[6/6] Burninate CoverLetter

diff --git a/patchwork/admin.py b/patchwork/admin.py
index f9a94c6f5c07..48fe43b93c99 100644
--- a/patchwork/admin.py
+++ b/patchwork/admin.py
@@ -11,7 +11,6 @@  from django.db.models import Prefetch
 from patchwork.models import Bundle
 from patchwork.models import Check
 from patchwork.models import Comment
-from patchwork.models import CoverLetter
 from patchwork.models import DelegationRule
 from patchwork.models import Patch
 from patchwork.models import Person
@@ -83,8 +82,6 @@  class SubmissionAdmin(admin.ModelAdmin):
 
 
 admin.site.register(Submission, SubmissionAdmin)
-admin.site.register(CoverLetter, SubmissionAdmin)
-
 
 class PatchAdmin(admin.ModelAdmin):
     list_display = ('name', 'submitter', 'project', 'state', 'date',
diff --git a/patchwork/api/cover.py b/patchwork/api/cover.py
index caf9a386efa5..8eb65f8cb942 100644
--- a/patchwork/api/cover.py
+++ b/patchwork/api/cover.py
@@ -15,7 +15,7 @@  from patchwork.api.filters import CoverLetterFilterSet
 from patchwork.api.embedded import PersonSerializer
 from patchwork.api.embedded import ProjectSerializer
 from patchwork.api.embedded import SeriesSerializer
-from patchwork.models import CoverLetter
+from patchwork.models import Submission
 
 
 class CoverLetterListSerializer(BaseHyperlinkedModelSerializer):
@@ -24,7 +24,7 @@  class CoverLetterListSerializer(BaseHyperlinkedModelSerializer):
     project = ProjectSerializer(read_only=True)
     submitter = PersonSerializer(read_only=True)
     mbox = SerializerMethodField()
-    series = SeriesSerializer(read_only=True)
+    series = SeriesSerializer(source='cl_series', read_only=True)
     comments = SerializerMethodField()
 
     def get_web_url(self, instance):
@@ -49,7 +49,7 @@  class CoverLetterListSerializer(BaseHyperlinkedModelSerializer):
         return data
 
     class Meta:
-        model = CoverLetter
+        model = Submission
         fields = ('id', 'url', 'web_url', 'project', 'msgid',
                   'list_archive_url', 'date', 'name', 'submitter', 'mbox',
                   'series', 'comments')
@@ -82,7 +82,7 @@  class CoverLetterDetailSerializer(CoverLetterListSerializer):
         return headers
 
     class Meta:
-        model = CoverLetter
+        model = Submission
         fields = CoverLetterListSerializer.Meta.fields + (
             'headers', 'content')
         read_only_fields = fields
@@ -100,8 +100,8 @@  class CoverLetterList(ListAPIView):
     ordering = 'id'
 
     def get_queryset(self):
-        return CoverLetter.objects.all()\
-            .select_related('project', 'submitter', 'series')\
+        return Submission.objects.filter(new_diff__isnull=True, new_pull_url__isnull=True)\
+            .select_related('project', 'submitter', 'cl_series')\
             .defer('content', 'headers')
 
 
@@ -111,5 +111,5 @@  class CoverLetterDetail(RetrieveAPIView):
     serializer_class = CoverLetterDetailSerializer
 
     def get_queryset(self):
-        return CoverLetter.objects.all()\
-            .select_related('project', 'submitter', 'series')
+        return Submission.objects.filter(new_diff__isnull=True, new_pull_url__isnull=True)\
+            .select_related('project', 'submitter', 'cl_series')
diff --git a/patchwork/api/embedded.py b/patchwork/api/embedded.py
index de4f31165ee7..a0196128bad4 100644
--- a/patchwork/api/embedded.py
+++ b/patchwork/api/embedded.py
@@ -107,7 +107,7 @@  class CoverLetterSerializer(SerializedRelatedField):
     class _Serializer(MboxMixin, WebURLMixin, BaseHyperlinkedModelSerializer):
 
