F(backend): add public media derivatives pipeline

core/management/commands/backfill_media_derivatives.py

@@ -0,0 +1,71 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from django.core.management.base import BaseCommand
+
+from apps.blog.models import Post
+from apps.events.models import Event
+from apps.gallery.models import Gallery
+from apps.users.models import User
+from core.media import safe_process_public_image
+
+
+@dataclass(frozen=True)
+class BackfillTarget:
+    label: str
+    queryset: object
+    field_name: str
+    family: str
+
+
+class Command(BaseCommand):
+    help = "Generate missing public image derivatives for existing media."
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            "--force",
+            action="store_true",
+            help="Regenerate derivatives even when sidecar files already exist.",
+        )
+
+    def handle(self, *args, **options):
+        force = options["force"]
+        processed = 0
+        skipped = 0
+        failed = 0
+
+        targets = (
+            BackfillTarget("events", Event.objects.exclude(featured_image="").exclude(featured_image__isnull=True), "featured_image", "event_featured"),
+            BackfillTarget("gallery", Gallery.objects.exclude(image="").exclude(image__isnull=True), "image", "gallery"),
+            BackfillTarget("blog", Post.objects.exclude(featured_image="").exclude(featured_image__isnull=True), "featured_image", "blog_featured"),
+            BackfillTarget("users", User.objects.exclude(profile_picture="").exclude(profile_picture__isnull=True), "profile_picture", "profile_picture"),
+        )
+
+        for target in targets:
+            self.stdout.write(self.style.NOTICE(f"Backfilling {target.label}..."))
+            for instance in target.queryset.iterator():
+                file_field = getattr(instance, target.field_name)
+                result = safe_process_public_image(file_field, target.family, force=force)
+                if result is None:
+                    failed += 1
+                    self.stdout.write(self.style.WARNING(f"failed: {target.label}#{instance.pk}"))
+                    continue
+
+                if hasattr(instance, "file_size") and hasattr(instance, "width") and hasattr(instance, "height"):
+                    type(instance).objects.filter(pk=instance.pk).update(
+                        file_size=result.file_size,
+                        width=result.width,
+                        height=result.height,
+                    )
+
+                if result.processed:
+                    processed += 1
+                else:
+                    skipped += 1
+
+        self.stdout.write(
+            self.style.SUCCESS(
+                f"Media derivative backfill finished. processed={processed} skipped={skipped} failed={failed}"
+            )
+        )