F(backend): add public media derivatives pipeline

apps/blog/models.py

@@ -5,6 +5,11 @@ from django.utils import timezone
 
 import markdown
 
+from core.media import (
+    delete_image_derivatives_by_name,
+    get_image_previous_name,
+    safe_process_public_image,
+)
 from core.models import BaseModel
 
 class Category(BaseModel):
@@ -67,6 +72,9 @@ class Post(BaseModel):
         return self.title
 
     def save(self, *args, **kwargs):
+        previous_image_name = get_image_previous_name(self, "featured_image")
+        current_image_name = self.featured_image.name if self.featured_image else None
+
         if not self.slug:
             self.slug = slugify(self.title)
         
@@ -84,6 +92,17 @@ class Post(BaseModel):
 
         super().save(*args, **kwargs)
 
+        if previous_image_name != current_image_name and previous_image_name:
+            delete_image_derivatives_by_name(
+                self.featured_image.storage if self.featured_image else None,
+                previous_image_name,
+                "blog_featured",
+                delete_original=True,
+            )
+
+        if previous_image_name != current_image_name and self.featured_image:
+            safe_process_public_image(self.featured_image, "blog_featured")
+
     @property
     def content_html(self):
         """Convert markdown content to HTML"""