         class Meta:
-            model = models.CoverLetter
+            model = models.Submission
             fields = ('id', 'url', 'web_url', 'msgid', 'list_archive_url',
                       'date', 'name', 'mbox')
             read_only_fields = fields
diff --git a/patchwork/api/filters.py b/patchwork/api/filters.py
index 37aca82d9ab2..4690fcab7479 100644
--- a/patchwork/api/filters.py
+++ b/patchwork/api/filters.py
@@ -15,13 +15,13 @@  from django.forms.widgets import MultipleHiddenInput
 from patchwork.compat import NAME_FIELD
 from patchwork.models import Bundle
 from patchwork.models import Check
-from patchwork.models import CoverLetter
 from patchwork.models import Event
 from patchwork.models import Patch
 from patchwork.models import Person
 from patchwork.models import Project
 from patchwork.models import Series
 from patchwork.models import State
+from patchwork.models import Submission
 
 
 # custom fields, filters
@@ -161,8 +161,13 @@  class CoverLetterFilterSet(TimestampMixin, FilterSet):
                         widget=MultipleHiddenInput)
     submitter = PersonFilter(queryset=Person.objects.all())
 
+    @property
+    def qs(self):
+        parent = super(CoverLetterFilterSet, self).qs
+        return parent.filter(new_diff__isnull=True, new_pull_url__isnull=True)
+
     class Meta:
-        model = CoverLetter
+        model = Submission
         fields = ('project', 'series', 'submitter')
 
 
@@ -191,6 +196,8 @@  class CheckFilterSet(TimestampMixin, FilterSet):
         model = Check
         fields = ('user', 'state', 'context')
 
+def get_coverletter_qs(request):
+    return Submission.objects.all().filter(new_diff__isnull=True, new_pull_url__isnull=True)
 
 class EventFilterSet(TimestampMixin, FilterSet):
 
@@ -203,7 +210,7 @@  class EventFilterSet(TimestampMixin, FilterSet):
                         widget=MultipleHiddenInput)
     patch = BaseFilter(queryset=Patch.objects.all(),
                        widget=MultipleHiddenInput)
-    cover = BaseFilter(queryset=CoverLetter.objects.all(),
+    cover = BaseFilter(queryset=get_coverletter_qs,
                        widget=MultipleHiddenInput)
 
     class Meta:
diff --git a/patchwork/management/commands/parsearchive.py b/patchwork/management/commands/parsearchive.py
index b7f1ea7313c2..39c640ccee8b 100644
--- a/patchwork/management/commands/parsearchive.py
+++ b/patchwork/management/commands/parsearchive.py
@@ -32,7 +32,7 @@  class Command(BaseCommand):
     def handle(self, *args, **options):
         results = {
             models.Patch: 0,
-            models.CoverLetter: 0,
+            models.Submission: 0,
             models.Comment: 0,
         }
         duplicates = 0
@@ -118,7 +118,7 @@  class Command(BaseCommand):
             '  %(errors)4d errors\n'
             'Total: %(new)s new entries' % {
                 'total': count,
-                'covers': results[models.CoverLetter],
+                'covers': results[models.Submission],
                 'patches': results[models.Patch],
                 'comments': results[models.Comment],
                 'duplicates': duplicates,
diff --git a/patchwork/migrations/0041_drop_coverletter.py b/patchwork/migrations/0041_drop_coverletter.py
new file mode 100644
index 000000000000..d504676fd7fc
--- /dev/null
+++ b/patchwork/migrations/0041_drop_coverletter.py
@@ -0,0 +1,29 @@ 
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.24 on 2019-09-17 17:56
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('patchwork', '0040_drop_old_diff_pull_url'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='event',
+            name='cover',
+            field=models.ForeignKey(blank=True, help_text=b'The cover letter that this event was created for.', null=True, on_delete=django.db.models.deletion.CASCADE, related_name='+', to='patchwork.Submission'),
+        ),
+        migrations.AlterField(
+            model_name='series',
+            name='cover_letter',
+            field=models.OneToOneField(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='cl_series', to='patchwork.Submission'),
+        ),
+        migrations.DeleteModel(
+            name='CoverLetter',
+        ),
+    ]
diff --git a/patchwork/models.py b/patchwork/models.py
index a96018004f75..4b6466614fd3 100644
--- a/patchwork/models.py
+++ b/patchwork/models.py
@@ -389,6 +389,12 @@  class Submission(FilenameMixin, EmailMixin, models.Model):
     def __str__(self):
         return self.name
 
