Add the beginnings of charts

This commit adds a lot of files, but most of them have no impact on any
other code. The thrust here is to start creating chart pages showing
which tracks and artists were most played for various time periods. Lots
still not working, but we're getting there.

vrobbler/apps/music/models.py

@@ -3,10 +3,10 @@ from typing import Dict, Optional
 from uuid import uuid4
 
 import musicbrainzngs
-from django.apps.config import cached_property
 from django.conf import settings
 from django.core.files.base import ContentFile
 from django.db import models
+from django.urls import reverse
 from django.utils.translation import gettext_lazy as _
 from django_extensions.db.models import TimeStampedModel
 from scrobbles.mixins import ScrobblableMixin
@@ -30,6 +30,29 @@ class Artist(TimeStampedModel):
     def mb_link(self):
         return f"https://musicbrainz.org/artist/{self.musicbrainz_id}"
 
+    def get_absolute_url(self):
+        return reverse('music:artist_detail', kwargs={'slug': self.uuid})
+
+    def scrobbles(self):
+        from scrobbles.models import Scrobble
+
+        return Scrobble.objects.filter(
+            track__in=self.track_set.all()
+        ).order_by('-timestamp')
+
+    @property
+    def tracks(self):
+        return (
+            self.track_set.all()
+            .annotate(scrobble_count=models.Count('scrobble'))
+            .order_by('-scrobble_count')
+        )
+
+    def charts(self):
+        from scrobbles.models import ChartRecord
+
+        return ChartRecord.objects.filter(track__artist=self).order_by('-year')
+
 
 class Album(TimeStampedModel):
     uuid = models.UUIDField(default=uuid4, editable=False, **BNULL)
@@ -135,14 +158,13 @@ class Track(ScrobblableMixin):
     def __str__(self):
         return f"{self.title} by {self.artist}"
 
+    def get_absolute_url(self):
+        return reverse('music:track_detail', kwargs={'slug': self.uuid})
+
     @property
     def mb_link(self):
         return f"https://musicbrainz.org/recording/{self.musicbrainz_id}"
 
-    @cached_property
-    def scrobble_count(self):
-        return self.scrobble_set.filter(in_progress=False).count()
-
     @classmethod
     def find_or_create(
         cls, artist_dict: Dict, album_dict: Dict, track_dict: Dict