
         if self.request.method == 'GET':
             permission_required = permission_document_view
@@ -289,8 +404,7 @@ class APIDocumentTypeView(generics.RetrieveUpdateDestroyAPIView):
         'GET': (permission_document_type_view,),
         'PUT': (permission_document_type_edit,),
         'PATCH': (permission_document_type_edit,),
-        'DELETE': (permission_document_type_delete,)
-    }
+        'DELETE': (permission_document_type_delete,)    }
     permission_classes = (MayanPermission,)
     queryset = DocumentType.objects.all()
 
@@ -423,7 +537,7 @@ class APIRecentDocumentListView(generics.ListAPIView):
 
 
 class APIDocumentVersionPageListView(generics.ListAPIView):
-    serializer_class = DocumentPageSerializer
+    serializer_class = DocumentVersionPageSerializer
 
     def get_document(self):
         document = get_object_or_404(Document, pk=self.kwargs['pk'])