+    def get_absolute_url(self):
+        return reverse('cover-detail', kwargs={'cover_id': self.id})
+
+    def get_mbox_url(self):
+        return reverse('cover-mbox', kwargs={'cover_id': self.id})
+
     class Meta:
         ordering = ['date']
         unique_together = [('msgid', 'project')]
@@ -402,15 +408,6 @@  class Submission(FilenameMixin, EmailMixin, models.Model):
         ]
 
 
-class CoverLetter(Submission):
-
-    def get_absolute_url(self):
-        return reverse('cover-detail', kwargs={'cover_id': self.id})
-
-    def get_mbox_url(self):
-        return reverse('cover-mbox', kwargs={'cover_id': self.id})
-
-
 @python_2_unicode_compatible
 class Patch(Submission):
     # patch metadata
@@ -739,7 +736,7 @@  class Series(FilenameMixin, models.Model):
                                 blank=True, on_delete=models.CASCADE)
 
     # content
-    cover_letter = models.OneToOneField(CoverLetter, related_name='series',
+    cover_letter = models.OneToOneField(Submission, related_name='cl_series',
                                         null=True,
                                         on_delete=models.CASCADE)
 
@@ -1030,7 +1027,7 @@  class Event(models.Model):
         on_delete=models.CASCADE,
         help_text='The series that this event was created for.')
     cover = models.ForeignKey(
-        CoverLetter, related_name='+', null=True, blank=True,
+        Submission, related_name='+', null=True, blank=True,
         on_delete=models.CASCADE,
         help_text='The cover letter that this event was created for.')
 
diff --git a/patchwork/parser.py b/patchwork/parser.py
index 7dc66bc05a5b..a122839f3f73 100644
--- a/patchwork/parser.py
+++ b/patchwork/parser.py
@@ -19,7 +19,6 @@  from django.db.utils import IntegrityError
 from django.utils import six
 
 from patchwork.models import Comment
-from patchwork.models import CoverLetter
 from patchwork.models import DelegationRule
 from patchwork.models import get_default_initial_patch_state
 from patchwork.models import Patch
@@ -1088,11 +1087,11 @@  def parse_mail(mail, list_id=None):
         if not is_comment:
             if not refs == []:
                 try:
-                    CoverLetter.objects.all().get(name=name)
-                except CoverLetter.DoesNotExist:
+                    Submission.objects.get(name=name, new_diff__isnull=True, new_pull_url__isnull=True)
+                except Submission.DoesNotExist:
                     # if no match, this is a new cover letter
                     is_cover_letter = True
-                except CoverLetter.MultipleObjectsReturned:
+                except Submission.MultipleObjectsReturned:
                     # if multiple cover letters are found, just ignore
                     pass
             else:
@@ -1135,7 +1134,7 @@  def parse_mail(mail, list_id=None):
                                  " in project %s!" % (msgid, project.name))
 
             try:
-                cover_letter = CoverLetter.objects.create(
+                cover_letter = Submission.objects.create(
                     msgid=msgid,
                     project=project,
                     name=name[:255],
diff --git a/patchwork/signals.py b/patchwork/signals.py
index 666199b68161..bbfdc0106fd7 100644
--- a/patchwork/signals.py
+++ b/patchwork/signals.py
@@ -10,11 +10,11 @@  from django.db.models.signals import pre_save
 from django.dispatch import receiver
 
 from patchwork.models import Check
-from patchwork.models import CoverLetter
 from patchwork.models import Event
 from patchwork.models import Patch
 from patchwork.models import PatchChangeNotification
 from patchwork.models import Series
+from patchwork.models import Submission
 
 
 @receiver(pre_save, sender=Patch)
@@ -54,7 +54,7 @@  def patch_change_callback(sender, instance, raw, **kwargs):
     notification.save()
 
 
-@receiver(post_save, sender=CoverLetter)
+@receiver(post_save, sender=Submission)
 def create_cover_created_event(sender, instance, created, raw, **kwargs):
 
     def create_event(cover):
diff --git a/patchwork/templates/patchwork/submission.html b/patchwork/templates/patchwork/submission.html
index e79dd92497a4..c4175a30e9c5 100644
--- a/patchwork/templates/patchwork/submission.html
+++ b/patchwork/templates/patchwork/submission.html
@@ -68,12 +68,12 @@  function toggle_div(link_id, headers_id)
    </div>
   </td>
  </tr>
-{% if submission.series %}
+{% if series %}
  <tr>
   <th>Series</th>
   <td>
-   <a href="{% url 'patch-list' project_id=project.linkname %}?series={{ submission.series.id }}">
-    {{ submission.series }}
+   <a href="{% url 'patch-list' project_id=project.linkname %}?series={{ series.id }}">
+    {{ series }}
    </a>
   </td>
  </tr>
@@ -85,7 +85,7 @@  function toggle_div(link_id, headers_id)
    >show</a>
    <div id="patchrelations" class="patchrelations" style="display:none;">
     <ul>
-    {% with submission.series.cover_letter as cover %}
+    {% with series.cover_letter as cover %}
      <li>
      {% if cover %}
       {% if cover == submission %}
@@ -98,7 +98,7 @@  function toggle_div(link_id, headers_id)
      {% endif %}
      </li>
     {% endwith %}
-    {% for sibling in submission.series.patches.all %}
+    {% for sibling in series.patches.all %}
      <li>
       {% if sibling == submission %}
        {{ sibling.name|default:"[no subject]"|truncatechars:100 }}
diff --git a/patchwork/tests/api/test_cover.py b/patchwork/tests/api/test_cover.py
index 0a0bf041abc5..faaeb9f30093 100644
--- a/patchwork/tests/api/test_cover.py
+++ b/patchwork/tests/api/test_cover.py
@@ -44,10 +44,9 @@  class TestCoverLetterAPI(utils.APITestCase):
 
         self.assertEqual(cover_obj.submitter.id,
                          cover_json['submitter']['id'])
-
-        if hasattr(cover_obj, 'series'):
+        if hasattr(cover_obj, 'cl_series'):
             self.assertEqual(1, len(cover_json['series']))
-            self.assertEqual(cover_obj.series.id,
+            self.assertEqual(cover_obj.cl_series.id,
                              cover_json['series'][0]['id'])
         else:
             self.assertEqual([], cover_json['series'])
diff --git a/patchwork/tests/test_series.py b/patchwork/tests/test_series.py
index deb93043d295..69798acf9624 100644
--- a/patchwork/tests/test_series.py
+++ b/patchwork/tests/test_series.py
@@ -36,7 +36,7 @@  class _BaseTestCase(TestCase):
         mbox = mailbox.mbox(os.path.join(TEST_SERIES_DIR, name), create=False)
         for msg in mbox:
             obj = parser.parse_mail(msg, project.listid)
-            if type(obj) == models.CoverLetter:
+            if type(obj) == models.Submission:
                 results[0].append(obj)
             elif type(obj) == models.Patch:
                 results[1].append(obj)
@@ -75,14 +75,14 @@  class _BaseTestCase(TestCase):
 
             patches_ = patches[start_idx:end_idx]
             for patch in patches_:
-                self.assertEqual(patch.series, series[idx])
-
                 # TODO(stephenfin): Rework this function into two different
                 # functions - we're clearly not always testing patches here
                 if isinstance(patch, models.Patch):
+                    self.assertEqual(patch.series, series[idx])
                     self.assertEqual(series[idx].patches.get(id=patch.id),
                                      patch)
                 else:
+                    self.assertEqual(patch.cl_series, series[idx])
                     self.assertEqual(series[idx].cover_letter, patch)
 
             start_idx = end_idx
@@ -660,13 +660,13 @@  class SeriesNameTestCase(TestCase):
 
         cover = self._parse_mail(mbox[0])
         cover_name = 'A sample series'
-        self.assertEqual(cover.series.name, cover_name)
+        self.assertEqual(cover.cl_series.name, cover_name)
 
         self._parse_mail(mbox[1])
-        self.assertEqual(cover.series.name, cover_name)
+        self.assertEqual(cover.cl_series.name, cover_name)
 
         self._parse_mail(mbox[2])
-        self.assertEqual(cover.series.name, cover_name)
+        self.assertEqual(cover.cl_series.name, cover_name)
 
         mbox.close()
 
@@ -714,7 +714,7 @@  class SeriesNameTestCase(TestCase):
         self.assertEqual(patch.series.name, patch.name)
 
         cover = self._parse_mail(mbox[2])
-        self.assertEqual(cover.series.name, 'A sample series')
+        self.assertEqual(cover.cl_series.name, 'A sample series')
 
         mbox.close()
 
diff --git a/patchwork/tests/utils.py b/patchwork/tests/utils.py
index 4ac9afe0de01..3934f6674f78 100644
--- a/patchwork/tests/utils.py
+++ b/patchwork/tests/utils.py
@@ -14,13 +14,13 @@  from django.contrib.auth.models import User
 from patchwork.models import Bundle
 from patchwork.models import Check
 from patchwork.models import Comment
-from patchwork.models import CoverLetter
 from patchwork.models import Patch
 from patchwork.models import Person
 from patchwork.models import Project
 from patchwork.models import Series
 from patchwork.models import SeriesReference
 from patchwork.models import State
+from patchwork.models import Submission
 from patchwork.tests import TEST_PATCH_DIR
 
 SAMPLE_DIFF = """--- /dev/null	2011-01-01 00:00:00.000000000 +0800
@@ -202,7 +202,7 @@  def create_patch(**kwargs):
 
 def create_cover(**kwargs):
     """Create 'CoverLetter' object."""
-    num = CoverLetter.objects.count()
+    num = Submission.objects.count() - Patch.objects.count()
 
     # NOTE(stephenfin): Despite first appearances, passing 'series' to the
     # 'create' function doesn't actually cause the relationship to be created.
@@ -230,7 +230,7 @@  def create_cover(**kwargs):
     }
     values.update(kwargs)
 
-    cover = CoverLetter.objects.create(**values)
+    cover = Submission.objects.create(**values)
 
     if series:
         series.add_cover_letter(cover)
diff --git a/patchwork/views/cover.py b/patchwork/views/cover.py
index 08b633a11f78..5ff1023f1a7e 100644
--- a/patchwork/views/cover.py
+++ b/patchwork/views/cover.py
@@ -10,7 +10,7 @@  from django.shortcuts import get_object_or_404
 from django.shortcuts import render
 from django.urls import reverse
 
-from patchwork.models import CoverLetter
+from patchwork.models import Patch
 from patchwork.models import Submission
 from patchwork.views.utils import cover_to_mbox
 
@@ -18,13 +18,14 @@  from patchwork.views.utils import cover_to_mbox
 def cover_detail(request, cover_id):
     # redirect to patches where necessary
     try:
-        cover = get_object_or_404(CoverLetter, id=cover_id)
-    except Http404 as exc:
-        submissions = Submission.objects.filter(id=cover_id)
-        if submissions:
+        patch = get_object_or_404(Patch, id=cover_id)
+        if patch:
             return HttpResponseRedirect(
                 reverse('patch-detail', kwargs={'patch_id': cover_id}))
-        raise exc
+    except Http404:
+        pass
+
+    cover = get_object_or_404(Submission, id=cover_id)
 
     context = {
         'submission': cover,
@@ -36,12 +37,22 @@  def cover_detail(request, cover_id):
     comments = comments.only('submitter', 'date', 'id', 'content',
                              'submission')
     context['comments'] = comments
+    context['series'] = cover.cl_series
 
     return render(request, 'patchwork/submission.html', context)
 
 
 def cover_mbox(request, cover_id):
-    cover = get_object_or_404(CoverLetter, id=cover_id)
+    # check if we should redirect to patch
+    try:
+        patch = get_object_or_404(Patch, id=cover_id)
+        if patch:
+            return HttpResponseRedirect(
+                reverse('patch-mbox', kwargs={'patch_id': cover_id}))
+    except Http404:
+        pass
+
+    cover = get_object_or_404(Submission, id=cover_id)
 
     response = HttpResponse(content_type='text/plain')
     response.write(cover_to_mbox(cover))
diff --git a/patchwork/views/patch.py b/patchwork/views/patch.py
index 277b2816e31e..6c5125ee5681 100644
--- a/patchwork/views/patch.py
+++ b/patchwork/views/patch.py
@@ -110,6 +110,7 @@  def patch_detail(request, patch_id):
     context['patchform'] = form
     context['createbundleform'] = createbundleform
     context['project'] = patch.project
+    context['series'] = patch.series
 
     return render(request, 'patchwork/submission.html', context)